src/runtime/sys_linux_arm64.s

// 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.

//
// System calls and other sys.stuff for arm64, Linux
//

#include "go_asm.h"
#include "go_tls.h"
#include "textflag.h"
#include "cgo/abi_arm64.h"

#define AT_FDCWD -100

#define CLOCK_REALTIME 0
#define CLOCK_MONOTONIC 1

#define SYS_exit		93
#define SYS_read		63
#define SYS_write		64
#define SYS_openat		56
#define SYS_close		57
#define SYS_pipe2		59
#define SYS_nanosleep		101
#define SYS_mmap		222
#define SYS_munmap		215
#define SYS_setitimer		103
#define SYS_clone		220
#define SYS_sched_yield		124
#define SYS_rt_sigreturn	139
#define SYS_rt_sigaction	134
#define SYS_rt_sigprocmask	135
#define SYS_sigaltstack		132
#define SYS_madvise		233
#define SYS_mincore		232
#define SYS_getpid		172
#define SYS_gettid		178
#define SYS_kill		129
#define SYS_tgkill		131
#define SYS_futex		98
#define SYS_sched_getaffinity	123
#define SYS_exit_group		94
#define SYS_clock_gettime	113
#define SYS_faccessat		48
#define SYS_socket		198
#define SYS_connect		203
#define SYS_brk			214
#define SYS_timer_create	107
#define SYS_timer_settime	110
#define SYS_timer_delete	111

TEXT runtime·exit(SB),NOSPLIT|NOFRAME,$0-4
	MOVW	code+0(FP), R0
	MOVD	$SYS_exit_group, R8
	SVC
	RET

// func exitThread(wait *atomic.Uint32)
TEXT runtime·exitThread(SB),NOSPLIT|NOFRAME,$0-8
	MOVD	wait+0(FP), R0
	// We're done using the stack.
	MOVW	$0, R1
	STLRW	R1, (R0)
	MOVW	$0, R0	// exit code
	MOVD	$SYS_exit, R8
	SVC
	JMP	0(PC)

TEXT runtime·open(SB),NOSPLIT|NOFRAME,$0-20
	MOVD	$AT_FDCWD, R0
	MOVD	name+0(FP), R1
	MOVW	mode+8(FP), R2
	MOVW	perm+12(FP), R3
	MOVD	$SYS_openat, R8
	SVC
	CMN	$4095, R0
	BCC	done
	MOVW	$-1, R0
done:
	MOVW	R0, ret+16(FP)
	RET

TEXT runtime·closefd(SB),NOSPLIT|NOFRAME,$0-12
	MOVW	fd+0(FP), R0
	MOVD	$SYS_close, R8
	SVC
	CMN	$4095, R0
	BCC	done
	MOVW	$-1, R0
done:
	MOVW	R0, ret+8(FP)
	RET

TEXT runtime·write1(SB),NOSPLIT|NOFRAME,$0-28
	MOVD	fd+0(FP), R0
	MOVD	p+8(FP), R1
	MOVW	n+16(FP), R2
	MOVD	$SYS_write, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

TEXT runtime·read(SB),NOSPLIT|NOFRAME,$0-28
	MOVW	fd+0(FP), R0
	MOVD	p+8(FP), R1
	MOVW	n+16(FP), R2
	MOVD	$SYS_read, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

// func pipe2(flags int32) (r, w int32, errno int32)
TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20
	MOVD	$r+8(FP), R0
	MOVW	flags+0(FP), R1
	MOVW	$SYS_pipe2, R8
	SVC
	MOVW	R0, errno+16(FP)
	RET

TEXT runtime·usleep(SB),NOSPLIT,$24-4
	MOVWU	usec+0(FP), R3
	MOVD	R3, R5
	MOVW	$1000000, R4
	UDIV	R4, R3
	MOVD	R3, 8(RSP)
	MUL	R3, R4
	SUB	R4, R5
	MOVW	$1000, R4
	MUL	R4, R5
	MOVD	R5, 16(RSP)

	// nanosleep(&ts, 0)
	ADD	$8, RSP, R0
	MOVD	$0, R1
	MOVD	$SYS_nanosleep, R8
	SVC
	RET

TEXT runtime·gettid(SB),NOSPLIT,$0-4
	MOVD	$SYS_gettid, R8
	SVC
	MOVW	R0, ret+0(FP)
	RET

TEXT runtime·raise(SB),NOSPLIT|NOFRAME,$0
	MOVD	$SYS_getpid, R8
	SVC
	MOVW	R0, R19
	MOVD	$SYS_gettid, R8
	SVC
	MOVW	R0, R1	// arg 2 tid
	MOVW	R19, R0	// arg 1 pid
	MOVW	sig+0(FP), R2	// arg 3
	MOVD	$SYS_tgkill, R8
	SVC
	RET

TEXT runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
	MOVD	$SYS_getpid, R8
	SVC
	MOVW	R0, R0		// arg 1 pid
	MOVW	sig+0(FP), R1	// arg 2
	MOVD	$SYS_kill, R8
	SVC
	RET

TEXT ·getpid(SB),NOSPLIT|NOFRAME,$0-8
	MOVD	$SYS_getpid, R8
	SVC
	MOVD	R0, ret+0(FP)
	RET

TEXT ·tgkill(SB),NOSPLIT,$0-24
	MOVD	tgid+0(FP), R0
	MOVD	tid+8(FP), R1
	MOVD	sig+16(FP), R2
	MOVD	$SYS_tgkill, R8
	SVC
	RET

TEXT runtime·setitimer(SB),NOSPLIT|NOFRAME,$0-24
	MOVW	mode+0(FP), R0
	MOVD	new+8(FP), R1
	MOVD	old+16(FP), R2
	MOVD	$SYS_setitimer, R8
	SVC
	RET

TEXT runtime·timer_create(SB),NOSPLIT,$0-28
	MOVW	clockid+0(FP), R0
	MOVD	sevp+8(FP), R1
	MOVD	timerid+16(FP), R2
	MOVD	$SYS_timer_create, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

TEXT runtime·timer_settime(SB),NOSPLIT,$0-28
	MOVW	timerid+0(FP), R0
	MOVW	flags+4(FP), R1
	MOVD	new+8(FP), R2
	MOVD	old+16(FP), R3
	MOVD	$SYS_timer_settime, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

TEXT runtime·timer_delete(SB),NOSPLIT,$0-12
	MOVW	timerid+0(FP), R0
	MOVD	$SYS_timer_delete, R8
	SVC
	MOVW	R0, ret+8(FP)
	RET

TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
	MOVD	addr+0(FP), R0
	MOVD	n+8(FP), R1
	MOVD	dst+16(FP), R2
	MOVD	$SYS_mincore, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

// func walltime() (sec int64, nsec int32)
TEXT runtime·walltime(SB),NOSPLIT,$24-12
	MOVD	RSP, R20	// R20 is unchanged by C code
	MOVD	RSP, R1

	MOVD	g_m(g), R21	// R21 = m

	// Set vdsoPC and vdsoSP for SIGPROF traceback.
	// Save the old values on stack and restore them on exit,
	// so this function is reentrant.
	MOVD	m_vdsoPC(R21), R2
	MOVD	m_vdsoSP(R21), R3
	MOVD	R2, 8(RSP)
	MOVD	R3, 16(RSP)

	MOVD	$ret-8(FP), R2 // caller's SP
	MOVD	LR, m_vdsoPC(R21)
	MOVD	R2, m_vdsoSP(R21)

	MOVD	m_curg(R21), R0
	CMP	g, R0
	BNE	noswitch

	MOVD	m_g0(R21), R3
	MOVD	(g_sched+gobuf_sp)(R3), R1	// Set RSP to g0 stack

noswitch:
	SUB	$16, R1
	BIC	$15, R1	// Align for C code
	MOVD	R1, RSP

	MOVW	$CLOCK_REALTIME, R0
	MOVD	runtime·vdsoClockgettimeSym(SB), R2
	CBZ	R2, fallback

	// Store g on gsignal's stack, so if we receive a signal
	// during VDSO code we can find the g.
	// If we don't have a signal stack, we won't receive signal,
	// so don't bother saving g.
	// When using cgo, we already saved g on TLS, also don't save
	// g here.
	// Also don't save g if we are already on the signal stack.
	// We won't get a nested signal.
	MOVBU	runtime·iscgo(SB), R22
	CBNZ	R22, nosaveg
	MOVD	m_gsignal(R21), R22          // g.m.gsignal
	CBZ	R22, nosaveg
	CMP	g, R22
	BEQ	nosaveg
	MOVD	(g_stack+stack_lo)(R22), R22 // g.m.gsignal.stack.lo
	MOVD	g, (R22)

	BL	(R2)

	MOVD	ZR, (R22)  // clear g slot, R22 is unchanged by C code

	B	finish

nosaveg:
	BL	(R2)
	B	finish

fallback:
	MOVD	$SYS_clock_gettime, R8
	SVC

finish:
	MOVD	0(RSP), R3	// sec
	MOVD	8(RSP), R5	// nsec

	MOVD	R20, RSP	// restore 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.
	MOVD	16(RSP), R1
	MOVD	R1, m_vdsoSP(R21)
	MOVD	8(RSP), R1
	MOVD	R1, m_vdsoPC(R21)

	MOVD	R3, sec+0(FP)
	MOVW	R5, nsec+8(FP)
	RET

TEXT runtime·nanotime1(SB),NOSPLIT,$24-8
	MOVD	RSP, R20	// R20 is unchanged by C code
	MOVD	RSP, R1

	MOVD	g_m(g), R21	// R21 = m

	// Set vdsoPC and vdsoSP for SIGPROF traceback.
	// Save the old values on stack and restore them on exit,
	// so this function is reentrant.
	MOVD	m_vdsoPC(R21), R2
	MOVD	m_vdsoSP(R21), R3
	MOVD	R2, 8(RSP)
	MOVD	R3, 16(RSP)

	MOVD	$ret-8(FP), R2 // caller's SP
	MOVD	LR, m_vdsoPC(R21)
	MOVD	R2, m_vdsoSP(R21)

	MOVD	m_curg(R21), R0
	CMP	g, R0
	BNE	noswitch

	MOVD	m_g0(R21), R3
	MOVD	(g_sched+gobuf_sp)(R3), R1	// Set RSP to g0 stack

noswitch:
	SUB	$32, R1
	BIC	$15, R1
	MOVD	R1, RSP

	MOVW	$CLOCK_MONOTONIC, R0
	MOVD	runtime·vdsoClockgettimeSym(SB), R2
	CBZ	R2, fallback

	// Store g on gsignal's stack, so if we receive a signal
	// during VDSO code we can find the g.
	// If we don't have a signal stack, we won't receive signal,
	// so don't bother saving g.
	// When using cgo, we already saved g on TLS, also don't save
	// g here.
	// Also don't save g if we are already on the signal stack.
	// We won't get a nested signal.
	MOVBU	runtime·iscgo(SB), R22
	CBNZ	R22, nosaveg
	MOVD	m_gsignal(R21), R22          // g.m.gsignal
	CBZ	R22, nosaveg
	CMP	g, R22
	BEQ	nosaveg
	MOVD	(g_stack+stack_lo)(R22), R22 // g.m.gsignal.stack.lo
	MOVD	g, (R22)

	BL	(R2)

	MOVD	ZR, (R22)  // clear g slot, R22 is unchanged by C code

	B	finish

nosaveg:
	BL	(R2)
	B	finish

fallback:
	MOVD	$SYS_clock_gettime, R8
	SVC

finish:
	MOVD	0(RSP), R3	// sec
	MOVD	8(RSP), R5	// nsec

	MOVD	R20, RSP	// restore 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.
	MOVD	16(RSP), R1
	MOVD	R1, m_vdsoSP(R21)
	MOVD	8(RSP), R1
	MOVD	R1, m_vdsoPC(R21)

	// sec is in R3, nsec in R5
	// return nsec in R3
	MOVD	$1000000000, R4
	MUL	R4, R3
	ADD	R5, R3
	MOVD	R3, ret+0(FP)
	RET

TEXT runtime·rtsigprocmask(SB),NOSPLIT|NOFRAME,$0-28
	MOVW	how+0(FP), R0
	MOVD	new+8(FP), R1
	MOVD	old+16(FP), R2
	MOVW	size+24(FP), R3
	MOVD	$SYS_rt_sigprocmask, R8
	SVC
	CMN	$4095, R0
	BCC	done
	MOVD	$0, R0
	MOVD	R0, (R0)	// crash
done:
	RET

TEXT runtime·rt_sigaction(SB),NOSPLIT|NOFRAME,$0-36
	MOVD	sig+0(FP), R0
	MOVD	new+8(FP), R1
	MOVD	old+16(FP), R2
	MOVD	size+24(FP), R3
	MOVD	$SYS_rt_sigaction, R8
	SVC
	MOVW	R0, ret+32(FP)
	RET

// Call the function stored in _cgo_sigaction using the GCC calling convention.
TEXT runtime·callCgoSigaction(SB),NOSPLIT,$0
	MOVD	sig+0(FP), R0
	MOVD	new+8(FP), R1
	MOVD	old+16(FP), R2
	MOVD	 _cgo_sigaction(SB), R3
	SUB	$16, RSP		// reserve 16 bytes for sp-8 where fp may be saved.
	BL	R3
	ADD	$16, RSP
	MOVW	R0, ret+24(FP)
	RET

TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
	MOVW	sig+8(FP), R0
	MOVD	info+16(FP), R1
	MOVD	ctx+24(FP), R2
	MOVD	fn+0(FP), R11
	BL	(R11)
	RET

// Called from c-abi, R0: sig, R1: info, R2: cxt
TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME,$176
	// Save callee-save registers in the case of signal forwarding.
	// Please refer to https://golang.org/issue/31827 .
	SAVE_R19_TO_R28(8*4)
	SAVE_F8_TO_F15(8*14)

	// this might be called in external code context,
	// where g is not set.
	// first save R0, because runtime·load_g will clobber it
	MOVW	R0, 8(RSP)
	MOVBU	runtime·iscgo(SB), R0
	CBZ	R0, 2(PC)
	BL	runtime·load_g(SB)

#ifdef GOEXPERIMENT_regabiargs
	// Restore signum to R0.
	MOVW	8(RSP), R0
	// R1 and R2 already contain info and ctx, respectively.
#else
	MOVD	R1, 16(RSP)
	MOVD	R2, 24(RSP)
#endif
	MOVD	$runtime·sigtrampgo<ABIInternal>(SB), R3
	BL	(R3)

	// Restore callee-save registers.
	RESTORE_R19_TO_R28(8*4)
	RESTORE_F8_TO_F15(8*14)

	RET

// Called from c-abi, R0: sig, R1: info, R2: cxt
TEXT runtime·sigprofNonGoWrapper<>(SB),NOSPLIT,$176
	// Save callee-save registers because it's a callback from c code.
	SAVE_R19_TO_R28(8*4)
	SAVE_F8_TO_F15(8*14)

#ifdef GOEXPERIMENT_regabiargs
	// R0, R1 and R2 already contain sig, info and ctx, respectively.
#else
	MOVW	R0, 8(RSP)	// sig
	MOVD	R1, 16(RSP)	// info
	MOVD	R2, 24(RSP)	// ctx
#endif
	CALL	runtime·sigprofNonGo<ABIInternal>(SB)

	// Restore callee-save registers.
	RESTORE_R19_TO_R28(8*4)
	RESTORE_F8_TO_F15(8*14)
	RET

// Called from c-abi, R0: sig, R1: info, R2: cxt
TEXT runtime·cgoSigtramp(SB),NOSPLIT|NOFRAME,$0
	// The stack unwinder, presumably written in C, may not be able to
	// handle Go frame correctly. So, this function is NOFRAME, and we
	// save/restore LR manually.
	MOVD	LR, R10
	// Save R27, g because they will be clobbered,
	// we need to restore them before jump to sigtramp.
	MOVD	R27, R11
	MOVD	g, R12

	// If no traceback function, do usual sigtramp.
	MOVD	runtime·cgoTraceback(SB), R6
	CBZ	R6, sigtramp

	// If no traceback support function, which means that
	// runtime/cgo was not linked in, do usual sigtramp.
	MOVD	_cgo_callers(SB), R7
	CBZ	R7, sigtramp

	// Figure out if we are currently in a cgo call.
	// If not, just do usual sigtramp.
	// first save R0, because runtime·load_g will clobber it.
	MOVD	R0, R8
	// Set up g register.
	CALL	runtime·load_g(SB)
	MOVD	R8, R0

	CBZ	g, sigtrampnog // g == nil
	MOVD	g_m(g), R6
	CBZ	R6, sigtramp    // g.m == nil
	MOVW	m_ncgo(R6), R7
	CBZW	R7, sigtramp    // g.m.ncgo = 0
	MOVD	m_curg(R6), R8
	CBZ	R8, sigtramp    // g.m.curg == nil
	MOVD	g_syscallsp(R8), R7
	CBZ	R7,	sigtramp    // g.m.curg.syscallsp == 0
	MOVD	m_cgoCallers(R6), R4 // R4 is the fifth arg in C calling convention.
	CBZ	R4,	sigtramp    // g.m.cgoCallers == nil
	MOVW	m_cgoCallersUse(R6), R8
	CBNZW	R8, 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.
	MOVD	runtime·cgoTraceback(SB), R3
	MOVD	$runtime·sigtramp(SB), R5
	MOVD	_cgo_callers(SB), R13
	MOVD	R10, LR // restore
	MOVD	R11, R27
	MOVD	R12, g
	B	(R13)

sigtramp:
	MOVD	R10, LR // restore
	MOVD	R11, R27
	MOVD	R12, g
	B	runtime·sigtramp(SB)

sigtrampnog:
	// Signal arrived on a non-Go thread. If this is SIGPROF, get a
	// stack trace.
	CMPW	$27, R0 // 27 == SIGPROF
	BNE	sigtramp

	// Lock sigprofCallersUse (cas from 0 to 1).
	MOVW	$1, R7
	MOVD	$runtime·sigprofCallersUse(SB), R8
load_store_loop:
	LDAXRW	(R8), R9
	CBNZW	R9, sigtramp // Skip stack trace if already locked.
	STLXRW	R7, (R8), R9
	CBNZ	R9, load_store_loop

	// Jump to the traceback function in runtime/cgo.
	// It will call back to sigprofNonGo, which will ignore the
	// arguments passed in registers.
	// First three arguments to traceback function are in registers already.
	MOVD	runtime·cgoTraceback(SB), R3
	MOVD	$runtime·sigprofCallers(SB), R4
	MOVD	$runtime·sigprofNonGoWrapper<>(SB), R5
	MOVD	_cgo_callers(SB), R13
	MOVD	R10, LR // restore
	MOVD	R11, R27
	MOVD	R12, g
	B	(R13)

TEXT runtime·sysMmap(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R0
	MOVD	n+8(FP), R1
	MOVW	prot+16(FP), R2
	MOVW	flags+20(FP), R3
	MOVW	fd+24(FP), R4
	MOVW	off+28(FP), R5

	MOVD	$SYS_mmap, R8
	SVC
	CMN	$4095, R0
	BCC	ok
	NEG	R0,R0
	MOVD	$0, p+32(FP)
	MOVD	R0, err+40(FP)
	RET
ok:
	MOVD	R0, p+32(FP)
	MOVD	$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,$0
	MOVD	addr+0(FP), R0
	MOVD	n+8(FP), R1
	MOVW	prot+16(FP), R2
	MOVW	flags+20(FP), R3
	MOVW	fd+24(FP), R4
	MOVW	off+28(FP), R5
	MOVD	_cgo_mmap(SB), R9
	SUB	$16, RSP		// reserve 16 bytes for sp-8 where fp may be saved.
	BL	R9
	ADD	$16, RSP
	MOVD	R0, ret+32(FP)
	RET

TEXT runtime·sysMunmap(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R0
	MOVD	n+8(FP), R1
	MOVD	$SYS_munmap, R8
	SVC
	CMN	$4095, R0
	BCC	cool
	MOVD	R0, 0xf0(R0)
cool:
	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,$0
	MOVD	addr+0(FP), R0
	MOVD	n+8(FP), R1
	MOVD	_cgo_munmap(SB), R9
	SUB	$16, RSP		// reserve 16 bytes for sp-8 where fp may be saved.
	BL	R9
	ADD	$16, RSP
	RET

TEXT runtime·madvise(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R0
	MOVD	n+8(FP), R1
	MOVW	flags+16(FP), R2
	MOVD	$SYS_madvise, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

// int64 futex(int32 *uaddr, int32 op, int32 val,
//	struct timespec *timeout, int32 *uaddr2, int32 val2);
TEXT runtime·futex(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R0
	MOVW	op+8(FP), R1
	MOVW	val+12(FP), R2
	MOVD	ts+16(FP), R3
	MOVD	addr2+24(FP), R4
	MOVW	val3+32(FP), R5
	MOVD	$SYS_futex, R8
	SVC
	MOVW	R0, ret+40(FP)
	RET

// int64 clone(int32 flags, void *stk, M *mp, G *gp, void (*fn)(void));
TEXT runtime·clone(SB),NOSPLIT|NOFRAME,$0
	MOVW	flags+0(FP), R0
	MOVD	stk+8(FP), R1

	// Copy mp, gp, fn off parent stack for use by child.
	MOVD	mp+16(FP), R10
	MOVD	gp+24(FP), R11
	MOVD	fn+32(FP), R12

	MOVD	R10, -8(R1)
	MOVD	R11, -16(R1)
	MOVD	R12, -24(R1)
	MOVD	$1234, R10
	MOVD	R10, -32(R1)

	MOVD	$SYS_clone, R8
	SVC

	// In parent, return.
	CMP	ZR, R0
	BEQ	child
	MOVW	R0, ret+40(FP)
	RET
child:

	// In child, on new stack.
	MOVD	-32(RSP), R10
	MOVD	$1234, R0
	CMP	R0, R10
	BEQ	good
	MOVD	$0, R0
	MOVD	R0, (R0)	// crash

good:
	// Initialize m->procid to Linux tid
	MOVD	$SYS_gettid, R8
	SVC

	MOVD	-24(RSP), R12     // fn
	MOVD	-16(RSP), R11     // g
	MOVD	-8(RSP), R10      // m

	CMP	$0, R10
	BEQ	nog
	CMP	$0, R11
	BEQ	nog

	MOVD	R0, m_procid(R10)

	// TODO: setup TLS.

	// In child, set up new stack
	MOVD	R10, g_m(R11)
	MOVD	R11, g
	//CALL	runtime·stackcheck(SB)

nog:
	// Call fn
	MOVD	R12, R0
	BL	(R0)

	// It shouldn't return.	 If it does, exit that thread.
	MOVW	$111, R0
again:
	MOVD	$SYS_exit, R8
	SVC
	B	again	// keep exiting

TEXT runtime·sigaltstack(SB),NOSPLIT|NOFRAME,$0
	MOVD	new+0(FP), R0
	MOVD	old+8(FP), R1
	MOVD	$SYS_sigaltstack, R8
	SVC
	CMN	$4095, R0
	BCC	ok
	MOVD	$0, R0
	MOVD	R0, (R0)	// crash
ok:
	RET

TEXT runtime·osyield(SB),NOSPLIT|NOFRAME,$0
	MOVD	$SYS_sched_yield, R8
	SVC
	RET

TEXT runtime·sched_getaffinity(SB),NOSPLIT|NOFRAME,$0
	MOVD	pid+0(FP), R0
	MOVD	len+8(FP), R1
	MOVD	buf+16(FP), R2
	MOVD	$SYS_sched_getaffinity, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

// int access(const char *name, int mode)
TEXT runtime·access(SB),NOSPLIT,$0-20
	MOVD	$AT_FDCWD, R0
	MOVD	name+0(FP), R1
	MOVW	mode+8(FP), R2
	MOVD	$SYS_faccessat, R8
	SVC
	MOVW	R0, ret+16(FP)
	RET

// int connect(int fd, const struct sockaddr *addr, socklen_t len)
TEXT runtime·connect(SB),NOSPLIT,$0-28
	MOVW	fd+0(FP), R0
	MOVD	addr+8(FP), R1
	MOVW	len+16(FP), R2
	MOVD	$SYS_connect, R8
	SVC
	MOVW	R0, ret+24(FP)
	RET

// int socket(int domain, int typ, int prot)
TEXT runtime·socket(SB),NOSPLIT,$0-20
	MOVW	domain+0(FP), R0
	MOVW	typ+4(FP), R1
	MOVW	prot+8(FP), R2
	MOVD	$SYS_socket, R8
	SVC
	MOVW	R0, ret+16(FP)
	RET

// func sbrk0() uintptr
TEXT runtime·sbrk0(SB),NOSPLIT,$0-8
	// Implemented as brk(NULL).
	MOVD	$0, R0
	MOVD	$SYS_brk, R8
	SVC
	MOVD	R0, ret+0(FP)
	RET

TEXT runtime·sigreturn(SB),NOSPLIT,$0-0
	RET