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TOMOYO Linux Cross Reference
Linux/tools/perf/tests/vmlinux-kallsyms.c

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  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 
 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 
 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 

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