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