xref: /linux/tools/perf/util/symbol-minimal.c (revision 2a3716544359d4312c81b0fa909a13301186da17) 
1 #include "debug.h"
2 #include "dso.h"
3 #include "symbol.h"
4 #include "symsrc.h"
5 
6 #include <errno.h>
7 #include <unistd.h>
8 #include <fcntl.h>
9 #include <string.h>
10 #include <stdlib.h>
11 #include <byteswap.h>
12 #include <sys/stat.h>
13 #include <linux/zalloc.h>
14 #include <internal/lib.h>
15 
16 static bool check_need_swap(int file_endian)
17 {
18 	const int data = 1;
19 	u8 *check = (u8 *)&data;
20 	int host_endian;
21 
22 	if (check[0] == 1)
23 		host_endian = ELFDATA2LSB;
24 	else
25 		host_endian = ELFDATA2MSB;
26 
27 	return host_endian != file_endian;
28 }
29 
30 #define NOTE_ALIGN(sz) (((sz) + 3) & ~3)
31 
32 #define NT_GNU_BUILD_ID	3
33 
34 static int read_build_id(void *note_data, size_t note_len, struct build_id *bid,
35 			 bool need_swap)
36 {
37 	size_t size = sizeof(bid->data);
38 	struct {
39 		u32 n_namesz;
40 		u32 n_descsz;
41 		u32 n_type;
42 	} *nhdr;
43 	void *ptr;
44 
45 	ptr = note_data;
46 	while ((ptr + sizeof(*nhdr)) < (note_data + note_len)) {
47 		const char *name;
48 		size_t namesz, descsz, remaining;
49 
50 		nhdr = ptr;
51 		if (need_swap) {
52 			nhdr->n_namesz = bswap_32(nhdr->n_namesz);
53 			nhdr->n_descsz = bswap_32(nhdr->n_descsz);
54 			nhdr->n_type = bswap_32(nhdr->n_type);
55 		}
56 
57 		namesz = NOTE_ALIGN(nhdr->n_namesz);
58 		descsz = NOTE_ALIGN(nhdr->n_descsz);
59 
60 		/* validate individually to avoid size_t overflow on 32-bit */
61 		remaining = note_data + note_len - ptr - sizeof(*nhdr);
62 		if (namesz > remaining || descsz > remaining - namesz) {
63 			pr_warning("%s: oversized note: n_namesz=%u, n_descsz=%u\n",
64 				   __func__, nhdr->n_namesz, nhdr->n_descsz);
65 			break;
66 		}
67 
68 		ptr += sizeof(*nhdr);
69 		name = ptr;
70 		ptr += namesz;
71 		if (nhdr->n_type == NT_GNU_BUILD_ID &&
72 		    nhdr->n_namesz == sizeof("GNU")) {
73 			if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
74 				size_t sz = min(size, descsz);
75 				memcpy(bid->data, ptr, sz);
76 				memset(bid->data + sz, 0, size - sz);
77 				bid->size = sz;
78 				return 0;
79 			}
80 		}
81 		ptr += descsz;
82 	}
83 
84 	return -1;
85 }
86 
87 int filename__read_debuglink(const char *filename __maybe_unused,
88 			     char *debuglink __maybe_unused,
89 			     size_t size __maybe_unused)
90 {
91 	return -1;
92 }
93 
94 /*
95  * Just try PT_NOTE header otherwise fails
96  */
97 int filename__read_build_id(const char *filename, struct build_id *bid)
98 {
99 	int fd, ret = -1;
100 	bool need_swap = false, elf32;
101 	union {
102 		struct {
103 			Elf32_Ehdr ehdr32;
104 			Elf32_Phdr *phdr32;
105 		};
106 		struct {
107 			Elf64_Ehdr ehdr64;
108 			Elf64_Phdr *phdr64;
109 		};
110 	} hdrs;
111 	void *phdr, *buf = NULL;
112 	ssize_t phdr_size, ehdr_size, buf_size = 0;
113 
114 	if (!filename)
115 		return -EFAULT;
116 
117 	errno = 0;
118 	if (!is_regular_file(filename))
119 		return errno == 0 ? -EWOULDBLOCK : -errno;
120 
121 	fd = open(filename, O_RDONLY);
122 	if (fd < 0)
123 		return -1;
124 
125 	if (read(fd, hdrs.ehdr32.e_ident, EI_NIDENT) != EI_NIDENT)
126 		goto out;
127 
128 	if (memcmp(hdrs.ehdr32.e_ident, ELFMAG, SELFMAG) ||
129 	    hdrs.ehdr32.e_ident[EI_VERSION] != EV_CURRENT)
130 		goto out;
131 
132 	need_swap = check_need_swap(hdrs.ehdr32.e_ident[EI_DATA]);
133 	elf32 = hdrs.ehdr32.e_ident[EI_CLASS] == ELFCLASS32;
134 	ehdr_size = (elf32 ? sizeof(hdrs.ehdr32) : sizeof(hdrs.ehdr64)) - EI_NIDENT;
135 
136 	if (read(fd,
137 		 (elf32 ? (void *)&hdrs.ehdr32 : (void *)&hdrs.ehdr64) + EI_NIDENT,
138 		 ehdr_size) != ehdr_size)
139 		goto out;
140 
141 	if (need_swap) {
142 		if (elf32) {
143 			hdrs.ehdr32.e_phoff = bswap_32(hdrs.ehdr32.e_phoff);
144 			hdrs.ehdr32.e_phentsize = bswap_16(hdrs.ehdr32.e_phentsize);
145 			hdrs.ehdr32.e_phnum = bswap_16(hdrs.ehdr32.e_phnum);
146 		} else {
147 			hdrs.ehdr64.e_phoff = bswap_64(hdrs.ehdr64.e_phoff);
148 			hdrs.ehdr64.e_phentsize = bswap_16(hdrs.ehdr64.e_phentsize);
149 			hdrs.ehdr64.e_phnum = bswap_16(hdrs.ehdr64.e_phnum);
150 		}
151 	}
152 	if ((elf32 && hdrs.ehdr32.e_phentsize != sizeof(Elf32_Phdr)) ||
153 	    (!elf32 && hdrs.ehdr64.e_phentsize != sizeof(Elf64_Phdr)))
154 		goto out;
155 
156 	phdr_size = elf32 ? sizeof(Elf32_Phdr) * hdrs.ehdr32.e_phnum
157 			  : sizeof(Elf64_Phdr) * hdrs.ehdr64.e_phnum;
158 	phdr = malloc(phdr_size);
159 	if (phdr == NULL)
160 		goto out;
161 
162 	lseek(fd, elf32 ? hdrs.ehdr32.e_phoff : hdrs.ehdr64.e_phoff, SEEK_SET);
163 	if (read(fd, phdr, phdr_size) != phdr_size)
164 		goto out_free;
165 
166 	if (elf32)
167 		hdrs.phdr32 = phdr;
168 	else
169 		hdrs.phdr64 = phdr;
170 
171 	for (int i = 0; i < (elf32 ? hdrs.ehdr32.e_phnum : hdrs.ehdr64.e_phnum); i++) {
172 		ssize_t p_filesz;
173 
174 		if (need_swap) {
175 			if (elf32) {
176 				hdrs.phdr32[i].p_type = bswap_32(hdrs.phdr32[i].p_type);
177 				hdrs.phdr32[i].p_offset = bswap_32(hdrs.phdr32[i].p_offset);
178 				hdrs.phdr32[i].p_filesz = bswap_32(hdrs.phdr32[i].p_filesz);
179 			} else {
180 				hdrs.phdr64[i].p_type = bswap_32(hdrs.phdr64[i].p_type);
181 				hdrs.phdr64[i].p_offset = bswap_64(hdrs.phdr64[i].p_offset);
182 				hdrs.phdr64[i].p_filesz = bswap_64(hdrs.phdr64[i].p_filesz);
183 			}
184 		}
185 		if ((elf32 ? hdrs.phdr32[i].p_type : hdrs.phdr64[i].p_type) != PT_NOTE)
186 			continue;
187 
188 		p_filesz = elf32 ? hdrs.phdr32[i].p_filesz : hdrs.phdr64[i].p_filesz;
189 		/* ssize_t can go negative with crafted ELF p_filesz values */
190 		if (p_filesz <= 0)
191 			continue;
192 		if (p_filesz > buf_size) {
193 			void *tmp;
194 
195 			buf_size = p_filesz;
196 			tmp = realloc(buf, buf_size);
197 			if (tmp == NULL)
198 				goto out_free;
199 			buf = tmp;
200 		}
201 		lseek(fd, elf32 ? hdrs.phdr32[i].p_offset : hdrs.phdr64[i].p_offset, SEEK_SET);
202 		if (read(fd, buf, p_filesz) != p_filesz)
203 			goto out_free;
204 
205 		ret = read_build_id(buf, p_filesz, bid, need_swap);
206 		if (ret == 0) {
207 			ret = bid->size;
208 			break;
209 		}
210 	}
211 out_free:
212 	free(buf);
213 	free(phdr);
214 out:
215 	close(fd);
216 	return ret;
217 }
218 
219 int sysfs__read_build_id(const char *filename, struct build_id *bid)
220 {
221 	int fd;
222 	int ret = -1;
223 	struct stat stbuf;
224 	size_t buf_size;
225 	void *buf;
226 
227 	fd = open(filename, O_RDONLY);
228 	if (fd < 0)
229 		return -1;
230 
231 	if (fstat(fd, &stbuf) < 0)
232 		goto out;
233 
234 	buf_size = stbuf.st_size;
235 	buf = malloc(buf_size);
236 	if (buf == NULL)
237 		goto out;
238 
239 	if (read(fd, buf, buf_size) != (ssize_t) buf_size)
240 		goto out_free;
241 
242 	ret = read_build_id(buf, buf_size, bid, false);
243 out_free:
244 	free(buf);
245 out:
246 	close(fd);
247 	return ret;
248 }
249 
250 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
251 	         enum dso_binary_type type)
252 {
253 	int fd = open(name, O_RDONLY);
254 	if (fd < 0)
255 		goto out_errno;
256 
257 	ss->name = strdup(name);
258 	if (!ss->name)
259 		goto out_close;
260 
261 	ss->fd = fd;
262 	ss->type = type;
263 
264 	return 0;
265 out_close:
266 	close(fd);
267 out_errno:
268 	RC_CHK_ACCESS(dso)->load_errno = errno;
269 	return -1;
270 }
271 
272 bool symsrc__possibly_runtime(struct symsrc *ss __maybe_unused)
273 {
274 	/* Assume all sym sources could be a runtime image. */
275 	return true;
276 }
277 
278 bool symsrc__has_symtab(struct symsrc *ss __maybe_unused)
279 {
280 	return false;
281 }
282 
283 void symsrc__destroy(struct symsrc *ss)
284 {
285 	zfree(&ss->name);
286 	close(ss->fd);
287 }
288 
289 int dso__synthesize_plt_symbols(struct dso *dso __maybe_unused,
290 				struct symsrc *ss __maybe_unused)
291 {
292 	return 0;
293 }
294 
295 static int fd__is_64_bit(int fd)
296 {
297 	u8 e_ident[EI_NIDENT];
298 
299 	if (lseek(fd, 0, SEEK_SET))
300 		return -1;
301 
302 	if (readn(fd, e_ident, sizeof(e_ident)) != sizeof(e_ident))
303 		return -1;
304 
305 	if (memcmp(e_ident, ELFMAG, SELFMAG) ||
306 	    e_ident[EI_VERSION] != EV_CURRENT)
307 		return -1;
308 
309 	return e_ident[EI_CLASS] == ELFCLASS64;
310 }
311 
312 enum dso_type dso__type_fd(int fd)
313 {
314 	Elf64_Ehdr ehdr;
315 	int ret;
316 
317 	ret = fd__is_64_bit(fd);
318 	if (ret < 0)
319 		return DSO__TYPE_UNKNOWN;
320 
321 	if (ret)
322 		return DSO__TYPE_64BIT;
323 
324 	if (readn(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
325 		return DSO__TYPE_UNKNOWN;
326 
327 	if (ehdr.e_machine == EM_X86_64)
328 		return DSO__TYPE_X32BIT;
329 
330 	return DSO__TYPE_32BIT;
331 }
332 
333 int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
334 		  struct symsrc *ss,
335 		  struct symsrc *runtime_ss __maybe_unused,
336 		  int kmodule __maybe_unused)
337 {
338 	struct build_id bid = { .size = 0, };
339 	int ret;
340 
341 	ret = fd__is_64_bit(ss->fd);
342 	if (ret >= 0)
343 		RC_CHK_ACCESS(dso)->is_64_bit = ret;
344 
345 	if (filename__read_build_id(ss->name, &bid) > 0)
346 		dso__set_build_id(dso, &bid);
347 	return 0;
348 }
349 
350 int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused,
351 		    mapfn_t mapfn __maybe_unused, void *data __maybe_unused,
352 		    bool *is_64_bit __maybe_unused)
353 {
354 	return -1;
355 }
356 
357 int kcore_extract__create(struct kcore_extract *kce __maybe_unused)
358 {
359 	return -1;
360 }
361 
362 void kcore_extract__delete(struct kcore_extract *kce __maybe_unused)
363 {
364 }
365 
366 int kcore_copy(const char *from_dir __maybe_unused,
367 	       const char *to_dir __maybe_unused)
368 {
369 	return -1;
370 }
371 
372 void symbol__elf_init(void)
373 {
374 }
375 
376 bool filename__has_section(const char *filename __maybe_unused, const char *sec __maybe_unused)
377 {
378 	return false;
379 }
380