From 73df946d56c74384511a194dd01dbe099584fd1a Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 15:14:23 +0200 Subject: Adding upstream version 1.16.10. Signed-off-by: Daniel Baumann --- src/runtime/cgo_sigaction.go | 87 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 src/runtime/cgo_sigaction.go (limited to 'src/runtime/cgo_sigaction.go') diff --git a/src/runtime/cgo_sigaction.go b/src/runtime/cgo_sigaction.go new file mode 100644 index 0000000..de634dc --- /dev/null +++ b/src/runtime/cgo_sigaction.go @@ -0,0 +1,87 @@ +// Copyright 2016 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. + +// Support for memory sanitizer. See runtime/cgo/sigaction.go. + +// +build linux,amd64 freebsd,amd64 linux,arm64 + +package runtime + +import "unsafe" + +// _cgo_sigaction is filled in by runtime/cgo when it is linked into the +// program, so it is only non-nil when using cgo. +//go:linkname _cgo_sigaction _cgo_sigaction +var _cgo_sigaction unsafe.Pointer + +//go:nosplit +//go:nowritebarrierrec +func sigaction(sig uint32, new, old *sigactiont) { + // racewalk.go avoids adding sanitizing instrumentation to package runtime, + // but we might be calling into instrumented C functions here, + // so we need the pointer parameters to be properly marked. + // + // Mark the input as having been written before the call + // and the output as read after. + if msanenabled && new != nil { + msanwrite(unsafe.Pointer(new), unsafe.Sizeof(*new)) + } + + if _cgo_sigaction == nil || inForkedChild { + sysSigaction(sig, new, old) + } else { + // We need to call _cgo_sigaction, which means we need a big enough stack + // for C. To complicate matters, we may be in libpreinit (before the + // runtime has been initialized) or in an asynchronous signal handler (with + // the current thread in transition between goroutines, or with the g0 + // system stack already in use). + + var ret int32 + + var g *g + if mainStarted { + g = getg() + } + sp := uintptr(unsafe.Pointer(&sig)) + switch { + case g == nil: + // No g: we're on a C stack or a signal stack. + ret = callCgoSigaction(uintptr(sig), new, old) + case sp < g.stack.lo || sp >= g.stack.hi: + // We're no longer on g's stack, so we must be handling a signal. It's + // possible that we interrupted the thread during a transition between g + // and g0, so we should stay on the current stack to avoid corrupting g0. + ret = callCgoSigaction(uintptr(sig), new, old) + default: + // We're running on g's stack, so either we're not in a signal handler or + // the signal handler has set the correct g. If we're on gsignal or g0, + // systemstack will make the call directly; otherwise, it will switch to + // g0 to ensure we have enough room to call a libc function. + // + // The function literal that we pass to systemstack is not nosplit, but + // that's ok: we'll be running on a fresh, clean system stack so the stack + // check will always succeed anyway. + systemstack(func() { + ret = callCgoSigaction(uintptr(sig), new, old) + }) + } + + const EINVAL = 22 + if ret == EINVAL { + // libc reserves certain signals — normally 32-33 — for pthreads, and + // returns EINVAL for sigaction calls on those signals. If we get EINVAL, + // fall back to making the syscall directly. + sysSigaction(sig, new, old) + } + } + + if msanenabled && old != nil { + msanread(unsafe.Pointer(old), unsafe.Sizeof(*old)) + } +} + +// callCgoSigaction calls the sigaction function in the runtime/cgo package +// using the GCC calling convention. It is implemented in assembly. +//go:noescape +func callCgoSigaction(sig uintptr, new, old *sigactiont) int32 -- cgit v1.2.3