linux: add a first chance handler helper

Change-Id: I504212d4ad0a51edf6aad8df9f5bde79f84b782d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1849267Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704289}

components/crash/content/app/crashpad_linux.cc

@@ -23,6 +23,32 @@
 
 namespace crash_reporter {
 
+namespace {
+
+// TODO(jperaza): This is the first chance handler type used by Breakpad and v8.
+// The Crashpad FirstChanceHandler type explicitly declares the third parameter
+// to be a ucontext_t* instead of a void*. Using a reinterpret cast to convert
+// one function type to another causes calling the handler to fail with SIGILL
+// when CFI is enabled. Use a helper with Crashpad's FirstChanceHandler type
+// to delegate to the real first chance handler instead of re-interpreting the
+// handler itself. This can be removed if the two function types converge.
+bool (*g_first_chance_handler)(int, siginfo_t*, void*);
+
+bool FirstChanceHandlerHelper(int signo,
+                              siginfo_t* siginfo,
+                              ucontext_t* context) {
+  return g_first_chance_handler(signo, siginfo, context);
+}
+
+}  // namespace
+
+void SetFirstChanceExceptionHandler(bool (*handler)(int, siginfo_t*, void*)) {
+  DCHECK(!g_first_chance_handler);
+  g_first_chance_handler = handler;
+  crashpad::CrashpadClient::SetFirstChanceExceptionHandler(
+      FirstChanceHandlerHelper);
+}
+
 // TODO(jperaza): Remove kEnableCrashpad and IsCrashpadEnabled() when Crashpad
 // is fully enabled on Linux.
 const char kEnableCrashpad[] = "enable-crashpad";
@@ -31,11 +57,6 @@ bool IsCrashpadEnabled() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(kEnableCrashpad);
 }
 
-void SetFirstChanceExceptionHandler(bool (*handler)(int, siginfo_t*, void*)) {
-  crashpad::CrashpadClient::SetFirstChanceExceptionHandler(
-      reinterpret_cast<crashpad::CrashpadClient::FirstChanceHandler>(handler));
-}
-
 bool GetHandlerSocket(int* fd, pid_t* pid) {
   return crashpad::CrashpadClient::GetHandlerSocket(fd, pid);
 }