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go/src/runtime/sys_linux_amd64.s
Austin Clements 193088b246 runtime: separate error result for mmap 
Currently mmap returns an unsafe.Pointer that encodes OS errors as
values less than 4096. In practice this is okay, but it borders on
being really unsafe: for example, the value has to be checked
immediately after return and if stack copying were ever to observe
such a value, it would panic. It's also not remotely idiomatic.

Fix this by making mmap return a separate pointer value and error,
like a normal Go function.

Updates #22218.

Change-Id: Iefd965095ffc82cc91118872753a5d39d785c3a6
Reviewed-on: https://go-review.googlesource.com/71270
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-10-18 19:22:08 +00:00

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// 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"
#define SYS_read 0
#define SYS_write 1
#define SYS_open 2
#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_access 21
#define SYS_sched_yield 24
#define SYS_mincore 27
#define SYS_madvise 28
#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_fcntl 72
#define SYS_getrlimit 97
#define SYS_sigaltstack 131
#define SYS_arch_prctl 158
#define SYS_gettid 186
#define SYS_tkill 200
#define SYS_futex 202
#define SYS_sched_getaffinity 204
#define SYS_epoll_create 213
#define SYS_exit_group 231
#define SYS_epoll_wait 232
#define SYS_epoll_ctl 233
#define SYS_pselect6 270
#define SYS_epoll_create1 291
TEXT runtime·exit(SB),NOSPLIT,$0-4
MOVL code+0(FP), DI
MOVL $SYS_exit_group, AX
SYSCALL
RET
// func exitThread(wait *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
MOVQ name+0(FP), DI
MOVL mode+8(FP), SI
MOVL perm+12(FP), DX
MOVL $SYS_open, 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·write(SB),NOSPLIT,$0-28
MOVQ fd+0(FP), DI
MOVQ p+8(FP), SI
MOVL n+16(FP), DX
MOVL $SYS_write, AX
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 $SYS_read, AX
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 $SYS_getrlimit, AX
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)
MOVL $1000, AX // usec to nsec
MULL DX
MOVQ AX, 8(SP)
// pselect6(0, 0, 0, 0, &ts, 0)
MOVL $0, DI
MOVL $0, SI
MOVL $0, DX
MOVL $0, R10
MOVQ SP, R8
MOVL $0, R9
MOVL $SYS_pselect6, 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_gettid, AX
SYSCALL
MOVL AX, DI // arg 1 tid
MOVL sig+0(FP), SI // arg 2
MOVL $SYS_tkill, 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 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·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 walltime() (sec int64, nsec int32)
TEXT runtime·walltime(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 $SYS_rt_sigprocmask, AX
SYSCALL
CMPQ AX, $0xfffffffffffff001
JLS 2(PC)
MOVL $0xf1, 0xf1 // crash
RET
TEXT runtime·sysSigaction(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
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,$72
// Save callee-saved C registers, since the caller may be a C signal handler.
MOVQ BX, bx-8(SP)
MOVQ BP, bp-16(SP) // save in case GOEXPERIMENT=noframepointer is set
MOVQ R12, r12-24(SP)
MOVQ R13, r13-32(SP)
MOVQ R14, r14-40(SP)
MOVQ R15, r15-48(SP)
// We don't save mxcsr or the x87 control word because sigtrampgo doesn't
// modify them.
MOVQ DX, ctx-56(SP)
MOVQ SI, info-64(SP)
MOVQ DI, signum-72(SP)
MOVQ $runtime·sigtrampgo(SB), AX
CALL AX
MOVQ r15-48(SP), R15
MOVQ r14-40(SP), R14
MOVQ r13-32(SP), R13
MOVQ r12-24(SP), R12
MOVQ bp-16(SP), BP
MOVQ bx-8(SP), BX
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, 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 $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
// 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 $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,$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 $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 R8, $0 // m
JEQ nog
CMPQ R9, $0 // g
JEQ nog
// Initialize m->procid to Linux tid
MOVL $SYS_gettid, AX
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 $SYS_exit, AX
SYSCALL
JMP -3(PC) // keep exiting
TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
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
// 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 $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
// int32 runtime·epollcreate(int32 size);
TEXT runtime·epollcreate(SB),NOSPLIT,$0
MOVL size+0(FP), DI
MOVL $SYS_epoll_create, AX
SYSCALL
MOVL AX, ret+8(FP)
RET
// int32 runtime·epollcreate1(int32 flags);
TEXT runtime·epollcreate1(SB),NOSPLIT,$0
MOVL flags+0(FP), DI
MOVL $SYS_epoll_create1, AX
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 $SYS_epoll_ctl, AX
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 $SYS_epoll_wait, AX
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 $SYS_fcntl, AX
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 $SYS_access, 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
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