1// Copyright (c) 2013, 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: Marcus Bulach
32// This is inspired by Doug Kwan's ARM's stacktrace code and Dai Mikurube's
33// stack trace for chromium on android.
34//
35
36#ifndef BASE_STACKTRACE_ANDROID_INL_H_
37#define BASE_STACKTRACE_ANDROID_INL_H_
38// Note: this file is included into stacktrace.cc more than once.
39// Anything that should only be defined once should be here:
40
41#include <stdint.h>   // for uintptr_t
42// See http://crbug.com/236855, would be better to use Bionic's
43// new get_backtrace().
44#include <unwind.h>
45
46/* Depends on the system definition for _Unwind_Context */
47#ifdef HAVE_UNWIND_CONTEXT_STRUCT
48typedef struct _Unwind_Context __unwind_context;
49#else
50typedef _Unwind_Context __unwind_context;
51#endif
52
53struct stack_crawl_state_t {
54  uintptr_t* frames;
55  size_t frame_count;
56  int max_depth;
57  int skip_count;
58  bool have_skipped_self;
59
60  stack_crawl_state_t(uintptr_t* frames, int max_depth, int skip_count)
61      : frames(frames),
62        frame_count(0),
63        max_depth(max_depth),
64        skip_count(skip_count),
65        have_skipped_self(false) {
66  }
67};
68
69static _Unwind_Reason_Code tracer(__unwind_context* context, void* arg) {
70  stack_crawl_state_t* state = static_cast<stack_crawl_state_t*>(arg);
71
72#if defined(__clang__)
73  // Vanilla Clang's unwind.h doesn't have _Unwind_GetIP for ARM.
74  // See http://crbug.com/236855, too.
75  uintptr_t ip = 0;
76  _Unwind_VRS_Get(context, _UVRSC_CORE, 15, _UVRSD_UINT32, &ip);
77  ip &= ~(uintptr_t)0x1;  // remove thumb mode bit
78#else
79  uintptr_t ip = _Unwind_GetIP(context);
80#endif
81
82  // The first stack frame is this function itself.  Skip it.
83  if (ip != 0 && !state->have_skipped_self) {
84    state->have_skipped_self = true;
85    return _URC_NO_REASON;
86  }
87
88  if (state->skip_count) {
89    --state->skip_count;
90    return _URC_NO_REASON;
91  }
92
93  state->frames[state->frame_count++] = ip;
94  if (state->frame_count >= state->max_depth)
95    return _URC_END_OF_STACK;
96  else
97    return _URC_NO_REASON;
98}
99
100#endif  // BASE_STACKTRACE_ANDROID_INL_H_
101
102// Note: this part of the file is included several times.
103// Do not put globals below.
104
105// The following 4 functions are generated from the code below:
106//   GetStack{Trace,Frames}()
107//   GetStack{Trace,Frames}WithContext()
108//
109// These functions take the following args:
110//   void** result: the stack-trace, as an array
111//   int* sizes: the size of each stack frame, as an array
112//               (GetStackFrames* only)
113//   int max_depth: the size of the result (and sizes) array(s)
114//   int skip_count: how many stack pointers to skip before storing in result
115//   void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
116int GET_STACK_TRACE_OR_FRAMES {
117  stack_crawl_state_t state(
118      reinterpret_cast<uintptr_t*>(result), max_depth, skip_count);
119  _Unwind_Backtrace(tracer, &state);
120  return state.frame_count;
121}
122