1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compiler.h>
3 #include <linux/rbtree.h>
4 #include <inttypes.h>
5 #include <string.h>
6 #include <ctype.h>
7 #include <stdlib.h>
8 #include "dso.h"
9 #include "map.h"
10 #include "symbol.h"
11 #include <internal/lib.h> // page_size
12 #include "tests.h"
13 #include "debug.h"
14 #include "machine.h"
15
16 #define UM(x) map__unmap_ip(kallsyms_map, (x))
17
is_ignored_symbol(const char * name,char type)18 static bool is_ignored_symbol(const char *name, char type)
19 {
20 /* Symbol names that exactly match to the following are ignored.*/
21 static const char * const ignored_symbols[] = {
22 /*
23 * Symbols which vary between passes. Passes 1 and 2 must have
24 * identical symbol lists. The kallsyms_* symbols below are
25 * only added after pass 1, they would be included in pass 2
26 * when --all-symbols is specified so exclude them to get a
27 * stable symbol list.
28 */
29 "kallsyms_addresses",
30 "kallsyms_offsets",
31 "kallsyms_relative_base",
32 "kallsyms_num_syms",
33 "kallsyms_names",
34 "kallsyms_markers",
35 "kallsyms_token_table",
36 "kallsyms_token_index",
37 /* Exclude linker generated symbols which vary between passes */
38 "_SDA_BASE_", /* ppc */
39 "_SDA2_BASE_", /* ppc */
40 NULL
41 };
42
43 /* Symbol names that begin with the following are ignored.*/
44 static const char * const ignored_prefixes[] = {
45 "$", /* local symbols for ARM, MIPS, etc. */
46 ".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
47 "__crc_", /* modversions */
48 "__efistub_", /* arm64 EFI stub namespace */
49 "__kvm_nvhe_$", /* arm64 local symbols in non-VHE KVM namespace */
50 "__kvm_nvhe_.L", /* arm64 local symbols in non-VHE KVM namespace */
51 "__AArch64ADRPThunk_", /* arm64 lld */
52 "__ARMV5PILongThunk_", /* arm lld */
53 "__ARMV7PILongThunk_",
54 "__ThumbV7PILongThunk_",
55 "__LA25Thunk_", /* mips lld */
56 "__microLA25Thunk_",
57 NULL
58 };
59
60 /* Symbol names that end with the following are ignored.*/
61 static const char * const ignored_suffixes[] = {
62 "_from_arm", /* arm */
63 "_from_thumb", /* arm */
64 "_veneer", /* arm */
65 NULL
66 };
67
68 /* Symbol names that contain the following are ignored.*/
69 static const char * const ignored_matches[] = {
70 ".long_branch.", /* ppc stub */
71 ".plt_branch.", /* ppc stub */
72 NULL
73 };
74
75 const char * const *p;
76
77 for (p = ignored_symbols; *p; p++)
78 if (!strcmp(name, *p))
79 return true;
80
81 for (p = ignored_prefixes; *p; p++)
82 if (!strncmp(name, *p, strlen(*p)))
83 return true;
84
85 for (p = ignored_suffixes; *p; p++) {
86 int l = strlen(name) - strlen(*p);
87
88 if (l >= 0 && !strcmp(name + l, *p))
89 return true;
90 }
91
92 for (p = ignored_matches; *p; p++) {
93 if (strstr(name, *p))
94 return true;
95 }
96
97 if (type == 'U' || type == 'u')
98 return true;
99 /* exclude debugging symbols */
100 if (type == 'N' || type == 'n')
101 return true;
102
103 if (toupper(type) == 'A') {
104 /* Keep these useful absolute symbols */
105 if (strcmp(name, "__kernel_syscall_via_break") &&
106 strcmp(name, "__kernel_syscall_via_epc") &&
107 strcmp(name, "__kernel_sigtramp") &&
108 strcmp(name, "__gp"))
109 return true;
110 }
111
112 return false;
113 }
114
test__vmlinux_matches_kallsyms(struct test_suite * test __maybe_unused,int subtest __maybe_unused)115 static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
116 int subtest __maybe_unused)
117 {
118 int err = TEST_FAIL;
119 struct rb_node *nd;
120 struct symbol *sym;
121 struct map *kallsyms_map, *vmlinux_map;
122 struct map_rb_node *rb_node;
123 struct machine kallsyms, vmlinux;
124 struct maps *maps;
125 u64 mem_start, mem_end;
126 bool header_printed;
127
128 /*
129 * Step 1:
130 *
131 * Init the machines that will hold kernel, modules obtained from
132 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
133 */
134 machine__init(&kallsyms, "", HOST_KERNEL_ID);
135 machine__init(&vmlinux, "", HOST_KERNEL_ID);
136
137 maps = machine__kernel_maps(&vmlinux);
138
139 /*
140 * Step 2:
141 *
142 * Create the kernel maps for kallsyms and the DSO where we will then
143 * load /proc/kallsyms. Also create the modules maps from /proc/modules
144 * and find the .ko files that match them in /lib/modules/`uname -r`/.
145 */
146 if (machine__create_kernel_maps(&kallsyms) < 0) {
147 pr_debug("machine__create_kernel_maps failed");
148 err = TEST_SKIP;
149 goto out;
150 }
151
152 /*
153 * Step 3:
154 *
155 * Load and split /proc/kallsyms into multiple maps, one per module.
156 * Do not use kcore, as this test was designed before kcore support
157 * and has parts that only make sense if using the non-kcore code.
158 * XXX: extend it to stress the kcorre code as well, hint: the list
159 * of modules extracted from /proc/kcore, in its current form, can't
160 * be compacted against the list of modules found in the "vmlinux"
161 * code and with the one got from /proc/modules from the "kallsyms" code.
162 */
163 if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
164 pr_debug("machine__load_kallsyms failed");
165 err = TEST_SKIP;
166 goto out;
167 }
168
169 /*
170 * Step 4:
171 *
172 * kallsyms will be internally on demand sorted by name so that we can
173 * find the reference relocation * symbol, i.e. the symbol we will use
174 * to see if the running kernel was relocated by checking if it has the
175 * same value in the vmlinux file we load.
176 */
177 kallsyms_map = machine__kernel_map(&kallsyms);
178
179 /*
180 * Step 5:
181 *
182 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
183 */
184 if (machine__create_kernel_maps(&vmlinux) < 0) {
185 pr_info("machine__create_kernel_maps failed");
186 goto out;
187 }
188
189 vmlinux_map = machine__kernel_map(&vmlinux);
190
191 /*
192 * Step 6:
193 *
194 * Locate a vmlinux file in the vmlinux path that has a buildid that
195 * matches the one of the running kernel.
196 *
197 * While doing that look if we find the ref reloc symbol, if we find it
198 * we'll have its ref_reloc_symbol.unrelocated_addr and then
199 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
200 * to fixup the symbols.
201 */
202 if (machine__load_vmlinux_path(&vmlinux) <= 0) {
203 pr_info("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
204 err = TEST_SKIP;
205 goto out;
206 }
207
208 err = 0;
209 /*
210 * Step 7:
211 *
212 * Now look at the symbols in the vmlinux DSO and check if we find all of them
213 * in the kallsyms dso. For the ones that are in both, check its names and
214 * end addresses too.
215 */
216 map__for_each_symbol(vmlinux_map, sym, nd) {
217 struct symbol *pair, *first_pair;
218
219 sym = rb_entry(nd, struct symbol, rb_node);
220
221 if (sym->start == sym->end)
222 continue;
223
224 mem_start = map__unmap_ip(vmlinux_map, sym->start);
225 mem_end = map__unmap_ip(vmlinux_map, sym->end);
226
227 first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
228 pair = first_pair;
229
230 if (pair && UM(pair->start) == mem_start) {
231 next_pair:
232 if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
233 /*
234 * kallsyms don't have the symbol end, so we
235 * set that by using the next symbol start - 1,
236 * in some cases we get this up to a page
237 * wrong, trace_kmalloc when I was developing
238 * this code was one such example, 2106 bytes
239 * off the real size. More than that and we
240 * _really_ have a problem.
241 */
242 s64 skew = mem_end - UM(pair->end);
243 if (llabs(skew) >= page_size)
244 pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
245 mem_start, sym->name, mem_end,
246 UM(pair->end));
247
248 /*
249 * Do not count this as a failure, because we
250 * could really find a case where it's not
251 * possible to get proper function end from
252 * kallsyms.
253 */
254 continue;
255 } else {
256 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
257 if (pair) {
258 if (UM(pair->start) == mem_start)
259 goto next_pair;
260
261 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
262 mem_start, sym->name, pair->name);
263 } else {
264 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
265 mem_start, sym->name, first_pair->name);
266 }
267
268 continue;
269 }
270 } else if (mem_start == map__end(kallsyms.vmlinux_map)) {
271 /*
272 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
273 * such as __indirect_thunk_end.
274 */
275 continue;
276 } else if (is_ignored_symbol(sym->name, sym->type)) {
277 /*
278 * Ignore hidden symbols, see scripts/kallsyms.c for the details
279 */
280 continue;
281 } else {
282 pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
283 mem_start, sym->name);
284 }
285
286 err = -1;
287 }
288
289 if (verbose <= 0)
290 goto out;
291
292 header_printed = false;
293
294 maps__for_each_entry(maps, rb_node) {
295 struct map *map = rb_node->map;
296 struct dso *dso = map__dso(map);
297 /*
298 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
299 * the kernel will have the path for the vmlinux file being used,
300 * so use the short name, less descriptive but the same ("[kernel]" in
301 * both cases.
302 */
303 struct map *pair = maps__find_by_name(kallsyms.kmaps, (dso->kernel ?
304 dso->short_name :
305 dso->name));
306 if (pair) {
307 map__set_priv(pair, 1);
308 } else {
309 if (!header_printed) {
310 pr_info("WARN: Maps only in vmlinux:\n");
311 header_printed = true;
312 }
313 map__fprintf(map, stderr);
314 }
315 }
316
317 header_printed = false;
318
319 maps__for_each_entry(maps, rb_node) {
320 struct map *pair, *map = rb_node->map;
321
322 mem_start = map__unmap_ip(vmlinux_map, map__start(map));
323 mem_end = map__unmap_ip(vmlinux_map, map__end(map));
324
325 pair = maps__find(kallsyms.kmaps, mem_start);
326 if (pair == NULL || map__priv(pair))
327 continue;
328
329 if (map__start(pair) == mem_start) {
330 struct dso *dso = map__dso(map);
331
332 if (!header_printed) {
333 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
334 header_printed = true;
335 }
336
337 pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
338 map__start(map), map__end(map), map__pgoff(map), dso->name);
339 if (mem_end != map__end(pair))
340 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
341 map__start(pair), map__end(pair), map__pgoff(pair));
342 pr_info(" %s\n", dso->name);
343 map__set_priv(pair, 1);
344 }
345 }
346
347 header_printed = false;
348
349 maps = machine__kernel_maps(&kallsyms);
350
351 maps__for_each_entry(maps, rb_node) {
352 struct map *map = rb_node->map;
353
354 if (!map__priv(map)) {
355 if (!header_printed) {
356 pr_info("WARN: Maps only in kallsyms:\n");
357 header_printed = true;
358 }
359 map__fprintf(map, stderr);
360 }
361 }
362 out:
363 machine__exit(&kallsyms);
364 machine__exit(&vmlinux);
365 return err;
366 }
367
368 DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);
369