1 files changed, 379 insertions, 0 deletions
diff --git a/src/runtime/runtime-gdb_unix_test.go b/src/runtime/runtime-gdb_unix_test.go
new file mode 100644
index 0000000..8b602d1
--- /dev/null
+++ b/src/runtime/runtime-gdb_unix_test.go
@@ -0,0 +1,379 @@
+// Copyright 2023 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 runtime_test
+
+import (
+	"bytes"
+	"fmt"
+	"internal/testenv"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"syscall"
+	"testing"
+)
+
+func canGenerateCore(t *testing.T) bool {
+	// Ensure there is enough RLIMIT_CORE available to generate a full core.
+	var lim syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_CORE, &lim)
+	if err != nil {
+		t.Fatalf("error getting rlimit: %v", err)
+	}
+	// Minimum RLIMIT_CORE max to allow. This is a conservative estimate.
+	// Most systems allow infinity.
+	const minRlimitCore = 100 << 20 // 100 MB
+	if lim.Max < minRlimitCore {
+		t.Skipf("RLIMIT_CORE max too low: %#+v", lim)
+	}
+
+	// Make sure core pattern will send core to the current directory.
+	b, err := os.ReadFile("/proc/sys/kernel/core_pattern")
+	if err != nil {
+		t.Fatalf("error reading core_pattern: %v", err)
+	}
+	if string(b) != "core\n" {
+		t.Skipf("Unexpected core pattern %q", string(b))
+	}
+
+	coreUsesPID := false
+	b, err = os.ReadFile("/proc/sys/kernel/core_uses_pid")
+	if err == nil {
+		switch string(bytes.TrimSpace(b)) {
+		case "0":
+		case "1":
+			coreUsesPID = true
+		default:
+			t.Skipf("unexpected core_uses_pid value %q", string(b))
+		}
+	}
+	return coreUsesPID
+}
+
+const coreSignalSource = `
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"runtime/debug"
+	"syscall"
+)
+
+var pipeFD = flag.Int("pipe-fd", -1, "FD of write end of control pipe")
+
+func enableCore() {
+	debug.SetTraceback("crash")
+
+	var lim syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_CORE, &lim)
+	if err != nil {
+		panic(fmt.Sprintf("error getting rlimit: %v", err))
+	}
+	lim.Cur = lim.Max
+	fmt.Fprintf(os.Stderr, "Setting RLIMIT_CORE = %+#v\n", lim)
+	err = syscall.Setrlimit(syscall.RLIMIT_CORE, &lim)
+	if err != nil {
+		panic(fmt.Sprintf("error setting rlimit: %v", err))
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	enableCore()
+
+	// Ready to go. Notify parent.
+	if err := syscall.Close(*pipeFD); err != nil {
+		panic(fmt.Sprintf("error closing control pipe fd %d: %v", *pipeFD, err))
+	}
+
+	for {}
+}
+`
+
+// TestGdbCoreSignalBacktrace tests that gdb can unwind the stack correctly
+// through a signal handler in a core file
+func TestGdbCoreSignalBacktrace(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		// N.B. This test isn't fundamentally Linux-only, but it needs
+		// to know how to enable/find core files on each OS.
+		t.Skip("Test only supported on Linux")
+	}
+	if runtime.GOARCH != "386" && runtime.GOARCH != "amd64" {
+		// TODO(go.dev/issue/25218): Other architectures use sigreturn
+		// via VDSO, which we somehow don't handle correctly.
+		t.Skip("Backtrace through signal handler only works on 386 and amd64")
+	}
+
+	checkGdbEnvironment(t)
+	t.Parallel()
+	checkGdbVersion(t)
+
+	coreUsesPID := canGenerateCore(t)
+
+	// Build the source code.
+	dir := t.TempDir()
+	src := filepath.Join(dir, "main.go")
+	err := os.WriteFile(src, []byte(coreSignalSource), 0644)
+	if err != nil {
+		t.Fatalf("failed to create file: %v", err)
+	}
+	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "a.exe", "main.go")
+	cmd.Dir = dir
+	out, err := testenv.CleanCmdEnv(cmd).CombinedOutput()
+	if err != nil {
+		t.Fatalf("building source %v\n%s", err, out)
+	}
+
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("error creating control pipe: %v", err)
+	}
+	defer r.Close()
+
+	// Start the test binary.
+	cmd = testenv.Command(t, "./a.exe", "-pipe-fd=3")
+	cmd.Dir = dir
+	cmd.ExtraFiles = []*os.File{w}
+	var output bytes.Buffer
+	cmd.Stdout = &output // for test logging
+	cmd.Stderr = &output
+
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("error starting test binary: %v", err)
+	}
+	w.Close()
+
+	pid := cmd.Process.Pid
+
+	// Wait for child to be ready.
+	var buf [1]byte
+	if _, err := r.Read(buf[:]); err != io.EOF {
+		t.Fatalf("control pipe read get err %v want io.EOF", err)
+	}
+
+	// 💥
+	if err := cmd.Process.Signal(os.Signal(syscall.SIGABRT)); err != nil {
+		t.Fatalf("erroring signaling child: %v", err)
+	}
+
+	err = cmd.Wait()
+	t.Logf("child output:\n%s", output.String())
+	if err == nil {
+		t.Fatalf("Wait succeeded, want SIGABRT")
+	}
+	ee, ok := err.(*exec.ExitError)
+	if !ok {
+		t.Fatalf("Wait err got %T %v, want exec.ExitError", ee, ee)
+	}
+	ws, ok := ee.Sys().(syscall.WaitStatus)
+	if !ok {
+		t.Fatalf("Sys got %T %v, want syscall.WaitStatus", ee.Sys(), ee.Sys())
+	}
+	if ws.Signal() != syscall.SIGABRT {
+		t.Fatalf("Signal got %d want SIGABRT", ws.Signal())
+	}
+	if !ws.CoreDump() {
+		t.Fatalf("CoreDump got %v want true", ws.CoreDump())
+	}
+
+	coreFile := "core"
+	if coreUsesPID {
+		coreFile += fmt.Sprintf(".%d", pid)
+	}
+
+	// Execute gdb commands.
+	args := []string{"-nx", "-batch",
+		"-iex", "add-auto-load-safe-path " + filepath.Join(testenv.GOROOT(t), "src", "runtime"),
+		"-ex", "backtrace",
+		filepath.Join(dir, "a.exe"),
+		filepath.Join(dir, coreFile),
+	}
+	cmd = testenv.Command(t, "gdb", args...)
+
+	got, err := cmd.CombinedOutput()
+	t.Logf("gdb output:\n%s", got)
+	if err != nil {
+		t.Fatalf("gdb exited with error: %v", err)
+	}
+
+	// We don't know which thread the fatal signal will land on, but we can still check for basics:
+	//
+	// 1. A frame in the signal handler: runtime.sigtramp
+	// 2. GDB detection of the signal handler: <signal handler called>
+	// 3. A frame before the signal handler: this could be foo, or somewhere in the scheduler
+
+	re := regexp.MustCompile(`#.* runtime\.sigtramp `)
+	if found := re.Find(got) != nil; !found {
+		t.Fatalf("could not find sigtramp in backtrace")
+	}
+
+	re = regexp.MustCompile("#.* <signal handler called>")
+	loc := re.FindIndex(got)
+	if loc == nil {
+		t.Fatalf("could not find signal handler marker in backtrace")
+	}
+	rest := got[loc[1]:]
+
+	// Look for any frames after the signal handler. We want to see
+	// symbolized frames, not garbage unknown frames.
+	//
+	// Since the signal might not be delivered to the main thread we can't
+	// look for main.main. Every thread should have a runtime frame though.
+	re = regexp.MustCompile(`#.* runtime\.`)
+	if found := re.Find(rest) != nil; !found {
+		t.Fatalf("could not find runtime symbol in backtrace after signal handler:\n%s", rest)
+	}
+}
+
+const coreCrashThreadSource = `
+package main
+
+/*
+#cgo CFLAGS: -g -O0
+#include <stdio.h>
+#include <stddef.h>
+void trigger_crash()
+{
+	int* ptr = NULL;
+	*ptr = 1024;
+}
+*/
+import "C"
+import (
+	"flag"
+	"fmt"
+	"os"
+	"runtime/debug"
+	"syscall"
+)
+
+func enableCore() {
+	debug.SetTraceback("crash")
+
+	var lim syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_CORE, &lim)
+	if err != nil {
+		panic(fmt.Sprintf("error getting rlimit: %v", err))
+	}
+	lim.Cur = lim.Max
+	fmt.Fprintf(os.Stderr, "Setting RLIMIT_CORE = %+#v\n", lim)
+	err = syscall.Setrlimit(syscall.RLIMIT_CORE, &lim)
+	if err != nil {
+		panic(fmt.Sprintf("error setting rlimit: %v", err))
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	enableCore()
+
+	C.trigger_crash()
+}
+`
+
+// TestGdbCoreCrashThreadBacktrace tests that runtime could let the fault thread to crash process
+// and make fault thread as number one thread while gdb in a core file
+func TestGdbCoreCrashThreadBacktrace(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		// N.B. This test isn't fundamentally Linux-only, but it needs
+		// to know how to enable/find core files on each OS.
+		t.Skip("Test only supported on Linux")
+	}
+	if runtime.GOARCH != "386" && runtime.GOARCH != "amd64" {
+		// TODO(go.dev/issue/25218): Other architectures use sigreturn
+		// via VDSO, which we somehow don't handle correctly.
+		t.Skip("Backtrace through signal handler only works on 386 and amd64")
+	}
+
+	testenv.SkipFlaky(t, 65138)
+
+	testenv.MustHaveCGO(t)
+	checkGdbEnvironment(t)
+	t.Parallel()
+	checkGdbVersion(t)
+
+	coreUsesPID := canGenerateCore(t)
+
+	// Build the source code.
+	dir := t.TempDir()
+	src := filepath.Join(dir, "main.go")
+	err := os.WriteFile(src, []byte(coreCrashThreadSource), 0644)
+	if err != nil {
+		t.Fatalf("failed to create file: %v", err)
+	}
+	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "a.exe", "main.go")
+	cmd.Dir = dir
+	out, err := testenv.CleanCmdEnv(cmd).CombinedOutput()
+	if err != nil {
+		t.Fatalf("building source %v\n%s", err, out)
+	}
+
+	// Start the test binary.
+	cmd = testenv.Command(t, "./a.exe")
+	cmd.Dir = dir
+	var output bytes.Buffer
+	cmd.Stdout = &output // for test logging
+	cmd.Stderr = &output
+
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("error starting test binary: %v", err)
+	}
+
+	pid := cmd.Process.Pid
+
+	err = cmd.Wait()
+	t.Logf("child output:\n%s", output.String())
+	if err == nil {
+		t.Fatalf("Wait succeeded, want SIGABRT")
+	}
+	ee, ok := err.(*exec.ExitError)
+	if !ok {
+		t.Fatalf("Wait err got %T %v, want exec.ExitError", ee, ee)
+	}
+	ws, ok := ee.Sys().(syscall.WaitStatus)
+	if !ok {
+		t.Fatalf("Sys got %T %v, want syscall.WaitStatus", ee.Sys(), ee.Sys())
+	}
+	if ws.Signal() != syscall.SIGABRT {
+		t.Fatalf("Signal got %d want SIGABRT", ws.Signal())
+	}
+	if !ws.CoreDump() {
+		t.Fatalf("CoreDump got %v want true", ws.CoreDump())
+	}
+
+	coreFile := "core"
+	if coreUsesPID {
+		coreFile += fmt.Sprintf(".%d", pid)
+	}
+
+	// Execute gdb commands.
+	args := []string{"-nx", "-batch",
+		"-iex", "add-auto-load-safe-path " + filepath.Join(testenv.GOROOT(t), "src", "runtime"),
+		"-ex", "backtrace",
+		filepath.Join(dir, "a.exe"),
+		filepath.Join(dir, coreFile),
+	}
+	cmd = testenv.Command(t, "gdb", args...)
+
+	got, err := cmd.CombinedOutput()
+	t.Logf("gdb output:\n%s", got)
+	if err != nil {
+		t.Fatalf("gdb exited with error: %v", err)
+	}
+
+	re := regexp.MustCompile(`#.* trigger_crash`)
+	if found := re.Find(got) != nil; !found {
+		t.Fatalf("could not find trigger_crash in backtrace")
+	}
+}