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Commit f30a810b authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Use async safe logging in signal handlers. 

Test: Boot on bullhead.
Test: Ran the libbacktrace tests on bullhead.
Test: Added a temporary log message in the signal handler, and ran the
Test: backtrace tests.
Change-Id: I0a6888c9f311af2c8cc7fbb4929315911bd2bb3c
parent 8fad110b

libbacktrace/Android.bp

+1 −1
Original line number Diff line number Diff line
@@ -110,7 +110,7 @@ cc_library { 
                "libunwind",

            ],



            static_libs: ["libcutils"],

            static_libs: ["libasync_safe", "libcutils"],

        },

    },

}

libbacktrace/BacktraceAsyncSafeLog.h

0 → 100644
+41 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2014 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



#ifndef _LIBBACKTRACE_BACKTRACE_ASYNC_SAFE_LOG_H

#define _LIBBACKTRACE_BACKTRACE_ASYNC_SAFE_LOG_H



#if defined(__ANDROID__)



#include <async_safe/log.h>



// Logging macros for use in signal handler, only available on target.

#define BACK_ASYNC_SAFE_LOGW(format, ...)                                                     \

  async_safe_format_log(ANDROID_LOG_WARN, "libbacktrace", "%s: " format, __PRETTY_FUNCTION__, \

                        ##__VA_ARGS__)



#define BACK_ASYNC_SAFE_LOGE(format, ...)                                                      \

  async_safe_format_log(ANDROID_LOG_ERROR, "libbacktrace", "%s: " format, __PRETTY_FUNCTION__, \

                        ##__VA_ARGS__)



#else



#define BACK_ASYNC_SAFE_LOGW(format, ...)



#define BACK_ASYNC_SAFE_LOGE(format, ...)



#endif



#endif  // _LIBBACKTRACE_BACKTRACE_ASYNC_SAFE_LOG_H

libbacktrace/BacktraceCurrent.cpp

+9 −8
Original line number Diff line number Diff line
@@ -31,8 +31,8 @@ 
#include <backtrace/Backtrace.h>

#include <backtrace/BacktraceMap.h>



#include "BacktraceAsyncSafeLog.h"

#include "BacktraceCurrent.h"

#include "BacktraceLog.h"

#include "ThreadEntry.h"

#include "thread_utils.h"
@@ -47,7 +47,7 @@ bool BacktraceCurrent::ReadWord(uintptr_t ptr, word_t* out_value) { 
    *out_value = *reinterpret_cast<word_t*>(ptr);

    return true;

  } else {

    BACK_LOGW("pointer %p not in a readable map", reinterpret_cast<void*>(ptr));

    BACK_ASYNC_SAFE_LOGW("pointer %p not in a readable map", reinterpret_cast<void*>(ptr));

    *out_value = static_cast<word_t>(-1);

    return false;

  }
@@ -114,7 +114,8 @@ class ErrnoRestorer { 
static void SignalLogOnly(int, siginfo_t*, void*) {

  ErrnoRestorer restore;



  BACK_LOGE("pid %d, tid %d: Received a spurious signal %d\n", getpid(), gettid(), THREAD_SIGNAL);

  BACK_ASYNC_SAFE_LOGE("pid %d, tid %d: Received a spurious signal %d\n", getpid(), gettid(),

                       THREAD_SIGNAL);

}



static void SignalHandler(int, siginfo_t*, void* sigcontext) {
@@ -122,7 +123,7 @@ static void SignalHandler(int, siginfo_t*, void* sigcontext) { 


  ThreadEntry* entry = ThreadEntry::Get(getpid(), gettid(), false);

  if (!entry) {

    BACK_LOGE("pid %d, tid %d entry not found", getpid(), gettid());

    BACK_ASYNC_SAFE_LOGE("pid %d, tid %d entry not found", getpid(), gettid());

    return;

  }
@@ -141,7 +142,7 @@ static void SignalHandler(int, siginfo_t*, void* sigcontext) { 
    entry->Wake();

  } else {

    // At this point, it is possible that entry has been freed, so just exit.

    BACK_LOGE("Timed out waiting for unwind thread to indicate it completed.");

    BACK_ASYNC_SAFE_LOGE("Timed out waiting for unwind thread to indicate it completed.");

  }

}
@@ -159,7 +160,7 @@ bool BacktraceCurrent::UnwindThread(size_t num_ignore_frames) { 
  act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;

  sigemptyset(&act.sa_mask);

  if (sigaction(THREAD_SIGNAL, &act, &oldact) != 0) {

    BACK_LOGE("sigaction failed: %s", strerror(errno));

    BACK_ASYNC_SAFE_LOGE("sigaction failed: %s", strerror(errno));

    ThreadEntry::Remove(entry);

    pthread_mutex_unlock(&g_sigaction_mutex);

    error_ = BACKTRACE_UNWIND_ERROR_INTERNAL;
@@ -212,7 +213,7 @@ bool BacktraceCurrent::UnwindThread(size_t num_ignore_frames) { 
    // Wait for the thread to indicate it is done with the ThreadEntry.

    if (!entry->Wait(3)) {

      // Send a warning, but do not mark as a failure to unwind.

      BACK_LOGW("Timed out waiting for signal handler to indicate it finished.");

      BACK_ASYNC_SAFE_LOGW("Timed out waiting for signal handler to indicate it finished.");

    }

  } else {

    // Check to see if the thread has disappeared.
@@ -220,7 +221,7 @@ bool BacktraceCurrent::UnwindThread(size_t num_ignore_frames) { 
      error_ = BACKTRACE_UNWIND_ERROR_THREAD_DOESNT_EXIST;

    } else {

      error_ = BACKTRACE_UNWIND_ERROR_THREAD_TIMEOUT;

      BACK_LOGE("Timed out waiting for signal handler to get ucontext data.");

      BACK_ASYNC_SAFE_LOGE("Timed out waiting for signal handler to get ucontext data.");

    }

  }

libbacktrace/ThreadEntry.cpp

+2 −2
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ 
#include <time.h>

#include <ucontext.h>



#include "BacktraceLog.h"

#include "BacktraceAsyncSafeLog.h"

#include "ThreadEntry.h"



// Initialize static member variables.
@@ -106,7 +106,7 @@ bool ThreadEntry::Wait(int value) { 
  while (wait_value_ != value) {

    int ret = pthread_cond_timedwait(&wait_cond_, &wait_mutex_, &ts);

    if (ret != 0) {

      BACK_LOGW("pthread_cond_timedwait for value %d failed: %s", value, strerror(ret));

      BACK_ASYNC_SAFE_LOGW("pthread_cond_timedwait for value %d failed: %s", value, strerror(ret));

      wait_completed = false;

      break;

    }