NonSFI NaCl: Plumb Exception IRT enough for breakpad.

components/nacl/loader/nonsfi/irt_thread.cc

Index: components/nacl/loader/nonsfi/irt_thread.cc
diff --git a/components/nacl/loader/nonsfi/irt_thread.cc b/components/nacl/loader/nonsfi/irt_thread.cc
index 3351bdc48b1dbbfee29eb063a668f6f1c7e102b6..b7f5c9a7e03c7dd708f630acc3f652260c4c13f4 100644
--- a/components/nacl/loader/nonsfi/irt_thread.cc
+++ b/components/nacl/loader/nonsfi/irt_thread.cc
@@ -6,9 +6,11 @@
 #include <pthread.h>
 #include <stdlib.h>
 
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/nacl/loader/nonsfi/irt_interfaces.h"
+#include "native_client/src/trusted/service_runtime/nacl_signal.h"
 
 namespace nacl {
 namespace nonsfi {
@@ -33,6 +35,7 @@ class ScopedPthreadAttrPtr {
 struct ThreadContext {
   void (*start_func)();
   void* thread_ptr;
+  void* signal_stack;
 };
 
 // A thread local pointer to support nacl_irt_tls.
@@ -45,6 +48,9 @@ void* ThreadMain(void *arg) {
   ::scoped_ptr<ThreadContext> context(static_cast<ThreadContext*>(arg));
   g_thread_ptr = context->thread_ptr;
 
+  DVLOG(4) << "Registering alternate signal stack: " << context->signal_stack;
+  NaClSignalStackRegister(context->signal_stack);

[Mark Seaborn, 2014/04/23 03:49:50]

This probably doesn't work: the seccomp sandbox will disallow sigaltstack().

Can you run the linux_rel_precise32 trybot, please?  That covers x86-32 Linux,
which is the only Chromium bot that runs Non-SFI NaCl tests currently.

I'd just omit the changes to this file for now.  We can fix the handling of
stack overflow crashes later.  NaClSignalStackAllocate() likely allocates a
stack that's too small for user code (because it wasn't intended for that
purpose).

[Junichi Uekawa, 2014/04/23 07:56:15]

I was wondering why my tests are succeeding and I guess of course I am not
testing thread creation path.

I'll revert changes to this file for now.

+
   // Release the memory of context before running start_func.
   void (*start_func)() = context->start_func;
   context.reset();
@@ -72,6 +78,10 @@ int IrtThreadCreate(void (*start_func)(), void* stack, void* thread_ptr) {
   ::scoped_ptr<ThreadContext> context(new ThreadContext);
   context->start_func = start_func;
   context->thread_ptr = thread_ptr;
+  if (!NaClSignalStackAllocate(&context->signal_stack)) {
+    DVLOG(1) << "Failed to allocate alternate stack\n";
+    return error;
+  }
 
   pthread_t tid;
   error = pthread_create(&tid, &attr, ThreadMain, context.get());