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) kallsyms_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 ".LASANPC", /* s390 kasan local symbols */
47 "__crc_", /* modversions */
48 "__efistub_", /* arm64 EFI stub namespace */
49 "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
50 "__AArch64ADRPThunk_", /* arm64 lld */
51 "__ARMV5PILongThunk_", /* arm lld */
52 "__ARMV7PILongThunk_",
53 "__ThumbV7PILongThunk_",
54 "__LA25Thunk_", /* mips lld */
55 "__microLA25Thunk_",
56 NULL
57 };
58
59 /* Symbol names that end with the following are ignored.*/
60 static const char * const ignored_suffixes[] = {
61 "_from_arm", /* arm */
62 "_from_thumb", /* arm */
63 "_veneer", /* arm */
64 NULL
65 };
66
67 /* Symbol names that contain the following are ignored.*/
68 static const char * const ignored_matches[] = {
69 ".long_branch.", /* ppc stub */
70 ".plt_branch.", /* ppc stub */
71 NULL
72 };
73
74 const char * const *p;
75
76 for (p = ignored_symbols; *p; p++)
77 if (!strcmp(name, *p))
78 return true;
79
80 for (p = ignored_prefixes; *p; p++)
81 if (!strncmp(name, *p, strlen(*p)))
82 return true;
83
84 for (p = ignored_suffixes; *p; p++) {
85 int l = strlen(name) - strlen(*p);
86
87 if (l >= 0 && !strcmp(name + l, *p))
88 return true;
89 }
90
91 for (p = ignored_matches; *p; p++) {
92 if (strstr(name, *p))
93 return true;
94 }
95
96 if (type == 'U' || type == 'u')
97 return true;
98 /* exclude debugging symbols */
99 if (type == 'N' || type == 'n')
100 return true;
101
102 if (toupper(type) == 'A') {
103 /* Keep these useful absolute symbols */
104 if (strcmp(name, "__kernel_syscall_via_break") &&
105 strcmp(name, "__kernel_syscall_via_epc") &&
106 strcmp(name, "__kernel_sigtramp") &&
107 strcmp(name, "__gp"))
108 return true;
109 }
110
111 return false;
112 }
113
test__vmlinux_matches_kallsyms(struct test_suite * test __maybe_unused,int subtest __maybe_unused)114 static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
115 int subtest __maybe_unused)
116 {
117 int err = TEST_FAIL;
118 struct rb_node *nd;
119 struct symbol *sym;
120 struct map *kallsyms_map, *vmlinux_map, *map;
121 struct machine kallsyms, vmlinux;
122 struct maps *maps;
123 u64 mem_start, mem_end;
124 bool header_printed;
125
126 /*
127 * Step 1:
128 *
129 * Init the machines that will hold kernel, modules obtained from
130 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
131 */
132 machine__init(&kallsyms, "", HOST_KERNEL_ID);
133 machine__init(&vmlinux, "", HOST_KERNEL_ID);
134
135 maps = machine__kernel_maps(&vmlinux);
136
137 /*
138 * Step 2:
139 *
140 * Create the kernel maps for kallsyms and the DSO where we will then
141 * load /proc/kallsyms. Also create the modules maps from /proc/modules
142 * and find the .ko files that match them in /lib/modules/`uname -r`/.
143 */
144 if (machine__create_kernel_maps(&kallsyms) < 0) {
145 pr_debug("machine__create_kernel_maps failed");
146 err = TEST_SKIP;
147 goto out;
148 }
149
150 /*
151 * Step 3:
152 *
153 * Load and split /proc/kallsyms into multiple maps, one per module.
154 * Do not use kcore, as this test was designed before kcore support
155 * and has parts that only make sense if using the non-kcore code.
156 * XXX: extend it to stress the kcorre code as well, hint: the list
157 * of modules extracted from /proc/kcore, in its current form, can't
158 * be compacted against the list of modules found in the "vmlinux"
159 * code and with the one got from /proc/modules from the "kallsyms" code.
160 */
161 if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
162 pr_debug("machine__load_kallsyms failed");
163 err = TEST_SKIP;
164 goto out;
165 }
166
167 /*
168 * Step 4:
169 *
170 * kallsyms will be internally on demand sorted by name so that we can
171 * find the reference relocation * symbol, i.e. the symbol we will use
172 * to see if the running kernel was relocated by checking if it has the
173 * same value in the vmlinux file we load.
174 */
175 kallsyms_map = machine__kernel_map(&kallsyms);
176
177 /*
178 * Step 5:
179 *
180 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
181 */
182 if (machine__create_kernel_maps(&vmlinux) < 0) {
183 pr_info("machine__create_kernel_maps failed");
184 goto out;
185 }
186
187 vmlinux_map = machine__kernel_map(&vmlinux);
188
189 /*
190 * Step 6:
191 *
192 * Locate a vmlinux file in the vmlinux path that has a buildid that
193 * matches the one of the running kernel.
194 *
195 * While doing that look if we find the ref reloc symbol, if we find it
196 * we'll have its ref_reloc_symbol.unrelocated_addr and then
197 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
198 * to fixup the symbols.
199 */
200 if (machine__load_vmlinux_path(&vmlinux) <= 0) {
201 pr_info("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
202 err = TEST_SKIP;
203 goto out;
204 }
205
206 err = 0;
207 /*
208 * Step 7:
209 *
210 * Now look at the symbols in the vmlinux DSO and check if we find all of them
211 * in the kallsyms dso. For the ones that are in both, check its names and
212 * end addresses too.
213 */
214 map__for_each_symbol(vmlinux_map, sym, nd) {
215 struct symbol *pair, *first_pair;
216
217 sym = rb_entry(nd, struct symbol, rb_node);
218
219 if (sym->start == sym->end)
220 continue;
221
222 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
223 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
224
225 first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
226 pair = first_pair;
227
228 if (pair && UM(pair->start) == mem_start) {
229 next_pair:
230 if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
231 /*
232 * kallsyms don't have the symbol end, so we
233 * set that by using the next symbol start - 1,
234 * in some cases we get this up to a page
235 * wrong, trace_kmalloc when I was developing
236 * this code was one such example, 2106 bytes
237 * off the real size. More than that and we
238 * _really_ have a problem.
239 */
240 s64 skew = mem_end - UM(pair->end);
241 if (llabs(skew) >= page_size)
242 pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
243 mem_start, sym->name, mem_end,
244 UM(pair->end));
245
246 /*
247 * Do not count this as a failure, because we
248 * could really find a case where it's not
249 * possible to get proper function end from
250 * kallsyms.
251 */
252 continue;
253 } else {
254 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
255 if (pair) {
256 if (UM(pair->start) == mem_start)
257 goto next_pair;
258
259 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
260 mem_start, sym->name, pair->name);
261 } else {
262 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
263 mem_start, sym->name, first_pair->name);
264 }
265
266 continue;
267 }
268 } else if (mem_start == kallsyms.vmlinux_map->end) {
269 /*
270 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
271 * such as __indirect_thunk_end.
272 */
273 continue;
274 } else if (is_ignored_symbol(sym->name, sym->type)) {
275 /*
276 * Ignore hidden symbols, see scripts/kallsyms.c for the details
277 */
278 continue;
279 } else {
280 pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
281 mem_start, sym->name);
282 }
283
284 err = -1;
285 }
286
287 if (verbose <= 0)
288 goto out;
289
290 header_printed = false;
291
292 maps__for_each_entry(maps, map) {
293 struct map *
294 /*
295 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
296 * the kernel will have the path for the vmlinux file being used,
297 * so use the short name, less descriptive but the same ("[kernel]" in
298 * both cases.
299 */
300 pair = maps__find_by_name(kallsyms.kmaps, (map->dso->kernel ?
301 map->dso->short_name :
302 map->dso->name));
303 if (pair) {
304 pair->priv = 1;
305 } else {
306 if (!header_printed) {
307 pr_info("WARN: Maps only in vmlinux:\n");
308 header_printed = true;
309 }
310 map__fprintf(map, stderr);
311 }
312 }
313
314 header_printed = false;
315
316 maps__for_each_entry(maps, map) {
317 struct map *pair;
318
319 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
320 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
321
322 pair = maps__find(kallsyms.kmaps, mem_start);
323 if (pair == NULL || pair->priv)
324 continue;
325
326 if (pair->start == mem_start) {
327 if (!header_printed) {
328 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
329 header_printed = true;
330 }
331
332 pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
333 map->start, map->end, map->pgoff, map->dso->name);
334 if (mem_end != pair->end)
335 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
336 pair->start, pair->end, pair->pgoff);
337 pr_info(" %s\n", pair->dso->name);
338 pair->priv = 1;
339 }
340 }
341
342 header_printed = false;
343
344 maps = machine__kernel_maps(&kallsyms);
345
346 maps__for_each_entry(maps, map) {
347 if (!map->priv) {
348 if (!header_printed) {
349 pr_info("WARN: Maps only in kallsyms:\n");
350 header_printed = true;
351 }
352 map__fprintf(map, stderr);
353 }
354 }
355 out:
356 machine__exit(&kallsyms);
357 machine__exit(&vmlinux);
358 return err;
359 }
360
361 DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);
362