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 return false;
54 }
55
56 if (ucontext) {
57 BACK_LOGW("Unwinding from a specified context not supported yet.");
58 return false;
59 }
60
61 addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
62 if (!addr_space_) {
63 BACK_LOGW("unw_create_addr_space failed.");
64 return false;
65 }
66
67 UnwindMap* map = static_cast<UnwindMap*>(GetMap());
68 unw_map_set(addr_space_, map->GetMapCursor());
69
70 upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
71 if (!upt_info_) {
72 BACK_LOGW("Failed to create upt info.");
73 return false;
74 }
75
76 unw_cursor_t cursor;
77 int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
78 if (ret < 0) {
79 BACK_LOGW("unw_init_remote failed %d", ret);
80 return false;
81 }
82
83 size_t num_frames = 0;
84 do {
85 unw_word_t pc;
86 ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
87 if (ret < 0) {
88 BACK_LOGW("Failed to read IP %d", ret);
89 break;
90 }
91 unw_word_t sp;
92 ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
93 if (ret < 0) {
94 BACK_LOGW("Failed to read SP %d", ret);
95 break;
96 }
97
98 if (num_ignore_frames == 0) {
99 frames_.resize(num_frames+1);
100 backtrace_frame_data_t* frame = &frames_.at(num_frames);
101 frame->num = num_frames;
102 frame->pc = static_cast<uintptr_t>(pc);
103 frame->sp = static_cast<uintptr_t>(sp);
104 frame->stack_size = 0;
105
106 if (num_frames > 0) {
107 backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
108 prev->stack_size = frame->sp - prev->sp;
109 }
110
111 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
112
113 FillInMap(frame->pc, &frame->map);
114
115 num_frames++;
116 } else {
117 num_ignore_frames--;
118 }
119 ret = unw_step (&cursor);
120 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
121
122 return true;
123 }
124
GetFunctionNameRaw(uintptr_t pc,uintptr_t * offset)125 std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
126 *offset = 0;
127 char buf[512];
128 unw_word_t value;
129 if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
130 upt_info_) >= 0 && buf[0] != '\0') {
131 *offset = static_cast<uintptr_t>(value);
132 return buf;
133 }
134 return "";
135 }
136