1 /*
2 * Copyright (C) 2011 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 #define LOG_TAG "Corkscrew"
18 //#define LOG_NDEBUG 0
19
20 #include "ptrace-arch.h"
21 #include <corkscrew/ptrace.h>
22
23 #include <errno.h>
24 #include <sys/ptrace.h>
25 #include <cutils/log.h>
26
27 static const uint32_t ELF_MAGIC = 0x464C457f; // "ELF\0177"
28
29 #ifndef PAGE_SIZE
30 #define PAGE_SIZE 4096
31 #endif
32
33 #ifndef PAGE_MASK
34 #define PAGE_MASK (~(PAGE_SIZE - 1))
35 #endif
36
init_memory(memory_t * memory,const map_info_t * map_info_list)37 void init_memory(memory_t* memory, const map_info_t* map_info_list) {
38 memory->tid = -1;
39 memory->map_info_list = map_info_list;
40 }
41
init_memory_ptrace(memory_t * memory,pid_t tid)42 void init_memory_ptrace(memory_t* memory, pid_t tid) {
43 memory->tid = tid;
44 memory->map_info_list = NULL;
45 }
46
try_get_word(const memory_t * memory,uintptr_t ptr,uint32_t * out_value)47 bool try_get_word(const memory_t* memory, uintptr_t ptr, uint32_t* out_value) {
48 ALOGV("try_get_word: reading word at 0x%08x", ptr);
49 if (ptr & 3) {
50 ALOGV("try_get_word: invalid pointer 0x%08x", ptr);
51 *out_value = 0xffffffffL;
52 return false;
53 }
54 if (memory->tid < 0) {
55 if (!is_readable_map(memory->map_info_list, ptr)) {
56 ALOGV("try_get_word: pointer 0x%08x not in a readable map", ptr);
57 *out_value = 0xffffffffL;
58 return false;
59 }
60 *out_value = *(uint32_t*)ptr;
61 return true;
62 } else {
63 // ptrace() returns -1 and sets errno when the operation fails.
64 // To disambiguate -1 from a valid result, we clear errno beforehand.
65 errno = 0;
66 *out_value = ptrace(PTRACE_PEEKTEXT, memory->tid, (void*)ptr, NULL);
67 if (*out_value == 0xffffffffL && errno) {
68 ALOGV("try_get_word: invalid pointer 0x%08x reading from tid %d, "
69 "ptrace() errno=%d", ptr, memory->tid, errno);
70 return false;
71 }
72 return true;
73 }
74 }
75
try_get_word_ptrace(pid_t tid,uintptr_t ptr,uint32_t * out_value)76 bool try_get_word_ptrace(pid_t tid, uintptr_t ptr, uint32_t* out_value) {
77 memory_t memory;
78 init_memory_ptrace(&memory, tid);
79 return try_get_word(&memory, ptr, out_value);
80 }
81
load_ptrace_map_info_data(pid_t pid,map_info_t * mi)82 static void load_ptrace_map_info_data(pid_t pid, map_info_t* mi) {
83 if (mi->is_executable && mi->is_readable) {
84 uint32_t elf_magic;
85 if (try_get_word_ptrace(pid, mi->start, &elf_magic) && elf_magic == ELF_MAGIC) {
86 map_info_data_t* data = (map_info_data_t*)calloc(1, sizeof(map_info_data_t));
87 if (data) {
88 mi->data = data;
89 if (mi->name[0]) {
90 data->symbol_table = load_symbol_table(mi->name);
91 }
92 #ifdef CORKSCREW_HAVE_ARCH
93 load_ptrace_map_info_data_arch(pid, mi, data);
94 #endif
95 }
96 }
97 }
98 }
99
load_ptrace_context(pid_t pid)100 ptrace_context_t* load_ptrace_context(pid_t pid) {
101 ptrace_context_t* context =
102 (ptrace_context_t*)calloc(1, sizeof(ptrace_context_t));
103 if (context) {
104 context->map_info_list = load_map_info_list(pid);
105 for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
106 load_ptrace_map_info_data(pid, mi);
107 }
108 }
109 return context;
110 }
111
free_ptrace_map_info_data(map_info_t * mi)112 static void free_ptrace_map_info_data(map_info_t* mi) {
113 map_info_data_t* data = (map_info_data_t*)mi->data;
114 if (data) {
115 if (data->symbol_table) {
116 free_symbol_table(data->symbol_table);
117 }
118 #ifdef CORKSCREW_HAVE_ARCH
119 free_ptrace_map_info_data_arch(mi, data);
120 #endif
121 free(data);
122 mi->data = NULL;
123 }
124 }
125
free_ptrace_context(ptrace_context_t * context)126 void free_ptrace_context(ptrace_context_t* context) {
127 for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
128 free_ptrace_map_info_data(mi);
129 }
130 free_map_info_list(context->map_info_list);
131 }
132
find_symbol_ptrace(const ptrace_context_t * context,uintptr_t addr,const map_info_t ** out_map_info,const symbol_t ** out_symbol)133 void find_symbol_ptrace(const ptrace_context_t* context,
134 uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol) {
135 const map_info_t* mi = find_map_info(context->map_info_list, addr);
136 const symbol_t* symbol = NULL;
137 if (mi) {
138 const map_info_data_t* data = (const map_info_data_t*)mi->data;
139 if (data && data->symbol_table) {
140 symbol = find_symbol(data->symbol_table, addr - mi->start);
141 }
142 }
143 *out_map_info = mi;
144 *out_symbol = symbol;
145 }
146