1#include "dso.h"
2#include "symbol.h"
3#include "symsrc.h"
4
5#include <errno.h>
6#include <unistd.h>
7#include <fcntl.h>
8#include <string.h>
9#include <stdlib.h>
10#include <byteswap.h>
11#include <sys/stat.h>
12#include <linux/zalloc.h>
13#include <internal/lib.h>
14
15static bool check_need_swap(int file_endian)
16{
17 const int data = 1;
18 u8 *check = (u8 *)&data;
19 int host_endian;
20
21 if (check[0] == 1)
22 host_endian = ELFDATA2LSB;
23 else
24 host_endian = ELFDATA2MSB;
25
26 return host_endian != file_endian;
27}
28
29#define NOTE_ALIGN(sz) (((sz) + 3) & ~3)
30
31#define NT_GNU_BUILD_ID 3
32
33static int read_build_id(void *note_data, size_t note_len, struct build_id *bid,
34 bool need_swap)
35{
36 size_t size = sizeof(bid->data);
37 struct {
38 u32 n_namesz;
39 u32 n_descsz;
40 u32 n_type;
41 } *nhdr;
42 void *ptr;
43
44 ptr = note_data;
45 while ((ptr + sizeof(*nhdr)) < (note_data + note_len)) {
46 const char *name;
47 size_t namesz, descsz;
48
49 nhdr = ptr;
50 if (need_swap) {
51 nhdr->n_namesz = bswap_32(nhdr->n_namesz);
52 nhdr->n_descsz = bswap_32(nhdr->n_descsz);
53 nhdr->n_type = bswap_32(nhdr->n_type);
54 }
55
56 namesz = NOTE_ALIGN(nhdr->n_namesz);
57 descsz = NOTE_ALIGN(nhdr->n_descsz);
58
59 ptr += sizeof(*nhdr);
60 name = ptr;
61 ptr += namesz;
62 if (nhdr->n_type == NT_GNU_BUILD_ID &&
63 nhdr->n_namesz == sizeof("GNU")) {
64 if (memcmp(p: name, q: "GNU", size: sizeof("GNU")) == 0) {
65 size_t sz = min(size, descsz);
66 memcpy(bid->data, ptr, sz);
67 memset(bid->data + sz, 0, size - sz);
68 bid->size = sz;
69 return 0;
70 }
71 }
72 ptr += descsz;
73 }
74
75 return -1;
76}
77
78int filename__read_debuglink(const char *filename __maybe_unused,
79 char *debuglink __maybe_unused,
80 size_t size __maybe_unused)
81{
82 return -1;
83}
84
85/*
86 * Just try PT_NOTE header otherwise fails
87 */
88int filename__read_build_id(const char *filename, struct build_id *bid)
89{
90 int fd, ret = -1;
91 bool need_swap = false, elf32;
92 union {
93 struct {
94 Elf32_Ehdr ehdr32;
95 Elf32_Phdr *phdr32;
96 };
97 struct {
98 Elf64_Ehdr ehdr64;
99 Elf64_Phdr *phdr64;
100 };
101 } hdrs;
102 void *phdr, *buf = NULL;
103 ssize_t phdr_size, ehdr_size, buf_size = 0;
104
105 if (!filename)
106 return -EFAULT;
107
108 errno = 0;
109 if (!is_regular_file(file: filename))
110 return errno == 0 ? -EWOULDBLOCK : -errno;
111
112 fd = open(filename, O_RDONLY);
113 if (fd < 0)
114 return -1;
115
116 if (read(fd, hdrs.ehdr32.e_ident, EI_NIDENT) != EI_NIDENT)
117 goto out;
118
119 if (memcmp(hdrs.ehdr32.e_ident, ELFMAG, SELFMAG) ||
120 hdrs.ehdr32.e_ident[EI_VERSION] != EV_CURRENT)
121 goto out;
122
123 need_swap = check_need_swap(hdrs.ehdr32.e_ident[EI_DATA]);
124 elf32 = hdrs.ehdr32.e_ident[EI_CLASS] == ELFCLASS32;
125 ehdr_size = (elf32 ? sizeof(hdrs.ehdr32) : sizeof(hdrs.ehdr64)) - EI_NIDENT;
126
127 if (read(fd,
128 (elf32 ? (void *)&hdrs.ehdr32 : (void *)&hdrs.ehdr64) + EI_NIDENT,
129 ehdr_size) != ehdr_size)
130 goto out;
131
132 if (need_swap) {
133 if (elf32) {
134 hdrs.ehdr32.e_phoff = bswap_32(hdrs.ehdr32.e_phoff);
135 hdrs.ehdr32.e_phentsize = bswap_16(hdrs.ehdr32.e_phentsize);
136 hdrs.ehdr32.e_phnum = bswap_16(hdrs.ehdr32.e_phnum);
137 } else {
138 hdrs.ehdr64.e_phoff = bswap_64(hdrs.ehdr64.e_phoff);
139 hdrs.ehdr64.e_phentsize = bswap_16(hdrs.ehdr64.e_phentsize);
140 hdrs.ehdr64.e_phnum = bswap_16(hdrs.ehdr64.e_phnum);
141 }
142 }
143 if ((elf32 && hdrs.ehdr32.e_phentsize != sizeof(Elf32_Phdr)) ||
144 (!elf32 && hdrs.ehdr64.e_phentsize != sizeof(Elf64_Phdr)))
145 goto out;
146
147 phdr_size = elf32 ? sizeof(Elf32_Phdr) * hdrs.ehdr32.e_phnum
148 : sizeof(Elf64_Phdr) * hdrs.ehdr64.e_phnum;
149 phdr = malloc(phdr_size);
150 if (phdr == NULL)
151 goto out;
152
153 lseek(fd, elf32 ? hdrs.ehdr32.e_phoff : hdrs.ehdr64.e_phoff, SEEK_SET);
154 if (read(fd, phdr, phdr_size) != phdr_size)
155 goto out_free;
156
157 if (elf32)
158 hdrs.phdr32 = phdr;
159 else
160 hdrs.phdr64 = phdr;
161
162 for (int i = 0; i < (elf32 ? hdrs.ehdr32.e_phnum : hdrs.ehdr64.e_phnum); i++) {
163 ssize_t p_filesz;
164
165 if (need_swap) {
166 if (elf32) {
167 hdrs.phdr32[i].p_type = bswap_32(hdrs.phdr32[i].p_type);
168 hdrs.phdr32[i].p_offset = bswap_32(hdrs.phdr32[i].p_offset);
169 hdrs.phdr32[i].p_filesz = bswap_32(hdrs.phdr32[i].p_offset);
170 } else {
171 hdrs.phdr64[i].p_type = bswap_32(hdrs.phdr64[i].p_type);
172 hdrs.phdr64[i].p_offset = bswap_64(hdrs.phdr64[i].p_offset);
173 hdrs.phdr64[i].p_filesz = bswap_64(hdrs.phdr64[i].p_filesz);
174 }
175 }
176 if ((elf32 ? hdrs.phdr32[i].p_type : hdrs.phdr64[i].p_type) != PT_NOTE)
177 continue;
178
179 p_filesz = elf32 ? hdrs.phdr32[i].p_filesz : hdrs.phdr64[i].p_filesz;
180 if (p_filesz > buf_size) {
181 void *tmp;
182
183 buf_size = p_filesz;
184 tmp = realloc(buf, buf_size);
185 if (tmp == NULL)
186 goto out_free;
187 buf = tmp;
188 }
189 lseek(fd, elf32 ? hdrs.phdr32[i].p_offset : hdrs.phdr64[i].p_offset, SEEK_SET);
190 if (read(fd, buf, p_filesz) != p_filesz)
191 goto out_free;
192
193 ret = read_build_id(note_data: buf, note_len: p_filesz, bid, need_swap);
194 if (ret == 0) {
195 ret = bid->size;
196 break;
197 }
198 }
199out_free:
200 free(buf);
201 free(phdr);
202out:
203 close(fd);
204 return ret;
205}
206
207int sysfs__read_build_id(const char *filename, struct build_id *bid)
208{
209 int fd;
210 int ret = -1;
211 struct stat stbuf;
212 size_t buf_size;
213 void *buf;
214
215 fd = open(filename, O_RDONLY);
216 if (fd < 0)
217 return -1;
218
219 if (fstat(fd, &stbuf) < 0)
220 goto out;
221
222 buf_size = stbuf.st_size;
223 buf = malloc(buf_size);
224 if (buf == NULL)
225 goto out;
226
227 if (read(fd, buf, buf_size) != (ssize_t) buf_size)
228 goto out_free;
229
230 ret = read_build_id(note_data: buf, note_len: buf_size, bid, need_swap: false);
231out_free:
232 free(buf);
233out:
234 close(fd);
235 return ret;
236}
237
238int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
239 enum dso_binary_type type)
240{
241 int fd = open(name, O_RDONLY);
242 if (fd < 0)
243 goto out_errno;
244
245 ss->name = strdup(name);
246 if (!ss->name)
247 goto out_close;
248
249 ss->fd = fd;
250 ss->type = type;
251
252 return 0;
253out_close:
254 close(fd);
255out_errno:
256 RC_CHK_ACCESS(dso)->load_errno = errno;
257 return -1;
258}
259
260bool symsrc__possibly_runtime(struct symsrc *ss __maybe_unused)
261{
262 /* Assume all sym sources could be a runtime image. */
263 return true;
264}
265
266bool symsrc__has_symtab(struct symsrc *ss __maybe_unused)
267{
268 return false;
269}
270
271void symsrc__destroy(struct symsrc *ss)
272{
273 zfree(&ss->name);
274 close(ss->fd);
275}
276
277int dso__synthesize_plt_symbols(struct dso *dso __maybe_unused,
278 struct symsrc *ss __maybe_unused)
279{
280 return 0;
281}
282
283static int fd__is_64_bit(int fd)
284{
285 u8 e_ident[EI_NIDENT];
286
287 if (lseek(fd, 0, SEEK_SET))
288 return -1;
289
290 if (readn(fd, e_ident, sizeof(e_ident)) != sizeof(e_ident))
291 return -1;
292
293 if (memcmp(e_ident, ELFMAG, SELFMAG) ||
294 e_ident[EI_VERSION] != EV_CURRENT)
295 return -1;
296
297 return e_ident[EI_CLASS] == ELFCLASS64;
298}
299
300enum dso_type dso__type_fd(int fd)
301{
302 Elf64_Ehdr ehdr;
303 int ret;
304
305 ret = fd__is_64_bit(fd);
306 if (ret < 0)
307 return DSO__TYPE_UNKNOWN;
308
309 if (ret)
310 return DSO__TYPE_64BIT;
311
312 if (readn(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
313 return DSO__TYPE_UNKNOWN;
314
315 if (ehdr.e_machine == EM_X86_64)
316 return DSO__TYPE_X32BIT;
317
318 return DSO__TYPE_32BIT;
319}
320
321int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
322 struct symsrc *ss,
323 struct symsrc *runtime_ss __maybe_unused,
324 int kmodule __maybe_unused)
325{
326 struct build_id bid = { .size = 0, };
327 int ret;
328
329 ret = fd__is_64_bit(fd: ss->fd);
330 if (ret >= 0)
331 RC_CHK_ACCESS(dso)->is_64_bit = ret;
332
333 if (filename__read_build_id(filename: ss->name, bid: &bid) > 0)
334 dso__set_build_id(dso, bid: &bid);
335 return 0;
336}
337
338int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused,
339 mapfn_t mapfn __maybe_unused, void *data __maybe_unused,
340 bool *is_64_bit __maybe_unused)
341{
342 return -1;
343}
344
345int kcore_extract__create(struct kcore_extract *kce __maybe_unused)
346{
347 return -1;
348}
349
350void kcore_extract__delete(struct kcore_extract *kce __maybe_unused)
351{
352}
353
354int kcore_copy(const char *from_dir __maybe_unused,
355 const char *to_dir __maybe_unused)
356{
357 return -1;
358}
359
360void symbol__elf_init(void)
361{
362}
363
364bool filename__has_section(const char *filename __maybe_unused, const char *sec __maybe_unused)
365{
366 return false;
367}
368

source code of linux/tools/perf/util/symbol-minimal.c