From 8a6c64f4fe726c956ea876cea0fed9494290130f Mon Sep 17 00:00:00 2001 From: qmuntal Date: Thu, 2 Oct 2025 15:12:30 +0200 Subject: [PATCH] syscall: use rawSyscall6 to call ptrace in forkAndExecInChild On darwin and openbsd, the autogenerated ptrace wrapper is nosplit because it is called from forkAndExecInChild. This makes it difficult to modify and improve the underlying syscall mechanism, as ptrace is almost over the nosplit limit. We better call ptrace directly using rawSyscall6 in forkAndExecInChild so that we can lift the ptrace nosplit restriction to. Doing so also fixes a long-standing inconsistency: forkAndExecInChild is documented to only allow rawSyscall, but the ptrace wrapper is using non-raw syscalls. Updates #64113 Change-Id: Ibbbb218511561c1a5cb5b6d288a691f9738b14a6 Reviewed-on: https://go-review.googlesource.com/c/go/+/708575 Reviewed-by: Michael Pratt Reviewed-by: David Chase LUCI-TryBot-Result: Go LUCI --- src/syscall/exec_libc2.go | 9 ++++++--- src/syscall/mksyscall.pl | 6 ------ src/syscall/zsyscall_darwin_amd64.go | 1 - src/syscall/zsyscall_darwin_arm64.go | 1 - src/syscall/zsyscall_openbsd_386.go | 1 - src/syscall/zsyscall_openbsd_amd64.go | 1 - src/syscall/zsyscall_openbsd_arm.go | 1 - src/syscall/zsyscall_openbsd_arm64.go | 1 - src/syscall/zsyscall_openbsd_ppc64.go | 1 - src/syscall/zsyscall_openbsd_riscv64.go | 1 - 10 files changed, 6 insertions(+), 17 deletions(-) diff --git a/src/syscall/exec_libc2.go b/src/syscall/exec_libc2.go index a0579627a3..5de09dfe99 100644 --- a/src/syscall/exec_libc2.go +++ b/src/syscall/exec_libc2.go @@ -59,7 +59,6 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr r1 uintptr nextfd int i int - err error pgrp _C_int cred *Credential ngroups, groups uintptr @@ -99,8 +98,12 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr // Enable tracing if requested. if sys.Ptrace { - if err = ptrace(PTRACE_TRACEME, 0, 0, 0); err != nil { - err1 = err.(Errno) + if runtime.GOOS == "ios" { + err1 = ENOSYS + goto childerror + } + _, _, err1 = rawSyscall6(abi.FuncPCABI0(libc_ptrace_trampoline), PTRACE_TRACEME, 0, 0, 0, 0, 0) + if err1 != 0 { goto childerror } } diff --git a/src/syscall/mksyscall.pl b/src/syscall/mksyscall.pl index b46a3f9438..6be94c9c44 100755 --- a/src/syscall/mksyscall.pl +++ b/src/syscall/mksyscall.pl @@ -141,12 +141,6 @@ while(<>) { # without reading the header. $text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n"; - if ((($darwin || ($openbsd && $libc)) && $func =~ /^ptrace(Ptr)?$/)) { - # The ptrace function is called from forkAndExecInChild where stack - # growth is forbidden. - $text .= "//go:nosplit\n" - } - # Go function header. my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : ""; $text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl; diff --git a/src/syscall/zsyscall_darwin_amd64.go b/src/syscall/zsyscall_darwin_amd64.go index 8812fb12cd..fe4a264ed2 100644 --- a/src/syscall/zsyscall_darwin_amd64.go +++ b/src/syscall/zsyscall_darwin_amd64.go @@ -2011,7 +2011,6 @@ func libc_fstatat64_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { if runtime.GOOS == "ios" { panic("unimplemented") diff --git a/src/syscall/zsyscall_darwin_arm64.go b/src/syscall/zsyscall_darwin_arm64.go index 22b096349d..8fd7392d5b 100644 --- a/src/syscall/zsyscall_darwin_arm64.go +++ b/src/syscall/zsyscall_darwin_arm64.go @@ -2011,7 +2011,6 @@ func libc_fstatat_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { if runtime.GOOS == "ios" { panic("unimplemented") diff --git a/src/syscall/zsyscall_openbsd_386.go b/src/syscall/zsyscall_openbsd_386.go index c8cf7f231b..d914e19da0 100644 --- a/src/syscall/zsyscall_openbsd_386.go +++ b/src/syscall/zsyscall_openbsd_386.go @@ -1839,7 +1839,6 @@ func libc_exit_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { _, _, e1 := syscall6(abi.FuncPCABI0(libc_ptrace_trampoline), uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0) if e1 != 0 { diff --git a/src/syscall/zsyscall_openbsd_amd64.go b/src/syscall/zsyscall_openbsd_amd64.go index 9188756a87..5efe4cd868 100644 --- a/src/syscall/zsyscall_openbsd_amd64.go +++ b/src/syscall/zsyscall_openbsd_amd64.go @@ -1839,7 +1839,6 @@ func libc_exit_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { _, _, e1 := syscall6(abi.FuncPCABI0(libc_ptrace_trampoline), uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0) if e1 != 0 { diff --git a/src/syscall/zsyscall_openbsd_arm.go b/src/syscall/zsyscall_openbsd_arm.go index ecdfa63672..db8ea482ef 100644 --- a/src/syscall/zsyscall_openbsd_arm.go +++ b/src/syscall/zsyscall_openbsd_arm.go @@ -1839,7 +1839,6 @@ func libc_exit_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { _, _, e1 := syscall6(abi.FuncPCABI0(libc_ptrace_trampoline), uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0) if e1 != 0 { diff --git a/src/syscall/zsyscall_openbsd_arm64.go b/src/syscall/zsyscall_openbsd_arm64.go index d28d3c5e1e..673791c824 100644 --- a/src/syscall/zsyscall_openbsd_arm64.go +++ b/src/syscall/zsyscall_openbsd_arm64.go @@ -1839,7 +1839,6 @@ func libc_exit_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { _, _, e1 := syscall6(abi.FuncPCABI0(libc_ptrace_trampoline), uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0) if e1 != 0 { diff --git a/src/syscall/zsyscall_openbsd_ppc64.go b/src/syscall/zsyscall_openbsd_ppc64.go index 0e6828bcaf..7e0dc88a4c 100644 --- a/src/syscall/zsyscall_openbsd_ppc64.go +++ b/src/syscall/zsyscall_openbsd_ppc64.go @@ -1839,7 +1839,6 @@ func libc_exit_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { _, _, e1 := syscall6(abi.FuncPCABI0(libc_ptrace_trampoline), uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0) if e1 != 0 { diff --git a/src/syscall/zsyscall_openbsd_riscv64.go b/src/syscall/zsyscall_openbsd_riscv64.go index 920147074d..7b5a89ceac 100644 --- a/src/syscall/zsyscall_openbsd_riscv64.go +++ b/src/syscall/zsyscall_openbsd_riscv64.go @@ -1839,7 +1839,6 @@ func libc_exit_trampoline() // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT -//go:nosplit func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) { _, _, e1 := syscall6(abi.FuncPCABI0(libc_ptrace_trampoline), uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0) if e1 != 0 { -- 2.52.0