runtime: treat SI_TKILL like SI_USER on Linux

On Linux a signal sent using tgkill will have si_code == SI_TKILL,
not SI_USER. Treat the two cases the same. Add a Linux-specific test.

Change the test to use the C pause function rather than sleeping
for a second, as that achieves the same effect.

This is a roll forward of CL 431255 which was rolled back in CL 431715.
This new version skips flaky tests on more systems, and marks a new method
nosplit.

Change-Id: Ibf2d3e6fc43d63d0a71afa8fcca6a11fda03f291
Reviewed-on: https://go-review.googlesource.com/c/go/+/432136
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

2 files changed, 59 insertions, 10 deletions

diff --git a/src/runtime/testdata/testprogcgo/segv.go b/src/runtime/testdata/testprogcgo/segv.go
index 0632475228..bf5aa313b3 100644
--- a/src/runtime/testdata/testprogcgo/segv.go
+++ b/src/runtime/testdata/testprogcgo/segv.go
@@ -2,18 +2,16 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !plan9 && !windows
-// +build !plan9,!windows
+//go:build unix
+// +build unix
 
 package main
 
+// #include <unistd.h>
 // static void nop() {}
 import "C"
 
-import (
-	"syscall"
-	"time"
-)
+import "syscall"
 
 func init() {
 	register("Segv", Segv)
@@ -35,8 +33,8 @@ func Segv() {
 
 	syscall.Kill(syscall.Getpid(), syscall.SIGSEGV)
 
-	// Give the OS time to deliver the signal.
-	time.Sleep(time.Second)
+	// Wait for the OS to deliver the signal.
+	C.pause()
 }
 
 func SegvInCgo() {
@@ -52,6 +50,6 @@ func SegvInCgo() {
 
 	syscall.Kill(syscall.Getpid(), syscall.SIGSEGV)
 
-	// Give the OS time to deliver the signal.
-	time.Sleep(time.Second)
+	// Wait for the OS to deliver the signal.
+	C.pause()
 }
diff --git a/src/runtime/testdata/testprogcgo/segv_linux.go b/src/runtime/testdata/testprogcgo/segv_linux.go
new file mode 100644
index 0000000000..fe93778781
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/segv_linux.go
@@ -0,0 +1,51 @@
+// 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()
+}