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 <android-base/logging.h>
27 #include <backtrace/Backtrace.h>
28
29 #include "BacktraceLog.h"
30 #include "UnwindCurrent.h"
31
GetFunctionNameRaw(uintptr_t pc,uintptr_t * offset)32 std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
33 if (!initialized_) {
34 // If init local is not called, then trying to get a function name will
35 // fail, so try to initialize first.
36 std::unique_ptr<unw_cursor_t> cursor(new unw_cursor_t);
37 if (unw_init_local(cursor.get(), &context_) < 0) {
38 return "";
39 }
40 initialized_ = true;
41 }
42
43 *offset = 0;
44 char buf[512];
45 unw_word_t value;
46 if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
47 &value, &context_) >= 0 && buf[0] != '\0') {
48 *offset = static_cast<uintptr_t>(value);
49 return buf;
50 }
51 return "";
52 }
53
GetUnwContextFromUcontext(const ucontext_t * ucontext)54 void UnwindCurrent::GetUnwContextFromUcontext(const ucontext_t* ucontext) {
55 unw_tdep_context_t* unw_context = reinterpret_cast<unw_tdep_context_t*>(&context_);
56
57 #if defined(__arm__)
58 unw_context->regs[0] = ucontext->uc_mcontext.arm_r0;
59 unw_context->regs[1] = ucontext->uc_mcontext.arm_r1;
60 unw_context->regs[2] = ucontext->uc_mcontext.arm_r2;
61 unw_context->regs[3] = ucontext->uc_mcontext.arm_r3;
62 unw_context->regs[4] = ucontext->uc_mcontext.arm_r4;
63 unw_context->regs[5] = ucontext->uc_mcontext.arm_r5;
64 unw_context->regs[6] = ucontext->uc_mcontext.arm_r6;
65 unw_context->regs[7] = ucontext->uc_mcontext.arm_r7;
66 unw_context->regs[8] = ucontext->uc_mcontext.arm_r8;
67 unw_context->regs[9] = ucontext->uc_mcontext.arm_r9;
68 unw_context->regs[10] = ucontext->uc_mcontext.arm_r10;
69 unw_context->regs[11] = ucontext->uc_mcontext.arm_fp;
70 unw_context->regs[12] = ucontext->uc_mcontext.arm_ip;
71 unw_context->regs[13] = ucontext->uc_mcontext.arm_sp;
72 unw_context->regs[14] = ucontext->uc_mcontext.arm_lr;
73 unw_context->regs[15] = ucontext->uc_mcontext.arm_pc;
74 #else
75 unw_context->uc_mcontext = ucontext->uc_mcontext;
76 #endif
77 }
78
UnwindFromContext(size_t num_ignore_frames,ucontext_t * ucontext)79 bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* ucontext) {
80 if (ucontext == nullptr) {
81 int ret = unw_getcontext(&context_);
82 if (ret < 0) {
83 BACK_LOGW("unw_getcontext failed %d", ret);
84 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
85 return false;
86 }
87 } else {
88 GetUnwContextFromUcontext(ucontext);
89 }
90
91 // The cursor structure is pretty large, do not put it on the stack.
92 std::unique_ptr<unw_cursor_t> cursor(new unw_cursor_t);
93 int ret = unw_init_local(cursor.get(), &context_);
94 if (ret < 0) {
95 BACK_LOGW("unw_init_local failed %d", ret);
96 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
97 return false;
98 }
99 initialized_ = true;
100
101 size_t num_frames = 0;
102 do {
103 unw_word_t pc;
104 ret = unw_get_reg(cursor.get(), UNW_REG_IP, &pc);
105 if (ret < 0) {
106 BACK_LOGW("Failed to read IP %d", ret);
107 break;
108 }
109 unw_word_t sp;
110 ret = unw_get_reg(cursor.get(), UNW_REG_SP, &sp);
111 if (ret < 0) {
112 BACK_LOGW("Failed to read SP %d", ret);
113 break;
114 }
115
116 frames_.resize(num_frames+1);
117 backtrace_frame_data_t* frame = &frames_.at(num_frames);
118 frame->num = num_frames;
119 frame->pc = static_cast<uintptr_t>(pc);
120 frame->sp = static_cast<uintptr_t>(sp);
121 frame->stack_size = 0;
122
123 FillInMap(frame->pc, &frame->map);
124 // Check to see if we should skip this frame because it's coming
125 // from within the library, and we are doing a local unwind.
126 if (ucontext != nullptr || num_frames != 0 || !DiscardFrame(*frame)) {
127 if (num_ignore_frames == 0) {
128 // GetFunctionName is an expensive call, only do it if we are
129 // keeping the frame.
130 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset, &frame->map);
131 if (num_frames > 0) {
132 // Set the stack size for the previous frame.
133 backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
134 prev->stack_size = frame->sp - prev->sp;
135 }
136 num_frames++;
137 } else {
138 num_ignore_frames--;
139 // Set the number of frames to zero to remove the frame added
140 // above. By definition, if we still have frames to ignore
141 // there should only be one frame in the vector.
142 CHECK(num_frames == 0);
143 frames_.resize(0);
144 }
145 }
146 // If the pc is in a device map, then don't try to step.
147 if (frame->map.flags & PROT_DEVICE_MAP) {
148 break;
149 }
150 // Verify the sp is not in a device map too.
151 backtrace_map_t map;
152 FillInMap(frame->sp, &map);
153 if (map.flags & PROT_DEVICE_MAP) {
154 break;
155 }
156 ret = unw_step (cursor.get());
157 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
158
159 return true;
160 }
161