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

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