tools/perf/tests/vmlinux-kallsyms.c

   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                 return -1;
  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("machine__load_vmlinux_path ");
 105                 goto out;
 106         }
 107
 108         err = 0;
 109         /*
 110          * Step 7:
 111          *
 112          * Now look at the symbols in the vmlinux DSO and check if we find all of them
 113          * in the kallsyms dso. For the ones that are in both, check its names and
 114          * end addresses too.
 115          */
 116         for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
 117                 struct symbol *pair, *first_pair;
 118                 bool backwards = true;
 119
 120                 sym  = rb_entry(nd, struct symbol, rb_node);
 121
 122                 if (sym->start == sym->end)
 123                         continue;
 124
 125                 first_pair = machine__find_kernel_symbol(&kallsyms, type, sym->start, NULL, NULL);
 126                 pair = first_pair;
 127
 128                 if (pair && pair->start == sym->start) {
 129 next_pair:
 130                         if (strcmp(sym->name, pair->name) == 0) {
 131                                 /*
 132                                  * kallsyms don't have the symbol end, so we
 133                                  * set that by using the next symbol start - 1,
 134                                  * in some cases we get this up to a page
 135                                  * wrong, trace_kmalloc when I was developing
 136                                  * this code was one such example, 2106 bytes
 137                                  * off the real size. More than that and we
 138                                  * _really_ have a problem.
 139                                  */
 140                                 s64 skew = sym->end - pair->end;
 141                                 if (llabs(skew) < page_size)
 142                                         continue;
 143
 144                                 pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 145                                          sym->start, sym->name, sym->end, pair->end);
 146                         } else {
 147                                 struct rb_node *nnd;
 148 detour:
 149                                 nnd = backwards ? rb_prev(&pair->rb_node) :
 150                                                   rb_next(&pair->rb_node);
 151                                 if (nnd) {
 152                                         struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
 153
 154                                         if (next->start == sym->start) {
 155                                                 pair = next;
 156                                                 goto next_pair;
 157                                         }
 158                                 }
 159
 160                                 if (backwards) {
 161                                         backwards = false;
 162                                         pair = first_pair;
 163                                         goto detour;
 164                                 }
 165
 166                                 pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
 167                                          sym->start, sym->name, pair->name);
 168                         }
 169                 } else
 170                         pr_debug("%#" PRIx64 ": %s not on kallsyms\n", sym->start, sym->name);
 171
 172                 err = -1;
 173         }
 174
 175         if (!verbose)
 176                 goto out;
 177
 178         pr_info("Maps only in vmlinux:\n");
 179
 180         for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
 181                 struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
 182                 /*
 183                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 184                  * the kernel will have the path for the vmlinux file being used,
 185                  * so use the short name, less descriptive but the same ("[kernel]" in
 186                  * both cases.
 187                  */
 188                 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
 189                                                 (pos->dso->kernel ?
 190                                                         pos->dso->short_name :
 191                                                         pos->dso->name));
 192                 if (pair)
 193                         pair->priv = 1;
 194                 else
 195                         map__fprintf(pos, stderr);
 196         }
 197
 198         pr_info("Maps in vmlinux with a different name in kallsyms:\n");
 199
 200         for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
 201                 struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
 202
 203                 pair = map_groups__find(&kallsyms.kmaps, type, pos->start);
 204                 if (pair == NULL || pair->priv)
 205                         continue;
 206
 207                 if (pair->start == pos->start) {
 208                         pair->priv = 1;
 209                         pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 210                                 pos->start, pos->end, pos->pgoff, pos->dso->name);
 211                         if (pos->pgoff != pair->pgoff || pos->end != pair->end)
 212                                 pr_info(": \n*%" PRIx64 "-%" PRIx64 " %" PRIx64 "",
 213                                         pair->start, pair->end, pair->pgoff);
 214                         pr_info(" %s\n", pair->dso->name);
 215                         pair->priv = 1;
 216                 }
 217         }
 218
 219         pr_info("Maps only in kallsyms:\n");
 220
 221         for (nd = rb_first(&kallsyms.kmaps.maps[type]);
 222              nd; nd = rb_next(nd)) {
 223                 struct map *pos = rb_entry(nd, struct map, rb_node);
 224
 225                 if (!pos->priv)
 226                         map__fprintf(pos, stderr);
 227         }
 228 out:
 229         return err;
 230 }