runtime: move Segv and TgkillSegv to testprog

The non-cgo test points Segv and TgkillSegv are currently in
testprogcgo. Although the test points don't explicitly use cgo,
being a cgo program, there is still some C code that runs when
the test point is invoked, such as thread creation code.

For the cgo test points, sometimes we fail to unwind the stack if
C code is involved. For the non-cgo ones, we want to always be
able to unwind the stack, so we check for stack unwinding failures.
But if a signal is landed in the small piece of C code mentioned
above, we may still fail to unwind. Move the non-cgo test points
to a pure-Go program to avoid this problem.

May fix #52963.
Updates #59029, #59443, #59492.

Change-Id: I35d99a0dd4c7cdb627e2083d2414887a24a2822d
Reviewed-on: https://go-review.googlesource.com/c/go/+/500535
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>

src/runtime/crash_cgo_test.go

@@ -648,7 +648,11 @@ func TestSegv(t *testing.T) {
 			}
 
 			t.Parallel()
-			got := runTestProg(t, "testprogcgo", test)
+			prog := "testprog"
+			if strings.HasSuffix(test, "InCgo") {
+				prog = "testprogcgo"
+			}
+			got := runTestProg(t, prog, test)
 			t.Log(got)
 			want := "SIGSEGV"
 			if !strings.Contains(got, want) {

src/runtime/testdata/testprog/segv.go

@@ -0,0 +1,32 @@
+// Copyright 2020 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
+
+package main
+
+import "syscall"
+
+func init() {
+	register("Segv", Segv)
+}
+
+var Sum int
+
+func Segv() {
+	c := make(chan bool)
+	go func() {
+		close(c)
+		for i := 0; ; i++ {
+			Sum += i
+		}
+	}()
+
+	<-c
+
+	syscall.Kill(syscall.Getpid(), syscall.SIGSEGV)
+
+	// Wait for the OS to deliver the signal.
+	select {}
+}

src/runtime/testdata/testprog/segv_linux.go

@@ -0,0 +1,29 @@
+// 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
+
+import "syscall"
+
+func init() {
+	register("TgkillSegv", TgkillSegv)
+}
+
+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.
+	select {}
+}

src/runtime/testdata/testprogcgo/segv.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build unix
-// +build unix
 
 package main
 
@@ -14,29 +13,9 @@ import "C"
 import "syscall"
 
 func init() {
-	register("Segv", Segv)
 	register("SegvInCgo", SegvInCgo)
 }
 
-var Sum int
-
-func Segv() {
-	c := make(chan bool)
-	go func() {
-		close(c)
-		for i := 0; ; i++ {
-			Sum += i
-		}
-	}()
-
-	<-c
-
-	syscall.Kill(syscall.Getpid(), syscall.SIGSEGV)
-
-	// Wait for the OS to deliver the signal.
-	C.pause()
-}
-
 func SegvInCgo() {
 	c := make(chan bool)
 	go func() {

src/runtime/testdata/testprogcgo/segv_linux.go

@@ -11,28 +11,9 @@ 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() {