src/runtime/sys_linux_amd64.s

// 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"

TEXT runtime·exit(SB),NOSPLIT,$0-4
	MOVL	code+0(FP), DI
	MOVL	$231, AX	// exitgroup - force all os threads to exit
	SYSCALL
	RET

TEXT runtime·exit1(SB),NOSPLIT,$0-4
	MOVL	code+0(FP), DI
	MOVL	$60, AX	// exit - exit the current os thread
	SYSCALL
	RET

TEXT runtime·open(SB),NOSPLIT,$0-20
	MOVQ	name+0(FP), DI
	MOVL	mode+8(FP), SI
	MOVL	perm+12(FP), DX
	MOVL	$2, AX			// syscall entry
	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	$3, AX			// syscall entry
	SYSCALL
	CMPQ	AX, $0xfffffffffffff001
	JLS	2(PC)
	MOVL	$-1, AX
	MOVL	AX, ret+8(FP)
	RET

TEXT runtime·write(SB),NOSPLIT,$0-28
	MOVQ	fd+0(FP), DI
	MOVQ	p+8(FP), SI
	MOVL	n+16(FP), DX
	MOVL	$1, AX			// syscall entry
	SYSCALL
	CMPQ	AX, $0xfffffffffffff001
	JLS	2(PC)
	MOVL	$-1, AX
	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	$0, AX			// syscall entry
	SYSCALL
	CMPQ	AX, $0xfffffffffffff001
	JLS	2(PC)
	MOVL	$-1, AX
	MOVL	AX, ret+24(FP)
	RET

TEXT runtime·getrlimit(SB),NOSPLIT,$0-20
	MOVL	kind+0(FP), DI
	MOVQ	limit+8(FP), SI
	MOVL	$97, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+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)
	MOVQ	DX, 8(SP)

	// select(0, 0, 0, 0, &tv)
	MOVL	$0, DI
	MOVL	$0, SI
	MOVL	$0, DX
	MOVL	$0, R10
	MOVQ	SP, R8
	MOVL	$23, AX
	SYSCALL
	RET

TEXT runtime·gettid(SB),NOSPLIT,$0-4
	MOVL	$186, AX	// syscall - gettid
	SYSCALL
	MOVL	AX, ret+0(FP)
	RET

TEXT runtime·raise(SB),NOSPLIT,$0
	MOVL	$186, AX	// syscall - gettid
	SYSCALL
	MOVL	AX, DI	// arg 1 tid
	MOVL	sig+0(FP), SI	// arg 2
	MOVL	$200, AX	// syscall - tkill
	SYSCALL
	RET

TEXT runtime·raiseproc(SB),NOSPLIT,$0
	MOVL	$39, AX	// syscall - getpid
	SYSCALL
	MOVL	AX, DI	// arg 1 pid
	MOVL	sig+0(FP), SI	// arg 2
	MOVL	$62, AX	// syscall - kill
	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	$38, AX			// syscall entry
	SYSCALL
	RET

TEXT runtime·mincore(SB),NOSPLIT,$0-28
	MOVQ	addr+0(FP), DI
	MOVQ	n+8(FP), SI
	MOVQ	dst+16(FP), DX
	MOVL	$27, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+24(FP)
	RET

// func now() (sec int64, nsec int32)
TEXT time·now(SB),NOSPLIT,$16
	// Be careful. We're calling a function with gcc calling convention here.
	// We're guaranteed 128 bytes on entry, and we've taken 16, and the
	// call uses another 8.
	// That leaves 104 for the gettime code to use. Hope that's enough!
	MOVQ	runtime·__vdso_clock_gettime_sym(SB), AX
	CMPQ	AX, $0
	JEQ	fallback
	MOVL	$0, DI // CLOCK_REALTIME
	LEAQ	0(SP), SI
	CALL	AX
	MOVQ	0(SP), AX	// sec
	MOVQ	8(SP), DX	// nsec
	MOVQ	AX, sec+0(FP)
	MOVL	DX, nsec+8(FP)
	RET
fallback:
	LEAQ	0(SP), DI
	MOVQ	$0, SI
	MOVQ	runtime·__vdso_gettimeofday_sym(SB), AX
	CALL	AX
	MOVQ	0(SP), AX	// sec
	MOVL	8(SP), DX	// usec
	IMULQ	$1000, DX
	MOVQ	AX, sec+0(FP)
	MOVL	DX, nsec+8(FP)
	RET

TEXT runtime·nanotime(SB),NOSPLIT,$16
	// Duplicate time.now here to avoid using up precious stack space.
	// See comment above in time.now.
	MOVQ	runtime·__vdso_clock_gettime_sym(SB), AX
	CMPQ	AX, $0
	JEQ	fallback
	MOVL	$1, DI // CLOCK_MONOTONIC
	LEAQ	0(SP), SI
	CALL	AX
	MOVQ	0(SP), AX	// sec
	MOVQ	8(SP), DX	// nsec
	// sec is in AX, nsec in DX
	// return nsec in AX
	IMULQ	$1000000000, AX
	ADDQ	DX, AX
	MOVQ	AX, ret+0(FP)
	RET
fallback:
	LEAQ	0(SP), DI
	MOVQ	$0, SI
	MOVQ	runtime·__vdso_gettimeofday_sym(SB), AX
	CALL	AX
	MOVQ	0(SP), AX	// sec
	MOVL	8(SP), DX	// usec
	IMULQ	$1000, DX
	// sec is in AX, nsec in DX
	// return nsec in AX
	IMULQ	$1000000000, AX
	ADDQ	DX, AX
	MOVQ	AX, ret+0(FP)
	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	$14, AX			// syscall entry
	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	$13, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+32(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
	PUSHQ	BP
	MOVQ	SP, BP
	ANDQ	$~15, SP     // alignment for x86_64 ABI
	CALL	AX
	MOVQ	BP, SP
	POPQ	BP
	RET

TEXT runtime·sigtramp(SB),NOSPLIT,$24
	MOVQ	DI, 0(SP)   // signum
	MOVQ	SI, 8(SP)   // info
	MOVQ	DX, 16(SP)  // ctx
	MOVQ	$runtime·sigtrampgo(SB), AX
	CALL AX
	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), BX
	LOCK
	CMPXCHGL	CX, 0(BX)
	JNZ	sigtramp  // Skip stack trace if already locked.

	// 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.
	MOVQ	runtime·cgoTraceback(SB), CX
	MOVQ	$runtime·sigprofCallers(SB), R8
	MOVQ	$runtime·sigprofNonGo(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/sigaction.c
// The code that cares about the precise instructions used is:
// https://gcc.gnu.org/viewcvs/gcc/trunk/libgcc/config/i386/linux-unwind.h?revision=219188&view=markup
TEXT runtime·sigreturn(SB),NOSPLIT,$0
	MOVQ	$15, AX	// rt_sigreturn
	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	$9, AX			// mmap
	SYSCALL
	CMPQ	AX, $0xfffffffffffff001
	JLS	3(PC)
	NOTQ	AX
	INCQ	AX
	MOVQ	AX, ret+32(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·munmap(SB),NOSPLIT,$0
	MOVQ	addr+0(FP), DI
	MOVQ	n+8(FP), SI
	MOVQ	$11, AX	// munmap
	SYSCALL
	CMPQ	AX, $0xfffffffffffff001
	JLS	2(PC)
	MOVL	$0xf1, 0xf1  // crash
	RET

TEXT runtime·madvise(SB),NOSPLIT,$0
	MOVQ	addr+0(FP), DI
	MOVQ	n+8(FP), SI
	MOVL	flags+16(FP), DX
	MOVQ	$28, AX	// madvise
	SYSCALL
	// ignore failure - maybe pages are locked
	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	$202, 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,$0
	MOVL	flags+0(FP), DI
	MOVQ	stk+8(FP), SI
	MOVQ	$0, DX
	MOVQ	$0, R10

	// Copy mp, gp, fn off parent stack for use by child.
	// Careful: Linux system call clobbers CX and R11.
	MOVQ	mp+16(FP), R8
	MOVQ	gp+24(FP), R9
	MOVQ	fn+32(FP), R12

	MOVL	$56, 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	R8, $0    // m
	JEQ	nog
	CMPQ	R9, $0    // g
	JEQ	nog

	// Initialize m->procid to Linux tid
	MOVL	$186, AX	// gettid
	SYSCALL
	MOVQ	AX, m_procid(R8)

	// Set FS to point at m->tls.
	LEAQ	m_tls(R8), DI
	CALL	runtime·settls(SB)

	// In child, set up new stack
	get_tls(CX)
	MOVQ	R8, g_m(R9)
	MOVQ	R9, g(CX)
	CALL	runtime·stackcheck(SB)

nog:
	// Call fn
	CALL	R12

	// It shouldn't return. If it does, exit that thread.
	MOVL	$111, DI
	MOVL	$60, AX
	SYSCALL
	JMP	-3(PC)	// keep exiting

TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
	MOVQ	new+0(FP), DI
	MOVQ	old+8(FP), SI
	MOVQ	$131, 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
	// Same as in sys_darwin_386.s:/ugliness, different constant.
	// DI currently holds m->tls, which must be fs:0x1d0.
	// See cgo/gcc_android_amd64.c for the derivation of the constant.
	SUBQ	$0x1d0, DI  // In android, the tls base 
#else
	ADDQ	$8, DI	// ELF wants to use -8(FS)
#endif
	MOVQ	DI, SI
	MOVQ	$0x1002, DI	// ARCH_SET_FS
	MOVQ	$158, AX	// arch_prctl
	SYSCALL
	CMPQ	AX, $0xfffffffffffff001
	JLS	2(PC)
	MOVL	$0xf1, 0xf1  // crash
	RET

TEXT runtime·osyield(SB),NOSPLIT,$0
	MOVL	$24, 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	$204, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+24(FP)
	RET

// int32 runtime·epollcreate(int32 size);
TEXT runtime·epollcreate(SB),NOSPLIT,$0
	MOVL    size+0(FP), DI
	MOVL    $213, AX                        // syscall entry
	SYSCALL
	MOVL	AX, ret+8(FP)
	RET

// int32 runtime·epollcreate1(int32 flags);
TEXT runtime·epollcreate1(SB),NOSPLIT,$0
	MOVL	flags+0(FP), DI
	MOVL	$291, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+8(FP)
	RET

// func epollctl(epfd, op, fd int32, ev *epollEvent) int
TEXT runtime·epollctl(SB),NOSPLIT,$0
	MOVL	epfd+0(FP), DI
	MOVL	op+4(FP), SI
	MOVL	fd+8(FP), DX
	MOVQ	ev+16(FP), R10
	MOVL	$233, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+24(FP)
	RET

// int32 runtime·epollwait(int32 epfd, EpollEvent *ev, int32 nev, int32 timeout);
TEXT runtime·epollwait(SB),NOSPLIT,$0
	MOVL	epfd+0(FP), DI
	MOVQ	ev+8(FP), SI
	MOVL	nev+16(FP), DX
	MOVL	timeout+20(FP), R10
	MOVL	$232, AX			// syscall entry
	SYSCALL
	MOVL	AX, ret+24(FP)
	RET

// void runtime·closeonexec(int32 fd);
TEXT runtime·closeonexec(SB),NOSPLIT,$0
	MOVL    fd+0(FP), DI  // fd
	MOVQ    $2, SI  // F_SETFD
	MOVQ    $1, DX  // FD_CLOEXEC
	MOVL	$72, AX  // fcntl
	SYSCALL
	RET


// int access(const char *name, int mode)
TEXT runtime·access(SB),NOSPLIT,$0
	MOVQ	name+0(FP), DI
	MOVL	mode+8(FP), SI
	MOVL	$21, AX  // syscall entry
	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	$42, AX  // syscall entry
	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	$41, AX  // syscall entry
	SYSCALL
	MOVL	AX, ret+16(FP)
	RET