1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
/*
* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
* Copyright (c) 2013-2021 The strace developers.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*/
#include "defs.h"
#include <limits.h>
#include "largefile_wrappers.h"
#include "mmap_cache.h"
#include "mmap_notify.h"
#include "xstring.h"
static unsigned int mmap_cache_generation;
static void
mmap_cache_invalidate(struct tcb *tcp, void *unused)
{
mmap_cache_generation++;
debug_func_msg("tgen=%u, ggen=%u, tcp=%p, cache=%p",
tcp->mmap_cache ? tcp->mmap_cache->generation : 0,
mmap_cache_generation, tcp,
tcp->mmap_cache ? tcp->mmap_cache->entry : 0);
}
void
mmap_cache_enable(void)
{
static bool use_mmap_cache;
if (!use_mmap_cache) {
mmap_notify_register_client(mmap_cache_invalidate, NULL);
use_mmap_cache = true;
}
}
/* deleting the cache */
static void
delete_mmap_cache(struct tcb *tcp, const char *caller)
{
debug_func_msg("tgen=%u, ggen=%u, tcp=%p, cache=%p, caller=%s",
tcp->mmap_cache ? tcp->mmap_cache->generation : 0,
mmap_cache_generation, tcp,
tcp->mmap_cache ? tcp->mmap_cache->entry : 0, caller);
if (!tcp->mmap_cache)
return;
while (tcp->mmap_cache->size) {
unsigned int i = --tcp->mmap_cache->size;
free(tcp->mmap_cache->entry[i].binary_filename);
tcp->mmap_cache->entry[i].binary_filename = NULL;
}
free(tcp->mmap_cache->entry);
tcp->mmap_cache->entry = NULL;
free(tcp->mmap_cache);
tcp->mmap_cache = NULL;
}
/*
* caching of /proc/ID/maps for each process to speed up stack tracing
*
* The cache must be refreshed after syscalls that affect memory mappings,
* e.g. mmap, mprotect, munmap, execve.
*/
extern enum mmap_cache_rebuild_result
mmap_cache_rebuild_if_invalid(struct tcb *tcp, const char *caller)
{
if (tcp->mmap_cache
&& tcp->mmap_cache->generation != mmap_cache_generation)
delete_mmap_cache(tcp, caller);
if (tcp->mmap_cache)
return MMAP_CACHE_REBUILD_READY;
char filename[sizeof("/proc/4294967296/maps")];
xsprintf(filename, "/proc/%u/maps", get_proc_pid(tcp->pid));
FILE *fp = fopen_stream(filename, "r");
if (!fp) {
perror_msg("fopen: %s", filename);
return MMAP_CACHE_REBUILD_NOCACHE;
}
struct mmap_cache_t cache = {
.free_fn = delete_mmap_cache,
.generation = mmap_cache_generation
};
/* start with a small dynamically-allocated array and then expand it */
size_t allocated = 0;
char buffer[PATH_MAX + 80];
while (fgets(buffer, sizeof(buffer), fp) != NULL) {
unsigned long start_addr, end_addr, mmap_offset;
char read_bit;
char write_bit;
char exec_bit;
char shared_bit;
unsigned long major, minor;
char binary_path[sizeof(buffer)];
if (sscanf(buffer, "%lx-%lx %c%c%c%c %lx %lx:%lx %*d %[^\n]",
&start_addr, &end_addr,
&read_bit, &write_bit, &exec_bit, &shared_bit,
&mmap_offset,
&major, &minor,
binary_path) != 10)
continue;
/* skip mappings that have unknown protection */
if (!(read_bit == '-' || read_bit == 'r'))
continue;
if (!(write_bit == '-' || write_bit == 'w'))
continue;
if (!(exec_bit == '-' || exec_bit == 'x'))
continue;
if (!(shared_bit == 'p' || shared_bit == 's'))
continue;
if (end_addr < start_addr) {
error_msg("%s: unrecognized file format", filename);
break;
}
struct mmap_cache_entry_t *entry;
/*
* sanity check to make sure that we're storing
* non-overlapping regions in ascending order
*/
if (cache.size > 0) {
entry = &cache.entry[cache.size - 1];
if (entry->start_addr == start_addr &&
entry->end_addr == end_addr) {
/* duplicate entry, e.g. [vsyscall] */
continue;
}
if (start_addr <= entry->start_addr ||
start_addr < entry->end_addr) {
debug_msg("%s: overlapping memory region: "
"\"%s\" [%08lx-%08lx] overlaps with "
"\"%s\" [%08lx-%08lx]",
filename, binary_path, start_addr,
end_addr, entry->binary_filename,
entry->start_addr, entry->end_addr);
continue;
}
}
if (cache.size >= allocated)
cache.entry = xgrowarray(cache.entry, &allocated,
sizeof(*cache.entry));
entry = &cache.entry[cache.size];
entry->start_addr = start_addr;
entry->end_addr = end_addr;
entry->mmap_offset = mmap_offset;
entry->protections = (
0
| ((read_bit == 'r')? MMAP_CACHE_PROT_READABLE : 0)
| ((write_bit == 'w')? MMAP_CACHE_PROT_WRITABLE : 0)
| ((exec_bit == 'x')? MMAP_CACHE_PROT_EXECUTABLE: 0)
| ((shared_bit == 's')? MMAP_CACHE_PROT_SHARED : 0)
);
entry->major = major;
entry->minor = minor;
entry->binary_filename = xstrdup(binary_path);
cache.size++;
}
fclose(fp);
if (!cache.size)
return MMAP_CACHE_REBUILD_NOCACHE;
tcp->mmap_cache = xobjdup(&cache);
debug_func_msg("tgen=%u, ggen=%u, tcp=%p, cache=%p, caller=%s",
tcp->mmap_cache->generation, mmap_cache_generation,
tcp, tcp->mmap_cache->entry, caller);
return MMAP_CACHE_REBUILD_RENEWED;
}
struct mmap_cache_entry_t *
mmap_cache_search(struct tcb *tcp, unsigned long ip)
{
if (!tcp->mmap_cache)
return NULL;
int lower = 0;
int upper = (int) tcp->mmap_cache->size - 1;
while (lower <= upper) {
int mid = (upper + lower) / 2;
struct mmap_cache_entry_t *entry = &tcp->mmap_cache->entry[mid];
if (ip >= entry->start_addr &&
ip < entry->end_addr)
return entry;
else if (ip < entry->start_addr)
upper = mid - 1;
else
lower = mid + 1;
}
return NULL;
}
struct mmap_cache_entry_t *
mmap_cache_search_custom(struct tcb *tcp, mmap_cache_search_fn fn, void *data)
{
for (unsigned int i = 0; i < tcp->mmap_cache->size; i++) {
if (fn(tcp->mmap_cache->entry + i, data))
return tcp->mmap_cache->entry + i;
}
return NULL;
}
|
