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      1 // Copyright (c) 2005, Google Inc.
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are
      6 // met:
      7 //
      8 //     * Redistributions of source code must retain the above copyright
      9 // notice, this list of conditions and the following disclaimer.
     10 //     * Redistributions in binary form must reproduce the above
     11 // copyright notice, this list of conditions and the following disclaimer
     12 // in the documentation and/or other materials provided with the
     13 // distribution.
     14 //     * Neither the name of Google Inc. nor the names of its
     15 // contributors may be used to endorse or promote products derived from
     16 // this software without specific prior written permission.
     17 //
     18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 
     30 // ---
     31 // Author: Arun Sharma
     32 //
     33 // Produce stack trace using libunwind
     34 
     35 #ifndef BASE_STACKTRACE_LIBINWIND_INL_H_
     36 #define BASE_STACKTRACE_LIBINWIND_INL_H_
     37 // Note: this file is included into stacktrace.cc more than once.
     38 // Anything that should only be defined once should be here:
     39 
     40 // We only need local unwinder.
     41 #define UNW_LOCAL_ONLY
     42 
     43 extern "C" {
     44 #include <assert.h>
     45 #include <string.h>   // for memset()
     46 #include <libunwind.h>
     47 }
     48 #include "gperftools/stacktrace.h"
     49 #include "base/logging.h"
     50 
     51 // Sometimes, we can try to get a stack trace from within a stack
     52 // trace, because libunwind can call mmap (maybe indirectly via an
     53 // internal mmap based memory allocator), and that mmap gets trapped
     54 // and causes a stack-trace request.  If were to try to honor that
     55 // recursive request, we'd end up with infinite recursion or deadlock.
     56 // Luckily, it's safe to ignore those subsequent traces.  In such
     57 // cases, we return 0 to indicate the situation.
     58 static __thread int recursive;
     59 
     60 #endif  // BASE_STACKTRACE_LIBINWIND_INL_H_
     61 
     62 // Note: this part of the file is included several times.
     63 // Do not put globals below.
     64 
     65 // The following 4 functions are generated from the code below:
     66 //   GetStack{Trace,Frames}()
     67 //   GetStack{Trace,Frames}WithContext()
     68 //
     69 // These functions take the following args:
     70 //   void** result: the stack-trace, as an array
     71 //   int* sizes: the size of each stack frame, as an array
     72 //               (GetStackFrames* only)
     73 //   int max_depth: the size of the result (and sizes) array(s)
     74 //   int skip_count: how many stack pointers to skip before storing in result
     75 //   void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
     76 int GET_STACK_TRACE_OR_FRAMES {
     77   void *ip;
     78   int n = 0;
     79   unw_cursor_t cursor;
     80   unw_context_t uc;
     81 #if IS_STACK_FRAMES
     82   unw_word_t sp = 0, next_sp = 0;
     83 #endif
     84 
     85   if (recursive) {
     86     return 0;
     87   }
     88   ++recursive;
     89 
     90   unw_getcontext(&uc);
     91   int ret = unw_init_local(&cursor, &uc);
     92   assert(ret >= 0);
     93   skip_count++;         // Do not include current frame
     94 
     95   while (skip_count--) {
     96     if (unw_step(&cursor) <= 0) {
     97       goto out;
     98     }
     99 #if IS_STACK_FRAMES
    100     if (unw_get_reg(&cursor, UNW_REG_SP, &next_sp)) {
    101       goto out;
    102     }
    103 #endif
    104   }
    105 
    106   while (n < max_depth) {
    107     if (unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip) < 0) {
    108       break;
    109     }
    110 #if IS_STACK_FRAMES
    111     sizes[n] = 0;
    112 #endif
    113     result[n++] = ip;
    114     if (unw_step(&cursor) <= 0) {
    115       break;
    116     }
    117 #if IS_STACK_FRAMES
    118     sp = next_sp;
    119     if (unw_get_reg(&cursor, UNW_REG_SP, &next_sp) , 0) {
    120       break;
    121     }
    122     sizes[n - 1] = next_sp - sp;
    123 #endif
    124   }
    125 out:
    126   --recursive;
    127   return n;
    128 }
    129