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Commit 17e91d44 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Rewrite libbacktrace using C++. 

The old code was essentially trying to be C++ in C and was awkward. This
change makes it all objects with a thin layer that C code can use.

There is a C++ backtrace object that is not very useful, this code will
replace it.

This change also includes moving the backtrace test to a gtest, and adding
coverage of all major functionality.

Bug: 8410085
Change-Id: Iae0f1b09b3dd60395f71ed66010c1ea5cdd37841
parent f1296b9e

debuggerd/backtrace.c

+7 −7
Original line number Diff line number Diff line
@@ -89,12 +89,12 @@ static void dump_thread(log_t* log, pid_t tid, bool attached, 


    wait_for_stop(tid, total_sleep_time_usec);



    backtrace_t backtrace;

    if (!backtrace_get_data(&backtrace, tid)) {

    backtrace_context_t context;

    if (!backtrace_create_context(&context, tid, -1, 0)) {

        _LOG(log, SCOPE_AT_FAULT, "Could not create backtrace context.\n");

    } else {

        dump_backtrace_to_log(&backtrace, log, SCOPE_AT_FAULT, "  ");

        backtrace_free_data(&backtrace);

        dump_backtrace_to_log(&context, log, SCOPE_AT_FAULT, "  ");

        backtrace_destroy_context(&context);

    }



    if (!attached && ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {
@@ -137,11 +137,11 @@ void dump_backtrace(int fd, int amfd, pid_t pid, pid_t tid, bool* detach_failed, 
    dump_process_footer(&log, pid);

}



void dump_backtrace_to_log(const backtrace_t* backtrace, log_t* log,

void dump_backtrace_to_log(const backtrace_context_t* context, log_t* log,

                           int scope_flags, const char* prefix) {

    char buf[512];

    for (size_t i = 0; i < backtrace->num_frames; i++) {

        backtrace_format_frame_data(&backtrace->frames[i], i, buf, sizeof(buf));

    for (size_t i = 0; i < context->backtrace->num_frames; i++) {

        backtrace_format_frame_data(context, i, buf, sizeof(buf));

        _LOG(log, scope_flags, "%s%s\n", prefix, buf);

    }

}

debuggerd/backtrace.h

+1 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ void dump_backtrace(int fd, int amfd, pid_t pid, pid_t tid, bool* detach_failed, 
        int* total_sleep_time_usec);



/* Dumps the backtrace in the backtrace data structure to the log. */

void dump_backtrace_to_log(const backtrace_t* backtrace, log_t* log,

void dump_backtrace_to_log(const backtrace_context_t* context, log_t* log,

        int scope_flags, const char* prefix);



#endif // _DEBUGGERD_BACKTRACE_H

debuggerd/tombstone.c

+35 −33
Original line number Diff line number Diff line
@@ -228,39 +228,39 @@ static void dump_thread_info(log_t* log, pid_t pid, pid_t tid, int scope_flags) 
    }

}



static void dump_stack_segment(const backtrace_t* backtrace, log_t* log,

static void dump_stack_segment(const backtrace_context_t* context, log_t* log,

        int scope_flags, uintptr_t *sp, size_t words, int label) {

    for (size_t i = 0; i < words; i++) {

        uint32_t stack_content;

        if (!backtrace_read_word(backtrace, *sp, &stack_content)) {

        if (!backtrace_read_word(context, *sp, &stack_content)) {

            break;

        }



        const char* map_name = backtrace_get_map_info(backtrace, stack_content, NULL);

        const char* map_name = backtrace_get_map_name(context, stack_content, NULL);

        if (!map_name) {

            map_name = "";

        }

        uintptr_t offset = 0;

        char* proc_name = backtrace_get_proc_name(backtrace, stack_content, &offset);

        if (proc_name) {

        char* func_name = backtrace_get_func_name(context, stack_content, &offset);

        if (func_name) {

            if (!i && label >= 0) {

                if (offset) {

                    _LOG(log, scope_flags, "    #%02d  %08x  %08x  %s (%s+%u)\n",

                            label, *sp, stack_content, map_name, proc_name, offset);

                            label, *sp, stack_content, map_name, func_name, offset);

                } else {

                    _LOG(log, scope_flags, "    #%02d  %08x  %08x  %s (%s)\n",

                            label, *sp, stack_content, map_name, proc_name);

                            label, *sp, stack_content, map_name, func_name);

                }

            } else {

                if (offset) {

                    _LOG(log, scope_flags, "         %08x  %08x  %s (%s+%u)\n",

                            *sp, stack_content, map_name, proc_name, offset);

                            *sp, stack_content, map_name, func_name, offset);

                } else {

                    _LOG(log, scope_flags, "         %08x  %08x  %s (%s)\n",

                            *sp, stack_content, map_name, proc_name);

                            *sp, stack_content, map_name, func_name);

                }

            }

            free(proc_name);

            free(func_name);

        } else {

            if (!i && label >= 0) {

                _LOG(log, scope_flags, "    #%02d  %08x  %08x  %s\n",
@@ -275,7 +275,8 @@ static void dump_stack_segment(const backtrace_t* backtrace, log_t* log, 
    }

}



static void dump_stack(const backtrace_t* backtrace, log_t* log, int scope_flags) {

static void dump_stack(const backtrace_context_t* context, log_t* log, int scope_flags) {

    const backtrace_t* backtrace = context->backtrace;

    size_t first = 0, last;

    for (size_t i = 0; i < backtrace->num_frames; i++) {

        if (backtrace->frames[i].sp) {
@@ -294,7 +295,7 @@ static void dump_stack(const backtrace_t* backtrace, log_t* log, int scope_flags 


    // Dump a few words before the first frame.

    uintptr_t sp = backtrace->frames[first].sp - STACK_WORDS * sizeof(uint32_t);

    dump_stack_segment(backtrace, log, scope_flags, &sp, STACK_WORDS, -1);

    dump_stack_segment(context, log, scope_flags, &sp, STACK_WORDS, -1);



    // Dump a few words from all successive frames.

    // Only log the first 3 frames, put the rest in the tombstone.
@@ -308,7 +309,7 @@ static void dump_stack(const backtrace_t* backtrace, log_t* log, int scope_flags 
            scope_flags &= (~SCOPE_AT_FAULT);

        }

        if (i == last) {

            dump_stack_segment(backtrace, log, scope_flags, &sp, STACK_WORDS, i);

            dump_stack_segment(context, log, scope_flags, &sp, STACK_WORDS, i);

            if (sp < frame->sp + frame->stack_size) {

                _LOG(log, scope_flags, "         ........  ........\n");

            }
@@ -319,19 +320,19 @@ static void dump_stack(const backtrace_t* backtrace, log_t* log, int scope_flags 
            } else if (words > STACK_WORDS) {

                words = STACK_WORDS;

            }

            dump_stack_segment(backtrace, log, scope_flags, &sp, words, i);

            dump_stack_segment(context, log, scope_flags, &sp, words, i);

        }

    }

}



static void dump_backtrace_and_stack(const backtrace_t* backtrace, log_t* log,

        int scope_flags) {

    if (backtrace->num_frames) {

static void dump_backtrace_and_stack(const backtrace_context_t* context,

        log_t* log, int scope_flags) {

    if (context->backtrace->num_frames) {

        _LOG(log, scope_flags, "\nbacktrace:\n");

        dump_backtrace_to_log(backtrace, log, scope_flags, "    ");

        dump_backtrace_to_log(context, log, scope_flags, "    ");



        _LOG(log, scope_flags, "\nstack:\n");

        dump_stack(backtrace, log, scope_flags);

        dump_stack(context, log, scope_flags);

    }

}
@@ -399,12 +400,13 @@ static void dump_nearby_maps(const backtrace_map_info_t* map_info_list, log_t* l 
    dump_map(log, prev, "map above", scope_flags);

}



static void dump_thread(const backtrace_t* backtrace, log_t* log, int scope_flags,

        int* total_sleep_time_usec) {

static void dump_thread(const backtrace_context_t* context, log_t* log,

        int scope_flags, int* total_sleep_time_usec) {

    const backtrace_t* backtrace = context->backtrace;

    wait_for_stop(backtrace->tid, total_sleep_time_usec);



    dump_registers(log, backtrace->tid, scope_flags);

    dump_backtrace_and_stack(backtrace, log, scope_flags);

    dump_backtrace_and_stack(context, log, scope_flags);

    if (IS_AT_FAULT(scope_flags)) {

        dump_memory_and_code(log, backtrace->tid, scope_flags);

        dump_nearby_maps(backtrace->map_info_list, log, backtrace->tid, scope_flags);
@@ -446,11 +448,11 @@ static bool dump_sibling_thread_report( 


        _LOG(log, 0, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");

        dump_thread_info(log, pid, new_tid, 0);

        backtrace_t new_backtrace;

        if (backtrace_get_data(&new_backtrace, new_tid)) {

            dump_thread(&new_backtrace, log, 0, total_sleep_time_usec);

        backtrace_context_t new_context;

        if (backtrace_create_context(&new_context, pid, new_tid, 0)) {

            dump_thread(&new_context, log, 0, total_sleep_time_usec);

            backtrace_destroy_context(&new_context);

        }

        backtrace_free_data(&new_backtrace);



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

            LOG("ptrace detach from %d failed: %s\n", new_tid, strerror(errno));
@@ -606,7 +608,7 @@ static void dump_logs(log_t* log, pid_t pid, bool tailOnly) 
    dump_log_file(log, pid, "/dev/log/main", tailOnly);

}



static void dump_abort_message(const backtrace_t* backtrace, log_t* log, uintptr_t address) {

static void dump_abort_message(const backtrace_context_t* context, log_t* log, uintptr_t address) {

  if (address == 0) {

    return;

  }
@@ -618,7 +620,7 @@ static void dump_abort_message(const backtrace_t* backtrace, log_t* log, uintptr 
  char* p = &msg[0];

  while (p < &msg[sizeof(msg)]) {

    uint32_t data;

    if (!backtrace_read_word(backtrace, address, &data)) {

    if (!backtrace_read_word(context, address, &data)) {

      break;

    }

    address += sizeof(uint32_t);
@@ -673,11 +675,11 @@ static bool dump_crash(log_t* log, pid_t pid, pid_t tid, int signal, uintptr_t a 
        dump_fault_addr(log, tid, signal);

    }



    backtrace_t backtrace;

    if (backtrace_get_data(&backtrace, tid)) {

        dump_abort_message(&backtrace, log, abort_msg_address);

        dump_thread(&backtrace, log, SCOPE_AT_FAULT, total_sleep_time_usec);

        backtrace_free_data(&backtrace);

    backtrace_context_t context;

    if (backtrace_create_context(&context, pid, tid, 0)) {

        dump_abort_message(&context, log, abort_msg_address);

        dump_thread(&context, log, SCOPE_AT_FAULT, total_sleep_time_usec);

        backtrace_destroy_context(&context);

    }



    if (want_logs) {

include/backtrace/Backtrace.h

0 → 100644
+85 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2013 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 _BACKTRACE_BACKTRACE_H

#define _BACKTRACE_BACKTRACE_H



#include <backtrace/backtrace.h>



#include <string>



class BacktraceImpl;



class Backtrace {

public:

  Backtrace(BacktraceImpl* impl);

  virtual ~Backtrace();



  // Get the current stack trace and store in the backtrace_ structure.

  virtual bool Unwind(size_t num_ignore_frames);



  // Get the function name and offset into the function given the pc.

  // If the string is empty, then no valid function name was found.

  virtual std::string GetFunctionName(uintptr_t pc, uintptr_t* offset);



  // Get the name of the map associated with the given pc. If NULL is returned,

  // then map_start is not set. Otherwise, map_start is the beginning of this

  // map.

  virtual const char* GetMapName(uintptr_t pc, uintptr_t* map_start);



  // Finds the memory map associated with the given ptr.

  virtual const backtrace_map_info_t* FindMapInfo(uintptr_t ptr);



  // Read the data at a specific address.

  virtual bool ReadWord(uintptr_t ptr, uint32_t* out_value) = 0;



  // Create a string representing the formatted line of backtrace information

  // for a single frame.

  virtual std::string FormatFrameData(size_t frame_num);



  pid_t Pid() { return backtrace_.pid; }

  pid_t Tid() { return backtrace_.tid; }

  size_t NumFrames() { return backtrace_.num_frames; }



  const backtrace_t* GetBacktrace() { return &backtrace_; }



  const backtrace_frame_data_t* GetFrame(size_t frame_num) {

    return &backtrace_.frames[frame_num];

  }



  // Create the correct Backtrace object based on what is to be unwound.

  // If pid < 0 or equals the current pid, then the Backtrace object

  // corresponds to the current process.

  // If pid < 0 or equals the current pid and tid >= 0, then the Backtrace

  // object corresponds to a thread in the current process.

  // If pid >= 0 and tid < 0, then the Backtrace object corresponds to a

  // different process.

  // Tracing a thread in a different process is not supported.

  static Backtrace* Create(pid_t pid, pid_t tid);



protected:

  virtual bool VerifyReadWordArgs(uintptr_t ptr, uint32_t* out_value);



  BacktraceImpl* impl_;



  backtrace_map_info_t* map_info_;



  backtrace_t backtrace_;



  friend class BacktraceImpl;

};



#endif // _BACKTRACE_BACKTRACE_H

include/backtrace/backtrace.h

+35 −25
Original line number Diff line number Diff line
@@ -21,9 +21,7 @@ 
#include <stdbool.h>

#include <inttypes.h>



#ifdef __cplusplus

extern "C" {

#endif

__BEGIN_DECLS



#define MAX_BACKTRACE_FRAMES 64
@@ -43,48 +41,58 @@ typedef struct { 
  size_t stack_size;      /* The size of the stack, zero indicate an unknown stack size. */

  const char* map_name;   /* The name of the map to which this pc belongs, NULL indicates the pc doesn't belong to a known map. */

  uintptr_t map_offset;   /* pc relative to the start of the map, only valid if map_name is not NULL. */

  char* proc_name;        /* The function name associated with this pc, NULL if not found. */

  uintptr_t proc_offset;  /* pc relative to the start of the procedure, only valid if proc_name is not NULL. */

  char* func_name;        /* The function name associated with this pc, NULL if not found. */

  uintptr_t func_offset;  /* pc relative to the start of the function, only valid if func_name is not NULL. */

} backtrace_frame_data_t;



typedef struct {

  backtrace_frame_data_t frames[MAX_BACKTRACE_FRAMES];

  size_t num_frames;



  pid_t pid;

  pid_t tid;

  backtrace_map_info_t* map_info_list;

  void* private_data;

} backtrace_t;



/* Gather the backtrace data for tid and fill in the backtrace structure.

 * If tid < 0, then gather the backtrace for the current thread.

typedef struct {

  void* data;

  const backtrace_t* backtrace;

} backtrace_context_t;



/* Create a context for the backtrace data and gather the backtrace.

 * If pid < 0, then gather the backtrace for the current process.

 */

bool backtrace_get_data(backtrace_t* backtrace, pid_t tid);

bool backtrace_create_context(

    backtrace_context_t* context, pid_t pid, pid_t tid, size_t num_ignore_frames);



/* Free any memory associated with the backtrace structure. */

void backtrace_free_data(backtrace_t* backtrace);

/* Gather the backtrace data for a pthread instead of a process. */

bool backtrace_create_thread_context(

    backtrace_context_t* context, pid_t tid, size_t num_ignore_frames);



/* Free any memory allocated during the context create. */

void backtrace_destroy_context(backtrace_context_t* context);



/* Read data at a specific address for a process. */

bool backtrace_read_word(

    const backtrace_t* backtrace, uintptr_t ptr, uint32_t* value);

    const backtrace_context_t* context, uintptr_t ptr, uint32_t* value);



/* Get information about the map associated with a pc. If NULL is

/* Get information about the map name associated with a pc. If NULL is

 * returned, then map_start is not set.

 */

const char* backtrace_get_map_info(

    const backtrace_t* backtrace, uintptr_t pc, uintptr_t* map_start);

const char* backtrace_get_map_name(

    const backtrace_context_t* context, uintptr_t pc, uintptr_t* map_start);



/* Get the procedure name and offest given the pc. If NULL is returned,

 * then proc_offset is not set. The returned string is allocated using

/* Get the function name and offset given the pc. If NULL is returned,

 * then func_offset is not set. The returned string is allocated using

 * malloc and must be freed by the caller.

 */

char* backtrace_get_proc_name(

    const backtrace_t* backtrace, uintptr_t pc, uintptr_t* proc_offset);

char* backtrace_get_func_name(

    const backtrace_context_t* context, uintptr_t pc, uintptr_t* func_offset);



/* Loads memory map from /proc/<tid>/maps. If tid < 0, then load the memory

/* Loads memory map from /proc/<pid>/maps. If pid < 0, then load the memory

 * map for the current process.

 */

backtrace_map_info_t* backtrace_create_map_info_list(pid_t tid);

backtrace_map_info_t* backtrace_create_map_info_list(pid_t pid);



/* Frees memory associated with the map list. */

void backtrace_destroy_map_info_list(backtrace_map_info_t* map_info_list);
@@ -95,10 +103,12 @@ const backtrace_map_info_t* backtrace_find_map_info( 


/* Create a formatted line of backtrace information for a single frame. */

void backtrace_format_frame_data(

    const backtrace_frame_data_t* frame, size_t frame_num, char *buf, size_t buf_size);

    const backtrace_context_t* context, size_t frame_num, char* buf,

    size_t buf_size);



/* Get the backtrace data structure associated with the context. */

const backtrace_t* backtrace_get_data(backtrace_context_t* context);



#ifdef __cplusplus

}

#endif

__END_DECLS



#endif /* _BACKTRACE_H */