components/nacl/loader/nonsfi/irt_exception_handling.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <errno.h>
   6 #include <pthread.h>
   7 #include <signal.h>
   8
   9 #include "components/nacl/loader/nonsfi/irt_interfaces.h"
  10 #include "native_client/src/include/nacl_macros.h"
  11 #include "native_client/src/shared/platform/nacl_log.h"
  12 #include "native_client/src/trusted/service_runtime/nacl_exception.h"
  13 #include "native_client/src/trusted/service_runtime/nacl_signal.h"
  14
  15 namespace nacl {
  16 namespace nonsfi {
  17 namespace {
  18
  19 // This is NonSFI version of exception handling codebase, NaCl side of
  20 // things resides in:
  21 // native_client/src/trusted/service_runtime/linux/nacl_signal.c
  22 // native_client/src/trusted/service_runtime/sys_exception.c
  23
  24 // Crash signals to handle.  The differences from SFI NaCl are that
  25 // NonSFI NaCl does not use NACL_THREAD_SUSPEND_SIGNAL (==SIGUSR1),
  26 // and SIGSYS is reserved for seccomp-bpf.
  27 const int kSignals[] = {
  28 #if !defined(__mips__)
  29   // This signal does not exist on MIPS.
  30   SIGSTKFLT,
  31 #endif
  32   SIGINT, SIGQUIT, SIGILL, SIGTRAP, SIGBUS, SIGFPE, SIGSEGV,
  33   // Handle SIGABRT in case someone sends it asynchronously using kill().
  34   SIGABRT
  35 };
  36
  37 pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  38 NaClExceptionHandler signal_handler_function_pointer = NULL;
  39
  40 // Signal handler, responsible for calling the registered handler.
  41 void SignalCatch(int sig, siginfo_t* info, void* uc) {
  42   if (signal_handler_function_pointer) {
  43     NaClSignalContext signal_context;
  44     NaClSignalContextFromHandler(&signal_context, uc);
  45     NaClExceptionFrame exception_frame;
  46     NaClSignalSetUpExceptionFrame(&exception_frame,
  47                                   &signal_context,
  48                                   0 /* context_user_addr,
  49                                        not useful for NonSFI NaCl. */);
  50     signal_handler_function_pointer(&exception_frame.context);
  51   }
  52   _exit(-1);
  53 }
  54
  55 int IrtExceptionHandler(NaClExceptionHandler handler,
  56                                NaClExceptionHandler* old_handler) {
  57   pthread_mutex_lock(&mutex);
  58   if (old_handler)
  59     *old_handler = signal_handler_function_pointer;
  60   signal_handler_function_pointer = handler;
  61   pthread_mutex_unlock(&mutex);
  62   return 0;
  63 }
  64
  65 int IrtExceptionStack(void* stack, size_t size) {
  66   // TODO(uekawa): Implement this function so that the exception stack
  67   // actually gets used for running an exception handler.  Currently
  68   // we don't switch stack, which means we can't handle stack overflow
  69   // exceptions.
  70   return 0;
  71 }
  72
  73 int IrtExceptionClearFlag(void) {
  74   // TODO(uekawa): Implement clear_flag() to behave like SFI NaCl's
  75   // implementation, so that a thread can handle a second exception
  76   // after handling a first exception
  77   return ENOSYS;
  78 }
  79
  80 }  // namespace
  81
  82 const struct nacl_irt_exception_handling kIrtExceptionHandling = {
  83   IrtExceptionHandler,
  84   IrtExceptionStack,
  85   IrtExceptionClearFlag,
  86 };
  87
  88 void InitializeSignalHandler() {
  89   struct sigaction sa;
  90   unsigned int a;
  91
  92   memset(&sa, 0, sizeof(sa));
  93   sigemptyset(&sa.sa_mask);
  94   sa.sa_sigaction = SignalCatch;
  95   sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
  96
  97   // Mask all signals we catch to prevent re-entry.
  98   for (a = 0; a < NACL_ARRAY_SIZE(kSignals); a++) {
  99     sigaddset(&sa.sa_mask, kSignals[a]);
 100   }
 101
 102   // Install all handlers.
 103   for (a = 0; a < NACL_ARRAY_SIZE(kSignals); a++) {
 104     if (sigaction(kSignals[a], &sa, NULL) != 0)
 105       NaClLog(LOG_FATAL, "sigaction to register signals failed.\n");
 106   }
 107 }
 108
 109 }  // namespace nonsfi
 110 }  // namespace nacl