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Christopher Ferrisdf290612014-01-22 19:21:07 -08001/*
2 * Copyright (C) 2014 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
Christopher Ferris2c43cff2015-03-26 19:18:36 -070017#include <stdint.h>
Dan Albertac2fe7e2014-05-21 18:21:02 -070018#include <stdlib.h>
Christopher Ferrisdf290612014-01-22 19:21:07 -080019#include <sys/types.h>
20#include <unistd.h>
21
22#include <backtrace/BacktraceMap.h>
23
24#include <libunwind.h>
25
Christopher Ferrise2960912014-03-07 19:42:19 -080026#include "BacktraceLog.h"
Christopher Ferrisdf290612014-01-22 19:21:07 -080027#include "UnwindMap.h"
28
29//-------------------------------------------------------------------------
30// libunwind has a single shared address space for the current process
31// aka local. If multiple maps are created for the current pid, then
32// only update the local address space once, and keep a reference count
33// of maps using the same map cursor.
34//-------------------------------------------------------------------------
Christopher Ferrisdf290612014-01-22 19:21:07 -080035UnwindMap::UnwindMap(pid_t pid) : BacktraceMap(pid) {
Christopher Ferrisdf290612014-01-22 19:21:07 -080036}
37
38UnwindMap::~UnwindMap() {
Christopher Ferrise2960912014-03-07 19:42:19 -080039 unw_map_cursor_destroy(&map_cursor_);
40 unw_map_cursor_clear(&map_cursor_);
Christopher Ferrisdf290612014-01-22 19:21:07 -080041}
42
Christopher Ferrise2960912014-03-07 19:42:19 -080043bool UnwindMap::GenerateMap() {
Christopher Ferrisdf290612014-01-22 19:21:07 -080044 // Use the map_cursor information to construct the BacktraceMap data
45 // rather than reparsing /proc/self/maps.
46 unw_map_cursor_reset(&map_cursor_);
Christopher Ferrise2960912014-03-07 19:42:19 -080047
Christopher Ferrisdf290612014-01-22 19:21:07 -080048 unw_map_t unw_map;
Christopher Ferrise2960912014-03-07 19:42:19 -080049 while (unw_map_cursor_get_next(&map_cursor_, &unw_map)) {
Christopher Ferrisdf290612014-01-22 19:21:07 -080050 backtrace_map_t map;
51
52 map.start = unw_map.start;
53 map.end = unw_map.end;
Christopher Ferris329ed7d2015-05-01 15:02:03 -070054 map.load_base = unw_map.load_base;
Christopher Ferrisdf290612014-01-22 19:21:07 -080055 map.flags = unw_map.flags;
56 map.name = unw_map.path;
57
58 // The maps are in descending order, but we want them in ascending order.
59 maps_.push_front(map);
60 }
61
62 return true;
63}
64
Christopher Ferrise2960912014-03-07 19:42:19 -080065bool UnwindMap::Build() {
66 return (unw_map_cursor_create(&map_cursor_, pid_) == 0) && GenerateMap();
67}
68
69UnwindMapLocal::UnwindMapLocal() : UnwindMap(getpid()), map_created_(false) {
70}
71
72UnwindMapLocal::~UnwindMapLocal() {
73 if (map_created_) {
74 unw_map_local_destroy();
75 unw_map_cursor_clear(&map_cursor_);
76 }
77}
78
79bool UnwindMapLocal::GenerateMap() {
80 // It's possible for the map to be regenerated while this loop is occurring.
81 // If that happens, get the map again, but only try at most three times
82 // before giving up.
83 for (int i = 0; i < 3; i++) {
84 maps_.clear();
85
86 unw_map_local_cursor_get(&map_cursor_);
87
88 unw_map_t unw_map;
89 int ret;
90 while ((ret = unw_map_local_cursor_get_next(&map_cursor_, &unw_map)) > 0) {
91 backtrace_map_t map;
92
93 map.start = unw_map.start;
94 map.end = unw_map.end;
Christopher Ferris329ed7d2015-05-01 15:02:03 -070095 map.load_base = unw_map.load_base;
Christopher Ferrise2960912014-03-07 19:42:19 -080096 map.flags = unw_map.flags;
97 map.name = unw_map.path;
98
99 free(unw_map.path);
100
101 // The maps are in descending order, but we want them in ascending order.
102 maps_.push_front(map);
103 }
104 // Check to see if the map changed while getting the data.
105 if (ret != -UNW_EINVAL) {
106 return true;
107 }
108 }
109
110 BACK_LOGW("Unable to generate the map.");
111 return false;
112}
113
114bool UnwindMapLocal::Build() {
115 return (map_created_ = (unw_map_local_create() == 0)) && GenerateMap();;
116}
117
Christopher Ferris12385e32015-02-06 13:22:01 -0800118void UnwindMapLocal::FillIn(uintptr_t addr, backtrace_map_t* map) {
119 BacktraceMap::FillIn(addr, map);
120 if (!IsValid(*map)) {
Christopher Ferrise2960912014-03-07 19:42:19 -0800121 // Check to see if the underlying map changed and regenerate the map
122 // if it did.
123 if (unw_map_local_cursor_valid(&map_cursor_) < 0) {
124 if (GenerateMap()) {
Christopher Ferris12385e32015-02-06 13:22:01 -0800125 BacktraceMap::FillIn(addr, map);
Christopher Ferrise2960912014-03-07 19:42:19 -0800126 }
127 }
128 }
Christopher Ferrise2960912014-03-07 19:42:19 -0800129}
130
Christopher Ferrisdf290612014-01-22 19:21:07 -0800131//-------------------------------------------------------------------------
132// BacktraceMap create function.
133//-------------------------------------------------------------------------
Christopher Ferrisdda47b72014-08-04 17:08:46 -0700134BacktraceMap* BacktraceMap::Create(pid_t pid, bool uncached) {
Christopher Ferrise2960912014-03-07 19:42:19 -0800135 BacktraceMap* map;
Christopher Ferrisdda47b72014-08-04 17:08:46 -0700136
137 if (uncached) {
138 // Force use of the base class to parse the maps when this call is made.
139 map = new BacktraceMap(pid);
140 } else if (pid == getpid()) {
Christopher Ferrise2960912014-03-07 19:42:19 -0800141 map = new UnwindMapLocal();
142 } else {
143 map = new UnwindMap(pid);
144 }
Christopher Ferrisdf290612014-01-22 19:21:07 -0800145 if (!map->Build()) {
146 delete map;
Christopher Ferris2c43cff2015-03-26 19:18:36 -0700147 return nullptr;
Christopher Ferrisdf290612014-01-22 19:21:07 -0800148 }
149 return map;
150}