[release-branch.go1.18] runtime: revert "call __fork instead of fork on darwin"

A recent comment on #57263 reports an unexplained crash in a cgo program
that is fixed by reverting the __fork fix. We don't have any viable fix for the
os/exec bug at this point, so give up on a fix for the January point releases.

This reverts CL 459179 (commit 07b6ffb79c).

Fixes #57689.

Change-Id: I3b81de6bded399f47862325129e86a65c83d8e3b
Reviewed-on: https://go-review.googlesource.com/c/go/+/461116
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Russ Cox 2023-01-08 17:33:12 -05:00
parent 476384ec7b
commit 87105e5b2e
7 changed files with 15 additions and 81 deletions

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@ -76,7 +76,7 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
// About to call fork.
// No more allocation or calls of non-assembly functions.
runtime_BeforeFork()
r1, _, err1 = rawSyscall(forkTrampoline, 0, 0, 0)
r1, _, err1 = rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
if err1 != 0 {
runtime_AfterFork()
return 0, err1
@ -260,6 +260,6 @@ childerror:
// send error code on pipe
rawSyscall(abi.FuncPCABI0(libc_write_trampoline), uintptr(pipe), uintptr(unsafe.Pointer(&err1)), unsafe.Sizeof(err1))
for {
rawSyscall(exitTrampoline, 253, 0, 0)
rawSyscall(abi.FuncPCABI0(libc_exit_trampoline), 253, 0, 0)
}
}

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@ -17,34 +17,6 @@ import (
"unsafe"
)
// These are called from exec_libc2.go in the child of fork.
// The names differ between macOS and OpenBSD, so we need
// to declare the specific ones used here to keep the exec_libc2.go
// code portable.
//
// We use __fork and __exit, not fork and exit, to avoid the libc atfork
// and atexit handlers. The atfork handlers have caused fork child
// hangs in the past (see #33565, #56784). The atexit handlers have
// not, but the non-libc ports all invoke the system call, so doing
// the same here makes sense. In general we wouldn't expect
// atexit handlers to work terribly well in a fork child anyway.
// (Also, perhaps the atfork handlers clear the atexit handlers,
// in which case we definitely need to avoid calling the libc exit
// if we bypass the libc fork.)
//
// Other calls that are made in the child after the fork are
// ptrace, setsid, setpgid, getpid, ioctl, chroot, setgroups,
// setgid, setuid, chdir, dup2, fcntl, close, execve, and write.
// Those are all simple kernel wrappers that should be safe
// to be called directly. The fcntl and ioctl functions do run
// some code around the kernel call, but they don't call any
// other functions, so for now we keep using them instead of
// calling the lower-level __fcntl and __ioctl functions.
var (
exitTrampoline = abi.FuncPCABI0(libc___exit_trampoline)
forkTrampoline = abi.FuncPCABI0(libc___fork_trampoline)
)
type SockaddrDatalink struct {
Len uint8
Family uint8
@ -230,12 +202,11 @@ func Kill(pid int, signum Signal) (err error) { return kill(pid, int(signum), 1)
//sys writev(fd int, iovecs []Iovec) (cnt uintptr, err error)
//sys mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
//sys munmap(addr uintptr, length uintptr) (err error)
//sysnb __fork() (pid int, err error)
//sysnb fork() (pid int, err error)
//sysnb ioctl(fd int, req int, arg int) (err error)
//sysnb ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_ioctl
//sysnb execve(path *byte, argv **byte, envp **byte) (err error)
//sysnb exit(res int) (err error)
//sysnb __exit(res int) (err error)
//sys sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error)
//sys fcntlPtr(fd int, cmd int, arg unsafe.Pointer) (val int, err error) = SYS_fcntl
//sys unlinkat(fd int, path string, flags int) (err error)

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@ -10,11 +10,6 @@ import (
"internal/abi"
)
var (
exitTrampoline = abi.FuncPCABI0(libc_exit_trampoline)
forkTrampoline = abi.FuncPCABI0(libc_fork_trampoline)
)
func init() {
execveOpenBSD = execve
}

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@ -1714,8 +1714,8 @@ func libc_munmap_trampoline()
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func __fork() (pid int, err error) {
r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc___fork_trampoline), 0, 0, 0)
func fork() (pid int, err error) {
r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
pid = int(r0)
if e1 != 0 {
err = errnoErr(e1)
@ -1723,9 +1723,9 @@ func __fork() (pid int, err error) {
return
}
func libc___fork_trampoline()
func libc_fork_trampoline()
//go:cgo_import_dynamic libc___fork __fork "/usr/lib/libSystem.B.dylib"
//go:cgo_import_dynamic libc_fork fork "/usr/lib/libSystem.B.dylib"
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
@ -1781,20 +1781,6 @@ func libc_exit_trampoline()
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func __exit(res int) (err error) {
_, _, e1 := rawSyscall(abi.FuncPCABI0(libc___exit_trampoline), uintptr(res), 0, 0)
if e1 != 0 {
err = errnoErr(e1)
}
return
}
func libc___exit_trampoline()
//go:cgo_import_dynamic libc___exit __exit "/usr/lib/libSystem.B.dylib"
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
var _p0 unsafe.Pointer
if len(mib) > 0 {

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@ -219,16 +219,14 @@ TEXT ·libc_mmap_trampoline(SB),NOSPLIT,$0-0
JMP libc_mmap(SB)
TEXT ·libc_munmap_trampoline(SB),NOSPLIT,$0-0
JMP libc_munmap(SB)
TEXT ·libc___fork_trampoline(SB),NOSPLIT,$0-0
JMP libc___fork(SB)
TEXT ·libc_fork_trampoline(SB),NOSPLIT,$0-0
JMP libc_fork(SB)
TEXT ·libc_ioctl_trampoline(SB),NOSPLIT,$0-0
JMP libc_ioctl(SB)
TEXT ·libc_execve_trampoline(SB),NOSPLIT,$0-0
JMP libc_execve(SB)
TEXT ·libc_exit_trampoline(SB),NOSPLIT,$0-0
JMP libc_exit(SB)
TEXT ·libc___exit_trampoline(SB),NOSPLIT,$0-0
JMP libc___exit(SB)
TEXT ·libc_sysctl_trampoline(SB),NOSPLIT,$0-0
JMP libc_sysctl(SB)
TEXT ·libc_unlinkat_trampoline(SB),NOSPLIT,$0-0

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@ -1714,8 +1714,8 @@ func libc_munmap_trampoline()
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func __fork() (pid int, err error) {
r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc___fork_trampoline), 0, 0, 0)
func fork() (pid int, err error) {
r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
pid = int(r0)
if e1 != 0 {
err = errnoErr(e1)
@ -1723,9 +1723,9 @@ func __fork() (pid int, err error) {
return
}
func libc___fork_trampoline()
func libc_fork_trampoline()
//go:cgo_import_dynamic libc___fork __fork "/usr/lib/libSystem.B.dylib"
//go:cgo_import_dynamic libc_fork fork "/usr/lib/libSystem.B.dylib"
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
@ -1781,20 +1781,6 @@ func libc_exit_trampoline()
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func __exit(res int) (err error) {
_, _, e1 := rawSyscall(abi.FuncPCABI0(libc___exit_trampoline), uintptr(res), 0, 0)
if e1 != 0 {
err = errnoErr(e1)
}
return
}
func libc___exit_trampoline()
//go:cgo_import_dynamic libc___exit __exit "/usr/lib/libSystem.B.dylib"
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
var _p0 unsafe.Pointer
if len(mib) > 0 {

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@ -219,16 +219,14 @@ TEXT ·libc_mmap_trampoline(SB),NOSPLIT,$0-0
JMP libc_mmap(SB)
TEXT ·libc_munmap_trampoline(SB),NOSPLIT,$0-0
JMP libc_munmap(SB)
TEXT ·libc___fork_trampoline(SB),NOSPLIT,$0-0
JMP libc___fork(SB)
TEXT ·libc_fork_trampoline(SB),NOSPLIT,$0-0
JMP libc_fork(SB)
TEXT ·libc_ioctl_trampoline(SB),NOSPLIT,$0-0
JMP libc_ioctl(SB)
TEXT ·libc_execve_trampoline(SB),NOSPLIT,$0-0
JMP libc_execve(SB)
TEXT ·libc_exit_trampoline(SB),NOSPLIT,$0-0
JMP libc_exit(SB)
TEXT ·libc___exit_trampoline(SB),NOSPLIT,$0-0
JMP libc___exit(SB)
TEXT ·libc_sysctl_trampoline(SB),NOSPLIT,$0-0
JMP libc_sysctl(SB)
TEXT ·libc_unlinkat_trampoline(SB),NOSPLIT,$0-0