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, *map;
27 struct machine kallsyms, vmlinux;
28 enum map_type type = MAP__FUNCTION;
29 struct maps *maps = &vmlinux.kmaps.maps[type];
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);
72
73 /*
74 * Step 5:
75 *
76 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
77 */
78 if (machine__create_kernel_maps(&vmlinux) < 0) {
79 pr_debug("machine__create_kernel_maps ");
80 goto out;
81 }
82
83 vmlinux_map = machine__kernel_map(&vmlinux);
84
85 /*
86 * Step 6:
87 *
88 * Locate a vmlinux file in the vmlinux path that has a buildid that
89 * matches the one of the running kernel.
90 *
91 * While doing that look if we find the ref reloc symbol, if we find it
92 * we'll have its ref_reloc_symbol.unrelocated_addr and then
93 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
94 * to fixup the symbols.
95 */
96 if (machine__load_vmlinux_path(&vmlinux, type,
97 vmlinux_matches_kallsyms_filter) <= 0) {
98 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
99 err = TEST_SKIP;
100 goto out;
101 }
102
103 err = 0;
104 /*
105 * Step 7:
106 *
107 * Now look at the symbols in the vmlinux DSO and check if we find all of them
108 * in the kallsyms dso. For the ones that are in both, check its names and
109 * end addresses too.
110 */
111 for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
112 struct symbol *pair, *first_pair;
113 bool backwards = true;
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, type,
124 mem_start, NULL, NULL);
125 pair = first_pair;
126
127 if (pair && UM(pair->start) == mem_start) {
128 next_pair:
129 if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
130 /*
131 * kallsyms don't have the symbol end, so we
132 * set that by using the next symbol start - 1,
133 * in some cases we get this up to a page
134 * wrong, trace_kmalloc when I was developing
135 * this code was one such example, 2106 bytes
136 * off the real size. More than that and we
137 * _really_ have a problem.
138 */
139 s64 skew = mem_end - UM(pair->end);
140 if (llabs(skew) >= page_size)
141 pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
142 mem_start, sym->name, mem_end,
143 UM(pair->end));
144
145 /*
146 * Do not count this as a failure, because we
147 * could really find a case where it's not
148 * possible to get proper function end from
149 * kallsyms.
150 */
151 continue;
152
153 } else {
154 struct rb_node *nnd;
155 detour:
156 nnd = backwards ? rb_prev(&pair->rb_node) :
157 rb_next(&pair->rb_node);
158 if (nnd) {
159 struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
160
161 if (UM(next->start) == mem_start) {
162 pair = next;
163 goto next_pair;
164 }
165 }
166
167 if (backwards) {
168 backwards = false;
169 pair = first_pair;
170 goto detour;
171 }
172
173 pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
174 mem_start, sym->name, pair->name);
175 }
176 } else
177 pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
178 mem_start, sym->name);
179
180 err = -1;
181 }
182
183 if (!verbose)
184 goto out;
185
186 pr_info("Maps only in vmlinux:\n");
187
188 for (map = maps__first(maps); map; map = map__next(map)) {
189 struct map *
190 /*
191 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
192 * the kernel will have the path for the vmlinux file being used,
193 * so use the short name, less descriptive but the same ("[kernel]" in
194 * both cases.
195 */
196 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
197 (map->dso->kernel ?
198 map->dso->short_name :
199 map->dso->name));
200 if (pair)
201 pair->priv = 1;
202 else
203 map__fprintf(map, stderr);
204 }
205
206 pr_info("Maps in vmlinux with a different name in kallsyms:\n");
207
208 for (map = maps__first(maps); map; map = map__next(map)) {
209 struct map *pair;
210
211 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
212 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
213
214 pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
215 if (pair == NULL || pair->priv)
216 continue;
217
218 if (pair->start == mem_start) {
219 pair->priv = 1;
220 pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
221 map->start, map->end, map->pgoff, map->dso->name);
222 if (mem_end != pair->end)
223 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
224 pair->start, pair->end, pair->pgoff);
225 pr_info(" %s\n", pair->dso->name);
226 pair->priv = 1;
227 }
228 }
229
230 pr_info("Maps only in kallsyms:\n");
231
232 maps = &kallsyms.kmaps.maps[type];
233
234 for (map = maps__first(maps); map; map = map__next(map)) {
235 if (!map->priv)
236 map__fprintf(map, stderr);
237 }
238 out:
239 machine__exit(&kallsyms);
240 machine__exit(&vmlinux);
241 return err;
242 }
243