1 /*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <stdint.h>
18 #include <ucontext.h>
19
20 #include <memory>
21 #include <string>
22
23 #define UNW_LOCAL_ONLY
24 #include <libunwind.h>
25
26 #include <backtrace/Backtrace.h>
27
28 #include "BacktraceLog.h"
29 #include "UnwindCurrent.h"
30
GetFunctionNameRaw(uintptr_t pc,uintptr_t * offset)31 std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
32 *offset = 0;
33 char buf[512];
34 unw_word_t value;
35 if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
36 &value, &context_) >= 0 && buf[0] != '\0') {
37 *offset = static_cast<uintptr_t>(value);
38 return buf;
39 }
40 return "";
41 }
42
GetUnwContextFromUcontext(const ucontext_t * ucontext)43 void UnwindCurrent::GetUnwContextFromUcontext(const ucontext_t* ucontext) {
44 unw_tdep_context_t* unw_context = reinterpret_cast<unw_tdep_context_t*>(&context_);
45
46 #if defined(__arm__)
47 unw_context->regs[0] = ucontext->uc_mcontext.arm_r0;
48 unw_context->regs[1] = ucontext->uc_mcontext.arm_r1;
49 unw_context->regs[2] = ucontext->uc_mcontext.arm_r2;
50 unw_context->regs[3] = ucontext->uc_mcontext.arm_r3;
51 unw_context->regs[4] = ucontext->uc_mcontext.arm_r4;
52 unw_context->regs[5] = ucontext->uc_mcontext.arm_r5;
53 unw_context->regs[6] = ucontext->uc_mcontext.arm_r6;
54 unw_context->regs[7] = ucontext->uc_mcontext.arm_r7;
55 unw_context->regs[8] = ucontext->uc_mcontext.arm_r8;
56 unw_context->regs[9] = ucontext->uc_mcontext.arm_r9;
57 unw_context->regs[10] = ucontext->uc_mcontext.arm_r10;
58 unw_context->regs[11] = ucontext->uc_mcontext.arm_fp;
59 unw_context->regs[12] = ucontext->uc_mcontext.arm_ip;
60 unw_context->regs[13] = ucontext->uc_mcontext.arm_sp;
61 unw_context->regs[14] = ucontext->uc_mcontext.arm_lr;
62 unw_context->regs[15] = ucontext->uc_mcontext.arm_pc;
63 #else
64 unw_context->uc_mcontext = ucontext->uc_mcontext;
65 #endif
66 }
67
UnwindFromContext(size_t num_ignore_frames,ucontext_t * ucontext)68 bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* ucontext) {
69 if (ucontext == nullptr) {
70 int ret = unw_getcontext(&context_);
71 if (ret < 0) {
72 BACK_LOGW("unw_getcontext failed %d", ret);
73 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
74 return false;
75 }
76 } else {
77 GetUnwContextFromUcontext(ucontext);
78 }
79
80 // The cursor structure is pretty large, do not put it on the stack.
81 std::unique_ptr<unw_cursor_t> cursor(new unw_cursor_t);
82 int ret = unw_init_local(cursor.get(), &context_);
83 if (ret < 0) {
84 BACK_LOGW("unw_init_local failed %d", ret);
85 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
86 return false;
87 }
88
89 size_t num_frames = 0;
90 do {
91 unw_word_t pc;
92 ret = unw_get_reg(cursor.get(), UNW_REG_IP, &pc);
93 if (ret < 0) {
94 BACK_LOGW("Failed to read IP %d", ret);
95 break;
96 }
97 unw_word_t sp;
98 ret = unw_get_reg(cursor.get(), UNW_REG_SP, &sp);
99 if (ret < 0) {
100 BACK_LOGW("Failed to read SP %d", ret);
101 break;
102 }
103
104 frames_.resize(num_frames+1);
105 backtrace_frame_data_t* frame = &frames_.at(num_frames);
106 frame->num = num_frames;
107 frame->pc = static_cast<uintptr_t>(pc);
108 frame->sp = static_cast<uintptr_t>(sp);
109 frame->stack_size = 0;
110
111 FillInMap(frame->pc, &frame->map);
112 // Check to see if we should skip this frame because it's coming
113 // from within the library, and we are doing a local unwind.
114 if (ucontext != nullptr || num_frames != 0 || !DiscardFrame(*frame)) {
115 if (num_ignore_frames == 0) {
116 // GetFunctionName is an expensive call, only do it if we are
117 // keeping the frame.
118 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
119 if (num_frames > 0) {
120 // Set the stack size for the previous frame.
121 backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
122 prev->stack_size = frame->sp - prev->sp;
123 }
124 num_frames++;
125 } else {
126 num_ignore_frames--;
127 }
128 }
129 ret = unw_step (cursor.get());
130 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
131
132 return true;
133 }
134