Revert "runtime: treat SI_TKILL like SI_USER on Linux"

This reverts CL 431255.

Reason for revert: breaks darwin-arm and linux-noopt builders.

Change-Id: I29332b935cc1e35fa039af3d70465e496361fcc9
Reviewed-on: https://go-review.googlesource.com/c/go/+/431715
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

10 files changed, 22 insertions, 107 deletions

diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index f0a27507b9..5e58712297 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -603,14 +603,8 @@ func TestSegv(t *testing.T) {
 		t.Skipf("no signals on %s", runtime.GOOS)
 	}
 
-	for _, test := range []string{"Segv", "SegvInCgo", "TgkillSegv", "TgkillSegvInCgo"} {
+	for _, test := range []string{"Segv", "SegvInCgo"} {
 		test := test
-
-		// The tgkill variants only run on Linux.
-		if runtime.GOOS != "linux" && strings.HasPrefix(test, "Tgkill") {
-			continue
-		}
-
 		t.Run(test, func(t *testing.T) {
 			t.Parallel()
 			got := runTestProg(t, "testprogcgo", test)
@@ -623,15 +617,6 @@ func TestSegv(t *testing.T) {
 				t.Errorf("did not see %q in output", want)
 			}
 
-			doNotWant := "fatal error:"
-			if strings.Contains(got, doNotWant) {
-				if runtime.GOOS == "darwin" && strings.Contains(got, "0xb01dfacedebac1e") {
-					// See the comment in signal_darwin_amd64.go.
-					t.Skip("skipping due to Darwin handling of malformed addresses")
-				}
-				t.Errorf("saw %q in output", doNotWant)
-			}
-
 			// No runtime errors like "runtime: unknown pc".
 			switch runtime.GOOS {
 			case "darwin", "illumos", "solaris":
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index e84f065e24..3ae665c83d 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -886,15 +886,3 @@ func runPerThreadSyscall() {
 
 	gp.m.needPerThreadSyscall.Store(0)
 }
-
-const (
-	_SI_USER  = 0
-	_SI_TKILL = -6
-)
-
-// sigFromUser reports whether the signal was sent because of a call
-// to kill or tgkill.
-func (c *sigctxt) sigFromUser() bool {
-	code := int32(c.sigcode())
-	return code == _SI_USER || code == _SI_TKILL
-}
diff --git a/src/runtime/os_linux_be64.go b/src/runtime/os_linux_be64.go
index d8d4ac2497..537515fcf2 100644
--- a/src/runtime/os_linux_be64.go
+++ b/src/runtime/os_linux_be64.go
@@ -11,6 +11,7 @@ package runtime
 const (
 	_SS_DISABLE  = 2
 	_NSIG        = 65
+	_SI_USER     = 0
 	_SIG_BLOCK   = 0
 	_SIG_UNBLOCK = 1
 	_SIG_SETMASK = 2
diff --git a/src/runtime/os_linux_generic.go b/src/runtime/os_linux_generic.go
index 15fafc14ea..bed9e66e15 100644
--- a/src/runtime/os_linux_generic.go
+++ b/src/runtime/os_linux_generic.go
@@ -9,6 +9,7 @@ package runtime
 const (
 	_SS_DISABLE  = 2
 	_NSIG        = 65
+	_SI_USER     = 0
 	_SIG_BLOCK   = 0
 	_SIG_UNBLOCK = 1
 	_SIG_SETMASK = 2
diff --git a/src/runtime/os_linux_mips64x.go b/src/runtime/os_linux_mips64x.go
index 11d35bc020..188db01034 100644
--- a/src/runtime/os_linux_mips64x.go
+++ b/src/runtime/os_linux_mips64x.go
@@ -27,6 +27,7 @@ func cputicks() int64 {
 const (
 	_SS_DISABLE  = 2
 	_NSIG        = 129
+	_SI_USER     = 0
 	_SIG_BLOCK   = 1
 	_SIG_UNBLOCK = 2
 	_SIG_SETMASK = 3
diff --git a/src/runtime/os_linux_mipsx.go b/src/runtime/os_linux_mipsx.go
index cdf83ff71d..73016f81d9 100644
--- a/src/runtime/os_linux_mipsx.go
+++ b/src/runtime/os_linux_mipsx.go
@@ -21,6 +21,7 @@ func cputicks() int64 {
 const (
 	_SS_DISABLE  = 2
 	_NSIG        = 128 + 1
+	_SI_USER     = 0
 	_SIG_BLOCK   = 1
 	_SIG_UNBLOCK = 2
 	_SIG_SETMASK = 3
diff --git a/src/runtime/os_unix_nonlinux.go b/src/runtime/os_unix_nonlinux.go
deleted file mode 100644
index 5c8a137f18..0000000000
--- a/src/runtime/os_unix_nonlinux.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2022 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.
-
-//go:build unix && !linux
-
-package runtime
-
-// sigFromUser reports whether the signal was sent because of a call
-// to kill.
-func (c *sigctxt) sigFromUser() bool {
-	return c.sigcode() == _SI_USER
-}
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 4c55e83747..545094c640 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -662,7 +662,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	if sig < uint32(len(sigtable)) {
 		flags = sigtable[sig].flags
 	}
-	if !c.sigFromUser() && flags&_SigPanic != 0 && gp.throwsplit {
+	if c.sigcode() != _SI_USER && flags&_SigPanic != 0 && gp.throwsplit {
 		// We can't safely sigpanic because it may grow the
 		// stack. Abort in the signal handler instead.
 		flags = _SigThrow
@@ -672,7 +672,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 		// causes a memory fault. Don't turn that into a panic.
 		flags = _SigThrow
 	}
-	if !c.sigFromUser() && flags&_SigPanic != 0 {
+	if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
 		// The signal is going to cause a panic.
 		// Arrange the stack so that it looks like the point
 		// where the signal occurred made a call to the
@@ -690,13 +690,13 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 		return
 	}
 
-	if c.sigFromUser() || flags&_SigNotify != 0 {
+	if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
 		if sigsend(sig) {
 			return
 		}
 	}
 
-	if c.sigFromUser() && signal_ignored(sig) {
+	if c.sigcode() == _SI_USER && signal_ignored(sig) {
 		return
 	}
 
@@ -706,7 +706,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 
 	// _SigThrow means that we should exit now.
 	// If we get here with _SigPanic, it means that the signal
-	// was sent to us by a program (c.sigFromUser() is true);
+	// was sent to us by a program (c.sigcode() == _SI_USER);
 	// in that case, if we didn't handle it in sigsend, we exit now.
 	if flags&(_SigThrow|_SigPanic) == 0 {
 		return
@@ -929,7 +929,7 @@ func raisebadsignal(sig uint32, c *sigctxt) {
 	//
 	// On FreeBSD, the libthr sigaction code prevents
 	// this from working so we fall through to raise.
-	if GOOS != "freebsd" && (isarchive || islibrary) && handler == _SIG_DFL && !c.sigFromUser() {
+	if GOOS != "freebsd" && (isarchive || islibrary) && handler == _SIG_DFL && c.sigcode() != _SI_USER {
 		return
 	}
 
@@ -1110,7 +1110,7 @@ func sigfwdgo(sig uint32, info *siginfo, ctx unsafe.Pointer) bool {
 	// Unfortunately, user generated SIGPIPEs will also be forwarded, because si_code
 	// is set to _SI_USER even for a SIGPIPE raised from a write to a closed socket
 	// or pipe.
-	if (c.sigFromUser() || flags&_SigPanic == 0) && sig != _SIGPIPE {
+	if (c.sigcode() == _SI_USER || flags&_SigPanic == 0) && sig != _SIGPIPE {
 		return false
 	}
 	// Determine if the signal occurred inside Go code. We test that:
diff --git a/src/runtime/testdata/testprogcgo/segv.go b/src/runtime/testdata/testprogcgo/segv.go
index bf5aa313b3..0632475228 100644
--- a/src/runtime/testdata/testprogcgo/segv.go
+++ b/src/runtime/testdata/testprogcgo/segv.go
@@ -2,16 +2,18 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build unix
-// +build unix
+//go:build !plan9 && !windows
+// +build !plan9,!windows
 
 package main
 
-// #include <unistd.h>
 // static void nop() {}
 import "C"
 
-import "syscall"
+import (
+	"syscall"
+	"time"
+)
 
 func init() {
 	register("Segv", Segv)
@@ -33,8 +35,8 @@ func Segv() {
 
 	syscall.Kill(syscall.Getpid(), syscall.SIGSEGV)
 
-	// Wait for the OS to deliver the signal.
-	C.pause()
+	// Give the OS time to deliver the signal.
+	time.Sleep(time.Second)
 }
 
 func SegvInCgo() {
@@ -50,6 +52,6 @@ func SegvInCgo() {
 
 	syscall.Kill(syscall.Getpid(), syscall.SIGSEGV)
 
-	// Wait for the OS to deliver the signal.
-	C.pause()
+	// Give the OS time to deliver the signal.
+	time.Sleep(time.Second)
 }
diff --git a/src/runtime/testdata/testprogcgo/segv_linux.go b/src/runtime/testdata/testprogcgo/segv_linux.go
deleted file mode 100644
index fe93778781..0000000000
--- a/src/runtime/testdata/testprogcgo/segv_linux.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2022 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.
-
-package main
-
-// #include <unistd.h>
-// static void nop() {}
-import "C"
-
-import "syscall"
-
-func init() {
-	register("TgkillSegv", TgkillSegv)
-	register("TgkillSegvInCgo", TgkillSegvInCgo)
-}
-
-func TgkillSegv() {
-	c := make(chan bool)
-	go func() {
-		close(c)
-		for i := 0; ; i++ {
-			// Sum defined in segv.go.
-			Sum += i
-		}
-	}()
-
-	<-c
-
-	syscall.Tgkill(syscall.Getpid(), syscall.Gettid(), syscall.SIGSEGV)
-
-	// Wait for the OS to deliver the signal.
-	C.pause()
-}
-
-func TgkillSegvInCgo() {
-	c := make(chan bool)
-	go func() {
-		close(c)
-		for {
-			C.nop()
-		}
-	}()
-
-	<-c
-
-	syscall.Tgkill(syscall.Getpid(), syscall.Gettid(), syscall.SIGSEGV)
-
-	// Wait for the OS to deliver the signal.
-	C.pause()
-}