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Commit 84ddb34a authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Fix debuggerd issues. 

- Fix a problem where a tid exits before the attach completes, and it
  causes debuggerd to self terminate.
- Fix a problem where sibling tid dumps do not properly wait for the tid
  to get signalled.

Bug: 17800180
Bug: 12567315
Change-Id: Ic3cd619cc2c72402f9a45f14abeed4721b50d64d
parent 4cafe2ff

debuggerd/backtrace.cpp

+3 −1
Original line number Diff line number Diff line
@@ -88,7 +88,9 @@ static void dump_thread( 
    return;

  }



  wait_for_stop(tid, total_sleep_time_usec);

  if (!attached && wait_for_sigstop(tid, total_sleep_time_usec, detach_failed) == -1) {

    return;

  }



  UniquePtr<Backtrace> backtrace(Backtrace::Create(tid, BACKTRACE_CURRENT_THREAD));

  if (backtrace->Unwind(0)) {

debuggerd/debuggerd.cpp

+19 −23
Original line number Diff line number Diff line
@@ -77,7 +77,7 @@ static void wait_for_user_action(const debugger_request_t &request) { 
        "*\n"

        "* Wait for gdb to start, then press the VOLUME DOWN key\n"

        "* to let the process continue crashing.\n"

        "********************************************************\n",

        "********************************************************",

        request.pid, exe, request.tid);



  // Wait for VOLUME DOWN.
@@ -129,11 +129,11 @@ static int read_request(int fd, debugger_request_t* out_request) { 
  socklen_t len = sizeof(cr);

  int status = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);

  if (status != 0) {

    ALOGE("cannot get credentials\n");

    ALOGE("cannot get credentials");

    return -1;

  }



  ALOGV("reading tid\n");

  ALOGV("reading tid");

  fcntl(fd, F_SETFL, O_NONBLOCK);



  pollfd pollfds[1];
@@ -227,6 +227,7 @@ static void handle_request(int fd) { 
      ALOGE("ptrace attach failed: %s\n", strerror(errno));

    } else {

      bool detach_failed = false;

      bool tid_unresponsive = false;

      bool attach_gdb = should_attach_gdb(&request);

      if (TEMP_FAILURE_RETRY(write(fd, "\0", 1)) != 1) {

        ALOGE("failed responding to client: %s\n", strerror(errno));
@@ -240,8 +241,9 @@ static void handle_request(int fd) { 


        int total_sleep_time_usec = 0;

        for (;;) {

          int signal = wait_for_signal(request.tid, &total_sleep_time_usec);

          if (signal < 0) {

          int signal = wait_for_sigstop(request.tid, &total_sleep_time_usec, &detach_failed);

          if (signal == -1) {

            tid_unresponsive = true;

            break;

          }
@@ -308,27 +310,21 @@ static void handle_request(int fd) { 
        free(tombstone_path);

      }



      ALOGV("detaching\n");

      if (!tid_unresponsive) {

        ALOGV("detaching");

        if (attach_gdb) {

          // stop the process so we can debug

          kill(request.pid, SIGSTOP);



        // detach so we can attach gdbserver

        }

        if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {

          ALOGE("ptrace detach from %d failed: %s\n", request.tid, strerror(errno));

          ALOGE("ptrace detach from %d failed: %s", request.tid, strerror(errno));

          detach_failed = true;

        }



        } else if (attach_gdb) {

          // if debug.db.uid is set, its value indicates if we should wait

          // for user action for the crashing process.

          // in this case, we log a message and turn the debug LED on

          // waiting for a gdb connection (for instance)

          wait_for_user_action(request);

      } else {

        // just detach

        if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {

          ALOGE("ptrace detach from %d failed: %s\n", request.tid, strerror(errno));

          detach_failed = true;

        }

      }

debuggerd/tombstone.cpp

+7 −7
Original line number Diff line number Diff line
@@ -374,11 +374,7 @@ static void dump_nearby_maps(BacktraceMap* map, log_t* log, pid_t tid) { 
  }

}



static void dump_thread(

    Backtrace* backtrace, log_t* log, int* total_sleep_time_usec) {



  wait_for_stop(backtrace->Tid(), total_sleep_time_usec);



static void dump_thread(Backtrace* backtrace, log_t* log) {

  dump_registers(log, backtrace->Tid());

  dump_backtrace_and_stack(backtrace, log);
@@ -421,13 +417,17 @@ static bool dump_sibling_thread_report( 
      continue;

    }



    if (wait_for_sigstop(new_tid, total_sleep_time_usec, &detach_failed) == -1) {

      continue;

    }



    log->current_tid = new_tid;

    _LOG(log, logtype::THREAD, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");

    dump_thread_info(log, pid, new_tid);



    UniquePtr<Backtrace> backtrace(Backtrace::Create(pid, new_tid, map));

    if (backtrace->Unwind(0)) {

      dump_thread(backtrace.get(), log, total_sleep_time_usec);

      dump_thread(backtrace.get(), log);

    }



    log->current_tid = log->crashed_tid;
@@ -628,7 +628,7 @@ static bool dump_crash(log_t* log, pid_t pid, pid_t tid, int signal, int si_code 
  UniquePtr<Backtrace> backtrace(Backtrace::Create(pid, tid, map.get()));

  if (backtrace->Unwind(0)) {

    dump_abort_message(backtrace.get(), log, abort_msg_address);

    dump_thread(backtrace.get(), log, total_sleep_time_usec);

    dump_thread(backtrace.get(), log);

  }



  if (want_logs) {

debuggerd/utility.cpp

+25 −29
Original line number Diff line number Diff line
@@ -28,8 +28,8 @@ 
#include <backtrace/Backtrace.h>

#include <log/log.h>



const int sleep_time_usec = 50000;         // 0.05 seconds

const int max_total_sleep_usec = 10000000; // 10 seconds

const int SLEEP_TIME_USEC = 50000;         // 0.05 seconds

const int MAX_TOTAL_SLEEP_USEC = 10000000; // 10 seconds



static int write_to_am(int fd, const char* buf, int len) {

  int to_write = len;
@@ -91,48 +91,44 @@ void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) { 
  }

}



int wait_for_signal(pid_t tid, int* total_sleep_time_usec) {

int wait_for_sigstop(pid_t tid, int* total_sleep_time_usec, bool* detach_failed) {

  bool allow_dead_tid = false;

  for (;;) {

    int status;

    pid_t n = waitpid(tid, &status, __WALL | WNOHANG);

    if (n < 0) {

      if (errno == EAGAIN)

        continue;

      ALOGE("waitpid failed: %s\n", strerror(errno));

      return -1;

    } else if (n > 0) {

      ALOGV("waitpid: n=%d status=%08x\n", n, status);

    pid_t n = TEMP_FAILURE_RETRY(waitpid(tid, &status, __WALL | WNOHANG));

    if (n == -1) {

      ALOGE("waitpid failed: tid %d, %s", tid, strerror(errno));

      break;

    } else if (n == tid) {

      if (WIFSTOPPED(status)) {

        return WSTOPSIG(status);

      } else {

        ALOGE("unexpected waitpid response: n=%d, status=%08x\n", n, status);

        return -1;

        // This is the only circumstance under which we can allow a detach

        // to fail with ESRCH, which indicates the tid has exited.

        allow_dead_tid = true;

        break;

      }

    }



    if (*total_sleep_time_usec > max_total_sleep_usec) {

      ALOGE("timed out waiting for tid=%d to die\n", tid);

      return -1;

    if (*total_sleep_time_usec > MAX_TOTAL_SLEEP_USEC) {

      ALOGE("timed out waiting for stop signal: tid=%d", tid);

      break;

    }



    // not ready yet

    ALOGV("not ready yet\n");

    usleep(sleep_time_usec);

    *total_sleep_time_usec += sleep_time_usec;

  }

    usleep(SLEEP_TIME_USEC);

    *total_sleep_time_usec += SLEEP_TIME_USEC;

  }



void wait_for_stop(pid_t tid, int* total_sleep_time_usec) {

  siginfo_t si;

  while (TEMP_FAILURE_RETRY(ptrace(PTRACE_GETSIGINFO, tid, 0, &si)) < 0 && errno == ESRCH) {

    if (*total_sleep_time_usec > max_total_sleep_usec) {

      ALOGE("timed out waiting for tid=%d to stop\n", tid);

      break;

  if (ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {

    if (allow_dead_tid && errno == ESRCH) {

      ALOGE("tid exited before attach completed: tid %d", tid);

    } else {

      *detach_failed = true;

      ALOGE("detach failed: tid %d, %s", tid, strerror(errno));

    }



    usleep(sleep_time_usec);

    *total_sleep_time_usec += sleep_time_usec;

  }

  return -1;

}



#if defined (__mips__)

debuggerd/utility.h

+2 −3
Original line number Diff line number Diff line
@@ -67,12 +67,11 @@ enum logtype { 
  LOGS

};



/* Log information onto the tombstone. */

// Log information onto the tombstone.

void _LOG(log_t* log, logtype ltype, const char *fmt, ...)

        __attribute__ ((format(printf, 3, 4)));



int wait_for_signal(pid_t tid, int* total_sleep_time_usec);

void wait_for_stop(pid_t tid, int* total_sleep_time_usec);

int wait_for_sigstop(pid_t, int*, bool*);



void dump_memory(log_t* log, pid_t tid, uintptr_t addr);