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 <sys/types.h>
19 #include <ucontext.h>
20
21 #include <libunwind.h>
22 #include <libunwind-ptrace.h>
23
24 #include <backtrace/Backtrace.h>
25 #include <backtrace/BacktraceMap.h>
26
27 #include "BacktraceLog.h"
28 #include "UnwindMap.h"
29 #include "UnwindPtrace.h"
30
UnwindPtrace(pid_t pid,pid_t tid,BacktraceMap * map)31 UnwindPtrace::UnwindPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
32 : BacktracePtrace(pid, tid, map), addr_space_(nullptr), upt_info_(nullptr) {
33 }
34
~UnwindPtrace()35 UnwindPtrace::~UnwindPtrace() {
36 if (upt_info_) {
37 _UPT_destroy(upt_info_);
38 upt_info_ = nullptr;
39 }
40 if (addr_space_) {
41 // Remove the map from the address space before destroying it.
42 // It will be freed in the UnwindMap destructor.
43 unw_map_set(addr_space_, nullptr);
44
45 unw_destroy_addr_space(addr_space_);
46 addr_space_ = nullptr;
47 }
48 }
49
Unwind(size_t num_ignore_frames,ucontext_t * ucontext)50 bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
51 if (GetMap() == nullptr) {
52 // Without a map object, we can't do anything.
53 error_ = BACKTRACE_UNWIND_ERROR_MAP_MISSING;
54 return false;
55 }
56
57 error_ = BACKTRACE_UNWIND_NO_ERROR;
58
59 if (ucontext) {
60 BACK_LOGW("Unwinding from a specified context not supported yet.");
61 error_ = BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION;
62 return false;
63 }
64
65 addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
66 if (!addr_space_) {
67 BACK_LOGW("unw_create_addr_space failed.");
68 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
69 return false;
70 }
71
72 UnwindMap* map = static_cast<UnwindMap*>(GetMap());
73 unw_map_set(addr_space_, map->GetMapCursor());
74
75 upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
76 if (!upt_info_) {
77 BACK_LOGW("Failed to create upt info.");
78 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
79 return false;
80 }
81
82 unw_cursor_t cursor;
83 int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
84 if (ret < 0) {
85 BACK_LOGW("unw_init_remote failed %d", ret);
86 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
87 return false;
88 }
89
90 size_t num_frames = 0;
91 do {
92 unw_word_t pc;
93 ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
94 if (ret < 0) {
95 BACK_LOGW("Failed to read IP %d", ret);
96 break;
97 }
98 unw_word_t sp;
99 ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
100 if (ret < 0) {
101 BACK_LOGW("Failed to read SP %d", ret);
102 break;
103 }
104
105 if (num_ignore_frames == 0) {
106 frames_.resize(num_frames+1);
107 backtrace_frame_data_t* frame = &frames_.at(num_frames);
108 frame->num = num_frames;
109 frame->pc = static_cast<uintptr_t>(pc);
110 frame->sp = static_cast<uintptr_t>(sp);
111 frame->stack_size = 0;
112
113 if (num_frames > 0) {
114 backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
115 prev->stack_size = frame->sp - prev->sp;
116 }
117
118 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
119
120 FillInMap(frame->pc, &frame->map);
121
122 num_frames++;
123 } else {
124 num_ignore_frames--;
125 }
126 ret = unw_step (&cursor);
127 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
128
129 return true;
130 }
131
GetFunctionNameRaw(uintptr_t pc,uintptr_t * offset)132 std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
133 *offset = 0;
134 char buf[512];
135 unw_word_t value;
136 if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
137 upt_info_) >= 0 && buf[0] != '\0') {
138 *offset = static_cast<uintptr_t>(value);
139 return buf;
140 }
141 return "";
142 }
143