Initial commit: Go 1.23 release state

src/runtime/sys_linux_amd64.s

@@ -0,0 +1,706 @@
+// 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.
+
+//
+// System calls and other sys.stuff for AMD64, Linux
+//
+
+#include "go_asm.h"
+#include "go_tls.h"
+#include "textflag.h"
+#include "cgo/abi_amd64.h"
+
+#define AT_FDCWD -100
+
+#define SYS_read		0
+#define SYS_write		1
+#define SYS_close		3
+#define SYS_mmap		9
+#define SYS_munmap		11
+#define SYS_brk 		12
+#define SYS_rt_sigaction	13
+#define SYS_rt_sigprocmask	14
+#define SYS_rt_sigreturn	15
+#define SYS_sched_yield 	24
+#define SYS_mincore		27
+#define SYS_madvise		28
+#define SYS_nanosleep		35
+#define SYS_setittimer		38
+#define SYS_getpid		39
+#define SYS_socket		41
+#define SYS_connect		42
+#define SYS_clone		56
+#define SYS_exit		60
+#define SYS_kill		62
+#define SYS_sigaltstack 	131
+#define SYS_arch_prctl		158
+#define SYS_gettid		186
+#define SYS_futex		202
+#define SYS_sched_getaffinity	204
+#define SYS_timer_create	222
+#define SYS_timer_settime	223
+#define SYS_timer_delete	226
+#define SYS_clock_gettime	228
+#define SYS_exit_group		231
+#define SYS_tgkill		234
+#define SYS_openat		257
+#define SYS_faccessat		269
+#define SYS_pipe2		293
+
+TEXT runtime·exit(SB),NOSPLIT,$0-4
+	MOVL	code+0(FP), DI
+	MOVL	$SYS_exit_group, AX
+	SYSCALL
+	RET
+
+// func exitThread(wait *atomic.Uint32)
+TEXT runtime·exitThread(SB),NOSPLIT,$0-8
+	MOVQ	wait+0(FP), AX
+	// We're done using the stack.
+	MOVL	$0, (AX)
+	MOVL	$0, DI	// exit code
+	MOVL	$SYS_exit, AX
+	SYSCALL
+	// We may not even have a stack any more.
+	INT	$3
+	JMP	0(PC)
+
+TEXT runtime·open(SB),NOSPLIT,$0-20
+	// This uses openat instead of open, because Android O blocks open.
+	MOVL	$AT_FDCWD, DI // AT_FDCWD, so this acts like open
+	MOVQ	name+0(FP), SI
+	MOVL	mode+8(FP), DX
+	MOVL	perm+12(FP), R10
+	MOVL	$SYS_openat, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
+	MOVL	AX, ret+16(FP)
+	RET
+
+TEXT runtime·closefd(SB),NOSPLIT,$0-12
+	MOVL	fd+0(FP), DI
+	MOVL	$SYS_close, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
+	MOVL	AX, ret+8(FP)
+	RET
+
+TEXT runtime·write1(SB),NOSPLIT,$0-28
+	MOVQ	fd+0(FP), DI
+	MOVQ	p+8(FP), SI
+	MOVL	n+16(FP), DX
+	MOVL	$SYS_write, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+TEXT runtime·read(SB),NOSPLIT,$0-28
+	MOVL	fd+0(FP), DI
+	MOVQ	p+8(FP), SI
+	MOVL	n+16(FP), DX
+	MOVL	$SYS_read, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+// func pipe2(flags int32) (r, w int32, errno int32)
+TEXT runtime·pipe2(SB),NOSPLIT,$0-20
+	LEAQ	r+8(FP), DI
+	MOVL	flags+0(FP), SI
+	MOVL	$SYS_pipe2, AX
+	SYSCALL
+	MOVL	AX, errno+16(FP)
+	RET
+
+TEXT runtime·usleep(SB),NOSPLIT,$16
+	MOVL	$0, DX
+	MOVL	usec+0(FP), AX
+	MOVL	$1000000, CX
+	DIVL	CX
+	MOVQ	AX, 0(SP)
+	MOVL	$1000, AX	// usec to nsec
+	MULL	DX
+	MOVQ	AX, 8(SP)
+
+	// nanosleep(&ts, 0)
+	MOVQ	SP, DI
+	MOVL	$0, SI
+	MOVL	$SYS_nanosleep, AX
+	SYSCALL
+	RET
+
+TEXT runtime·gettid(SB),NOSPLIT,$0-4
+	MOVL	$SYS_gettid, AX
+	SYSCALL
+	MOVL	AX, ret+0(FP)
+	RET
+
+TEXT runtime·raise(SB),NOSPLIT,$0
+	MOVL	$SYS_getpid, AX
+	SYSCALL
+	MOVL	AX, R12
+	MOVL	$SYS_gettid, AX
+	SYSCALL
+	MOVL	AX, SI	// arg 2 tid
+	MOVL	R12, DI	// arg 1 pid
+	MOVL	sig+0(FP), DX	// arg 3
+	MOVL	$SYS_tgkill, AX
+	SYSCALL
+	RET
+
+TEXT runtime·raiseproc(SB),NOSPLIT,$0
+	MOVL	$SYS_getpid, AX
+	SYSCALL
+	MOVL	AX, DI	// arg 1 pid
+	MOVL	sig+0(FP), SI	// arg 2
+	MOVL	$SYS_kill, AX
+	SYSCALL
+	RET
+
+TEXT ·getpid(SB),NOSPLIT,$0-8
+	MOVL	$SYS_getpid, AX
+	SYSCALL
+	MOVQ	AX, ret+0(FP)
+	RET
+
+TEXT ·tgkill(SB),NOSPLIT,$0
+	MOVQ	tgid+0(FP), DI
+	MOVQ	tid+8(FP), SI
+	MOVQ	sig+16(FP), DX
+	MOVL	$SYS_tgkill, AX
+	SYSCALL
+	RET
+
+TEXT runtime·setitimer(SB),NOSPLIT,$0-24
+	MOVL	mode+0(FP), DI
+	MOVQ	new+8(FP), SI
+	MOVQ	old+16(FP), DX
+	MOVL	$SYS_setittimer, AX
+	SYSCALL
+	RET
+
+TEXT runtime·timer_create(SB),NOSPLIT,$0-28
+	MOVL	clockid+0(FP), DI
+	MOVQ	sevp+8(FP), SI
+	MOVQ	timerid+16(FP), DX
+	MOVL	$SYS_timer_create, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+TEXT runtime·timer_settime(SB),NOSPLIT,$0-28
+	MOVL	timerid+0(FP), DI
+	MOVL	flags+4(FP), SI
+	MOVQ	new+8(FP), DX
+	MOVQ	old+16(FP), R10
+	MOVL	$SYS_timer_settime, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+TEXT runtime·timer_delete(SB),NOSPLIT,$0-12
+	MOVL	timerid+0(FP), DI
+	MOVL	$SYS_timer_delete, AX
+	SYSCALL
+	MOVL	AX, ret+8(FP)
+	RET
+
+TEXT runtime·mincore(SB),NOSPLIT,$0-28
+	MOVQ	addr+0(FP), DI
+	MOVQ	n+8(FP), SI
+	MOVQ	dst+16(FP), DX
+	MOVL	$SYS_mincore, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+// func nanotime1() int64
+TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
+	// We don't know how much stack space the VDSO code will need,
+	// so switch to g0.
+	// In particular, a kernel configured with CONFIG_OPTIMIZE_INLINING=n
+	// and hardening can use a full page of stack space in gettime_sym
+	// due to stack probes inserted to avoid stack/heap collisions.
+	// See issue #20427.
+
+	MOVQ	SP, R12	// Save old SP; R12 unchanged by C code.
+
+	MOVQ	g_m(R14), BX // BX unchanged by C code.
+
+	// Set vdsoPC and vdsoSP for SIGPROF traceback.
+	// Save the old values on stack and restore them on exit,
+	// so this function is reentrant.
+	MOVQ	m_vdsoPC(BX), CX
+	MOVQ	m_vdsoSP(BX), DX
+	MOVQ	CX, 0(SP)
+	MOVQ	DX, 8(SP)
+
+	LEAQ	ret+0(FP), DX
+	MOVQ	-8(DX), CX
+	MOVQ	CX, m_vdsoPC(BX)
+	MOVQ	DX, m_vdsoSP(BX)
+
+	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
+	JNE	noswitch
+
+	MOVQ	m_g0(BX), DX
+	MOVQ	(g_sched+gobuf_sp)(DX), SP	// Set SP to g0 stack
+
+noswitch:
+	SUBQ	$16, SP		// Space for results
+	ANDQ	$~15, SP	// Align for C code
+
+	MOVL	$1, DI // CLOCK_MONOTONIC
+	LEAQ	0(SP), SI
+	MOVQ	runtime·vdsoClockgettimeSym(SB), AX
+	CMPQ	AX, $0
+	JEQ	fallback
+	CALL	AX
+ret:
+	MOVQ	0(SP), AX	// sec
+	MOVQ	8(SP), DX	// nsec
+	MOVQ	R12, SP		// Restore real SP
+	// Restore vdsoPC, vdsoSP
+	// We don't worry about being signaled between the two stores.
+	// If we are not in a signal handler, we'll restore vdsoSP to 0,
+	// and no one will care about vdsoPC. If we are in a signal handler,
+	// we cannot receive another signal.
+	MOVQ	8(SP), CX
+	MOVQ	CX, m_vdsoSP(BX)
+	MOVQ	0(SP), CX
+	MOVQ	CX, m_vdsoPC(BX)
+	// sec is in AX, nsec in DX
+	// return nsec in AX
+	IMULQ	$1000000000, AX
+	ADDQ	DX, AX
+	MOVQ	AX, ret+0(FP)
+	RET
+fallback:
+	MOVQ	$SYS_clock_gettime, AX
+	SYSCALL
+	JMP	ret
+
+TEXT runtime·rtsigprocmask(SB),NOSPLIT,$0-28
+	MOVL	how+0(FP), DI
+	MOVQ	new+8(FP), SI
+	MOVQ	old+16(FP), DX
+	MOVL	size+24(FP), R10
+	MOVL	$SYS_rt_sigprocmask, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$0xf1, 0xf1  // crash
+	RET
+
+TEXT runtime·rt_sigaction(SB),NOSPLIT,$0-36
+	MOVQ	sig+0(FP), DI
+	MOVQ	new+8(FP), SI
+	MOVQ	old+16(FP), DX
+	MOVQ	size+24(FP), R10
+	MOVL	$SYS_rt_sigaction, AX
+	SYSCALL
+	MOVL	AX, ret+32(FP)
+	RET
+
+// Call the function stored in _cgo_sigaction using the GCC calling convention.
+TEXT runtime·callCgoSigaction(SB),NOSPLIT,$16
+	MOVQ	sig+0(FP), DI
+	MOVQ	new+8(FP), SI
+	MOVQ	old+16(FP), DX
+	MOVQ	_cgo_sigaction(SB), AX
+	MOVQ	SP, BX	// callee-saved
+	ANDQ	$~15, SP	// alignment as per amd64 psABI
+	CALL	AX
+	MOVQ	BX, SP
+	MOVL	AX, ret+24(FP)
+	RET
+
+TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
+	MOVQ	fn+0(FP),    AX
+	MOVL	sig+8(FP),   DI
+	MOVQ	info+16(FP), SI
+	MOVQ	ctx+24(FP),  DX
+	MOVQ	SP, BX		// callee-saved
+	ANDQ	$~15, SP     // alignment for x86_64 ABI
+	CALL	AX
+	MOVQ	BX, SP
+	RET
+
+// Called using C ABI.
+TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME|NOFRAME,$0
+	// Transition from C ABI to Go ABI.
+	PUSH_REGS_HOST_TO_ABI0()
+
+	// Set up ABIInternal environment: g in R14, cleared X15.
+	get_tls(R12)
+	MOVQ	g(R12), R14
+	PXOR	X15, X15
+
+	// Reserve space for spill slots.
+	NOP	SP		// disable vet stack checking
+	ADJSP   $24
+
+	// Call into the Go signal handler
+	MOVQ	DI, AX	// sig
+	MOVQ	SI, BX	// info
+	MOVQ	DX, CX	// ctx
+	CALL	·sigtrampgo<ABIInternal>(SB)
+
+	ADJSP	$-24
+
+	POP_REGS_HOST_TO_ABI0()
+	RET
+
+// Called using C ABI.
+TEXT runtime·sigprofNonGoWrapper<>(SB),NOSPLIT|NOFRAME,$0
+	// Transition from C ABI to Go ABI.
+	PUSH_REGS_HOST_TO_ABI0()
+
+	// Set up ABIInternal environment: g in R14, cleared X15.
+	get_tls(R12)
+	MOVQ	g(R12), R14
+	PXOR	X15, X15
+
+	// Reserve space for spill slots.
+	NOP	SP		// disable vet stack checking
+	ADJSP   $24
+
+	// Call into the Go signal handler
+	MOVQ	DI, AX	// sig
+	MOVQ	SI, BX	// info
+	MOVQ	DX, CX	// ctx
+	CALL	·sigprofNonGo<ABIInternal>(SB)
+
+	ADJSP	$-24
+
+	POP_REGS_HOST_TO_ABI0()
+	RET
+
+// Used instead of sigtramp in programs that use cgo.
+// Arguments from kernel are in DI, SI, DX.
+TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
+	// If no traceback function, do usual sigtramp.
+	MOVQ	runtime·cgoTraceback(SB), AX
+	TESTQ	AX, AX
+	JZ	sigtramp
+
+	// If no traceback support function, which means that
+	// runtime/cgo was not linked in, do usual sigtramp.
+	MOVQ	_cgo_callers(SB), AX
+	TESTQ	AX, AX
+	JZ	sigtramp
+
+	// Figure out if we are currently in a cgo call.
+	// If not, just do usual sigtramp.
+	get_tls(CX)
+	MOVQ	g(CX),AX
+	TESTQ	AX, AX
+	JZ	sigtrampnog     // g == nil
+	MOVQ	g_m(AX), AX
+	TESTQ	AX, AX
+	JZ	sigtramp        // g.m == nil
+	MOVL	m_ncgo(AX), CX
+	TESTL	CX, CX
+	JZ	sigtramp        // g.m.ncgo == 0
+	MOVQ	m_curg(AX), CX
+	TESTQ	CX, CX
+	JZ	sigtramp        // g.m.curg == nil
+	MOVQ	g_syscallsp(CX), CX
+	TESTQ	CX, CX
+	JZ	sigtramp        // g.m.curg.syscallsp == 0
+	MOVQ	m_cgoCallers(AX), R8
+	TESTQ	R8, R8
+	JZ	sigtramp        // g.m.cgoCallers == nil
+	MOVL	m_cgoCallersUse(AX), CX
+	TESTL	CX, CX
+	JNZ	sigtramp	// g.m.cgoCallersUse != 0
+
+	// Jump to a function in runtime/cgo.
+	// That function, written in C, will call the user's traceback
+	// function with proper unwind info, and will then call back here.
+	// The first three arguments, and the fifth, are already in registers.
+	// Set the two remaining arguments now.
+	MOVQ	runtime·cgoTraceback(SB), CX
+	MOVQ	$runtime·sigtramp(SB), R9
+	MOVQ	_cgo_callers(SB), AX
+	JMP	AX
+
+sigtramp:
+	JMP	runtime·sigtramp(SB)
+
+sigtrampnog:
+	// Signal arrived on a non-Go thread. If this is SIGPROF, get a
+	// stack trace.
+	CMPL	DI, $27 // 27 == SIGPROF
+	JNZ	sigtramp
+
+	// Lock sigprofCallersUse.
+	MOVL	$0, AX
+	MOVL	$1, CX
+	MOVQ	$runtime·sigprofCallersUse(SB), R11
+	LOCK
+	CMPXCHGL	CX, 0(R11)
+	JNZ	sigtramp  // Skip stack trace if already locked.
+
+	// Jump to the traceback function in runtime/cgo.
+	// It will call back to sigprofNonGo, via sigprofNonGoWrapper, to convert
+	// the arguments to the Go calling convention.
+	// First three arguments to traceback function are in registers already.
+	MOVQ	runtime·cgoTraceback(SB), CX
+	MOVQ	$runtime·sigprofCallers(SB), R8
+	MOVQ	$runtime·sigprofNonGoWrapper<>(SB), R9
+	MOVQ	_cgo_callers(SB), AX
+	JMP	AX
+
+// For cgo unwinding to work, this function must look precisely like
+// the one in glibc. The glibc source code is:
+// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c;h=afdce87381228f0cf32fa9fa6c8c4efa5179065c#l80
+// The code that cares about the precise instructions used is:
+// https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgcc/config/i386/linux-unwind.h;h=5486223d60272c73d5103b29ae592d2ee998e1cf#l49
+//
+// For gdb unwinding to work, this function must look precisely like the one in
+// glibc and must be named "__restore_rt" or contain the string "sigaction" in
+// the name. The gdb source code is:
+// https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/amd64-linux-tdep.c;h=cbbac1a0c64e1deb8181b9d0ff6404e328e2979d#l178
+TEXT runtime·sigreturn__sigaction(SB),NOSPLIT,$0
+	MOVQ	$SYS_rt_sigreturn, AX
+	SYSCALL
+	INT $3	// not reached
+
+TEXT runtime·sysMmap(SB),NOSPLIT,$0
+	MOVQ	addr+0(FP), DI
+	MOVQ	n+8(FP), SI
+	MOVL	prot+16(FP), DX
+	MOVL	flags+20(FP), R10
+	MOVL	fd+24(FP), R8
+	MOVL	off+28(FP), R9
+
+	MOVL	$SYS_mmap, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	ok
+	NOTQ	AX
+	INCQ	AX
+	MOVQ	$0, p+32(FP)
+	MOVQ	AX, err+40(FP)
+	RET
+ok:
+	MOVQ	AX, p+32(FP)
+	MOVQ	$0, err+40(FP)
+	RET
+
+// Call the function stored in _cgo_mmap using the GCC calling convention.
+// This must be called on the system stack.
+TEXT runtime·callCgoMmap(SB),NOSPLIT,$16
+	MOVQ	addr+0(FP), DI
+	MOVQ	n+8(FP), SI
+	MOVL	prot+16(FP), DX
+	MOVL	flags+20(FP), CX
+	MOVL	fd+24(FP), R8
+	MOVL	off+28(FP), R9
+	MOVQ	_cgo_mmap(SB), AX
+	MOVQ	SP, BX
+	ANDQ	$~15, SP	// alignment as per amd64 psABI
+	MOVQ	BX, 0(SP)
+	CALL	AX
+	MOVQ	0(SP), SP
+	MOVQ	AX, ret+32(FP)
+	RET
+
+TEXT runtime·sysMunmap(SB),NOSPLIT,$0
+	MOVQ	addr+0(FP), DI
+	MOVQ	n+8(FP), SI
+	MOVQ	$SYS_munmap, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$0xf1, 0xf1  // crash
+	RET
+
+// Call the function stored in _cgo_munmap using the GCC calling convention.
+// This must be called on the system stack.
+TEXT runtime·callCgoMunmap(SB),NOSPLIT,$16-16
+	MOVQ	addr+0(FP), DI
+	MOVQ	n+8(FP), SI
+	MOVQ	_cgo_munmap(SB), AX
+	MOVQ	SP, BX
+	ANDQ	$~15, SP	// alignment as per amd64 psABI
+	MOVQ	BX, 0(SP)
+	CALL	AX
+	MOVQ	0(SP), SP
+	RET
+
+TEXT runtime·madvise(SB),NOSPLIT,$0
+	MOVQ	addr+0(FP), DI
+	MOVQ	n+8(FP), SI
+	MOVL	flags+16(FP), DX
+	MOVQ	$SYS_madvise, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+// int64 futex(int32 *uaddr, int32 op, int32 val,
+//	struct timespec *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex(SB),NOSPLIT,$0
+	MOVQ	addr+0(FP), DI
+	MOVL	op+8(FP), SI
+	MOVL	val+12(FP), DX
+	MOVQ	ts+16(FP), R10
+	MOVQ	addr2+24(FP), R8
+	MOVL	val3+32(FP), R9
+	MOVL	$SYS_futex, AX
+	SYSCALL
+	MOVL	AX, ret+40(FP)
+	RET
+
+// int32 clone(int32 flags, void *stk, M *mp, G *gp, void (*fn)(void));
+TEXT runtime·clone(SB),NOSPLIT|NOFRAME,$0
+	MOVL	flags+0(FP), DI
+	MOVQ	stk+8(FP), SI
+	MOVQ	$0, DX
+	MOVQ	$0, R10
+	MOVQ    $0, R8
+	// Copy mp, gp, fn off parent stack for use by child.
+	// Careful: Linux system call clobbers CX and R11.
+	MOVQ	mp+16(FP), R13
+	MOVQ	gp+24(FP), R9
+	MOVQ	fn+32(FP), R12
+	CMPQ	R13, $0    // m
+	JEQ	nog1
+	CMPQ	R9, $0    // g
+	JEQ	nog1
+	LEAQ	m_tls(R13), R8
+#ifdef GOOS_android
+	// Android stores the TLS offset in runtime·tls_g.
+	SUBQ	runtime·tls_g(SB), R8
+#else
+	ADDQ	$8, R8	// ELF wants to use -8(FS)
+#endif
+	ORQ 	$0x00080000, DI //add flag CLONE_SETTLS(0x00080000) to call clone
+nog1:
+	MOVL	$SYS_clone, AX
+	SYSCALL
+
+	// In parent, return.
+	CMPQ	AX, $0
+	JEQ	3(PC)
+	MOVL	AX, ret+40(FP)
+	RET
+
+	// In child, on new stack.
+	MOVQ	SI, SP
+
+	// If g or m are nil, skip Go-related setup.
+	CMPQ	R13, $0    // m
+	JEQ	nog2
+	CMPQ	R9, $0    // g
+	JEQ	nog2
+
+	// Initialize m->procid to Linux tid
+	MOVL	$SYS_gettid, AX
+	SYSCALL
+	MOVQ	AX, m_procid(R13)
+
+	// In child, set up new stack
+	get_tls(CX)
+	MOVQ	R13, g_m(R9)
+	MOVQ	R9, g(CX)
+	MOVQ	R9, R14 // set g register
+	CALL	runtime·stackcheck(SB)
+
+nog2:
+	// Call fn. This is the PC of an ABI0 function.
+	CALL	R12
+
+	// It shouldn't return. If it does, exit that thread.
+	MOVL	$111, DI
+	MOVL	$SYS_exit, AX
+	SYSCALL
+	JMP	-3(PC)	// keep exiting
+
+TEXT runtime·sigaltstack(SB),NOSPLIT,$0
+	MOVQ	new+0(FP), DI
+	MOVQ	old+8(FP), SI
+	MOVQ	$SYS_sigaltstack, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$0xf1, 0xf1  // crash
+	RET
+
+// set tls base to DI
+TEXT runtime·settls(SB),NOSPLIT,$32
+#ifdef GOOS_android
+	// Android stores the TLS offset in runtime·tls_g.
+	SUBQ	runtime·tls_g(SB), DI
+#else
+	ADDQ	$8, DI	// ELF wants to use -8(FS)
+#endif
+	MOVQ	DI, SI
+	MOVQ	$0x1002, DI	// ARCH_SET_FS
+	MOVQ	$SYS_arch_prctl, AX
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$0xf1, 0xf1  // crash
+	RET
+
+TEXT runtime·osyield(SB),NOSPLIT,$0
+	MOVL	$SYS_sched_yield, AX
+	SYSCALL
+	RET
+
+TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
+	MOVQ	pid+0(FP), DI
+	MOVQ	len+8(FP), SI
+	MOVQ	buf+16(FP), DX
+	MOVL	$SYS_sched_getaffinity, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+// int access(const char *name, int mode)
+TEXT runtime·access(SB),NOSPLIT,$0
+	// This uses faccessat instead of access, because Android O blocks access.
+	MOVL	$AT_FDCWD, DI // AT_FDCWD, so this acts like access
+	MOVQ	name+0(FP), SI
+	MOVL	mode+8(FP), DX
+	MOVL	$0, R10
+	MOVL	$SYS_faccessat, AX
+	SYSCALL
+	MOVL	AX, ret+16(FP)
+	RET
+
+// int connect(int fd, const struct sockaddr *addr, socklen_t addrlen)
+TEXT runtime·connect(SB),NOSPLIT,$0-28
+	MOVL	fd+0(FP), DI
+	MOVQ	addr+8(FP), SI
+	MOVL	len+16(FP), DX
+	MOVL	$SYS_connect, AX
+	SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
+// int socket(int domain, int type, int protocol)
+TEXT runtime·socket(SB),NOSPLIT,$0-20
+	MOVL	domain+0(FP), DI
+	MOVL	typ+4(FP), SI
+	MOVL	prot+8(FP), DX
+	MOVL	$SYS_socket, AX
+	SYSCALL
+	MOVL	AX, ret+16(FP)
+	RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$0-8
+	// Implemented as brk(NULL).
+	MOVQ	$0, DI
+	MOVL	$SYS_brk, AX
+	SYSCALL
+	MOVQ	AX, ret+0(FP)
+	RET