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 = -1;
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 = machine__kernel_maps(&vmlinux);
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 /*
136 * Step 2:
137 *
138 * Create the kernel maps for kallsyms and the DSO where we will then
139 * load /proc/kallsyms. Also create the modules maps from /proc/modules
140 * and find the .ko files that match them in /lib/modules/`uname -r`/.
141 */
142 if (machine__create_kernel_maps(&kallsyms) < 0) {
143 pr_debug("machine__create_kernel_maps ");
144 goto out;
145 }
146
147 /*
148 * Step 3:
149 *
150 * Load and split /proc/kallsyms into multiple maps, one per module.
151 * Do not use kcore, as this test was designed before kcore support
152 * and has parts that only make sense if using the non-kcore code.
153 * XXX: extend it to stress the kcorre code as well, hint: the list
154 * of modules extracted from /proc/kcore, in its current form, can't
155 * be compacted against the list of modules found in the "vmlinux"
156 * code and with the one got from /proc/modules from the "kallsyms" code.
157 */
158 if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
159 pr_debug("dso__load_kallsyms ");
160 goto out;
161 }
162
163 /*
164 * Step 4:
165 *
166 * kallsyms will be internally on demand sorted by name so that we can
167 * find the reference relocation * symbol, i.e. the symbol we will use
168 * to see if the running kernel was relocated by checking if it has the
169 * same value in the vmlinux file we load.
170 */
171 kallsyms_map = machine__kernel_map(&kallsyms);
172
173 /*
174 * Step 5:
175 *
176 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
177 */
178 if (machine__create_kernel_maps(&vmlinux) < 0) {
179 pr_debug("machine__create_kernel_maps ");
180 goto out;
181 }
182
183 vmlinux_map = machine__kernel_map(&vmlinux);
184
185 /*
186 * Step 6:
187 *
188 * Locate a vmlinux file in the vmlinux path that has a buildid that
189 * matches the one of the running kernel.
190 *
191 * While doing that look if we find the ref reloc symbol, if we find it
192 * we'll have its ref_reloc_symbol.unrelocated_addr and then
193 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
194 * to fixup the symbols.
195 */
196 if (machine__load_vmlinux_path(&vmlinux) <= 0) {
197 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
198 err = TEST_SKIP;
199 goto out;
200 }
201
202 err = 0;
203 /*
204 * Step 7:
205 *
206 * Now look at the symbols in the vmlinux DSO and check if we find all of them
207 * in the kallsyms dso. For the ones that are in both, check its names and
208 * end addresses too.
209 */
210 map__for_each_symbol(vmlinux_map, sym, nd) {
211 struct symbol *pair, *first_pair;
212
213 sym = rb_entry(nd, struct symbol, rb_node);
214
215 if (sym->start == sym->end)
216 continue;
217
218 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
219 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
220
221 first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
222 pair = first_pair;
223
224 if (pair && UM(pair->start) == mem_start) {
225 next_pair:
226 if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
227 /*
228 * kallsyms don't have the symbol end, so we
229 * set that by using the next symbol start - 1,
230 * in some cases we get this up to a page
231 * wrong, trace_kmalloc when I was developing
232 * this code was one such example, 2106 bytes
233 * off the real size. More than that and we
234 * _really_ have a problem.
235 */
236 s64 skew = mem_end - UM(pair->end);
237 if (llabs(skew) >= page_size)
238 pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
239 mem_start, sym->name, mem_end,
240 UM(pair->end));
241
242 /*
243 * Do not count this as a failure, because we
244 * could really find a case where it's not
245 * possible to get proper function end from
246 * kallsyms.
247 */
248 continue;
249 } else {
250 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
251 if (pair) {
252 if (UM(pair->start) == mem_start)
253 goto next_pair;
254
255 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
256 mem_start, sym->name, pair->name);
257 } else {
258 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
259 mem_start, sym->name, first_pair->name);
260 }
261
262 continue;
263 }
264 } else if (mem_start == kallsyms.vmlinux_map->end) {
265 /*
266 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
267 * such as __indirect_thunk_end.
268 */
269 continue;
270 } else if (is_ignored_symbol(sym->name, sym->type)) {
271 /*
272 * Ignore hidden symbols, see scripts/kallsyms.c for the details
273 */
274 continue;
275 } else {
276 pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
277 mem_start, sym->name);
278 }
279
280 err = -1;
281 }
282
283 if (verbose <= 0)
284 goto out;
285
286 header_printed = false;
287
288 maps__for_each_entry(maps, map) {
289 struct map *
290 /*
291 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
292 * the kernel will have the path for the vmlinux file being used,
293 * so use the short name, less descriptive but the same ("[kernel]" in
294 * both cases.
295 */
296 pair = maps__find_by_name(&kallsyms.kmaps, (map->dso->kernel ?
297 map->dso->short_name :
298 map->dso->name));
299 if (pair) {
300 pair->priv = 1;
301 } else {
302 if (!header_printed) {
303 pr_info("WARN: Maps only in vmlinux:\n");
304 header_printed = true;
305 }
306 map__fprintf(map, stderr);
307 }
308 }
309
310 header_printed = false;
311
312 maps__for_each_entry(maps, map) {
313 struct map *pair;
314
315 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
316 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
317
318 pair = maps__find(&kallsyms.kmaps, mem_start);
319 if (pair == NULL || pair->priv)
320 continue;
321
322 if (pair->start == mem_start) {
323 if (!header_printed) {
324 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
325 header_printed = true;
326 }
327
328 pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
329 map->start, map->end, map->pgoff, map->dso->name);
330 if (mem_end != pair->end)
331 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
332 pair->start, pair->end, pair->pgoff);
333 pr_info(" %s\n", pair->dso->name);
334 pair->priv = 1;
335 }
336 }
337
338 header_printed = false;
339
340 maps = machine__kernel_maps(&kallsyms);
341
342 maps__for_each_entry(maps, map) {
343 if (!map->priv) {
344 if (!header_printed) {
345 pr_info("WARN: Maps only in kallsyms:\n");
346 header_printed = true;
347 }
348 map__fprintf(map, stderr);
349 }
350 }
351 out:
352 machine__exit(&kallsyms);
353 machine__exit(&vmlinux);
354 return err;
355 }
356
357 DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);
358