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 <stdlib.h>
7 #include "dso.h"
8 #include "map.h"
9 #include "symbol.h"
10 #include <internal/lib.h> // page_size
11 #include "tests.h"
12 #include "debug.h"
13 #include "machine.h"
14
15 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
16
17 int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest __maybe_unused)
18 {
19 int err = -1;
20 struct rb_node *nd;
21 struct symbol *sym;
22 struct map *kallsyms_map, *vmlinux_map, *map;
23 struct machine kallsyms, vmlinux;
24 struct maps *maps = machine__kernel_maps(&vmlinux);
25 u64 mem_start, mem_end;
26 bool header_printed;
27
28 /*
29 * Step 1:
30 *
31 * Init the machines that will hold kernel, modules obtained from
32 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
33 */
34 machine__init(&kallsyms, "", HOST_KERNEL_ID);
35 machine__init(&vmlinux, "", HOST_KERNEL_ID);
36
37 /*
38 * Step 2:
39 *
40 * Create the kernel maps for kallsyms and the DSO where we will then
41 * load /proc/kallsyms. Also create the modules maps from /proc/modules
42 * and find the .ko files that match them in /lib/modules/`uname -r`/.
43 */
44 if (machine__create_kernel_maps(&kallsyms) < 0) {
45 pr_debug("machine__create_kernel_maps ");
46 goto out;
47 }
48
49 /*
50 * Step 3:
51 *
52 * Load and split /proc/kallsyms into multiple maps, one per module.
53 * Do not use kcore, as this test was designed before kcore support
54 * and has parts that only make sense if using the non-kcore code.
55 * XXX: extend it to stress the kcorre code as well, hint: the list
56 * of modules extracted from /proc/kcore, in its current form, can't
57 * be compacted against the list of modules found in the "vmlinux"
58 * code and with the one got from /proc/modules from the "kallsyms" code.
59 */
60 if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
61 pr_debug("dso__load_kallsyms ");
62 goto out;
63 }
64
65 /*
66 * Step 4:
67 *
68 * kallsyms will be internally on demand sorted by name so that we can
69 * find the reference relocation * symbol, i.e. the symbol we will use
70 * to see if the running kernel was relocated by checking if it has the
71 * same value in the vmlinux file we load.
72 */
73 kallsyms_map = machine__kernel_map(&kallsyms);
74
75 /*
76 * Step 5:
77 *
78 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
79 */
80 if (machine__create_kernel_maps(&vmlinux) < 0) {
81 pr_debug("machine__create_kernel_maps ");
82 goto out;
83 }
84
85 vmlinux_map = machine__kernel_map(&vmlinux);
86
87 /*
88 * Step 6:
89 *
90 * Locate a vmlinux file in the vmlinux path that has a buildid that
91 * matches the one of the running kernel.
92 *
93 * While doing that look if we find the ref reloc symbol, if we find it
94 * we'll have its ref_reloc_symbol.unrelocated_addr and then
95 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
96 * to fixup the symbols.
97 */
98 if (machine__load_vmlinux_path(&vmlinux) <= 0) {
99 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
100 err = TEST_SKIP;
101 goto out;
102 }
103
104 err = 0;
105 /*
106 * Step 7:
107 *
108 * Now look at the symbols in the vmlinux DSO and check if we find all of them
109 * in the kallsyms dso. For the ones that are in both, check its names and
110 * end addresses too.
111 */
112 map__for_each_symbol(vmlinux_map, sym, nd) {
113 struct symbol *pair, *first_pair;
114
115 sym = rb_entry(nd, struct symbol, rb_node);
116
117 if (sym->start == sym->end)
118 continue;
119
120 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
121 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
122
123 first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
124 pair = first_pair;
125
126 if (pair && UM(pair->start) == mem_start) {
127 next_pair:
128 if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
129 /*
130 * kallsyms don't have the symbol end, so we
131 * set that by using the next symbol start - 1,
132 * in some cases we get this up to a page
133 * wrong, trace_kmalloc when I was developing
134 * this code was one such example, 2106 bytes
135 * off the real size. More than that and we
136 * _really_ have a problem.
137 */
138 s64 skew = mem_end - UM(pair->end);
139 if (llabs(skew) >= page_size)
140 pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
141 mem_start, sym->name, mem_end,
142 UM(pair->end));
143
144 /*
145 * Do not count this as a failure, because we
146 * could really find a case where it's not
147 * possible to get proper function end from
148 * kallsyms.
149 */
150 continue;
151 } else {
152 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
153 if (pair) {
154 if (UM(pair->start) == mem_start)
155 goto next_pair;
156
157 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
158 mem_start, sym->name, pair->name);
159 } else {
160 pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
161 mem_start, sym->name, first_pair->name);
162 }
163
164 continue;
165 }
166 } else if (mem_start == kallsyms.vmlinux_map->end) {
167 /*
168 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
169 * such as __indirect_thunk_end.
170 */
171 continue;
172 } else {
173 pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
174 mem_start, sym->name);
175 }
176
177 err = -1;
178 }
179
180 if (verbose <= 0)
181 goto out;
182
183 header_printed = false;
184
185 for (map = maps__first(maps); map; map = map__next(map)) {
186 struct map *
187 /*
188 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
189 * the kernel will have the path for the vmlinux file being used,
190 * so use the short name, less descriptive but the same ("[kernel]" in
191 * both cases.
192 */
193 pair = map_groups__find_by_name(&kallsyms.kmaps,
194 (map->dso->kernel ?
195 map->dso->short_name :
196 map->dso->name));
197 if (pair) {
198 pair->priv = 1;
199 } else {
200 if (!header_printed) {
201 pr_info("WARN: Maps only in vmlinux:\n");
202 header_printed = true;
203 }
204 map__fprintf(map, stderr);
205 }
206 }
207
208 header_printed = false;
209
210 for (map = maps__first(maps); map; map = map__next(map)) {
211 struct map *pair;
212
213 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
214 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
215
216 pair = map_groups__find(&kallsyms.kmaps, mem_start);
217 if (pair == NULL || pair->priv)
218 continue;
219
220 if (pair->start == mem_start) {
221 if (!header_printed) {
222 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
223 header_printed = true;
224 }
225
226 pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
227 map->start, map->end, map->pgoff, map->dso->name);
228 if (mem_end != pair->end)
229 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
230 pair->start, pair->end, pair->pgoff);
231 pr_info(" %s\n", pair->dso->name);
232 pair->priv = 1;
233 }
234 }
235
236 header_printed = false;
237
238 maps = machine__kernel_maps(&kallsyms);
239
240 for (map = maps__first(maps); map; map = map__next(map)) {
241 if (!map->priv) {
242 if (!header_printed) {
243 pr_info("WARN: Maps only in kallsyms:\n");
244 header_printed = true;
245 }
246 map__fprintf(map, stderr);
247 }
248 }
249 out:
250 machine__exit(&kallsyms);
251 machine__exit(&vmlinux);
252 return err;
253 }