Initial commit: Go 1.23 release state

src/runtime/cgo/abi_amd64.h

@@ -0,0 +1,99 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Macros for transitioning from the host ABI to Go ABI0.
+//
+// These save the frame pointer, so in general, functions that use
+// these should have zero frame size to suppress the automatic frame
+// pointer, though it's harmless to not do this.
+
+#ifdef GOOS_windows
+
+// REGS_HOST_TO_ABI0_STACK is the stack bytes used by
+// PUSH_REGS_HOST_TO_ABI0.
+#define REGS_HOST_TO_ABI0_STACK (28*8 + 8)
+
+// PUSH_REGS_HOST_TO_ABI0 prepares for transitioning from
+// the host ABI to Go ABI0 code. It saves all registers that are
+// callee-save in the host ABI and caller-save in Go ABI0 and prepares
+// for entry to Go.
+//
+// Save DI SI BP BX R12 R13 R14 R15 X6-X15 registers and the DF flag.
+// Clear the DF flag for the Go ABI.
+// MXCSR matches the Go ABI, so we don't have to set that,
+// and Go doesn't modify it, so we don't have to save it.
+#define PUSH_REGS_HOST_TO_ABI0()	\
+	PUSHFQ			\
+	CLD			\
+	ADJSP	$(REGS_HOST_TO_ABI0_STACK - 8)	\
+	MOVQ	DI, (0*0)(SP)	\
+	MOVQ	SI, (1*8)(SP)	\
+	MOVQ	BP, (2*8)(SP)	\
+	MOVQ	BX, (3*8)(SP)	\
+	MOVQ	R12, (4*8)(SP)	\
+	MOVQ	R13, (5*8)(SP)	\
+	MOVQ	R14, (6*8)(SP)	\
+	MOVQ	R15, (7*8)(SP)	\
+	MOVUPS	X6, (8*8)(SP)	\
+	MOVUPS	X7, (10*8)(SP)	\
+	MOVUPS	X8, (12*8)(SP)	\
+	MOVUPS	X9, (14*8)(SP)	\
+	MOVUPS	X10, (16*8)(SP)	\
+	MOVUPS	X11, (18*8)(SP)	\
+	MOVUPS	X12, (20*8)(SP)	\
+	MOVUPS	X13, (22*8)(SP)	\
+	MOVUPS	X14, (24*8)(SP)	\
+	MOVUPS	X15, (26*8)(SP)
+
+#define POP_REGS_HOST_TO_ABI0()	\
+	MOVQ	(0*0)(SP), DI	\
+	MOVQ	(1*8)(SP), SI	\
+	MOVQ	(2*8)(SP), BP	\
+	MOVQ	(3*8)(SP), BX	\
+	MOVQ	(4*8)(SP), R12	\
+	MOVQ	(5*8)(SP), R13	\
+	MOVQ	(6*8)(SP), R14	\
+	MOVQ	(7*8)(SP), R15	\
+	MOVUPS	(8*8)(SP), X6	\
+	MOVUPS	(10*8)(SP), X7	\
+	MOVUPS	(12*8)(SP), X8	\
+	MOVUPS	(14*8)(SP), X9	\
+	MOVUPS	(16*8)(SP), X10	\
+	MOVUPS	(18*8)(SP), X11	\
+	MOVUPS	(20*8)(SP), X12	\
+	MOVUPS	(22*8)(SP), X13	\
+	MOVUPS	(24*8)(SP), X14	\
+	MOVUPS	(26*8)(SP), X15	\
+	ADJSP	$-(REGS_HOST_TO_ABI0_STACK - 8)	\
+	POPFQ
+
+#else
+// SysV ABI
+
+#define REGS_HOST_TO_ABI0_STACK (6*8)
+
+// SysV MXCSR matches the Go ABI, so we don't have to set that,
+// and Go doesn't modify it, so we don't have to save it.
+// Both SysV and Go require DF to be cleared, so that's already clear.
+// The SysV and Go frame pointer conventions are compatible.
+#define PUSH_REGS_HOST_TO_ABI0()	\
+	ADJSP	$(REGS_HOST_TO_ABI0_STACK)	\
+	MOVQ	BP, (5*8)(SP)	\
+	LEAQ	(5*8)(SP), BP	\
+	MOVQ	BX, (0*8)(SP)	\
+	MOVQ	R12, (1*8)(SP)	\
+	MOVQ	R13, (2*8)(SP)	\
+	MOVQ	R14, (3*8)(SP)	\
+	MOVQ	R15, (4*8)(SP)
+
+#define POP_REGS_HOST_TO_ABI0()	\
+	MOVQ	(0*8)(SP), BX	\
+	MOVQ	(1*8)(SP), R12	\
+	MOVQ	(2*8)(SP), R13	\
+	MOVQ	(3*8)(SP), R14	\
+	MOVQ	(4*8)(SP), R15	\
+	MOVQ	(5*8)(SP), BP	\
+	ADJSP	$-(REGS_HOST_TO_ABI0_STACK)
+
+#endif

src/runtime/cgo/abi_arm64.h

@@ -0,0 +1,43 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Macros for transitioning from the host ABI to Go ABI0.
+//
+// These macros save and restore the callee-saved registers
+// from the stack, but they don't adjust stack pointer, so
+// the user should prepare stack space in advance.
+// SAVE_R19_TO_R28(offset) saves R19 ~ R28 to the stack space
+// of ((offset)+0*8)(RSP) ~ ((offset)+9*8)(RSP).
+//
+// SAVE_F8_TO_F15(offset) saves F8 ~ F15 to the stack space
+// of ((offset)+0*8)(RSP) ~ ((offset)+7*8)(RSP).
+//
+// R29 is not saved because Go will save and restore it.
+
+#define SAVE_R19_TO_R28(offset) \
+	STP	(R19, R20), ((offset)+0*8)(RSP) \
+	STP	(R21, R22), ((offset)+2*8)(RSP) \
+	STP	(R23, R24), ((offset)+4*8)(RSP) \
+	STP	(R25, R26), ((offset)+6*8)(RSP) \
+	STP	(R27, g), ((offset)+8*8)(RSP)
+
+#define RESTORE_R19_TO_R28(offset) \
+	LDP	((offset)+0*8)(RSP), (R19, R20) \
+	LDP	((offset)+2*8)(RSP), (R21, R22) \
+	LDP	((offset)+4*8)(RSP), (R23, R24) \
+	LDP	((offset)+6*8)(RSP), (R25, R26) \
+	LDP	((offset)+8*8)(RSP), (R27, g) /* R28 */
+
+#define SAVE_F8_TO_F15(offset) \
+	FSTPD	(F8, F9), ((offset)+0*8)(RSP) \
+	FSTPD	(F10, F11), ((offset)+2*8)(RSP) \
+	FSTPD	(F12, F13), ((offset)+4*8)(RSP) \
+	FSTPD	(F14, F15), ((offset)+6*8)(RSP)
+
+#define RESTORE_F8_TO_F15(offset) \
+	FLDPD	((offset)+0*8)(RSP), (F8, F9) \
+	FLDPD	((offset)+2*8)(RSP), (F10, F11) \
+	FLDPD	((offset)+4*8)(RSP), (F12, F13) \
+	FLDPD	((offset)+6*8)(RSP), (F14, F15)
+

src/runtime/cgo/abi_loong64.h

@@ -0,0 +1,60 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Macros for transitioning from the host ABI to Go ABI0.
+//
+// These macros save and restore the callee-saved registers
+// from the stack, but they don't adjust stack pointer, so
+// the user should prepare stack space in advance.
+// SAVE_R22_TO_R31(offset) saves R22 ~ R31 to the stack space
+// of ((offset)+0*8)(R3) ~ ((offset)+9*8)(R3).
+//
+// SAVE_F24_TO_F31(offset) saves F24 ~ F31 to the stack space
+// of ((offset)+0*8)(R3) ~ ((offset)+7*8)(R3).
+//
+// Note: g is R22
+
+#define SAVE_R22_TO_R31(offset)	\
+	MOVV	g,   ((offset)+(0*8))(R3)	\
+	MOVV	R23, ((offset)+(1*8))(R3)	\
+	MOVV	R24, ((offset)+(2*8))(R3)	\
+	MOVV	R25, ((offset)+(3*8))(R3)	\
+	MOVV	R26, ((offset)+(4*8))(R3)	\
+	MOVV	R27, ((offset)+(5*8))(R3)	\
+	MOVV	R28, ((offset)+(6*8))(R3)	\
+	MOVV	R29, ((offset)+(7*8))(R3)	\
+	MOVV	R30, ((offset)+(8*8))(R3)	\
+	MOVV	R31, ((offset)+(9*8))(R3)
+
+#define SAVE_F24_TO_F31(offset)	\
+	MOVD	F24, ((offset)+(0*8))(R3)	\
+	MOVD	F25, ((offset)+(1*8))(R3)	\
+	MOVD	F26, ((offset)+(2*8))(R3)	\
+	MOVD	F27, ((offset)+(3*8))(R3)	\
+	MOVD	F28, ((offset)+(4*8))(R3)	\
+	MOVD	F29, ((offset)+(5*8))(R3)	\
+	MOVD	F30, ((offset)+(6*8))(R3)	\
+	MOVD	F31, ((offset)+(7*8))(R3)
+
+#define RESTORE_R22_TO_R31(offset)	\
+	MOVV	((offset)+(0*8))(R3),  g	\
+	MOVV	((offset)+(1*8))(R3), R23	\
+	MOVV	((offset)+(2*8))(R3), R24	\
+	MOVV	((offset)+(3*8))(R3), R25	\
+	MOVV	((offset)+(4*8))(R3), R26	\
+	MOVV	((offset)+(5*8))(R3), R27	\
+	MOVV	((offset)+(6*8))(R3), R28	\
+	MOVV	((offset)+(7*8))(R3), R29	\
+	MOVV	((offset)+(8*8))(R3), R30	\
+	MOVV	((offset)+(9*8))(R3), R31
+
+#define RESTORE_F24_TO_F31(offset)	\
+	MOVD	((offset)+(0*8))(R3), F24	\
+	MOVD	((offset)+(1*8))(R3), F25	\
+	MOVD	((offset)+(2*8))(R3), F26	\
+	MOVD	((offset)+(3*8))(R3), F27	\
+	MOVD	((offset)+(4*8))(R3), F28	\
+	MOVD	((offset)+(5*8))(R3), F29	\
+	MOVD	((offset)+(6*8))(R3), F30	\
+	MOVD	((offset)+(7*8))(R3), F31

src/runtime/cgo/abi_ppc64x.h

@@ -0,0 +1,195 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Macros for transitioning from the host ABI to Go ABI
+//
+// On PPC64/ELFv2 targets, the following registers are callee
+// saved when called from C. They must be preserved before
+// calling into Go which does not preserve any of them.
+//
+//	R14-R31
+//	CR2-4
+//	VR20-31
+//	F14-F31
+//
+// xcoff(aix) and ELFv1 are similar, but may only require a
+// subset of these.
+//
+// These macros assume a 16 byte aligned stack pointer. This
+// is required by ELFv1, ELFv2, and AIX PPC64.
+
+#define SAVE_GPR_SIZE (18*8)
+#define SAVE_GPR(offset)               \
+	MOVD	R14, (offset+8*0)(R1)  \
+	MOVD	R15, (offset+8*1)(R1)  \
+	MOVD	R16, (offset+8*2)(R1)  \
+	MOVD	R17, (offset+8*3)(R1)  \
+	MOVD	R18, (offset+8*4)(R1)  \
+	MOVD	R19, (offset+8*5)(R1)  \
+	MOVD	R20, (offset+8*6)(R1)  \
+	MOVD	R21, (offset+8*7)(R1)  \
+	MOVD	R22, (offset+8*8)(R1)  \
+	MOVD	R23, (offset+8*9)(R1)  \
+	MOVD	R24, (offset+8*10)(R1) \
+	MOVD	R25, (offset+8*11)(R1) \
+	MOVD	R26, (offset+8*12)(R1) \
+	MOVD	R27, (offset+8*13)(R1) \
+	MOVD	R28, (offset+8*14)(R1) \
+	MOVD	R29, (offset+8*15)(R1) \
+	MOVD	g,   (offset+8*16)(R1) \
+	MOVD	R31, (offset+8*17)(R1)
+
+#define RESTORE_GPR(offset)            \
+	MOVD	(offset+8*0)(R1), R14  \
+	MOVD	(offset+8*1)(R1), R15  \
+	MOVD	(offset+8*2)(R1), R16  \
+	MOVD	(offset+8*3)(R1), R17  \
+	MOVD	(offset+8*4)(R1), R18  \
+	MOVD	(offset+8*5)(R1), R19  \
+	MOVD	(offset+8*6)(R1), R20  \
+	MOVD	(offset+8*7)(R1), R21  \
+	MOVD	(offset+8*8)(R1), R22  \
+	MOVD	(offset+8*9)(R1), R23  \
+	MOVD	(offset+8*10)(R1), R24 \
+	MOVD	(offset+8*11)(R1), R25 \
+	MOVD	(offset+8*12)(R1), R26 \
+	MOVD	(offset+8*13)(R1), R27 \
+	MOVD	(offset+8*14)(R1), R28 \
+	MOVD	(offset+8*15)(R1), R29 \
+	MOVD	(offset+8*16)(R1), g   \
+	MOVD	(offset+8*17)(R1), R31
+
+#define SAVE_FPR_SIZE (18*8)
+#define SAVE_FPR(offset)               \
+	FMOVD	F14, (offset+8*0)(R1)  \
+	FMOVD	F15, (offset+8*1)(R1)  \
+	FMOVD	F16, (offset+8*2)(R1)  \
+	FMOVD	F17, (offset+8*3)(R1)  \
+	FMOVD	F18, (offset+8*4)(R1)  \
+	FMOVD	F19, (offset+8*5)(R1)  \
+	FMOVD	F20, (offset+8*6)(R1)  \
+	FMOVD	F21, (offset+8*7)(R1)  \
+	FMOVD	F22, (offset+8*8)(R1)  \
+	FMOVD	F23, (offset+8*9)(R1)  \
+	FMOVD	F24, (offset+8*10)(R1) \
+	FMOVD	F25, (offset+8*11)(R1) \
+	FMOVD	F26, (offset+8*12)(R1) \
+	FMOVD	F27, (offset+8*13)(R1) \
+	FMOVD	F28, (offset+8*14)(R1) \
+	FMOVD	F29, (offset+8*15)(R1) \
+	FMOVD	F30, (offset+8*16)(R1) \
+	FMOVD	F31, (offset+8*17)(R1)
+
+#define RESTORE_FPR(offset)            \
+	FMOVD	(offset+8*0)(R1), F14  \
+	FMOVD	(offset+8*1)(R1), F15  \
+	FMOVD	(offset+8*2)(R1), F16  \
+	FMOVD	(offset+8*3)(R1), F17  \
+	FMOVD	(offset+8*4)(R1), F18  \
+	FMOVD	(offset+8*5)(R1), F19  \
+	FMOVD	(offset+8*6)(R1), F20  \
+	FMOVD	(offset+8*7)(R1), F21  \
+	FMOVD	(offset+8*8)(R1), F22  \
+	FMOVD	(offset+8*9)(R1), F23  \
+	FMOVD	(offset+8*10)(R1), F24 \
+	FMOVD	(offset+8*11)(R1), F25 \
+	FMOVD	(offset+8*12)(R1), F26 \
+	FMOVD	(offset+8*13)(R1), F27 \
+	FMOVD	(offset+8*14)(R1), F28 \
+	FMOVD	(offset+8*15)(R1), F29 \
+	FMOVD	(offset+8*16)(R1), F30 \
+	FMOVD	(offset+8*17)(R1), F31
+
+// Save and restore VR20-31 (aka VSR56-63). These
+// macros must point to a 16B aligned offset.
+#define SAVE_VR_SIZE (12*16)
+#define SAVE_VR(offset, rtmp)         \
+	MOVD	$(offset+16*0), rtmp  \
+	STVX	V20, (rtmp)(R1)       \
+	MOVD	$(offset+16*1), rtmp  \
+	STVX	V21, (rtmp)(R1)       \
+	MOVD	$(offset+16*2), rtmp  \
+	STVX	V22, (rtmp)(R1)       \
+	MOVD	$(offset+16*3), rtmp  \
+	STVX	V23, (rtmp)(R1)       \
+	MOVD	$(offset+16*4), rtmp  \
+	STVX	V24, (rtmp)(R1)       \
+	MOVD	$(offset+16*5), rtmp  \
+	STVX	V25, (rtmp)(R1)       \
+	MOVD	$(offset+16*6), rtmp  \
+	STVX	V26, (rtmp)(R1)       \
+	MOVD	$(offset+16*7), rtmp  \
+	STVX	V27, (rtmp)(R1)       \
+	MOVD	$(offset+16*8), rtmp  \
+	STVX	V28, (rtmp)(R1)       \
+	MOVD	$(offset+16*9), rtmp  \
+	STVX	V29, (rtmp)(R1)       \
+	MOVD	$(offset+16*10), rtmp \
+	STVX	V30, (rtmp)(R1)       \
+	MOVD	$(offset+16*11), rtmp \
+	STVX	V31, (rtmp)(R1)
+
+#define RESTORE_VR(offset, rtmp)      \
+	MOVD	$(offset+16*0), rtmp  \
+	LVX	(rtmp)(R1), V20       \
+	MOVD	$(offset+16*1), rtmp  \
+	LVX	(rtmp)(R1), V21       \
+	MOVD	$(offset+16*2), rtmp  \
+	LVX	(rtmp)(R1), V22       \
+	MOVD	$(offset+16*3), rtmp  \
+	LVX	(rtmp)(R1), V23       \
+	MOVD	$(offset+16*4), rtmp  \
+	LVX	(rtmp)(R1), V24       \
+	MOVD	$(offset+16*5), rtmp  \
+	LVX	(rtmp)(R1), V25       \
+	MOVD	$(offset+16*6), rtmp  \
+	LVX	(rtmp)(R1), V26       \
+	MOVD	$(offset+16*7), rtmp  \
+	LVX	(rtmp)(R1), V27       \
+	MOVD	$(offset+16*8), rtmp  \
+	LVX	(rtmp)(R1), V28       \
+	MOVD	$(offset+16*9), rtmp  \
+	LVX	(rtmp)(R1), V29       \
+	MOVD	$(offset+16*10), rtmp \
+	LVX	(rtmp)(R1), V30       \
+	MOVD	$(offset+16*11), rtmp \
+	LVX	(rtmp)(R1), V31
+
+// LR and CR are saved in the caller's frame. The callee must
+// make space for all other callee-save registers.
+#define SAVE_ALL_REG_SIZE (SAVE_GPR_SIZE+SAVE_FPR_SIZE+SAVE_VR_SIZE)
+
+// Stack a frame and save all callee-save registers following the
+// host OS's ABI. Fortunately, this is identical for AIX, ELFv1, and
+// ELFv2. All host ABIs require the stack pointer to maintain 16 byte
+// alignment, and save the callee-save registers in the same places.
+//
+// To restate, R1 is assumed to be aligned when this macro is used.
+// This assumes the caller's frame is compliant with the host ABI.
+// CR and LR are saved into the caller's frame per the host ABI.
+// R0 is initialized to $0 as expected by Go.
+#define STACK_AND_SAVE_HOST_TO_GO_ABI(extra)                       \
+	MOVD	LR, R0                                             \
+	MOVD	R0, 16(R1)                                         \
+	MOVW	CR, R0                                             \
+	MOVD	R0, 8(R1)                                          \
+	MOVDU	R1, -(extra)-FIXED_FRAME-SAVE_ALL_REG_SIZE(R1)     \
+	SAVE_GPR(extra+FIXED_FRAME)                                \
+	SAVE_FPR(extra+FIXED_FRAME+SAVE_GPR_SIZE)                  \
+	SAVE_VR(extra+FIXED_FRAME+SAVE_GPR_SIZE+SAVE_FPR_SIZE, R0) \
+	MOVD	$0, R0
+
+// This unstacks the frame, restoring all callee-save registers
+// as saved by STACK_AND_SAVE_HOST_TO_GO_ABI.
+//
+// R0 is not guaranteed to contain $0 after this macro.
+#define UNSTACK_AND_RESTORE_GO_TO_HOST_ABI(extra)                     \
+	RESTORE_GPR(extra+FIXED_FRAME)                                \
+	RESTORE_FPR(extra+FIXED_FRAME+SAVE_GPR_SIZE)                  \
+	RESTORE_VR(extra+FIXED_FRAME+SAVE_GPR_SIZE+SAVE_FPR_SIZE, R0) \
+	ADD 	$(extra+FIXED_FRAME+SAVE_ALL_REG_SIZE), R1            \
+	MOVD	16(R1), R0                                            \
+	MOVD	R0, LR                                                \
+	MOVD	8(R1), R0                                             \
+	MOVW	R0, CR

src/runtime/cgo/asm_386.s

@@ -0,0 +1,42 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVL	_crosscall2_ptr(SB), AX
+	MOVL	$crosscall2_trampoline<>(SB), BX
+	MOVL	BX, (AX)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT,$28-16
+	MOVL BP, 24(SP)
+	MOVL BX, 20(SP)
+	MOVL SI, 16(SP)
+	MOVL DI, 12(SP)
+
+	MOVL	ctxt+12(FP), AX
+	MOVL	AX, 8(SP)
+	MOVL	a+4(FP), AX
+	MOVL	AX, 4(SP)
+	MOVL	fn+0(FP), AX
+	MOVL	AX, 0(SP)
+	CALL	runtime·cgocallback(SB)
+
+	MOVL 12(SP), DI
+	MOVL 16(SP), SI
+	MOVL 20(SP), BX
+	MOVL 24(SP), BP
+	RET

src/runtime/cgo/asm_amd64.s

@@ -0,0 +1,47 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+#include "abi_amd64.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVQ	_crosscall2_ptr(SB), AX
+	MOVQ	$crosscall2_trampoline<>(SB), BX
+	MOVQ	BX, (AX)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+// This signature is known to SWIG, so we can't change it.
+TEXT crosscall2(SB),NOSPLIT,$0-0
+	PUSH_REGS_HOST_TO_ABI0()
+
+	// Make room for arguments to cgocallback.
+	ADJSP	$0x18
+#ifndef GOOS_windows
+	MOVQ	DI, 0x0(SP)	/* fn */
+	MOVQ	SI, 0x8(SP)	/* arg */
+	// Skip n in DX.
+	MOVQ	CX, 0x10(SP)	/* ctxt */
+#else
+	MOVQ	CX, 0x0(SP)	/* fn */
+	MOVQ	DX, 0x8(SP)	/* arg */
+	// Skip n in R8.
+	MOVQ	R9, 0x10(SP)	/* ctxt */
+#endif
+
+	CALL	runtime·cgocallback(SB)
+
+	ADJSP	$-0x18
+	POP_REGS_HOST_TO_ABI0()
+	RET

src/runtime/cgo/asm_arm.s

@@ -0,0 +1,69 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVW	_crosscall2_ptr(SB), R1
+	MOVW	$crosscall2_trampoline<>(SB), R2
+	MOVW	R2, (R1)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	SUB	$(8*9), R13 // Reserve space for the floating point registers.
+	// The C arguments arrive in R0, R1, R2, and R3. We want to
+	// pass R0, R1, and R3 to Go, so we push those on the stack.
+	// Also, save C callee-save registers R4-R12.
+	MOVM.WP	[R0, R1, R3, R4, R5, R6, R7, R8, R9, g, R11, R12], (R13)
+	// Finally, save the link register R14. This also puts the
+	// arguments we pushed for cgocallback where they need to be,
+	// starting at 4(R13).
+	MOVW.W	R14, -4(R13)
+
+	// Skip floating point registers if goarmsoftfp!=0.
+	MOVB    runtime·goarmsoftfp(SB), R11
+	CMP     $0, R11
+	BNE     skipfpsave
+	MOVD	F8, (13*4+8*1)(R13)
+	MOVD	F9, (13*4+8*2)(R13)
+	MOVD	F10, (13*4+8*3)(R13)
+	MOVD	F11, (13*4+8*4)(R13)
+	MOVD	F12, (13*4+8*5)(R13)
+	MOVD	F13, (13*4+8*6)(R13)
+	MOVD	F14, (13*4+8*7)(R13)
+	MOVD	F15, (13*4+8*8)(R13)
+
+skipfpsave:
+	BL	runtime·load_g(SB)
+	// We set up the arguments to cgocallback when saving registers above.
+	BL	runtime·cgocallback(SB)
+
+	MOVB    runtime·goarmsoftfp(SB), R11
+	CMP     $0, R11
+	BNE     skipfprest
+	MOVD	(13*4+8*1)(R13), F8
+	MOVD	(13*4+8*2)(R13), F9
+	MOVD	(13*4+8*3)(R13), F10
+	MOVD	(13*4+8*4)(R13), F11
+	MOVD	(13*4+8*5)(R13), F12
+	MOVD	(13*4+8*6)(R13), F13
+	MOVD	(13*4+8*7)(R13), F14
+	MOVD	(13*4+8*8)(R13), F15
+
+skipfprest:
+	MOVW.P	4(R13), R14
+	MOVM.IAW	(R13), [R0, R1, R3, R4, R5, R6, R7, R8, R9, g, R11, R12]
+	ADD	$(8*9), R13
+	MOVW	R14, R15

src/runtime/cgo/asm_arm64.s

@@ -0,0 +1,50 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+#include "abi_arm64.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVD	_crosscall2_ptr(SB), R1
+	MOVD	$crosscall2_trampoline<>(SB), R2
+	MOVD	R2, (R1)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	/*
+	 * We still need to save all callee save register as before, and then
+	 *  push 3 args for fn (R0, R1, R3), skipping R2.
+	 * Also note that at procedure entry in gc world, 8(RSP) will be the
+	 *  first arg.
+	 */
+	SUB	$(8*24), RSP
+	STP	(R0, R1), (8*1)(RSP)
+	MOVD	R3, (8*3)(RSP)
+
+	SAVE_R19_TO_R28(8*4)
+	SAVE_F8_TO_F15(8*14)
+	STP	(R29, R30), (8*22)(RSP)
+
+
+	// Initialize Go ABI environment
+	BL	runtime·load_g(SB)
+	BL	runtime·cgocallback(SB)
+
+	RESTORE_R19_TO_R28(8*4)
+	RESTORE_F8_TO_F15(8*14)
+	LDP	(8*22)(RSP), (R29, R30)
+
+	ADD	$(8*24), RSP
+	RET

src/runtime/cgo/asm_loong64.s

@@ -0,0 +1,53 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+#include "abi_loong64.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVV	_crosscall2_ptr(SB), R5
+	MOVV	$crosscall2_trampoline<>(SB), R6
+	MOVV	R6, (R5)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	/*
+	 * We still need to save all callee save register as before, and then
+	 * push 3 args for fn (R4, R5, R7), skipping R6.
+	 * Also note that at procedure entry in gc world, 8(R29) will be the
+	 *  first arg.
+	 */
+
+	ADDV	$(-23*8), R3
+	MOVV	R4, (1*8)(R3) // fn unsafe.Pointer
+	MOVV	R5, (2*8)(R3) // a unsafe.Pointer
+	MOVV	R7, (3*8)(R3) // ctxt uintptr
+
+	SAVE_R22_TO_R31((4*8))
+	SAVE_F24_TO_F31((14*8))
+	MOVV	R1, (22*8)(R3)
+
+	// Initialize Go ABI environment
+	JAL	runtime·load_g(SB)
+
+	JAL	runtime·cgocallback(SB)
+
+	RESTORE_R22_TO_R31((4*8))
+	RESTORE_F24_TO_F31((14*8))
+	MOVV	(22*8)(R3), R1
+
+	ADDV	$(23*8), R3
+
+	RET

src/runtime/cgo/asm_mips64x.s

@@ -0,0 +1,95 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips64 || mips64le
+
+#include "textflag.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVV	_crosscall2_ptr(SB), R5
+	MOVV	$crosscall2_trampoline<>(SB), R6
+	MOVV	R6, (R5)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	/*
+	 * We still need to save all callee save register as before, and then
+	 *  push 3 args for fn (R4, R5, R7), skipping R6.
+	 * Also note that at procedure entry in gc world, 8(R29) will be the
+	 *  first arg.
+	 */
+#ifndef GOMIPS64_softfloat
+	ADDV	$(-8*23), R29
+#else
+	ADDV	$(-8*15), R29
+#endif
+	MOVV	R4, (8*1)(R29) // fn unsafe.Pointer
+	MOVV	R5, (8*2)(R29) // a unsafe.Pointer
+	MOVV	R7, (8*3)(R29) // ctxt uintptr
+	MOVV	R16, (8*4)(R29)
+	MOVV	R17, (8*5)(R29)
+	MOVV	R18, (8*6)(R29)
+	MOVV	R19, (8*7)(R29)
+	MOVV	R20, (8*8)(R29)
+	MOVV	R21, (8*9)(R29)
+	MOVV	R22, (8*10)(R29)
+	MOVV	R23, (8*11)(R29)
+	MOVV	RSB, (8*12)(R29)
+	MOVV	g, (8*13)(R29)
+	MOVV	R31, (8*14)(R29)
+#ifndef GOMIPS64_softfloat
+	MOVD	F24, (8*15)(R29)
+	MOVD	F25, (8*16)(R29)
+	MOVD	F26, (8*17)(R29)
+	MOVD	F27, (8*18)(R29)
+	MOVD	F28, (8*19)(R29)
+	MOVD	F29, (8*20)(R29)
+	MOVD	F30, (8*21)(R29)
+	MOVD	F31, (8*22)(R29)
+#endif
+	// Initialize Go ABI environment
+	// prepare SB register = PC & 0xffffffff00000000
+	BGEZAL	R0, 1(PC)
+	SRLV	$32, R31, RSB
+	SLLV	$32, RSB
+	JAL	runtime·load_g(SB)
+
+	JAL	runtime·cgocallback(SB)
+
+	MOVV	(8*4)(R29), R16
+	MOVV	(8*5)(R29), R17
+	MOVV	(8*6)(R29), R18
+	MOVV	(8*7)(R29), R19
+	MOVV	(8*8)(R29), R20
+	MOVV	(8*9)(R29), R21
+	MOVV	(8*10)(R29), R22
+	MOVV	(8*11)(R29), R23
+	MOVV	(8*12)(R29), RSB
+	MOVV	(8*13)(R29), g
+	MOVV	(8*14)(R29), R31
+#ifndef GOMIPS64_softfloat
+	MOVD	(8*15)(R29), F24
+	MOVD	(8*16)(R29), F25
+	MOVD	(8*17)(R29), F26
+	MOVD	(8*18)(R29), F27
+	MOVD	(8*19)(R29), F28
+	MOVD	(8*20)(R29), F29
+	MOVD	(8*21)(R29), F30
+	MOVD	(8*22)(R29), F31
+	ADDV	$(8*23), R29
+#else
+	ADDV	$(8*15), R29
+#endif
+	RET

src/runtime/cgo/asm_mipsx.s

@@ -0,0 +1,88 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips || mipsle
+
+#include "textflag.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVW	_crosscall2_ptr(SB), R5
+	MOVW	$crosscall2_trampoline<>(SB), R6
+	MOVW	R6, (R5)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	/*
+	 * We still need to save all callee save register as before, and then
+	 *  push 3 args for fn (R4, R5, R7), skipping R6.
+	 * Also note that at procedure entry in gc world, 4(R29) will be the
+	 *  first arg.
+	 */
+
+	// Space for 9 caller-saved GPR + LR + 6 caller-saved FPR.
+	// O32 ABI allows us to smash 16 bytes argument area of caller frame.
+#ifndef GOMIPS_softfloat
+	SUBU	$(4*14+8*6-16), R29
+#else
+	SUBU	$(4*14-16), R29	// For soft-float, no FPR.
+#endif
+	MOVW	R4, (4*1)(R29)	// fn unsafe.Pointer
+	MOVW	R5, (4*2)(R29)	// a unsafe.Pointer
+	MOVW	R7, (4*3)(R29)	// ctxt uintptr
+	MOVW	R16, (4*4)(R29)
+	MOVW	R17, (4*5)(R29)
+	MOVW	R18, (4*6)(R29)
+	MOVW	R19, (4*7)(R29)
+	MOVW	R20, (4*8)(R29)
+	MOVW	R21, (4*9)(R29)
+	MOVW	R22, (4*10)(R29)
+	MOVW	R23, (4*11)(R29)
+	MOVW	g, (4*12)(R29)
+	MOVW	R31, (4*13)(R29)
+#ifndef GOMIPS_softfloat
+	MOVD	F20, (4*14)(R29)
+	MOVD	F22, (4*14+8*1)(R29)
+	MOVD	F24, (4*14+8*2)(R29)
+	MOVD	F26, (4*14+8*3)(R29)
+	MOVD	F28, (4*14+8*4)(R29)
+	MOVD	F30, (4*14+8*5)(R29)
+#endif
+	JAL	runtime·load_g(SB)
+
+	JAL	runtime·cgocallback(SB)
+
+	MOVW	(4*4)(R29), R16
+	MOVW	(4*5)(R29), R17
+	MOVW	(4*6)(R29), R18
+	MOVW	(4*7)(R29), R19
+	MOVW	(4*8)(R29), R20
+	MOVW	(4*9)(R29), R21
+	MOVW	(4*10)(R29), R22
+	MOVW	(4*11)(R29), R23
+	MOVW	(4*12)(R29), g
+	MOVW	(4*13)(R29), R31
+#ifndef GOMIPS_softfloat
+	MOVD	(4*14)(R29), F20
+	MOVD	(4*14+8*1)(R29), F22
+	MOVD	(4*14+8*2)(R29), F24
+	MOVD	(4*14+8*3)(R29), F26
+	MOVD	(4*14+8*4)(R29), F28
+	MOVD	(4*14+8*5)(R29), F30
+
+	ADDU	$(4*14+8*6-16), R29
+#else
+	ADDU	$(4*14-16), R29
+#endif
+	RET

src/runtime/cgo/asm_ppc64x.s

@@ -0,0 +1,70 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ppc64 || ppc64le
+
+#include "textflag.h"
+#include "asm_ppc64x.h"
+#include "abi_ppc64x.h"
+
+#ifdef GO_PPC64X_HAS_FUNCDESC
+// crosscall2 is marked with go:cgo_export_static. On AIX, this creates and exports
+// the symbol name and descriptor as the AIX linker expects, but does not work if
+// referenced from within Go. Create and use an aliased descriptor of crosscall2
+// to workaround this.
+DEFINE_PPC64X_FUNCDESC(_crosscall2<>, crosscall2)
+#define CROSSCALL2_FPTR $_crosscall2<>(SB)
+#else
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+#define CROSSCALL2_FPTR $crosscall2_trampoline<>(SB)
+#endif
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVD	_crosscall2_ptr(SB), R5
+	MOVD	CROSSCALL2_FPTR, R6
+	MOVD	R6, (R5)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+// The value of R2 is saved on the new stack frame, and not
+// the caller's frame due to issue #43228.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	// Start with standard C stack frame layout and linkage, allocate
+	// 32 bytes of argument space, save callee-save regs, and set R0 to $0.
+	STACK_AND_SAVE_HOST_TO_GO_ABI(32)
+	// The above will not preserve R2 (TOC). Save it in case Go is
+	// compiled without a TOC pointer (e.g -buildmode=default).
+	MOVD	R2, 24(R1)
+
+	// Load the current g.
+	BL	runtime·load_g(SB)
+
+#ifdef GO_PPC64X_HAS_FUNCDESC
+	// Load the real entry address from the first slot of the function descriptor.
+	// The first argument fn might be null, that means dropm in pthread key destructor.
+	CMP	R3, $0
+	BEQ	nil_fn
+	MOVD	8(R3), R2
+	MOVD	(R3), R3
+nil_fn:
+#endif
+	MOVD	R3, FIXED_FRAME+0(R1)	// fn unsafe.Pointer
+	MOVD	R4, FIXED_FRAME+8(R1)	// a unsafe.Pointer
+	// Skip R5 = n uint32
+	MOVD	R6, FIXED_FRAME+16(R1)	// ctxt uintptr
+	BL	runtime·cgocallback(SB)
+
+	// Restore the old frame, and R2.
+	MOVD	24(R1), R2
+	UNSTACK_AND_RESTORE_GO_TO_HOST_ABI(32)
+	RET

src/runtime/cgo/asm_riscv64.s

@@ -0,0 +1,91 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOV	_crosscall2_ptr(SB), X7
+	MOV	$crosscall2_trampoline<>(SB), X8
+	MOV	X8, (X7)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	/*
+	 * Push arguments for fn (X10, X11, X13), along with all callee-save
+	 * registers. Note that at procedure entry the first argument is at
+	 * 8(X2).
+	 */
+	ADD	$(-8*29), X2
+	MOV	X10, (8*1)(X2) // fn unsafe.Pointer
+	MOV	X11, (8*2)(X2) // a unsafe.Pointer
+	MOV	X13, (8*3)(X2) // ctxt uintptr
+	MOV	X8, (8*4)(X2)
+	MOV	X9, (8*5)(X2)
+	MOV	X18, (8*6)(X2)
+	MOV	X19, (8*7)(X2)
+	MOV	X20, (8*8)(X2)
+	MOV	X21, (8*9)(X2)
+	MOV	X22, (8*10)(X2)
+	MOV	X23, (8*11)(X2)
+	MOV	X24, (8*12)(X2)
+	MOV	X25, (8*13)(X2)
+	MOV	X26, (8*14)(X2)
+	MOV	g, (8*15)(X2)
+	MOV	X1, (8*16)(X2)
+	MOVD	F8, (8*17)(X2)
+	MOVD	F9, (8*18)(X2)
+	MOVD	F18, (8*19)(X2)
+	MOVD	F19, (8*20)(X2)
+	MOVD	F20, (8*21)(X2)
+	MOVD	F21, (8*22)(X2)
+	MOVD	F22, (8*23)(X2)
+	MOVD	F23, (8*24)(X2)
+	MOVD	F24, (8*25)(X2)
+	MOVD	F25, (8*26)(X2)
+	MOVD	F26, (8*27)(X2)
+	MOVD	F27, (8*28)(X2)
+
+	// Initialize Go ABI environment
+	CALL	runtime·load_g(SB)
+	CALL	runtime·cgocallback(SB)
+
+	MOV	(8*4)(X2), X8
+	MOV	(8*5)(X2), X9
+	MOV	(8*6)(X2), X18
+	MOV	(8*7)(X2), X19
+	MOV	(8*8)(X2), X20
+	MOV	(8*9)(X2), X21
+	MOV	(8*10)(X2), X22
+	MOV	(8*11)(X2), X23
+	MOV	(8*12)(X2), X24
+	MOV	(8*13)(X2), X25
+	MOV	(8*14)(X2), X26
+	MOV	(8*15)(X2), g
+	MOV	(8*16)(X2), X1
+	MOVD	(8*17)(X2), F8
+	MOVD	(8*18)(X2), F9
+	MOVD	(8*19)(X2), F18
+	MOVD	(8*20)(X2), F19
+	MOVD	(8*21)(X2), F20
+	MOVD	(8*22)(X2), F21
+	MOVD	(8*23)(X2), F22
+	MOVD	(8*24)(X2), F23
+	MOVD	(8*25)(X2), F24
+	MOVD	(8*26)(X2), F25
+	MOVD	(8*27)(X2), F26
+	MOVD	(8*28)(X2), F27
+	ADD	$(8*29), X2
+
+	RET

src/runtime/cgo/asm_s390x.s

@@ -0,0 +1,68 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
+// Use a local trampoline, to avoid taking the address of a dynamically exported
+// function.
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	MOVD	_crosscall2_ptr(SB), R1
+	MOVD	$crosscall2_trampoline<>(SB), R2
+	MOVD	R2, (R1)
+	RET
+
+TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	crosscall2(SB)
+
+// Called by C code generated by cmd/cgo.
+// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
+// Saves C callee-saved registers and calls cgocallback with three arguments.
+// fn is the PC of a func(a unsafe.Pointer) function.
+TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
+	// Start with standard C stack frame layout and linkage.
+
+	// Save R6-R15 in the register save area of the calling function.
+	STMG	R6, R15, 48(R15)
+
+	// Allocate 96 bytes on the stack.
+	MOVD	$-96(R15), R15
+
+	// Save F8-F15 in our stack frame.
+	FMOVD	F8, 32(R15)
+	FMOVD	F9, 40(R15)
+	FMOVD	F10, 48(R15)
+	FMOVD	F11, 56(R15)
+	FMOVD	F12, 64(R15)
+	FMOVD	F13, 72(R15)
+	FMOVD	F14, 80(R15)
+	FMOVD	F15, 88(R15)
+
+	// Initialize Go ABI environment.
+	BL	runtime·load_g(SB)
+
+	MOVD	R2, 8(R15)	// fn unsafe.Pointer
+	MOVD	R3, 16(R15)	// a unsafe.Pointer
+	// Skip R4 = n uint32
+	MOVD	R5, 24(R15)	// ctxt uintptr
+	BL	runtime·cgocallback(SB)
+
+	FMOVD	32(R15), F8
+	FMOVD	40(R15), F9
+	FMOVD	48(R15), F10
+	FMOVD	56(R15), F11
+	FMOVD	64(R15), F12
+	FMOVD	72(R15), F13
+	FMOVD	80(R15), F14
+	FMOVD	88(R15), F15
+
+	// De-allocate stack frame.
+	MOVD	$96(R15), R15
+
+	// Restore R6-R15.
+	LMG	48(R15), R6, R15
+
+	RET
+

src/runtime/cgo/asm_wasm.s

@@ -0,0 +1,11 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
+	UNDEF
+
+TEXT crosscall2(SB), NOSPLIT, $0
+	UNDEF

src/runtime/cgo/callbacks.go

@@ -0,0 +1,152 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgo
+
+import "unsafe"
+
+// These utility functions are available to be called from code
+// compiled with gcc via crosscall2.
+
+// The declaration of crosscall2 is:
+//   void crosscall2(void (*fn)(void *), void *, int);
+//
+// We need to export the symbol crosscall2 in order to support
+// callbacks from shared libraries. This applies regardless of
+// linking mode.
+//
+// Compatibility note: SWIG uses crosscall2 in exactly one situation:
+// to call _cgo_panic using the pattern shown below. We need to keep
+// that pattern working. In particular, crosscall2 actually takes four
+// arguments, but it works to call it with three arguments when
+// calling _cgo_panic.
+//
+//go:cgo_export_static crosscall2
+//go:cgo_export_dynamic crosscall2
+
+// Panic. The argument is converted into a Go string.
+
+// Call like this in code compiled with gcc:
+//   struct { const char *p; } a;
+//   a.p = /* string to pass to panic */;
+//   crosscall2(_cgo_panic, &a, sizeof a);
+//   /* The function call will not return.  */
+
+// TODO: We should export a regular C function to panic, change SWIG
+// to use that instead of the above pattern, and then we can drop
+// backwards-compatibility from crosscall2 and stop exporting it.
+
+//go:linkname _runtime_cgo_panic_internal runtime._cgo_panic_internal
+func _runtime_cgo_panic_internal(p *byte)
+
+//go:linkname _cgo_panic _cgo_panic
+//go:cgo_export_static _cgo_panic
+//go:cgo_export_dynamic _cgo_panic
+func _cgo_panic(a *struct{ cstr *byte }) {
+	_runtime_cgo_panic_internal(a.cstr)
+}
+
+//go:cgo_import_static x_cgo_init
+//go:linkname x_cgo_init x_cgo_init
+//go:linkname _cgo_init _cgo_init
+var x_cgo_init byte
+var _cgo_init = &x_cgo_init
+
+//go:cgo_import_static x_cgo_thread_start
+//go:linkname x_cgo_thread_start x_cgo_thread_start
+//go:linkname _cgo_thread_start _cgo_thread_start
+var x_cgo_thread_start byte
+var _cgo_thread_start = &x_cgo_thread_start
+
+// Creates a new system thread without updating any Go state.
+//
+// This method is invoked during shared library loading to create a new OS
+// thread to perform the runtime initialization. This method is similar to
+// _cgo_sys_thread_start except that it doesn't update any Go state.
+
+//go:cgo_import_static x_cgo_sys_thread_create
+//go:linkname x_cgo_sys_thread_create x_cgo_sys_thread_create
+//go:linkname _cgo_sys_thread_create _cgo_sys_thread_create
+var x_cgo_sys_thread_create byte
+var _cgo_sys_thread_create = &x_cgo_sys_thread_create
+
+// Indicates whether a dummy thread key has been created or not.
+//
+// When calling go exported function from C, we register a destructor
+// callback, for a dummy thread key, by using pthread_key_create.
+
+//go:cgo_import_static x_cgo_pthread_key_created
+//go:linkname x_cgo_pthread_key_created x_cgo_pthread_key_created
+//go:linkname _cgo_pthread_key_created _cgo_pthread_key_created
+var x_cgo_pthread_key_created byte
+var _cgo_pthread_key_created = &x_cgo_pthread_key_created
+
+// Export crosscall2 to a c function pointer variable.
+// Used to dropm in pthread key destructor, while C thread is exiting.
+
+//go:cgo_import_static x_crosscall2_ptr
+//go:linkname x_crosscall2_ptr x_crosscall2_ptr
+//go:linkname _crosscall2_ptr _crosscall2_ptr
+var x_crosscall2_ptr byte
+var _crosscall2_ptr = &x_crosscall2_ptr
+
+// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
+// It's for the runtime package to call at init time.
+func set_crosscall2()
+
+//go:linkname _set_crosscall2 runtime.set_crosscall2
+var _set_crosscall2 = set_crosscall2
+
+// Store the g into the thread-specific value.
+// So that pthread_key_destructor will dropm when the thread is exiting.
+
+//go:cgo_import_static x_cgo_bindm
+//go:linkname x_cgo_bindm x_cgo_bindm
+//go:linkname _cgo_bindm _cgo_bindm
+var x_cgo_bindm byte
+var _cgo_bindm = &x_cgo_bindm
+
+// Notifies that the runtime has been initialized.
+//
+// We currently block at every CGO entry point (via _cgo_wait_runtime_init_done)
+// to ensure that the runtime has been initialized before the CGO call is
+// executed. This is necessary for shared libraries where we kickoff runtime
+// initialization in a separate thread and return without waiting for this
+// thread to complete the init.
+
+//go:cgo_import_static x_cgo_notify_runtime_init_done
+//go:linkname x_cgo_notify_runtime_init_done x_cgo_notify_runtime_init_done
+//go:linkname _cgo_notify_runtime_init_done _cgo_notify_runtime_init_done
+var x_cgo_notify_runtime_init_done byte
+var _cgo_notify_runtime_init_done = &x_cgo_notify_runtime_init_done
+
+// Sets the traceback context function. See runtime.SetCgoTraceback.
+
+//go:cgo_import_static x_cgo_set_context_function
+//go:linkname x_cgo_set_context_function x_cgo_set_context_function
+//go:linkname _cgo_set_context_function _cgo_set_context_function
+var x_cgo_set_context_function byte
+var _cgo_set_context_function = &x_cgo_set_context_function
+
+// Calls a libc function to execute background work injected via libc
+// interceptors, such as processing pending signals under the thread
+// sanitizer.
+//
+// Left as a nil pointer if no libc interceptors are expected.
+
+//go:cgo_import_static _cgo_yield
+//go:linkname _cgo_yield _cgo_yield
+var _cgo_yield unsafe.Pointer
+
+//go:cgo_export_static _cgo_topofstack
+//go:cgo_export_dynamic _cgo_topofstack
+
+// x_cgo_getstackbound gets the thread's C stack size and
+// set the G's stack bound based on the stack size.
+
+//go:cgo_import_static x_cgo_getstackbound
+//go:linkname x_cgo_getstackbound x_cgo_getstackbound
+//go:linkname _cgo_getstackbound _cgo_getstackbound
+var x_cgo_getstackbound byte
+var _cgo_getstackbound = &x_cgo_getstackbound

src/runtime/cgo/callbacks_aix.go

@@ -0,0 +1,12 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgo
+
+// These functions must be exported in order to perform
+// longcall on cgo programs (cf gcc_aix_ppc64.c).
+//
+//go:cgo_export_static __cgo_topofstack
+//go:cgo_export_static runtime.rt0_go
+//go:cgo_export_static _rt0_ppc64_aix_lib

src/runtime/cgo/callbacks_traceback.go

@@ -0,0 +1,17 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || linux
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+// Calls the traceback function passed to SetCgoTraceback.
+
+//go:cgo_import_static x_cgo_callers
+//go:linkname x_cgo_callers x_cgo_callers
+//go:linkname _cgo_callers _cgo_callers
+var x_cgo_callers byte
+var _cgo_callers = &x_cgo_callers

src/runtime/cgo/cgo.go

@@ -0,0 +1,40 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package cgo contains runtime support for code generated
+by the cgo tool.  See the documentation for the cgo command
+for details on using cgo.
+*/
+package cgo
+
+/*
+
+#cgo darwin,!arm64 LDFLAGS: -lpthread
+#cgo darwin,arm64 LDFLAGS: -framework CoreFoundation
+#cgo dragonfly LDFLAGS: -lpthread
+#cgo freebsd LDFLAGS: -lpthread
+#cgo android LDFLAGS: -llog
+#cgo !android,linux LDFLAGS: -lpthread
+#cgo netbsd LDFLAGS: -lpthread
+#cgo openbsd LDFLAGS: -lpthread
+#cgo aix LDFLAGS: -Wl,-berok
+#cgo solaris LDFLAGS: -lxnet
+#cgo solaris LDFLAGS: -lsocket
+
+// Use -fno-stack-protector to avoid problems locating the
+// proper support functions. See issues #52919, #54313, #58385.
+#cgo CFLAGS: -Wall -Werror -fno-stack-protector
+
+#cgo solaris CPPFLAGS: -D_POSIX_PTHREAD_SEMANTICS
+
+*/
+import "C"
+
+import "runtime/internal/sys"
+
+// Incomplete is used specifically for the semantics of incomplete C types.
+type Incomplete struct {
+	_ sys.NotInHeap
+}

src/runtime/cgo/dragonfly.go

@@ -0,0 +1,19 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build dragonfly
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+// Supply environ and __progname, because we don't
+// link against the standard DragonFly crt0.o and the
+// libc dynamic library needs them.
+
+//go:linkname _environ environ
+//go:linkname _progname __progname
+
+var _environ uintptr
+var _progname uintptr

src/runtime/cgo/freebsd.go

@@ -0,0 +1,22 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build freebsd
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+// Supply environ and __progname, because we don't
+// link against the standard FreeBSD crt0.o and the
+// libc dynamic library needs them.
+
+//go:linkname _environ environ
+//go:linkname _progname __progname
+
+//go:cgo_export_dynamic environ
+//go:cgo_export_dynamic __progname
+
+var _environ uintptr
+var _progname uintptr

src/runtime/cgo/gcc_386.S

@@ -0,0 +1,48 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_386.S"
+
+/*
+ * Windows still insists on underscore prefixes for C function names.
+ */
+#if defined(_WIN32)
+#define EXT(s) _##s
+#else
+#define EXT(s) s
+#endif
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard x86 ABI, where %ebp, %ebx, %esi,
+ * and %edi are callee-save, so they must be saved explicitly.
+ */
+.globl EXT(crosscall1)
+EXT(crosscall1):
+	pushl %ebp
+	movl %esp, %ebp
+	pushl %ebx
+	pushl %esi
+	pushl %edi
+
+	movl 16(%ebp), %eax	/* g */
+	pushl %eax
+	movl 12(%ebp), %eax	/* setg_gcc */
+	call *%eax
+	popl %eax
+
+	movl 8(%ebp), %eax	/* fn */
+	call *%eax
+
+	popl %edi
+	popl %esi
+	popl %ebx
+	popl %ebp
+	ret
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",@progbits
+#endif

src/runtime/cgo/gcc_aix_ppc64.S

@@ -0,0 +1,132 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_aix_ppc64.S"
+
+/*
+ * void crosscall_ppc64(void (*fn)(void), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard ppc64 C ABI, where r2, r14-r31, f14-f31 are
+ * callee-save, so they must be saved explicitly.
+ * AIX has a special assembly syntax and keywords that can be mixed with
+ * Linux assembly.
+ */
+  .toc
+  .csect .text[PR]
+  .globl crosscall_ppc64
+  .globl .crosscall_ppc64
+  .csect crosscall_ppc64[DS]
+crosscall_ppc64:
+  .llong .crosscall_ppc64, TOC[tc0], 0
+  .csect .text[PR]
+.crosscall_ppc64:
+	// Start with standard C stack frame layout and linkage
+	mflr	0
+	std	0, 16(1)	// Save LR in caller's frame
+	std	2, 40(1)	// Save TOC in caller's frame
+	bl	saveregs
+	stdu	1, -296(1)
+
+	// Set up Go ABI constant registers
+	// Must match _cgo_reginit in runtime package.
+	xor 0, 0, 0
+
+	// Restore g pointer (r30 in Go ABI, which may have been clobbered by C)
+	mr	30, 4
+
+	// Call fn
+	mr	12, 3
+	mtctr	12
+	bctrl
+
+	addi	1, 1, 296
+	bl	restoreregs
+	ld	2, 40(1)
+	ld	0, 16(1)
+	mtlr	0
+	blr
+
+saveregs:
+	// Save callee-save registers
+	// O=-288; for R in {14..31}; do echo "\tstd\t$R, $O(1)"; ((O+=8)); done; for F in f{14..31}; do echo "\tstfd\t$F, $O(1)"; ((O+=8)); done
+	std	14, -288(1)
+	std	15, -280(1)
+	std	16, -272(1)
+	std	17, -264(1)
+	std	18, -256(1)
+	std	19, -248(1)
+	std	20, -240(1)
+	std	21, -232(1)
+	std	22, -224(1)
+	std	23, -216(1)
+	std	24, -208(1)
+	std	25, -200(1)
+	std	26, -192(1)
+	std	27, -184(1)
+	std	28, -176(1)
+	std	29, -168(1)
+	std	30, -160(1)
+	std	31, -152(1)
+	stfd	14, -144(1)
+	stfd	15, -136(1)
+	stfd	16, -128(1)
+	stfd	17, -120(1)
+	stfd	18, -112(1)
+	stfd	19, -104(1)
+	stfd	20, -96(1)
+	stfd	21, -88(1)
+	stfd	22, -80(1)
+	stfd	23, -72(1)
+	stfd	24, -64(1)
+	stfd	25, -56(1)
+	stfd	26, -48(1)
+	stfd	27, -40(1)
+	stfd	28, -32(1)
+	stfd	29, -24(1)
+	stfd	30, -16(1)
+	stfd	31, -8(1)
+
+	blr
+
+restoreregs:
+	// O=-288; for R in {14..31}; do echo "\tld\t$R, $O(1)"; ((O+=8)); done; for F in {14..31}; do echo "\tlfd\t$F, $O(1)"; ((O+=8)); done
+	ld	14, -288(1)
+	ld	15, -280(1)
+	ld	16, -272(1)
+	ld	17, -264(1)
+	ld	18, -256(1)
+	ld	19, -248(1)
+	ld	20, -240(1)
+	ld	21, -232(1)
+	ld	22, -224(1)
+	ld	23, -216(1)
+	ld	24, -208(1)
+	ld	25, -200(1)
+	ld	26, -192(1)
+	ld	27, -184(1)
+	ld	28, -176(1)
+	ld	29, -168(1)
+	ld	30, -160(1)
+	ld	31, -152(1)
+	lfd	14, -144(1)
+	lfd	15, -136(1)
+	lfd	16, -128(1)
+	lfd	17, -120(1)
+	lfd	18, -112(1)
+	lfd	19, -104(1)
+	lfd	20, -96(1)
+	lfd	21, -88(1)
+	lfd	22, -80(1)
+	lfd	23, -72(1)
+	lfd	24, -64(1)
+	lfd	25, -56(1)
+	lfd	26, -48(1)
+	lfd	27, -40(1)
+	lfd	28, -32(1)
+	lfd	29, -24(1)
+	lfd	30, -16(1)
+	lfd	31, -8(1)
+
+	blr

src/runtime/cgo/gcc_aix_ppc64.c

@@ -0,0 +1,35 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+ * On AIX, call to _cgo_topofstack and Go main are forced to be a longcall.
+ * Without it, ld might add trampolines in the middle of .text section
+ * to reach these functions which are normally declared in runtime package.
+ */
+extern int __attribute__((longcall)) __cgo_topofstack(void);
+extern int __attribute__((longcall)) runtime_rt0_go(int argc, char **argv);
+extern void __attribute__((longcall)) _rt0_ppc64_aix_lib(void);
+
+int _cgo_topofstack(void) {
+	return __cgo_topofstack();
+}
+
+int main(int argc, char **argv) {
+	return runtime_rt0_go(argc, argv);
+}
+
+static void libinit(void) __attribute__ ((constructor));
+
+/*
+ * libinit aims to replace .init_array section which isn't available on aix.
+ * Using __attribute__ ((constructor)) let gcc handles this instead of
+ * adding special code in cmd/link.
+ * However, it will be called for every Go programs which has cgo.
+ * Inside _rt0_ppc64_aix_lib(), runtime.isarchive is checked in order
+ * to know if this program is a c-archive or a simple cgo program.
+ * If it's not set, _rt0_ppc64_ax_lib() returns directly.
+ */
+static void libinit() {
+	_rt0_ppc64_aix_lib();
+}

src/runtime/cgo/gcc_amd64.S

@@ -0,0 +1,55 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_amd64.S"
+
+/*
+ * Apple still insists on underscore prefixes for C function names.
+ */
+#if defined(__APPLE__)
+#define EXT(s) _##s
+#else
+#define EXT(s) s
+#endif
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard x86-64 ABI, where %rbx, %rbp, %r12-%r15
+ * are callee-save so they must be saved explicitly.
+ * The standard x86-64 ABI passes the three arguments m, g, fn
+ * in %rdi, %rsi, %rdx.
+ */
+.globl EXT(crosscall1)
+EXT(crosscall1):
+	pushq %rbx
+	pushq %rbp
+	pushq %r12
+	pushq %r13
+	pushq %r14
+	pushq %r15
+
+#if defined(_WIN64)
+	movq %r8, %rdi	/* arg of setg_gcc */
+	call *%rdx	/* setg_gcc */
+	call *%rcx	/* fn */
+#else
+	movq %rdi, %rbx
+	movq %rdx, %rdi	/* arg of setg_gcc */
+	call *%rsi	/* setg_gcc */
+	call *%rbx	/* fn */
+#endif
+
+	popq %r15
+	popq %r14
+	popq %r13
+	popq %r12
+	popq %rbp
+	popq %rbx
+	ret
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",@progbits
+#endif

src/runtime/cgo/gcc_android.c

@@ -0,0 +1,90 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <stdarg.h>
+#include <android/log.h>
+#include <pthread.h>
+#include <dlfcn.h>
+#include "libcgo.h"
+
+void
+fatalf(const char* format, ...)
+{
+	va_list ap;
+
+	// Write to both stderr and logcat.
+	//
+	// When running from an .apk, /dev/stderr and /dev/stdout
+	// redirect to /dev/null. And when running a test binary
+	// via adb shell, it's easy to miss logcat.
+
+	fprintf(stderr, "runtime/cgo: ");
+	va_start(ap, format);
+	vfprintf(stderr, format, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+
+	va_start(ap, format);
+	__android_log_vprint(ANDROID_LOG_FATAL, "runtime/cgo", format, ap);
+	va_end(ap);
+
+	abort();
+}
+
+// Truncated to a different magic value on 32-bit; that's ok.
+#define magic1 (0x23581321345589ULL)
+
+// From https://android.googlesource.com/platform/bionic/+/refs/heads/android10-tests-release/libc/private/bionic_asm_tls.h#69.
+#define TLS_SLOT_APP 2
+
+// inittls allocates a thread-local storage slot for g.
+//
+// It finds the first available slot using pthread_key_create and uses
+// it as the offset value for runtime.tls_g.
+static void
+inittls(void **tlsg, void **tlsbase)
+{
+	pthread_key_t k;
+	int i, err;
+	void *handle, *get_ver, *off;
+
+	// Check for Android Q where we can use the free TLS_SLOT_APP slot.
+	handle = dlopen("libc.so", RTLD_LAZY);
+	if (handle == NULL) {
+		fatalf("inittls: failed to dlopen main program");
+		return;
+	}
+	// android_get_device_api_level is introduced in Android Q, so its mere presence
+	// is enough.
+	get_ver = dlsym(handle, "android_get_device_api_level");
+	dlclose(handle);
+	if (get_ver != NULL) {
+		off = (void *)(TLS_SLOT_APP*sizeof(void *));
+		// tlsg is initialized to Q's free TLS slot. Verify it while we're here.
+		if (*tlsg != off) {
+			fatalf("tlsg offset wrong, got %ld want %ld\n", *tlsg, off);
+		}
+		return;
+	}
+
+	err = pthread_key_create(&k, nil);
+	if(err != 0) {
+		fatalf("pthread_key_create failed: %d", err);
+	}
+	pthread_setspecific(k, (void*)magic1);
+	// If thread local slots are laid out as we expect, our magic word will
+	// be located at some low offset from tlsbase. However, just in case something went
+	// wrong, the search is limited to sensible offsets. PTHREAD_KEYS_MAX was the
+	// original limit, but issue 19472 made a higher limit necessary.
+	for (i=0; i<384; i++) {
+		if (*(tlsbase+i) == (void*)magic1) {
+			*tlsg = (void*)(i*sizeof(void *));
+			pthread_setspecific(k, 0);
+			return;
+		}
+	}
+	fatalf("inittls: could not find pthread key");
+}
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase) = inittls;

src/runtime/cgo/gcc_arm.S

@@ -0,0 +1,31 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_arm.S"
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard ARM EABI, where r4-r11 are callee-save, so they
+ * must be saved explicitly.
+ */
+.globl crosscall1
+crosscall1:
+	push {r4, r5, r6, r7, r8, r9, r10, r11, ip, lr}
+	mov r4, r0
+	mov r5, r1
+	mov r0, r2
+
+	// Because the assembler might target an earlier revision of the ISA
+	// by default, we encode BLX as a .word.
+	.word 0xe12fff35 // blx r5 // setg(g)
+	.word 0xe12fff34 // blx r4 // fn()
+
+	pop {r4, r5, r6, r7, r8, r9, r10, r11, ip, pc}
+
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_arm64.S

@@ -0,0 +1,84 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_arm64.S"
+
+/*
+ * Apple still insists on underscore prefixes for C function names.
+ */
+#if defined(__APPLE__)
+#define EXT(s) _##s
+#else
+#define EXT(s) s
+#endif
+
+// Apple's ld64 wants 4-byte alignment for ARM code sections.
+// .align in both Apple as and GNU as treat n as aligning to 2**n bytes.
+.align	2
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard ARM EABI, where x19-x29 are callee-save, so they
+ * must be saved explicitly, along with x30 (LR).
+ */
+.globl EXT(crosscall1)
+EXT(crosscall1):
+	.cfi_startproc
+	stp x29, x30, [sp, #-96]!
+	.cfi_def_cfa_offset 96
+	.cfi_offset 29, -96
+	.cfi_offset 30, -88
+	mov x29, sp
+	.cfi_def_cfa_register 29
+	stp x19, x20, [sp, #80]
+	.cfi_offset 19, -16
+	.cfi_offset 20, -8
+	stp x21, x22, [sp, #64]
+	.cfi_offset 21, -32
+	.cfi_offset 22, -24
+	stp x23, x24, [sp, #48]
+	.cfi_offset 23, -48
+	.cfi_offset 24, -40
+	stp x25, x26, [sp, #32]
+	.cfi_offset 25, -64
+	.cfi_offset 26, -56
+	stp x27, x28, [sp, #16]
+	.cfi_offset 27, -80
+	.cfi_offset 28, -72
+
+	mov x19, x0
+	mov x20, x1
+	mov x0, x2
+
+	blr x20
+	blr x19
+
+	ldp x27, x28, [sp, #16]
+	.cfi_restore 27
+	.cfi_restore 28
+	ldp x25, x26, [sp, #32]
+	.cfi_restore 25
+	.cfi_restore 26
+	ldp x23, x24, [sp, #48]
+	.cfi_restore 23
+	.cfi_restore 24
+	ldp x21, x22, [sp, #64]
+	.cfi_restore 21
+	.cfi_restore 22
+	ldp x19, x20, [sp, #80]
+	.cfi_restore 19
+	.cfi_restore 20
+	ldp x29, x30, [sp], #96
+	.cfi_restore 29
+	.cfi_restore 30
+	.cfi_def_cfa 31, 0
+	ret
+	.cfi_endproc
+
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_context.c

@@ -0,0 +1,20 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix || windows
+
+#include "libcgo.h"
+
+// Releases the cgo traceback context.
+void _cgo_release_context(uintptr_t ctxt) {
+	void (*pfn)(struct context_arg*);
+
+	pfn = _cgo_get_context_function();
+	if (ctxt != 0 && pfn != nil) {
+		struct context_arg arg;
+
+		arg.Context = ctxt;
+		(*pfn)(&arg);
+	}
+}

src/runtime/cgo/gcc_darwin_amd64.c

@@ -0,0 +1,60 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <string.h> /* for strerror */
+#include <pthread.h>
+#include <signal.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	size = pthread_get_stacksize_np(pthread_self());
+	pthread_attr_init(&attr);
+	pthread_attr_setstacksize(&attr, size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
+		abort();
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_darwin_arm64.c

@@ -0,0 +1,139 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <limits.h>
+#include <pthread.h>
+#include <signal.h>
+#include <string.h> /* for strerror */
+#include <sys/param.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+#include <TargetConditionals.h>
+
+#if TARGET_OS_IPHONE
+#include <CoreFoundation/CFBundle.h>
+#include <CoreFoundation/CFString.h>
+#endif
+
+static void *threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	//fprintf(stderr, "runtime/cgo: _cgo_sys_thread_start: fn=%p, g=%p\n", ts->fn, ts->g); // debug
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	size = pthread_get_stacksize_np(pthread_self());
+	pthread_attr_init(&attr);
+	pthread_attr_setstacksize(&attr, size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
+		abort();
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+#if TARGET_OS_IPHONE
+	darwin_arm_init_thread_exception_port();
+#endif
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}
+
+#if TARGET_OS_IPHONE
+
+// init_working_dir sets the current working directory to the app root.
+// By default ios/arm64 processes start in "/".
+static void
+init_working_dir()
+{
+	CFBundleRef bundle = CFBundleGetMainBundle();
+	if (bundle == NULL) {
+		fprintf(stderr, "runtime/cgo: no main bundle\n");
+		return;
+	}
+	CFURLRef url_ref = CFBundleCopyResourceURL(bundle, CFSTR("Info"), CFSTR("plist"), NULL);
+	if (url_ref == NULL) {
+		// No Info.plist found. It can happen on Corellium virtual devices.
+		return;
+	}
+	CFStringRef url_str_ref = CFURLGetString(url_ref);
+	char buf[MAXPATHLEN];
+	Boolean res = CFStringGetCString(url_str_ref, buf, sizeof(buf), kCFStringEncodingUTF8);
+	CFRelease(url_ref);
+	if (!res) {
+		fprintf(stderr, "runtime/cgo: cannot get URL string\n");
+		return;
+	}
+
+	// url is of the form "file:///path/to/Info.plist".
+	// strip it down to the working directory "/path/to".
+	int url_len = strlen(buf);
+	if (url_len < sizeof("file://")+sizeof("/Info.plist")) {
+		fprintf(stderr, "runtime/cgo: bad URL: %s\n", buf);
+		return;
+	}
+	buf[url_len-sizeof("/Info.plist")+1] = 0;
+	char *dir = &buf[0] + sizeof("file://")-1;
+
+	if (chdir(dir) != 0) {
+		fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", dir);
+	}
+
+	// The test harness in go_ios_exec passes the relative working directory
+	// in the GoExecWrapperWorkingDirectory property of the app bundle.
+	CFStringRef wd_ref = CFBundleGetValueForInfoDictionaryKey(bundle, CFSTR("GoExecWrapperWorkingDirectory"));
+	if (wd_ref != NULL) {
+		if (!CFStringGetCString(wd_ref, buf, sizeof(buf), kCFStringEncodingUTF8)) {
+			fprintf(stderr, "runtime/cgo: cannot get GoExecWrapperWorkingDirectory string\n");
+			return;
+		}
+		if (chdir(buf) != 0) {
+			fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", buf);
+		}
+	}
+}
+
+#endif // TARGET_OS_IPHONE
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	//fprintf(stderr, "x_cgo_init = %p\n", &x_cgo_init); // aid debugging in presence of ASLR
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+
+#if TARGET_OS_IPHONE
+	darwin_arm_init_mach_exception_handler();
+	darwin_arm_init_thread_exception_port();
+	init_working_dir();
+#endif
+}

src/runtime/cgo/gcc_dragonfly_amd64.c

@@ -0,0 +1,60 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <sys/types.h>
+#include <sys/signalvar.h>
+#include <pthread.h>
+#include <signal.h>
+#include <string.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	SIGFILLSET(ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_fatalf.c

@@ -0,0 +1,23 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build aix || (!android && linux) || dragonfly || freebsd || netbsd || openbsd || solaris
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "libcgo.h"
+
+void
+fatalf(const char* format, ...)
+{
+	va_list ap;
+
+	fprintf(stderr, "runtime/cgo: ");
+	va_start(ap, format);
+	vfprintf(stderr, format, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+	abort();
+}

src/runtime/cgo/gcc_freebsd.c

@@ -0,0 +1,71 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build freebsd && (386 || arm || arm64 || riscv64)
+
+#include <sys/types.h>
+#include <sys/signalvar.h>
+#include <machine/sysarch.h>
+#include <pthread.h>
+#include <signal.h>
+#include <string.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+#ifdef ARM_TP_ADDRESS
+// ARM_TP_ADDRESS is (ARM_VECTORS_HIGH + 0x1000) or 0xffff1000
+// and is known to runtime.read_tls_fallback. Verify it with
+// cpp.
+#if ARM_TP_ADDRESS != 0xffff1000
+#error Wrong ARM_TP_ADDRESS!
+#endif
+#endif
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	SIGFILLSET(ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_freebsd_amd64.c

@@ -0,0 +1,71 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <sys/types.h>
+#include <errno.h>
+#include <sys/signalvar.h>
+#include <pthread.h>
+#include <signal.h>
+#include <string.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	uintptr *pbounds;
+
+	// Deal with memory sanitizer/clang interaction.
+	// See gcc_linux_amd64.c for details.
+	setg_gcc = setg;
+	pbounds = (uintptr*)malloc(2 * sizeof(uintptr));
+	if (pbounds == NULL) {
+		fatalf("malloc failed: %s", strerror(errno));
+	}
+	_cgo_set_stacklo(g, pbounds);
+	free(pbounds);
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	SIGFILLSET(ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	_cgo_tsan_acquire();
+	free(v);
+	_cgo_tsan_release();
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_freebsd_sigaction.c

@@ -0,0 +1,80 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build freebsd && amd64
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include <signal.h>
+
+#include "libcgo.h"
+
+// go_sigaction_t is a C version of the sigactiont struct from
+// os_freebsd.go.  This definition — and its conversion to and from struct
+// sigaction — are specific to freebsd/amd64.
+typedef struct {
+        uint32_t __bits[_SIG_WORDS];
+} go_sigset_t;
+typedef struct {
+	uintptr_t handler;
+	int32_t flags;
+	go_sigset_t mask;
+} go_sigaction_t;
+
+int32_t
+x_cgo_sigaction(intptr_t signum, const go_sigaction_t *goact, go_sigaction_t *oldgoact) {
+	int32_t ret;
+	struct sigaction act;
+	struct sigaction oldact;
+	size_t i;
+
+	_cgo_tsan_acquire();
+
+	memset(&act, 0, sizeof act);
+	memset(&oldact, 0, sizeof oldact);
+
+	if (goact) {
+		if (goact->flags & SA_SIGINFO) {
+			act.sa_sigaction = (void(*)(int, siginfo_t*, void*))(goact->handler);
+		} else {
+			act.sa_handler = (void(*)(int))(goact->handler);
+		}
+		sigemptyset(&act.sa_mask);
+		for (i = 0; i < 8 * sizeof(goact->mask); i++) {
+			if (goact->mask.__bits[i/32] & ((uint32_t)(1)<<(i&31))) {
+				sigaddset(&act.sa_mask, i+1);
+			}
+		}
+		act.sa_flags = goact->flags;
+	}
+
+	ret = sigaction(signum, goact ? &act : NULL, oldgoact ? &oldact : NULL);
+	if (ret == -1) {
+		// runtime.sigaction expects _cgo_sigaction to return errno on error.
+		_cgo_tsan_release();
+		return errno;
+	}
+
+	if (oldgoact) {
+		if (oldact.sa_flags & SA_SIGINFO) {
+			oldgoact->handler = (uintptr_t)(oldact.sa_sigaction);
+		} else {
+			oldgoact->handler = (uintptr_t)(oldact.sa_handler);
+		}
+		for (i = 0 ; i < _SIG_WORDS; i++) {
+			oldgoact->mask.__bits[i] = 0;
+		}
+		for (i = 0; i < 8 * sizeof(oldgoact->mask); i++) {
+			if (sigismember(&oldact.sa_mask, i+1) == 1) {
+				oldgoact->mask.__bits[i/32] |= (uint32_t)(1)<<(i&31);
+			}
+		}
+		oldgoact->flags = oldact.sa_flags;
+	}
+
+	_cgo_tsan_release();
+	return ret;
+}

src/runtime/cgo/gcc_libinit.c

@@ -0,0 +1,178 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+// When cross-compiling with clang to linux/armv5, atomics are emulated
+// and cause a compiler warning. This results in a build failure since
+// cgo uses -Werror. See #65290.
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wunknown-warning-option"
+#pragma GCC diagnostic ignored "-Watomic-alignment"
+
+#include <pthread.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h> // strerror
+#include <time.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER;
+static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
+static int runtime_init_done;
+
+// pthread_g is a pthread specific key, for storing the g that binded to the C thread.
+// The registered pthread_key_destructor will dropm, when the pthread-specified value g is not NULL,
+// while a C thread is exiting.
+static pthread_key_t pthread_g;
+static void pthread_key_destructor(void* g);
+uintptr_t x_cgo_pthread_key_created;
+void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
+
+// The context function, used when tracing back C calls into Go.
+static void (*cgo_context_function)(struct context_arg*);
+
+void
+x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
+	pthread_t p;
+	int err = _cgo_try_pthread_create(&p, NULL, func, arg);
+	if (err != 0) {
+		fprintf(stderr, "pthread_create failed: %s", strerror(err));
+		abort();
+	}
+}
+
+uintptr_t
+_cgo_wait_runtime_init_done(void) {
+	void (*pfn)(struct context_arg*);
+	pfn = __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
+
+	int done = 2;
+	if (__atomic_load_n(&runtime_init_done, __ATOMIC_CONSUME) != done) {
+		pthread_mutex_lock(&runtime_init_mu);
+		while (__atomic_load_n(&runtime_init_done, __ATOMIC_CONSUME) == 0) {
+			pthread_cond_wait(&runtime_init_cond, &runtime_init_mu);
+		}
+
+		// The key and x_cgo_pthread_key_created are for the whole program,
+		// whereas the specific and destructor is per thread.
+		if (x_cgo_pthread_key_created == 0 && pthread_key_create(&pthread_g, pthread_key_destructor) == 0) {
+			x_cgo_pthread_key_created = 1;
+		}
+
+
+		// TODO(iant): For the case of a new C thread calling into Go, such
+		// as when using -buildmode=c-archive, we know that Go runtime
+		// initialization is complete but we do not know that all Go init
+		// functions have been run. We should not fetch cgo_context_function
+		// until they have been, because that is where a call to
+		// SetCgoTraceback is likely to occur. We are going to wait for Go
+		// initialization to be complete anyhow, later, by waiting for
+		// main_init_done to be closed in cgocallbackg1. We should wait here
+		// instead. See also issue #15943.
+		pfn = __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
+
+		__atomic_store_n(&runtime_init_done, done, __ATOMIC_RELEASE);
+		pthread_mutex_unlock(&runtime_init_mu);
+	}
+
+	if (pfn != nil) {
+		struct context_arg arg;
+
+		arg.Context = 0;
+		(*pfn)(&arg);
+		return arg.Context;
+	}
+	return 0;
+}
+
+// _cgo_set_stacklo sets g->stacklo based on the stack size.
+// This is common code called from x_cgo_init, which is itself
+// called by rt0_go in the runtime package.
+void _cgo_set_stacklo(G *g, uintptr *pbounds)
+{
+	uintptr bounds[2];
+
+	// pbounds can be passed in by the caller; see gcc_linux_amd64.c.
+	if (pbounds == NULL) {
+		pbounds = &bounds[0];
+	}
+
+	x_cgo_getstackbound(pbounds);
+
+	g->stacklo = *pbounds;
+
+	// Sanity check the results now, rather than getting a
+	// morestack on g0 crash.
+	if (g->stacklo >= g->stackhi) {
+		fprintf(stderr, "runtime/cgo: bad stack bounds: lo=%p hi=%p\n", (void*)(g->stacklo), (void*)(g->stackhi));
+		abort();
+	}
+}
+
+// Store the g into a thread-specific value associated with the pthread key pthread_g.
+// And pthread_key_destructor will dropm when the thread is exiting.
+void x_cgo_bindm(void* g) {
+	// We assume this will always succeed, otherwise, there might be extra M leaking,
+	// when a C thread exits after a cgo call.
+	// We only invoke this function once per thread in runtime.needAndBindM,
+	// and the next calls just reuse the bound m.
+	pthread_setspecific(pthread_g, g);
+}
+
+void
+x_cgo_notify_runtime_init_done(void* dummy __attribute__ ((unused))) {
+	pthread_mutex_lock(&runtime_init_mu);
+	__atomic_store_n(&runtime_init_done, 1, __ATOMIC_RELEASE);
+	pthread_cond_broadcast(&runtime_init_cond);
+	pthread_mutex_unlock(&runtime_init_mu);
+}
+
+// Sets the context function to call to record the traceback context
+// when calling a Go function from C code. Called from runtime.SetCgoTraceback.
+void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
+	__atomic_store_n(&cgo_context_function, context, __ATOMIC_RELEASE);
+}
+
+// Gets the context function.
+void (*(_cgo_get_context_function(void)))(struct context_arg*) {
+	return __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
+}
+
+// _cgo_try_pthread_create retries pthread_create if it fails with
+// EAGAIN.
+int
+_cgo_try_pthread_create(pthread_t* thread, const pthread_attr_t* attr, void* (*pfn)(void*), void* arg) {
+	int tries;
+	int err;
+	struct timespec ts;
+
+	for (tries = 0; tries < 20; tries++) {
+		err = pthread_create(thread, attr, pfn, arg);
+		if (err == 0) {
+			pthread_detach(*thread);
+			return 0;
+		}
+		if (err != EAGAIN) {
+			return err;
+		}
+		ts.tv_sec = 0;
+		ts.tv_nsec = (tries + 1) * 1000 * 1000; // Milliseconds.
+		nanosleep(&ts, nil);
+	}
+	return EAGAIN;
+}
+
+static void
+pthread_key_destructor(void* g) {
+	if (x_crosscall2_ptr != NULL) {
+		// fn == NULL means dropm.
+		// We restore g by using the stored g, before dropm in runtime.cgocallback,
+		// since the g stored in the TLS by Go might be cleared in some platforms,
+		// before this destructor invoked.
+		x_crosscall2_ptr(NULL, g, 0, 0);
+	}
+}

src/runtime/cgo/gcc_libinit_windows.c

@@ -0,0 +1,158 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <process.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include "libcgo.h"
+#include "libcgo_windows.h"
+
+// Ensure there's one symbol marked __declspec(dllexport).
+// If there are no exported symbols, the unfortunate behavior of
+// the binutils linker is to also strip the relocations table,
+// resulting in non-PIE binary. The other option is the
+// --export-all-symbols flag, but we don't need to export all symbols
+// and this may overflow the export table (#40795).
+// See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
+__declspec(dllexport) int _cgo_dummy_export;
+
+static volatile LONG runtime_init_once_gate = 0;
+static volatile LONG runtime_init_once_done = 0;
+
+static CRITICAL_SECTION runtime_init_cs;
+
+static HANDLE runtime_init_wait;
+static int runtime_init_done;
+
+uintptr_t x_cgo_pthread_key_created;
+void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
+
+// Pre-initialize the runtime synchronization objects
+void
+_cgo_preinit_init() {
+	 runtime_init_wait = CreateEvent(NULL, TRUE, FALSE, NULL);
+	 if (runtime_init_wait == NULL) {
+		fprintf(stderr, "runtime: failed to create runtime initialization wait event.\n");
+		abort();
+	 }
+
+	 InitializeCriticalSection(&runtime_init_cs);
+}
+
+// Make sure that the preinit sequence has run.
+void
+_cgo_maybe_run_preinit() {
+	 if (!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
+			if (InterlockedIncrement(&runtime_init_once_gate) == 1) {
+				 _cgo_preinit_init();
+				 InterlockedIncrement(&runtime_init_once_done);
+			} else {
+				 // Decrement to avoid overflow.
+				 InterlockedDecrement(&runtime_init_once_gate);
+				 while(!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
+						Sleep(0);
+				 }
+			}
+	 }
+}
+
+void
+x_cgo_sys_thread_create(void (*func)(void*), void* arg) {
+	_cgo_beginthread(func, arg);
+}
+
+int
+_cgo_is_runtime_initialized() {
+	 EnterCriticalSection(&runtime_init_cs);
+	 int status = runtime_init_done;
+	 LeaveCriticalSection(&runtime_init_cs);
+	 return status;
+}
+
+uintptr_t
+_cgo_wait_runtime_init_done(void) {
+	void (*pfn)(struct context_arg*);
+
+	 _cgo_maybe_run_preinit();
+	while (!_cgo_is_runtime_initialized()) {
+			WaitForSingleObject(runtime_init_wait, INFINITE);
+	}
+	pfn = _cgo_get_context_function();
+	if (pfn != nil) {
+		struct context_arg arg;
+
+		arg.Context = 0;
+		(*pfn)(&arg);
+		return arg.Context;
+	}
+	return 0;
+}
+
+// Should not be used since x_cgo_pthread_key_created will always be zero.
+void x_cgo_bindm(void* dummy) {
+	fprintf(stderr, "unexpected cgo_bindm on Windows\n");
+	abort();
+}
+
+void
+x_cgo_notify_runtime_init_done(void* dummy) {
+	 _cgo_maybe_run_preinit();
+
+	 EnterCriticalSection(&runtime_init_cs);
+	runtime_init_done = 1;
+	 LeaveCriticalSection(&runtime_init_cs);
+
+	 if (!SetEvent(runtime_init_wait)) {
+		fprintf(stderr, "runtime: failed to signal runtime initialization complete.\n");
+		abort();
+	}
+}
+
+// The context function, used when tracing back C calls into Go.
+static void (*cgo_context_function)(struct context_arg*);
+
+// Sets the context function to call to record the traceback context
+// when calling a Go function from C code. Called from runtime.SetCgoTraceback.
+void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
+	EnterCriticalSection(&runtime_init_cs);
+	cgo_context_function = context;
+	LeaveCriticalSection(&runtime_init_cs);
+}
+
+// Gets the context function.
+void (*(_cgo_get_context_function(void)))(struct context_arg*) {
+	void (*ret)(struct context_arg*);
+
+	EnterCriticalSection(&runtime_init_cs);
+	ret = cgo_context_function;
+	LeaveCriticalSection(&runtime_init_cs);
+	return ret;
+}
+
+void _cgo_beginthread(void (*func)(void*), void* arg) {
+	int tries;
+	uintptr_t thandle;
+
+	for (tries = 0; tries < 20; tries++) {
+		thandle = _beginthread(func, 0, arg);
+		if (thandle == -1 && errno == EACCES) {
+			// "Insufficient resources", try again in a bit.
+			//
+			// Note that the first Sleep(0) is a yield.
+			Sleep(tries); // milliseconds
+			continue;
+		} else if (thandle == -1) {
+			break;
+		}
+		return; // Success!
+	}
+
+	fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
+	abort();
+}

src/runtime/cgo/gcc_linux.c

@@ -0,0 +1,66 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && (386 || arm || loong64 || mips || mipsle || mips64 || mips64le || riscv64)
+
+#include <pthread.h>
+#include <string.h>
+#include <signal.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void *threadentry(void*);
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase) __attribute__((common));
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	setg_gcc = setg;
+
+	_cgo_set_stacklo(g, NULL);
+
+	if (x_cgo_inittls) {
+		x_cgo_inittls(tlsg, tlsbase);
+	}
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_linux_amd64.c

@@ -0,0 +1,91 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include <errno.h>
+#include <string.h> // strerror
+#include <signal.h>
+#include <stdlib.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+// This will be set in gcc_android.c for android-specific customization.
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase) __attribute__((common));
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	uintptr *pbounds;
+
+	/* The memory sanitizer distributed with versions of clang
+	   before 3.8 has a bug: if you call mmap before malloc, mmap
+	   may return an address that is later overwritten by the msan
+	   library.  Avoid this problem by forcing a call to malloc
+	   here, before we ever call malloc.
+
+	   This is only required for the memory sanitizer, so it's
+	   unfortunate that we always run it.  It should be possible
+	   to remove this when we no longer care about versions of
+	   clang before 3.8.  The test for this is
+	   misc/cgo/testsanitizers.
+
+	   GCC works hard to eliminate a seemingly unnecessary call to
+	   malloc, so we actually use the memory we allocate.  */
+
+	setg_gcc = setg;
+	pbounds = (uintptr*)malloc(2 * sizeof(uintptr));
+	if (pbounds == NULL) {
+		fatalf("malloc failed: %s", strerror(errno));
+	}
+	_cgo_set_stacklo(g, pbounds);
+	free(pbounds);
+
+	if (x_cgo_inittls) {
+		x_cgo_inittls(tlsg, tlsbase);
+	}
+}
+
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	_cgo_tsan_acquire();
+	free(v);
+	_cgo_tsan_release();
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_linux_arm64.c

@@ -0,0 +1,87 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+#include <stdlib.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void *threadentry(void*);
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase) __attribute__((common));
+static void (*setg_gcc)(void*);
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	uintptr *pbounds;
+
+	/* The memory sanitizer distributed with versions of clang
+	   before 3.8 has a bug: if you call mmap before malloc, mmap
+	   may return an address that is later overwritten by the msan
+	   library.  Avoid this problem by forcing a call to malloc
+	   here, before we ever call malloc.
+
+	   This is only required for the memory sanitizer, so it's
+	   unfortunate that we always run it.  It should be possible
+	   to remove this when we no longer care about versions of
+	   clang before 3.8.  The test for this is
+	   misc/cgo/testsanitizers.
+
+	   GCC works hard to eliminate a seemingly unnecessary call to
+	   malloc, so we actually use the memory we allocate.  */
+
+	setg_gcc = setg;
+	pbounds = (uintptr*)malloc(2 * sizeof(uintptr));
+	if (pbounds == NULL) {
+		fatalf("malloc failed: %s", strerror(errno));
+	}
+	_cgo_set_stacklo(g, pbounds);
+	free(pbounds);
+
+	if (x_cgo_inittls) {
+		x_cgo_inittls(tlsg, tlsbase);
+	}
+}

src/runtime/cgo/gcc_linux_ppc64x.S

@@ -0,0 +1,86 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && (ppc64 || ppc64le)
+
+.file "gcc_linux_ppc64x.S"
+
+// Define a frame which has no argument space, but is compatible with
+// a call into a Go ABI. We allocate 32B to match FIXED_FRAME with
+// similar semantics, except we store the backchain pointer, not the
+// LR at offset 0. R2 is stored in the Go TOC save slot (offset 24).
+.set GPR_OFFSET, 32
+.set FPR_OFFSET, GPR_OFFSET + 18*8
+.set VR_OFFSET, FPR_OFFSET + 18*8
+.set FRAME_SIZE, VR_OFFSET + 12*16
+
+.macro FOR_EACH_GPR opcode r=14
+.ifge 31 - \r
+	\opcode \r, GPR_OFFSET + 8*(\r-14)(1)
+	FOR_EACH_GPR \opcode "(\r+1)"
+.endif
+.endm
+
+.macro FOR_EACH_FPR opcode fr=14
+.ifge 31 - \fr
+	\opcode \fr, FPR_OFFSET + 8*(\fr-14)(1)
+	FOR_EACH_FPR \opcode "(\fr+1)"
+.endif
+.endm
+
+.macro FOR_EACH_VR opcode vr=20
+.ifge 31 - \vr
+	li 0, VR_OFFSET + 16*(\vr-20)
+	\opcode \vr, 1, 0
+	FOR_EACH_VR \opcode "(\vr+1)"
+.endif
+.endm
+
+/*
+ * void crosscall_ppc64(void (*fn)(void), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard ppc64 C ABI, where r2, r14-r31, f14-f31 are
+ * callee-save, so they must be saved explicitly.
+ */
+.globl crosscall_ppc64
+crosscall_ppc64:
+	// Start with standard C stack frame layout and linkage
+	mflr	%r0
+	std	%r0, 16(%r1)	// Save LR in caller's frame
+	mfcr	%r0
+	std	%r0, 8(%r1)	// Save CR in caller's frame
+	stdu	%r1, -FRAME_SIZE(%r1)
+	std	%r2, 24(%r1)
+
+	FOR_EACH_GPR std
+	FOR_EACH_FPR stfd
+	FOR_EACH_VR stvx
+
+	// Set up Go ABI constant registers
+	li	%r0, 0
+
+	// Restore g pointer (r30 in Go ABI, which may have been clobbered by C)
+	mr	%r30, %r4
+
+	// Call fn
+	mr	%r12, %r3
+	mtctr	%r3
+	bctrl
+
+	FOR_EACH_GPR ld
+	FOR_EACH_FPR lfd
+	FOR_EACH_VR lvx
+
+	ld	%r2, 24(%r1)
+	addi	%r1, %r1, FRAME_SIZE
+	ld	%r0, 16(%r1)
+	mtlr	%r0
+	ld	%r0, 8(%r1)
+	mtcr	%r0
+	blr
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_linux_s390x.c

@@ -0,0 +1,63 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include <string.h>
+#include <signal.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void *threadentry(void*);
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsbase)
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall_s390x(void (*fn)(void), void *g);
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	// Save g for this thread in C TLS
+	setg_gcc((void*)ts.g);
+
+	crosscall_s390x(ts.fn, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_loong64.S

@@ -0,0 +1,67 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_loong64.S"
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard lp64d ABI, where $r1, $r3, $r23-$r30, and $f24-$f31
+ * are callee-save, so they must be saved explicitly, along with $r1 (LR).
+ */
+.globl crosscall1
+crosscall1:
+	addi.d	$r3, $r3, -160
+	st.d	$r1, $r3, 0
+	st.d	$r23, $r3, 8
+	st.d	$r24, $r3, 16
+	st.d	$r25, $r3, 24
+	st.d	$r26, $r3, 32
+	st.d	$r27, $r3, 40
+	st.d	$r28, $r3, 48
+	st.d	$r29, $r3, 56
+	st.d	$r30, $r3, 64
+	st.d	$r2, $r3, 72
+	st.d	$r22, $r3, 80
+	fst.d	$f24, $r3, 88
+	fst.d	$f25, $r3, 96
+	fst.d	$f26, $r3, 104
+	fst.d	$f27, $r3, 112
+	fst.d	$f28, $r3, 120
+	fst.d	$f29, $r3, 128
+	fst.d	$f30, $r3, 136
+	fst.d	$f31, $r3, 144
+
+	move	$r18, $r4 // save R4
+	move	$r19, $r6
+	jirl	$r1, $r5, 0	// call setg_gcc (clobbers R4)
+	jirl	$r1, $r18, 0	// call fn
+
+	ld.d	$r23, $r3, 8
+	ld.d	$r24, $r3, 16
+	ld.d	$r25, $r3, 24
+	ld.d	$r26, $r3, 32
+	ld.d	$r27, $r3, 40
+	ld.d	$r28, $r3, 48
+	ld.d	$r29, $r3, 56
+	ld.d	$r30, $r3, 64
+	ld.d	$r2, $r3, 72
+	ld.d	$r22, $r3, 80
+	fld.d	$f24, $r3, 88
+	fld.d	$f25, $r3, 96
+	fld.d	$f26, $r3, 104
+	fld.d	$f27, $r3, 112
+	fld.d	$f28, $r3, 120
+	fld.d	$f29, $r3, 128
+	fld.d	$f30, $r3, 136
+	fld.d	$f31, $r3, 144
+	ld.d	$r1, $r3, 0
+	addi.d	$r3, $r3, 160
+	jirl	$r0, $r1, 0
+
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_mips64x.S

@@ -0,0 +1,89 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips64 || mips64le
+
+.file "gcc_mips64x.S"
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard MIPS N64 ABI, where $16-$23, $28, $30, and $f24-$f31
+ * are callee-save, so they must be saved explicitly, along with $31 (LR).
+ */
+.globl crosscall1
+.set noat
+crosscall1:
+#ifndef __mips_soft_float
+	daddiu	$29, $29, -160
+#else
+	daddiu	$29, $29, -96 // For soft-float, no need to make room for FP registers
+#endif
+	sd	$31, 0($29)
+	sd	$16, 8($29)
+	sd	$17, 16($29)
+	sd	$18, 24($29)
+	sd	$19, 32($29)
+	sd	$20, 40($29)
+	sd	$21, 48($29)
+	sd	$22, 56($29)
+	sd	$23, 64($29)
+	sd	$28, 72($29)
+	sd	$30, 80($29)
+#ifndef __mips_soft_float
+	sdc1	$f24, 88($29)
+	sdc1	$f25, 96($29)
+	sdc1	$f26, 104($29)
+	sdc1	$f27, 112($29)
+	sdc1	$f28, 120($29)
+	sdc1	$f29, 128($29)
+	sdc1	$f30, 136($29)
+	sdc1	$f31, 144($29)
+#endif
+
+	// prepare SB register = pc & 0xffffffff00000000
+	bal	1f
+1:
+	dsrl	$28, $31, 32
+	dsll	$28, $28, 32
+
+	move	$20, $4 // save R4
+	move	$1, $6
+	jalr	$5	// call setg_gcc (clobbers R4)
+	jalr	$20	// call fn
+
+	ld	$16, 8($29)
+	ld	$17, 16($29)
+	ld	$18, 24($29)
+	ld	$19, 32($29)
+	ld	$20, 40($29)
+	ld	$21, 48($29)
+	ld	$22, 56($29)
+	ld	$23, 64($29)
+	ld	$28, 72($29)
+	ld	$30, 80($29)
+#ifndef __mips_soft_float
+	ldc1	$f24, 88($29)
+	ldc1	$f25, 96($29)
+	ldc1	$f26, 104($29)
+	ldc1	$f27, 112($29)
+	ldc1	$f28, 120($29)
+	ldc1	$f29, 128($29)
+	ldc1	$f30, 136($29)
+	ldc1	$f31, 144($29)
+#endif
+	ld	$31, 0($29)
+#ifndef __mips_soft_float
+	daddiu	$29, $29, 160
+#else
+	daddiu	$29, $29, 96
+#endif
+	jr	$31
+
+.set at
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_mipsx.S

@@ -0,0 +1,77 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build mips || mipsle
+
+.file "gcc_mipsx.S"
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard MIPS O32 ABI, where $16-$23, $30, and $f20-$f31
+ * are callee-save, so they must be saved explicitly, along with $31 (LR).
+ */
+.globl crosscall1
+.set noat
+crosscall1:
+#ifndef __mips_soft_float
+	addiu	$29, $29, -88
+#else
+	addiu	$29, $29, -40 // For soft-float, no need to make room for FP registers
+#endif
+	sw	$31, 0($29)
+	sw	$16, 4($29)
+	sw	$17, 8($29)
+	sw	$18, 12($29)
+	sw	$19, 16($29)
+	sw	$20, 20($29)
+	sw	$21, 24($29)
+	sw	$22, 28($29)
+	sw	$23, 32($29)
+	sw	$30, 36($29)
+
+#ifndef __mips_soft_float
+	sdc1	$f20, 40($29)
+	sdc1	$f22, 48($29)
+	sdc1	$f24, 56($29)
+	sdc1	$f26, 64($29)
+	sdc1	$f28, 72($29)
+	sdc1	$f30, 80($29)
+#endif
+	move	$20, $4 // save R4
+	move	$4, $6
+	jalr	$5	// call setg_gcc
+	jalr	$20	// call fn
+
+	lw	$16, 4($29)
+	lw	$17, 8($29)
+	lw	$18, 12($29)
+	lw	$19, 16($29)
+	lw	$20, 20($29)
+	lw	$21, 24($29)
+	lw	$22, 28($29)
+	lw	$23, 32($29)
+	lw	$30, 36($29)
+#ifndef __mips_soft_float
+	ldc1	$f20, 40($29)
+	ldc1	$f22, 48($29)
+	ldc1	$f24, 56($29)
+	ldc1	$f26, 64($29)
+	ldc1	$f28, 72($29)
+	ldc1	$f30, 80($29)
+#endif
+	lw	$31, 0($29)
+#ifndef __mips_soft_float
+	addiu	$29, $29, 88
+#else
+	addiu	$29, $29, 40
+#endif
+	jr	$31
+
+.set at
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_mmap.c

@@ -0,0 +1,39 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (linux && (amd64 || arm64 || loong64 || ppc64le)) || (freebsd && amd64)
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+#include "libcgo.h"
+
+uintptr_t
+x_cgo_mmap(void *addr, uintptr_t length, int32_t prot, int32_t flags, int32_t fd, uint32_t offset) {
+	void *p;
+
+	_cgo_tsan_acquire();
+	p = mmap(addr, length, prot, flags, fd, offset);
+	_cgo_tsan_release();
+	if (p == MAP_FAILED) {
+		/* This is what the Go code expects on failure.  */
+		return (uintptr_t)errno;
+	}
+	return (uintptr_t)p;
+}
+
+void
+x_cgo_munmap(void *addr, uintptr_t length) {
+	int r;
+
+	_cgo_tsan_acquire();
+	r = munmap(addr, length);
+	_cgo_tsan_release();
+	if (r < 0) {
+		/* The Go runtime is not prepared for munmap to fail.  */
+		abort();
+	}
+}

src/runtime/cgo/gcc_netbsd.c

@@ -0,0 +1,73 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build netbsd && (386 || amd64 || arm || arm64)
+
+#include <sys/types.h>
+#include <pthread.h>
+#include <signal.h>
+#include <string.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+	stack_t ss;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	// On NetBSD, a new thread inherits the signal stack of the
+	// creating thread. That confuses minit, so we remove that
+	// signal stack here before calling the regular mstart. It's
+	// a bit baroque to remove a signal stack here only to add one
+	// in minit, but it's a simple change that keeps NetBSD
+	// working like other OS's. At this point all signals are
+	// blocked, so there is no race.
+	memset(&ss, 0, sizeof ss);
+	ss.ss_flags = SS_DISABLE;
+	sigaltstack(&ss, nil);
+
+	crosscall1(ts.fn, setg_gcc, ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_openbsd.c

@@ -0,0 +1,61 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build openbsd && (386 || arm || amd64 || arm64 || riscv64)
+
+#include <sys/types.h>
+#include <pthread.h>
+#include <signal.h>
+#include <string.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_ppc64x.c

@@ -0,0 +1,67 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ppc64 || ppc64le
+
+#include <pthread.h>
+#include <string.h>
+#include <signal.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void *threadentry(void*);
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsbase)
+{
+	setg_gcc = setg;
+	_cgo_set_stacklo(g, NULL);
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
+	ts->g->stackhi = size;
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall_ppc64(void (*fn)(void), void *g);
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	_cgo_tsan_acquire();
+	free(v);
+	_cgo_tsan_release();
+
+	// Save g for this thread in C TLS
+	setg_gcc((void*)ts.g);
+
+	crosscall_ppc64(ts.fn, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_riscv64.S

@@ -0,0 +1,82 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_riscv64.S"
+
+/*
+ * void crosscall1(void (*fn)(void), void (*setg_gcc)(void *g), void *g)
+ *
+ * Calling into the gc tool chain, where all registers are caller save.
+ * Called from standard RISCV ELF psABI, where x8-x9, x18-x27, f8-f9 and
+ * f18-f27 are callee-save, so they must be saved explicitly, along with
+ * x1 (LR).
+ */
+.globl crosscall1
+crosscall1:
+	sd	x1, -200(sp)
+	addi	sp, sp, -200
+	sd	x8, 8(sp)
+	sd	x9, 16(sp)
+	sd	x18, 24(sp)
+	sd	x19, 32(sp)
+	sd	x20, 40(sp)
+	sd	x21, 48(sp)
+	sd	x22, 56(sp)
+	sd	x23, 64(sp)
+	sd	x24, 72(sp)
+	sd	x25, 80(sp)
+	sd	x26, 88(sp)
+	sd	x27, 96(sp)
+	fsd	f8, 104(sp)
+	fsd	f9, 112(sp)
+	fsd	f18, 120(sp)
+	fsd	f19, 128(sp)
+	fsd	f20, 136(sp)
+	fsd	f21, 144(sp)
+	fsd	f22, 152(sp)
+	fsd	f23, 160(sp)
+	fsd	f24, 168(sp)
+	fsd	f25, 176(sp)
+	fsd	f26, 184(sp)
+	fsd	f27, 192(sp)
+
+	// a0 = *fn, a1 = *setg_gcc, a2 = *g
+	mv	s1, a0
+	mv	s0, a1
+	mv	a0, a2
+	jalr	ra, s0	// call setg_gcc (clobbers x30 aka g)
+	jalr	ra, s1	// call fn
+
+	ld	x1, 0(sp)
+	ld	x8, 8(sp)
+	ld	x9, 16(sp)
+	ld	x18, 24(sp)
+	ld	x19, 32(sp)
+	ld	x20, 40(sp)
+	ld	x21, 48(sp)
+	ld	x22, 56(sp)
+	ld	x23, 64(sp)
+	ld	x24, 72(sp)
+	ld	x25, 80(sp)
+	ld	x26, 88(sp)
+	ld	x27, 96(sp)
+	fld	f8, 104(sp)
+	fld	f9, 112(sp)
+	fld	f18, 120(sp)
+	fld	f19, 128(sp)
+	fld	f20, 136(sp)
+	fld	f21, 144(sp)
+	fld	f22, 152(sp)
+	fld	f23, 160(sp)
+	fld	f24, 168(sp)
+	fld	f25, 176(sp)
+	fld	f26, 184(sp)
+	fld	f27, 192(sp)
+	addi	sp, sp, 200
+
+	jr	ra
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_s390x.S

@@ -0,0 +1,58 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+.file "gcc_s390x.S"
+
+/*
+ * void crosscall_s390x(void (*fn)(void), void *g)
+ *
+ * Calling into the go tool chain, where all registers are caller save.
+ * Called from standard s390x C ABI, where r6-r13, r15, and f8-f15 are
+ * callee-save, so they must be saved explicitly.
+ */
+.globl crosscall_s390x
+crosscall_s390x:
+	/* save r6-r15 in the register save area of the calling function */
+	stmg    %r6, %r15, 48(%r15)
+
+	/* allocate 64 bytes of stack space to save f8-f15 */
+	lay     %r15, -64(%r15)
+
+	/* save callee-saved floating point registers */
+	std     %f8, 0(%r15)
+	std     %f9, 8(%r15)
+	std     %f10, 16(%r15)
+	std     %f11, 24(%r15)
+	std     %f12, 32(%r15)
+	std     %f13, 40(%r15)
+	std     %f14, 48(%r15)
+	std     %f15, 56(%r15)
+
+	/* restore g pointer */
+	lgr     %r13, %r3
+
+	/* call fn */
+	basr    %r14, %r2
+
+	/* restore floating point registers */
+	ld      %f8, 0(%r15)
+	ld      %f9, 8(%r15)
+	ld      %f10, 16(%r15)
+	ld      %f11, 24(%r15)
+	ld      %f12, 32(%r15)
+	ld      %f13, 40(%r15)
+	ld      %f14, 48(%r15)
+	ld      %f15, 56(%r15)
+
+	/* de-allocate stack frame */
+	la      %r15, 64(%r15)
+
+	/* restore general purpose registers */
+	lmg     %r6, %r15, 48(%r15)
+
+	br      %r14 /* restored by lmg */
+
+#ifdef __ELF__
+.section .note.GNU-stack,"",%progbits
+#endif

src/runtime/cgo/gcc_setenv.c

@@ -0,0 +1,27 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+#include "libcgo.h"
+
+#include <stdlib.h>
+
+/* Stub for calling setenv */
+void
+x_cgo_setenv(char **arg)
+{
+	_cgo_tsan_acquire();
+	setenv(arg[0], arg[1], 1);
+	_cgo_tsan_release();
+}
+
+/* Stub for calling unsetenv */
+void
+x_cgo_unsetenv(char **arg)
+{
+	_cgo_tsan_acquire();
+	unsetenv(arg[0]);
+	_cgo_tsan_release();
+}

src/runtime/cgo/gcc_sigaction.c

@@ -0,0 +1,82 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && (amd64 || arm64 || ppc64le)
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include <signal.h>
+
+#include "libcgo.h"
+
+// go_sigaction_t is a C version of the sigactiont struct from
+// defs_linux_amd64.go.  This definition — and its conversion to and from struct
+// sigaction — are specific to linux/amd64.
+typedef struct {
+	uintptr_t handler;
+	uint64_t flags;
+	uintptr_t restorer;
+	uint64_t mask;
+} go_sigaction_t;
+
+// SA_RESTORER is part of the kernel interface.
+// This is Linux i386/amd64 specific.
+#ifndef SA_RESTORER
+#define SA_RESTORER 0x4000000
+#endif
+
+int32_t
+x_cgo_sigaction(intptr_t signum, const go_sigaction_t *goact, go_sigaction_t *oldgoact) {
+	int32_t ret;
+	struct sigaction act;
+	struct sigaction oldact;
+	size_t i;
+
+	_cgo_tsan_acquire();
+
+	memset(&act, 0, sizeof act);
+	memset(&oldact, 0, sizeof oldact);
+
+	if (goact) {
+		if (goact->flags & SA_SIGINFO) {
+			act.sa_sigaction = (void(*)(int, siginfo_t*, void*))(goact->handler);
+		} else {
+			act.sa_handler = (void(*)(int))(goact->handler);
+		}
+		sigemptyset(&act.sa_mask);
+		for (i = 0; i < 8 * sizeof(goact->mask); i++) {
+			if (goact->mask & ((uint64_t)(1)<<i)) {
+				sigaddset(&act.sa_mask, (int)(i+1));
+			}
+		}
+		act.sa_flags = (int)(goact->flags & ~(uint64_t)SA_RESTORER);
+	}
+
+	ret = sigaction((int)signum, goact ? &act : NULL, oldgoact ? &oldact : NULL);
+	if (ret == -1) {
+		// runtime.rt_sigaction expects _cgo_sigaction to return errno on error.
+		_cgo_tsan_release();
+		return errno;
+	}
+
+	if (oldgoact) {
+		if (oldact.sa_flags & SA_SIGINFO) {
+			oldgoact->handler = (uintptr_t)(oldact.sa_sigaction);
+		} else {
+			oldgoact->handler = (uintptr_t)(oldact.sa_handler);
+		}
+		oldgoact->mask = 0;
+		for (i = 0; i < 8 * sizeof(oldgoact->mask); i++) {
+			if (sigismember(&oldact.sa_mask, (int)(i+1)) == 1) {
+				oldgoact->mask |= (uint64_t)(1)<<i;
+			}
+		}
+		oldgoact->flags = (uint64_t)oldact.sa_flags;
+	}
+
+	_cgo_tsan_release();
+	return ret;
+}

src/runtime/cgo/gcc_signal2_ios_arm64.c

@@ -0,0 +1,11 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build lldb
+
+// Used by gcc_signal_darwin_arm64.c when doing the test build during cgo.
+// We hope that for real binaries the definition provided by Go will take precedence
+// and the linker will drop this .o file altogether, which is why this definition
+// is all by itself in its own file.
+void __attribute__((weak)) xx_cgo_panicmem(void) {}

src/runtime/cgo/gcc_signal_ios_arm64.c

@@ -0,0 +1,213 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Emulation of the Unix signal SIGSEGV.
+//
+// On iOS, Go tests and apps under development are run by lldb.
+// The debugger uses a task-level exception handler to intercept signals.
+// Despite having a 'handle' mechanism like gdb, lldb will not allow a
+// SIGSEGV to pass to the running program. For Go, this means we cannot
+// generate a panic, which cannot be recovered, and so tests fail.
+//
+// We work around this by registering a thread-level mach exception handler
+// and intercepting EXC_BAD_ACCESS. The kernel offers thread handlers a
+// chance to resolve exceptions before the task handler, so we can generate
+// the panic and avoid lldb's SIGSEGV handler.
+//
+// The dist tool enables this by build flag when testing.
+
+//go:build lldb
+
+#include <limits.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <mach/arm/thread_status.h>
+#include <mach/exception_types.h>
+#include <mach/mach.h>
+#include <mach/mach_init.h>
+#include <mach/mach_port.h>
+#include <mach/thread_act.h>
+#include <mach/thread_status.h>
+
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+void xx_cgo_panicmem(void);
+uintptr_t x_cgo_panicmem = (uintptr_t)xx_cgo_panicmem;
+
+static pthread_mutex_t mach_exception_handler_port_set_mu;
+static mach_port_t mach_exception_handler_port_set = MACH_PORT_NULL;
+
+kern_return_t
+catch_exception_raise(
+	mach_port_t exception_port,
+	mach_port_t thread,
+	mach_port_t task,
+	exception_type_t exception,
+	exception_data_t code_vector,
+	mach_msg_type_number_t code_count)
+{
+	kern_return_t ret;
+	arm_unified_thread_state_t thread_state;
+	mach_msg_type_number_t state_count = ARM_UNIFIED_THREAD_STATE_COUNT;
+
+	// Returning KERN_SUCCESS intercepts the exception.
+	//
+	// Returning KERN_FAILURE lets the exception fall through to the
+	// next handler, which is the standard signal emulation code
+	// registered on the task port.
+
+	if (exception != EXC_BAD_ACCESS) {
+		return KERN_FAILURE;
+	}
+
+	ret = thread_get_state(thread, ARM_UNIFIED_THREAD_STATE, (thread_state_t)&thread_state, &state_count);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: thread_get_state failed: %d\n", ret);
+		abort();
+	}
+
+	// Bounce call to sigpanic through asm that makes it look like
+	// we call sigpanic directly from the faulting code.
+#ifdef __arm64__
+	thread_state.ts_64.__x[1] = thread_state.ts_64.__lr;
+	thread_state.ts_64.__x[2] = thread_state.ts_64.__pc;
+	thread_state.ts_64.__pc = x_cgo_panicmem;
+#else
+	thread_state.ts_32.__r[1] = thread_state.ts_32.__lr;
+	thread_state.ts_32.__r[2] = thread_state.ts_32.__pc;
+	thread_state.ts_32.__pc = x_cgo_panicmem;
+#endif
+
+	if (0) {
+		// Useful debugging logic when panicmem is broken.
+		//
+		// Sends the first SIGSEGV and lets lldb catch the
+		// second one, avoiding a loop that locks up iOS
+		// devices requiring a hard reboot.
+		fprintf(stderr, "runtime/cgo: caught exc_bad_access\n");
+		fprintf(stderr, "__lr = %llx\n", thread_state.ts_64.__lr);
+		fprintf(stderr, "__pc = %llx\n", thread_state.ts_64.__pc);
+		static int pass1 = 0;
+		if (pass1) {
+			return KERN_FAILURE;
+		}
+		pass1 = 1;
+	}
+
+	ret = thread_set_state(thread, ARM_UNIFIED_THREAD_STATE, (thread_state_t)&thread_state, state_count);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: thread_set_state failed: %d\n", ret);
+		abort();
+	}
+
+	return KERN_SUCCESS;
+}
+
+void
+darwin_arm_init_thread_exception_port()
+{
+	// Called by each new OS thread to bind its EXC_BAD_ACCESS exception
+	// to mach_exception_handler_port_set.
+	int ret;
+	mach_port_t port = MACH_PORT_NULL;
+
+	ret = mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &port);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: mach_port_allocate failed: %d\n", ret);
+		abort();
+	}
+	ret = mach_port_insert_right(
+		mach_task_self(),
+		port,
+		port,
+		MACH_MSG_TYPE_MAKE_SEND);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: mach_port_insert_right failed: %d\n", ret);
+		abort();
+	}
+
+	ret = thread_set_exception_ports(
+		mach_thread_self(),
+		EXC_MASK_BAD_ACCESS,
+		port,
+		EXCEPTION_DEFAULT,
+		THREAD_STATE_NONE);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: thread_set_exception_ports failed: %d\n", ret);
+		abort();
+	}
+
+	ret = pthread_mutex_lock(&mach_exception_handler_port_set_mu);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: pthread_mutex_lock failed: %d\n", ret);
+		abort();
+	}
+	ret = mach_port_move_member(
+		mach_task_self(),
+		port,
+		mach_exception_handler_port_set);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: mach_port_move_member failed: %d\n", ret);
+		abort();
+	}
+	ret = pthread_mutex_unlock(&mach_exception_handler_port_set_mu);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: pthread_mutex_unlock failed: %d\n", ret);
+		abort();
+	}
+}
+
+static void*
+mach_exception_handler(void *port)
+{
+	// Calls catch_exception_raise.
+	extern boolean_t exc_server();
+	mach_msg_server(exc_server, 2048, (mach_port_t)(uintptr_t)port, 0);
+	abort(); // never returns
+}
+
+void
+darwin_arm_init_mach_exception_handler()
+{
+	pthread_mutex_init(&mach_exception_handler_port_set_mu, NULL);
+
+	// Called once per process to initialize a mach port server, listening
+	// for EXC_BAD_ACCESS thread exceptions.
+	int ret;
+	pthread_t thr = NULL;
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+
+	ret = mach_port_allocate(
+		mach_task_self(),
+		MACH_PORT_RIGHT_PORT_SET,
+		&mach_exception_handler_port_set);
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: mach_port_allocate failed for port_set: %d\n", ret);
+		abort();
+	}
+
+	// Block all signals to the exception handler thread
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	// Start a thread to handle exceptions.
+	uintptr_t port_set = (uintptr_t)mach_exception_handler_port_set;
+	pthread_attr_init(&attr);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+	ret = _cgo_try_pthread_create(&thr, &attr, mach_exception_handler, (void*)port_set);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (ret) {
+		fprintf(stderr, "runtime/cgo: pthread_create failed: %d\n", ret);
+		abort();
+	}
+	pthread_attr_destroy(&attr);
+}

src/runtime/cgo/gcc_signal_ios_nolldb.c

@@ -0,0 +1,10 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !lldb && ios && arm64
+
+#include <stdint.h>
+
+void darwin_arm_init_thread_exception_port() {}
+void darwin_arm_init_mach_exception_handler() {}

src/runtime/cgo/gcc_solaris_amd64.c

@@ -0,0 +1,83 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include <string.h>
+#include <signal.h>
+#include <ucontext.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static void* threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	ucontext_t ctx;
+
+	setg_gcc = setg;
+	if (getcontext(&ctx) != 0)
+		perror("runtime/cgo: getcontext failed");
+	g->stacklo = (uintptr_t)ctx.uc_stack.ss_sp;
+
+	// Solaris processes report a tiny stack when run with "ulimit -s unlimited".
+	// Correct that as best we can: assume it's at least 1 MB.
+	// See golang.org/issue/12210.
+	if(ctx.uc_stack.ss_size < 1024*1024)
+		g->stacklo -= 1024*1024 - ctx.uc_stack.ss_size;
+
+	// Sanity check the results now, rather than getting a
+	// morestack on g0 crash.
+	if (g->stacklo >= g->stackhi) {
+		fatalf("bad stack bounds: lo=%p hi=%p", (void*)(g->stacklo), (void*)(g->stackhi));
+	}
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	sigset_t ign, oset;
+	pthread_t p;
+	void *base;
+	size_t size;
+	int err;
+
+	sigfillset(&ign);
+	pthread_sigmask(SIG_SETMASK, &ign, &oset);
+
+	pthread_attr_init(&attr);
+
+	if (pthread_attr_getstack(&attr, &base, &size) != 0)
+		perror("runtime/cgo: pthread_attr_getstack failed");
+	if (size == 0) {
+		ts->g->stackhi = 2 << 20;
+		if (pthread_attr_setstack(&attr, NULL, ts->g->stackhi) != 0)
+			perror("runtime/cgo: pthread_attr_setstack failed");
+	} else {
+		ts->g->stackhi = size;
+	}
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
+
+	pthread_sigmask(SIG_SETMASK, &oset, nil);
+
+	if (err != 0) {
+		fatalf("pthread_create failed: %s", strerror(err));
+	}
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+	return nil;
+}

src/runtime/cgo/gcc_stack_darwin.c

@@ -0,0 +1,25 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+void
+x_cgo_getstackbound(uintptr bounds[2])
+{
+	void* addr;
+	size_t size;
+	pthread_t p;
+
+	p = pthread_self();
+	addr = pthread_get_stackaddr_np(p); // high address (!)
+	size = pthread_get_stacksize_np(p);
+
+	// bounds points into the Go stack. TSAN can't see the synchronization
+	// in Go around stack reuse.
+	_cgo_tsan_acquire();
+	bounds[0] = (uintptr)addr - size;
+	bounds[1] = (uintptr)addr;
+	_cgo_tsan_release();
+}

src/runtime/cgo/gcc_stack_unix.c

@@ -0,0 +1,47 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix && !darwin
+
+#ifndef _GNU_SOURCE // pthread_getattr_np
+#define _GNU_SOURCE
+#endif
+
+#include <pthread.h>
+#include "libcgo.h"
+
+void
+x_cgo_getstackbound(uintptr bounds[2])
+{
+	pthread_attr_t attr;
+	void *addr;
+	size_t size;
+
+	// Needed before pthread_getattr_np, too, since before glibc 2.32
+	// it did not call pthread_attr_init in all cases (see #65625).
+	pthread_attr_init(&attr);
+#if defined(__GLIBC__) || (defined(__sun) && !defined(__illumos__))
+	// pthread_getattr_np is a GNU extension supported in glibc.
+	// Solaris is not glibc but does support pthread_getattr_np
+	// (and the fallback doesn't work...). Illumos does not.
+	pthread_getattr_np(pthread_self(), &attr);  // GNU extension
+	pthread_attr_getstack(&attr, &addr, &size); // low address
+#elif defined(__illumos__)
+	pthread_attr_get_np(pthread_self(), &attr);
+	pthread_attr_getstack(&attr, &addr, &size); // low address
+#else
+	// We don't know how to get the current stacks, so assume they are the
+	// same as the default stack bounds.
+	pthread_attr_getstacksize(&attr, &size);
+	addr = __builtin_frame_address(0) + 4096 - size;
+#endif
+	pthread_attr_destroy(&attr);
+
+	// bounds points into the Go stack. TSAN can't see the synchronization
+	// in Go around stack reuse.
+	_cgo_tsan_acquire();
+	bounds[0] = (uintptr)addr;
+	bounds[1] = (uintptr)addr + size;
+	_cgo_tsan_release();
+}

src/runtime/cgo/gcc_stack_windows.c

@@ -0,0 +1,7 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "libcgo.h"
+
+void x_cgo_getstackbound(uintptr bounds[2]) {} // no-op for now

src/runtime/cgo/gcc_traceback.c

@@ -0,0 +1,46 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || linux
+
+#include <stdint.h>
+#include "libcgo.h"
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#if __has_feature(memory_sanitizer)
+#include <sanitizer/msan_interface.h>
+#endif
+
+// Call the user's traceback function and then call sigtramp.
+// The runtime signal handler will jump to this code.
+// We do it this way so that the user's traceback function will be called
+// by a C function with proper unwind info.
+void
+x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(struct cgoTracebackArg*), uintptr_t* cgoCallers, void (*sigtramp)(uintptr_t, void*, void*)) {
+	struct cgoTracebackArg arg;
+
+	arg.Context = 0;
+	arg.SigContext = (uintptr_t)(context);
+	arg.Buf = cgoCallers;
+	arg.Max = 32; // must match len(runtime.cgoCallers)
+
+#if __has_feature(memory_sanitizer)
+        // This function is called directly from the signal handler.
+        // The arguments are passed in registers, so whether msan
+        // considers cgoCallers to be initialized depends on whether
+        // it considers the appropriate register to be initialized.
+        // That can cause false reports in rare cases.
+        // Explicitly unpoison the memory to avoid that.
+        // See issue #47543 for more details.
+        __msan_unpoison(&arg, sizeof arg);
+#endif
+
+	_cgo_tsan_acquire();
+	(*cgoTraceback)(&arg);
+	_cgo_tsan_release();
+	sigtramp(sig, info, context);
+}

src/runtime/cgo/gcc_util.c

@@ -0,0 +1,69 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "libcgo.h"
+
+/* Stub for creating a new thread */
+void
+x_cgo_thread_start(ThreadStart *arg)
+{
+	ThreadStart *ts;
+
+	/* Make our own copy that can persist after we return. */
+	_cgo_tsan_acquire();
+	ts = malloc(sizeof *ts);
+	_cgo_tsan_release();
+	if(ts == nil) {
+		fprintf(stderr, "runtime/cgo: out of memory in thread_start\n");
+		abort();
+	}
+	*ts = *arg;
+
+	_cgo_sys_thread_start(ts);	/* OS-dependent half */
+}
+
+#ifndef CGO_TSAN
+void(* const _cgo_yield)() = NULL;
+#else
+
+#include <string.h>
+
+char x_cgo_yield_strncpy_src = 0;
+char x_cgo_yield_strncpy_dst = 0;
+size_t x_cgo_yield_strncpy_n = 0;
+
+/*
+Stub for allowing libc interceptors to execute.
+
+_cgo_yield is set to NULL if we do not expect libc interceptors to exist.
+*/
+static void
+x_cgo_yield()
+{
+	/*
+	The libc function(s) we call here must form a no-op and include at least one
+	call that triggers TSAN to process pending asynchronous signals.
+
+	sleep(0) would be fine, but it's not portable C (so it would need more header
+	guards).
+	free(NULL) has a fast-path special case in TSAN, so it doesn't
+	trigger signal delivery.
+	free(malloc(0)) would work (triggering the interceptors in malloc), but
+	it also runs a bunch of user-supplied malloc hooks.
+
+	So we choose strncpy(_, _, 0): it requires an extra header,
+	but it's standard and should be very efficient.
+
+	GCC 7 has an unfortunate habit of optimizing out strncpy calls (see
+	https://golang.org/issue/21196), so the arguments here need to be global
+	variables with external linkage in order to ensure that the call traps all the
+	way down into libc.
+	*/
+	strncpy(&x_cgo_yield_strncpy_dst, &x_cgo_yield_strncpy_src,
+	        x_cgo_yield_strncpy_n);
+}
+
+void(* const _cgo_yield)() = &x_cgo_yield;
+
+#endif  /* GO_TSAN */

src/runtime/cgo/gcc_windows_386.c

@@ -0,0 +1,53 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <process.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include "libcgo.h"
+#include "libcgo_windows.h"
+
+static void threadentry(void*);
+static void (*setg_gcc)(void*);
+static DWORD *tls_g;
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	setg_gcc = setg;
+	tls_g = (DWORD *)tlsg;
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	_cgo_beginthread(threadentry, ts);
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	// minit queries stack bounds from the OS.
+
+	/*
+	 * Set specific keys in thread local storage.
+	 */
+	asm volatile (
+		"movl %0, %%fs:0(%1)\n"	// MOVL tls0, 0(tls_g)(FS)
+		"movl %%fs:0(%1), %%eax\n"	// MOVL 0(tls_g)(FS), tmp
+		"movl %2, 0(%%eax)\n"	// MOVL g, 0(AX)
+		:: "r"(ts.tls), "r"(*tls_g), "r"(ts.g) : "%eax"
+	);
+
+	crosscall1(ts.fn, setg_gcc, ts.g);
+}

src/runtime/cgo/gcc_windows_amd64.c

@@ -0,0 +1,52 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <process.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include "libcgo.h"
+#include "libcgo_windows.h"
+
+static void threadentry(void*);
+static void (*setg_gcc)(void*);
+static DWORD *tls_g;
+
+void
+x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
+{
+	setg_gcc = setg;
+	tls_g = (DWORD *)tlsg;
+}
+
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	_cgo_beginthread(threadentry, ts);
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+static void
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	// minit queries stack bounds from the OS.
+
+	/*
+	 * Set specific keys in thread local storage.
+	 */
+	asm volatile (
+	  "movq %0, %%gs:0(%1)\n"	// MOVL tls0, 0(tls_g)(GS)
+	  :: "r"(ts.tls), "r"(*tls_g)
+	);
+
+	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
+}

src/runtime/cgo/gcc_windows_arm64.c

@@ -0,0 +1,40 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <process.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include "libcgo.h"
+#include "libcgo_windows.h"
+
+static void threadentry(void*);
+static void (*setg_gcc)(void*);
+
+void
+x_cgo_init(G *g, void (*setg)(void*))
+{
+	setg_gcc = setg;
+}
+
+void
+_cgo_sys_thread_start(ThreadStart *ts)
+{
+	_cgo_beginthread(threadentry, ts);
+}
+
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+
+static void
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	crosscall1(ts.fn, setg_gcc, (void *)ts.g);
+}

src/runtime/cgo/handle.go

@@ -0,0 +1,144 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgo
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+// Handle provides a way to pass values that contain Go pointers
+// (pointers to memory allocated by Go) between Go and C without
+// breaking the cgo pointer passing rules. A Handle is an integer
+// value that can represent any Go value. A Handle can be passed
+// through C and back to Go, and Go code can use the Handle to
+// retrieve the original Go value.
+//
+// The underlying type of Handle is guaranteed to fit in an integer type
+// that is large enough to hold the bit pattern of any pointer. The zero
+// value of a Handle is not valid, and thus is safe to use as a sentinel
+// in C APIs.
+//
+// For instance, on the Go side:
+//
+//	package main
+//
+//	/*
+//	#include <stdint.h> // for uintptr_t
+//
+//	extern void MyGoPrint(uintptr_t handle);
+//	void myprint(uintptr_t handle);
+//	*/
+//	import "C"
+//	import "runtime/cgo"
+//
+//	//export MyGoPrint
+//	func MyGoPrint(handle C.uintptr_t) {
+//		h := cgo.Handle(handle)
+//		val := h.Value().(string)
+//		println(val)
+//		h.Delete()
+//	}
+//
+//	func main() {
+//		val := "hello Go"
+//		C.myprint(C.uintptr_t(cgo.NewHandle(val)))
+//		// Output: hello Go
+//	}
+//
+// and on the C side:
+//
+//	#include <stdint.h> // for uintptr_t
+//
+//	// A Go function
+//	extern void MyGoPrint(uintptr_t handle);
+//
+//	// A C function
+//	void myprint(uintptr_t handle) {
+//	    MyGoPrint(handle);
+//	}
+//
+// Some C functions accept a void* argument that points to an arbitrary
+// data value supplied by the caller. It is not safe to coerce a [cgo.Handle]
+// (an integer) to a Go [unsafe.Pointer], but instead we can pass the address
+// of the cgo.Handle to the void* parameter, as in this variant of the
+// previous example:
+//
+//	package main
+//
+//	/*
+//	extern void MyGoPrint(void *context);
+//	static inline void myprint(void *context) {
+//	    MyGoPrint(context);
+//	}
+//	*/
+//	import "C"
+//	import (
+//		"runtime/cgo"
+//		"unsafe"
+//	)
+//
+//	//export MyGoPrint
+//	func MyGoPrint(context unsafe.Pointer) {
+//		h := *(*cgo.Handle)(context)
+//		val := h.Value().(string)
+//		println(val)
+//		h.Delete()
+//	}
+//
+//	func main() {
+//		val := "hello Go"
+//		h := cgo.NewHandle(val)
+//		C.myprint(unsafe.Pointer(&h))
+//		// Output: hello Go
+//	}
+type Handle uintptr
+
+// NewHandle returns a handle for a given value.
+//
+// The handle is valid until the program calls Delete on it. The handle
+// uses resources, and this package assumes that C code may hold on to
+// the handle, so a program must explicitly call Delete when the handle
+// is no longer needed.
+//
+// The intended use is to pass the returned handle to C code, which
+// passes it back to Go, which calls Value.
+func NewHandle(v any) Handle {
+	h := handleIdx.Add(1)
+	if h == 0 {
+		panic("runtime/cgo: ran out of handle space")
+	}
+
+	handles.Store(h, v)
+	return Handle(h)
+}
+
+// Value returns the associated Go value for a valid handle.
+//
+// The method panics if the handle is invalid.
+func (h Handle) Value() any {
+	v, ok := handles.Load(uintptr(h))
+	if !ok {
+		panic("runtime/cgo: misuse of an invalid Handle")
+	}
+	return v
+}
+
+// Delete invalidates a handle. This method should only be called once
+// the program no longer needs to pass the handle to C and the C code
+// no longer has a copy of the handle value.
+//
+// The method panics if the handle is invalid.
+func (h Handle) Delete() {
+	_, ok := handles.LoadAndDelete(uintptr(h))
+	if !ok {
+		panic("runtime/cgo: misuse of an invalid Handle")
+	}
+}
+
+var (
+	handles   = sync.Map{} // map[Handle]interface{}
+	handleIdx atomic.Uintptr
+)

src/runtime/cgo/handle_test.go

@@ -0,0 +1,103 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgo
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestHandle(t *testing.T) {
+	v := 42
+
+	tests := []struct {
+		v1 any
+		v2 any
+	}{
+		{v1: v, v2: v},
+		{v1: &v, v2: &v},
+		{v1: nil, v2: nil},
+	}
+
+	for _, tt := range tests {
+		h1 := NewHandle(tt.v1)
+		h2 := NewHandle(tt.v2)
+
+		if uintptr(h1) == 0 || uintptr(h2) == 0 {
+			t.Fatalf("NewHandle returns zero")
+		}
+
+		if uintptr(h1) == uintptr(h2) {
+			t.Fatalf("Duplicated Go values should have different handles, but got equal")
+		}
+
+		h1v := h1.Value()
+		h2v := h2.Value()
+		if !reflect.DeepEqual(h1v, h2v) || !reflect.DeepEqual(h1v, tt.v1) {
+			t.Fatalf("Value of a Handle got wrong, got %+v %+v, want %+v", h1v, h2v, tt.v1)
+		}
+
+		h1.Delete()
+		h2.Delete()
+	}
+
+	siz := 0
+	handles.Range(func(k, v any) bool {
+		siz++
+		return true
+	})
+	if siz != 0 {
+		t.Fatalf("handles are not cleared, got %d, want %d", siz, 0)
+	}
+}
+
+func TestInvalidHandle(t *testing.T) {
+	t.Run("zero", func(t *testing.T) {
+		h := Handle(0)
+
+		defer func() {
+			if r := recover(); r != nil {
+				return
+			}
+			t.Fatalf("Delete of zero handle did not trigger a panic")
+		}()
+
+		h.Delete()
+	})
+
+	t.Run("invalid", func(t *testing.T) {
+		h := NewHandle(42)
+
+		defer func() {
+			if r := recover(); r != nil {
+				h.Delete()
+				return
+			}
+			t.Fatalf("Invalid handle did not trigger a panic")
+		}()
+
+		Handle(h + 1).Delete()
+	})
+}
+
+func BenchmarkHandle(b *testing.B) {
+	b.Run("non-concurrent", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			h := NewHandle(i)
+			_ = h.Value()
+			h.Delete()
+		}
+	})
+	b.Run("concurrent", func(b *testing.B) {
+		b.RunParallel(func(pb *testing.PB) {
+			var v int
+			for pb.Next() {
+				h := NewHandle(v)
+				_ = h.Value()
+				h.Delete()
+			}
+		})
+	})
+}

src/runtime/cgo/iscgo.go

@@ -0,0 +1,17 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The runtime package contains an uninitialized definition
+// for runtime·iscgo. Override it to tell the runtime we're here.
+// There are various function pointers that should be set too,
+// but those depend on dynamic linker magic to get initialized
+// correctly, and sometimes they break. This variable is a
+// backup: it depends only on old C style static linking rules.
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+//go:linkname _iscgo runtime.iscgo
+var _iscgo bool = true

src/runtime/cgo/libcgo.h

@@ -0,0 +1,151 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#undef nil
+#define nil ((void*)0)
+#define nelem(x) (sizeof(x)/sizeof((x)[0]))
+
+typedef uint32_t uint32;
+typedef uint64_t uint64;
+typedef uintptr_t uintptr;
+
+/*
+ * The beginning of the per-goroutine structure,
+ * as defined in ../pkg/runtime/runtime.h.
+ * Just enough to edit these two fields.
+ */
+typedef struct G G;
+struct G
+{
+	uintptr stacklo;
+	uintptr stackhi;
+};
+
+/*
+ * Arguments to the _cgo_thread_start call.
+ * Also known to ../pkg/runtime/runtime.h.
+ */
+typedef struct ThreadStart ThreadStart;
+struct ThreadStart
+{
+	G *g;
+	uintptr *tls;
+	void (*fn)(void);
+};
+
+/*
+ * Called by 5c/6c/8c world.
+ * Makes a local copy of the ThreadStart and
+ * calls _cgo_sys_thread_start(ts).
+ */
+extern void (*_cgo_thread_start)(ThreadStart *ts);
+
+/*
+ * Creates a new operating system thread without updating any Go state
+ * (OS dependent).
+ */
+extern void (*_cgo_sys_thread_create)(void* (*func)(void*), void* arg);
+
+/*
+ * Indicates whether a dummy pthread per-thread variable is allocated.
+ */
+extern uintptr_t *_cgo_pthread_key_created;
+
+/*
+ * Creates the new operating system thread (OS, arch dependent).
+ */
+void _cgo_sys_thread_start(ThreadStart *ts);
+
+/*
+ * Waits for the Go runtime to be initialized (OS dependent).
+ * If runtime.SetCgoTraceback is used to set a context function,
+ * calls the context function and returns the context value.
+ */
+uintptr_t _cgo_wait_runtime_init_done(void);
+
+/*
+ * Get the low and high boundaries of the stack.
+ */
+void x_cgo_getstackbound(uintptr bounds[2]);
+
+/*
+ * Prints error then calls abort. For linux and android.
+ */
+void fatalf(const char* format, ...) __attribute__ ((noreturn));
+
+/*
+ * Registers the current mach thread port for EXC_BAD_ACCESS processing.
+ */
+void darwin_arm_init_thread_exception_port(void);
+
+/*
+ * Starts a mach message server processing EXC_BAD_ACCESS.
+ */
+void darwin_arm_init_mach_exception_handler(void);
+
+/*
+ * The cgo context function. See runtime.SetCgoTraceback.
+ */
+struct context_arg {
+	uintptr_t Context;
+};
+extern void (*(_cgo_get_context_function(void)))(struct context_arg*);
+
+/*
+ * The argument for the cgo traceback callback. See runtime.SetCgoTraceback.
+ */
+struct cgoTracebackArg {
+	uintptr_t  Context;
+	uintptr_t  SigContext;
+	uintptr_t* Buf;
+	uintptr_t  Max;
+};
+
+/*
+ * TSAN support.  This is only useful when building with
+ *   CGO_CFLAGS="-fsanitize=thread" CGO_LDFLAGS="-fsanitize=thread" go install
+ */
+#undef CGO_TSAN
+#if defined(__has_feature)
+# if __has_feature(thread_sanitizer)
+#  define CGO_TSAN
+# endif
+#elif defined(__SANITIZE_THREAD__)
+# define CGO_TSAN
+#endif
+
+#ifdef CGO_TSAN
+
+// These must match the definitions in yesTsanProlog in cmd/cgo/out.go.
+// In general we should call _cgo_tsan_acquire when we enter C code,
+// and call _cgo_tsan_release when we return to Go code.
+// This is only necessary when calling code that might be instrumented
+// by TSAN, which mostly means system library calls that TSAN intercepts.
+// See the comment in cmd/cgo/out.go for more details.
+
+long long _cgo_sync __attribute__ ((common));
+
+extern void __tsan_acquire(void*);
+extern void __tsan_release(void*);
+
+__attribute__ ((unused))
+static void _cgo_tsan_acquire() {
+	__tsan_acquire(&_cgo_sync);
+}
+
+__attribute__ ((unused))
+static void _cgo_tsan_release() {
+	__tsan_release(&_cgo_sync);
+}
+
+#else // !defined(CGO_TSAN)
+
+#define _cgo_tsan_acquire()
+#define _cgo_tsan_release()
+
+#endif // !defined(CGO_TSAN)

src/runtime/cgo/libcgo_unix.h

@@ -0,0 +1,20 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+ * Initialize g->stacklo.
+ */
+extern void _cgo_set_stacklo(G *, uintptr *);
+
+/*
+ * Call pthread_create, retrying on EAGAIN.
+ */
+extern int _cgo_try_pthread_create(pthread_t*, const pthread_attr_t*, void* (*)(void*), void*);
+
+/*
+ * Same as _cgo_try_pthread_create, but passing on the pthread_create function.
+ * Only defined on OpenBSD.
+ */
+extern int _cgo_openbsd_try_pthread_create(int (*)(pthread_t*, const pthread_attr_t*, void *(*pfn)(void*), void*),
+	pthread_t*, const pthread_attr_t*, void* (*)(void*), void* arg);

src/runtime/cgo/libcgo_windows.h

@@ -0,0 +1,6 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Call _beginthread, aborting on failure.
+void _cgo_beginthread(void (*func)(void*), void* arg);

src/runtime/cgo/linux.go

@@ -0,0 +1,74 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Linux system call wrappers that provide POSIX semantics through the
+// corresponding cgo->libc (nptl) wrappers for various system calls.
+
+//go:build linux
+
+package cgo
+
+import "unsafe"
+
+// Each of the following entries is needed to ensure that the
+// syscall.syscall_linux code can conditionally call these
+// function pointers:
+//
+//  1. find the C-defined function start
+//  2. force the local byte alias to be mapped to that location
+//  3. map the Go pointer to the function to the syscall package
+
+//go:cgo_import_static _cgo_libc_setegid
+//go:linkname _cgo_libc_setegid _cgo_libc_setegid
+//go:linkname cgo_libc_setegid syscall.cgo_libc_setegid
+var _cgo_libc_setegid byte
+var cgo_libc_setegid = unsafe.Pointer(&_cgo_libc_setegid)
+
+//go:cgo_import_static _cgo_libc_seteuid
+//go:linkname _cgo_libc_seteuid _cgo_libc_seteuid
+//go:linkname cgo_libc_seteuid syscall.cgo_libc_seteuid
+var _cgo_libc_seteuid byte
+var cgo_libc_seteuid = unsafe.Pointer(&_cgo_libc_seteuid)
+
+//go:cgo_import_static _cgo_libc_setregid
+//go:linkname _cgo_libc_setregid _cgo_libc_setregid
+//go:linkname cgo_libc_setregid syscall.cgo_libc_setregid
+var _cgo_libc_setregid byte
+var cgo_libc_setregid = unsafe.Pointer(&_cgo_libc_setregid)
+
+//go:cgo_import_static _cgo_libc_setresgid
+//go:linkname _cgo_libc_setresgid _cgo_libc_setresgid
+//go:linkname cgo_libc_setresgid syscall.cgo_libc_setresgid
+var _cgo_libc_setresgid byte
+var cgo_libc_setresgid = unsafe.Pointer(&_cgo_libc_setresgid)
+
+//go:cgo_import_static _cgo_libc_setresuid
+//go:linkname _cgo_libc_setresuid _cgo_libc_setresuid
+//go:linkname cgo_libc_setresuid syscall.cgo_libc_setresuid
+var _cgo_libc_setresuid byte
+var cgo_libc_setresuid = unsafe.Pointer(&_cgo_libc_setresuid)
+
+//go:cgo_import_static _cgo_libc_setreuid
+//go:linkname _cgo_libc_setreuid _cgo_libc_setreuid
+//go:linkname cgo_libc_setreuid syscall.cgo_libc_setreuid
+var _cgo_libc_setreuid byte
+var cgo_libc_setreuid = unsafe.Pointer(&_cgo_libc_setreuid)
+
+//go:cgo_import_static _cgo_libc_setgroups
+//go:linkname _cgo_libc_setgroups _cgo_libc_setgroups
+//go:linkname cgo_libc_setgroups syscall.cgo_libc_setgroups
+var _cgo_libc_setgroups byte
+var cgo_libc_setgroups = unsafe.Pointer(&_cgo_libc_setgroups)
+
+//go:cgo_import_static _cgo_libc_setgid
+//go:linkname _cgo_libc_setgid _cgo_libc_setgid
+//go:linkname cgo_libc_setgid syscall.cgo_libc_setgid
+var _cgo_libc_setgid byte
+var cgo_libc_setgid = unsafe.Pointer(&_cgo_libc_setgid)
+
+//go:cgo_import_static _cgo_libc_setuid
+//go:linkname _cgo_libc_setuid _cgo_libc_setuid
+//go:linkname cgo_libc_setuid syscall.cgo_libc_setuid
+var _cgo_libc_setuid byte
+var cgo_libc_setuid = unsafe.Pointer(&_cgo_libc_setuid)

src/runtime/cgo/linux_syscall.c

@@ -0,0 +1,85 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux
+
+#ifndef _GNU_SOURCE // setres[ug]id() API.
+#define _GNU_SOURCE
+#endif
+
+#include <grp.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+#include "libcgo.h"
+
+/*
+ * Assumed POSIX compliant libc system call wrappers. For linux, the
+ * glibc/nptl/setxid mechanism ensures that POSIX semantics are
+ * honored for all pthreads (by default), and this in turn with cgo
+ * ensures that all Go threads launched with cgo are kept in sync for
+ * these function calls.
+ */
+
+// argset_t matches runtime/cgocall.go:argset.
+typedef struct {
+	uintptr_t* args;
+	uintptr_t retval;
+} argset_t;
+
+// libc backed posix-compliant syscalls.
+
+#define SET_RETVAL(fn) \
+  uintptr_t ret = (uintptr_t) fn ; \
+  if (ret == (uintptr_t) -1) {	   \
+    x->retval = (uintptr_t) errno; \
+  } else                           \
+    x->retval = ret
+
+void
+_cgo_libc_setegid(argset_t* x) {
+	SET_RETVAL(setegid((gid_t) x->args[0]));
+}
+
+void
+_cgo_libc_seteuid(argset_t* x) {
+	SET_RETVAL(seteuid((uid_t) x->args[0]));
+}
+
+void
+_cgo_libc_setgid(argset_t* x) {
+	SET_RETVAL(setgid((gid_t) x->args[0]));
+}
+
+void
+_cgo_libc_setgroups(argset_t* x) {
+	SET_RETVAL(setgroups((size_t) x->args[0], (const gid_t *) x->args[1]));
+}
+
+void
+_cgo_libc_setregid(argset_t* x) {
+	SET_RETVAL(setregid((gid_t) x->args[0], (gid_t) x->args[1]));
+}
+
+void
+_cgo_libc_setresgid(argset_t* x) {
+	SET_RETVAL(setresgid((gid_t) x->args[0], (gid_t) x->args[1],
+			     (gid_t) x->args[2]));
+}
+
+void
+_cgo_libc_setresuid(argset_t* x) {
+	SET_RETVAL(setresuid((uid_t) x->args[0], (uid_t) x->args[1],
+			     (uid_t) x->args[2]));
+}
+
+void
+_cgo_libc_setreuid(argset_t* x) {
+	SET_RETVAL(setreuid((uid_t) x->args[0], (uid_t) x->args[1]));
+}
+
+void
+_cgo_libc_setuid(argset_t* x) {
+	SET_RETVAL(setuid((uid_t) x->args[0]));
+}

src/runtime/cgo/mmap.go

@@ -0,0 +1,31 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (linux && (amd64 || arm64 || loong64)) || (freebsd && amd64)
+
+package cgo
+
+// Import "unsafe" because we use go:linkname.
+import _ "unsafe"
+
+// When using cgo, call the C library for mmap, so that we call into
+// any sanitizer interceptors. This supports using the memory
+// sanitizer with Go programs. The memory sanitizer only applies to
+// C/C++ code; this permits that code to see the Go code as normal
+// program addresses that have been initialized.
+
+// To support interceptors that look for both mmap and munmap,
+// also call the C library for munmap.
+
+//go:cgo_import_static x_cgo_mmap
+//go:linkname x_cgo_mmap x_cgo_mmap
+//go:linkname _cgo_mmap _cgo_mmap
+var x_cgo_mmap byte
+var _cgo_mmap = &x_cgo_mmap
+
+//go:cgo_import_static x_cgo_munmap
+//go:linkname x_cgo_munmap x_cgo_munmap
+//go:linkname _cgo_munmap _cgo_munmap
+var x_cgo_munmap byte
+var _cgo_munmap = &x_cgo_munmap

src/runtime/cgo/netbsd.go

@@ -0,0 +1,21 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build netbsd
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+// Supply environ and __progname, because we don't
+// link against the standard NetBSD crt0.o and the
+// libc dynamic library needs them.
+
+//go:linkname _environ environ
+//go:linkname _progname __progname
+//go:linkname ___ps_strings __ps_strings
+
+var _environ uintptr
+var _progname uintptr
+var ___ps_strings uintptr

src/runtime/cgo/openbsd.go

@@ -0,0 +1,21 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build openbsd
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+// Supply __guard_local because we don't link against the standard
+// OpenBSD crt0.o and the libc dynamic library needs it.
+
+//go:linkname _guard_local __guard_local
+
+var _guard_local uintptr
+
+// This is normally marked as hidden and placed in the
+// .openbsd.randomdata section.
+//
+//go:cgo_export_dynamic __guard_local __guard_local

src/runtime/cgo/setenv.go

@@ -0,0 +1,21 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+package cgo
+
+import _ "unsafe" // for go:linkname
+
+//go:cgo_import_static x_cgo_setenv
+//go:linkname x_cgo_setenv x_cgo_setenv
+//go:linkname _cgo_setenv runtime._cgo_setenv
+var x_cgo_setenv byte
+var _cgo_setenv = &x_cgo_setenv
+
+//go:cgo_import_static x_cgo_unsetenv
+//go:linkname x_cgo_unsetenv x_cgo_unsetenv
+//go:linkname _cgo_unsetenv runtime._cgo_unsetenv
+var x_cgo_unsetenv byte
+var _cgo_unsetenv = &x_cgo_unsetenv

src/runtime/cgo/sigaction.go

@@ -0,0 +1,22 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (linux && amd64) || (freebsd && amd64) || (linux && arm64) || (linux && ppc64le)
+
+package cgo
+
+// Import "unsafe" because we use go:linkname.
+import _ "unsafe"
+
+// When using cgo, call the C library for sigaction, so that we call into
+// any sanitizer interceptors. This supports using the sanitizers
+// with Go programs. The thread and memory sanitizers only apply to
+// C/C++ code; this permits that code to see the Go runtime's existing signal
+// handlers when registering new signal handlers for the process.
+
+//go:cgo_import_static x_cgo_sigaction
+//go:linkname x_cgo_sigaction x_cgo_sigaction
+//go:linkname _cgo_sigaction _cgo_sigaction
+var x_cgo_sigaction byte
+var _cgo_sigaction = &x_cgo_sigaction

src/runtime/cgo/signal_ios_arm64.go

@@ -0,0 +1,10 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgo
+
+import _ "unsafe"
+
+//go:cgo_export_static xx_cgo_panicmem xx_cgo_panicmem
+func xx_cgo_panicmem()

src/runtime/cgo/signal_ios_arm64.s

@@ -0,0 +1,56 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// xx_cgo_panicmem is the entrypoint for SIGSEGV as intercepted via a
+// mach thread port as EXC_BAD_ACCESS. As the segfault may have happened
+// in C code, we first need to load_g then call xx_cgo_panicmem.
+//
+//	R1 - LR at moment of fault
+//	R2 - PC at moment of fault
+TEXT xx_cgo_panicmem(SB),NOSPLIT|NOFRAME,$0
+	// If in external C code, we need to load the g register.
+	BL  runtime·load_g(SB)
+	CMP $0, g
+	BNE ongothread
+
+	// On a foreign thread.
+	// TODO(crawshaw): call badsignal
+	MOVD.W $0, -16(RSP)
+	MOVW $139, R1
+	MOVW R1, 8(RSP)
+	B    runtime·exit(SB)
+
+ongothread:
+	// Trigger a SIGSEGV panic.
+	//
+	// The goal is to arrange the stack so it looks like the runtime
+	// function sigpanic was called from the PC that faulted. It has
+	// to be sigpanic, as the stack unwinding code in traceback.go
+	// looks explicitly for it.
+	//
+	// To do this we call into runtime·setsigsegv, which sets the
+	// appropriate state inside the g object. We give it the faulting
+	// PC on the stack, then put it in the LR before calling sigpanic.
+
+	// Build a 32-byte stack frame for us for this call.
+	// Saved LR (none available) is at the bottom,
+	// then the PC argument for setsigsegv,
+	// then a copy of the LR for us to restore.
+	MOVD.W $0, -32(RSP)
+	MOVD R1, 8(RSP)
+	MOVD R2, 16(RSP)
+	BL runtime·setsigsegv(SB)
+	MOVD 8(RSP), R1
+	MOVD 16(RSP), R2
+
+	// Build a 16-byte stack frame for the simulated
+	// call to sigpanic, by taking 16 bytes away from the
+	// 32-byte stack frame above.
+	// The saved LR in this frame is the LR at time of fault,
+	// and the LR on entry to sigpanic is the PC at time of fault.
+	MOVD.W R1, 16(RSP)
+	MOVD R2, R30
+	B runtime·sigpanic(SB)