NonSFI NaCl: Plumb Exception IRT enough for breakpad.

components/nacl/loader/nonsfi/irt_exception_handling.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <errno.h>
+#include <pthread.h>
+#include <signal.h>
+
+#include "base/atomicops.h"

[Mark Seaborn, 2014/04/25 15:42:02]

Not used?

[Junichi Uekawa, 2014/04/25 22:13:53]

Done.

+#include "components/nacl/loader/nonsfi/irt_interfaces.h"
+#include "native_client/src/include/nacl_macros.h"
+#include "native_client/src/trusted/service_runtime/nacl_exception.h"
+#include "native_client/src/trusted/service_runtime/nacl_signal.h"
+
+namespace nacl {
+namespace nonsfi {
+namespace {
+
+// This is NonSFI version of exception handling codebase, NaCl side of
+// things resides in:
+// native_client/src/trusted/service_runtime/linux/nacl_signal.c
+// native_client/src/trusted/service_runtime/sys_exception.c
+
+// Crash signals to handle.  The differences from SFI NaCl are that
+// NonSFI NaCl does not use NACL_THREAD_SUSPEND_SIGNAL (==SIGUSR1),
+// and SIGSYS is reserved for seccomp-bpf.
+static const int kSignals[] = {

[Mark Seaborn, 2014/04/25 15:42:02]

Don't need "static" here since this is in an anon namespace.

Same for others below.

[Junichi Uekawa, 2014/04/25 22:13:53]

Done.

+  SIGSTKFLT,
+  SIGINT, SIGQUIT, SIGILL, SIGTRAP, SIGBUS, SIGFPE, SIGSEGV,
+  // Handle SIGABRT in case someone sends it asynchronously using kill().
+  SIGABRT
+};
+
+pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+NaClExceptionHandler signal_handler_function_pointer = NULL;
+
+// Signal handler, responsible for calling the registered handler.
+static void SignalCatch(int sig, siginfo_t* info, void* uc) {
+  if (signal_handler_function_pointer) {
+    NaClSignalContext signal_context;
+    NaClSignalContextFromHandler(&signal_context, uc);
+    NaClExceptionFrame exception_frame;
+    NaClSignalSetUpExceptionFrame(&exception_frame,
+                                  &signal_context,
+                                  0 /* context_user_addr,
+                                       not useful for NonSFI NaCl. */);
+    signal_handler_function_pointer(&exception_frame.context);
+  }
+  _exit(-1);
+}
+
+static int IrtExceptionHandler(NaClExceptionHandler handler,
+                               NaClExceptionHandler* old_handler) {
+  pthread_mutex_lock(&mutex);
+  if (old_handler)
+    *old_handler = signal_handler_function_pointer;
+  signal_handler_function_pointer = handler;
+  pthread_mutex_unlock(&mutex);
+  return 0;
+}
+
+static int IrtExceptionStack(void* stack, size_t size) {
+  // TODO(uekawa): Implement this function so that the exception stack
+  // actually gets used for running an exception handler.  Currently
+  // we don't switch stack, which means we can't handle stack overflow
+  // exceptions.
+  return 0;
+}
+
+static int IrtExceptionClearFlag(void) {
+  // TODO(uekawa): Implement clear_flag() to behave like SFI NaCl's
+  // implementation, so that a thread can handle a second exception
+  // after handling a first exception
+  return -ENOSYS;

[Mark Seaborn, 2014/04/25 15:42:02]

This should be "return ENOSYS".  IRT functions return positive errno values.

[Junichi Uekawa, 2014/04/25 22:13:53]

Done.

+}
+
+}  // namespace
+
+const struct nacl_irt_exception_handling kIrtExceptionHandling = {
+  IrtExceptionHandler,
+  IrtExceptionStack,
+  IrtExceptionClearFlag,
+};
+
+void InitializeSignalHandler() {
+  struct sigaction sa;
+  unsigned int a;
+
+  memset(&sa, 0, sizeof(sa));
+  sigemptyset(&sa.sa_mask);
+  sa.sa_sigaction = SignalCatch;
+  sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
+
+  // Mask all signals we catch to prevent re-entry.
+  for (a = 0; a < NACL_ARRAY_SIZE(kSignals); a++) {
+    sigaddset(&sa.sa_mask, kSignals[a]);
+  }
+
+  // Install all handlers.
+  for (a = 0; a < NACL_ARRAY_SIZE(kSignals); a++) {
+    if (sigaction(kSignals[a], &sa, NULL) != 0)
+      NaClLog(LOG_FATAL, "sigaction to register signals failed.\n");
+  }
+}
+
+}  // namespace nonsfi
+}  // namespace nacl