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 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
  20
  21 int test__vmlinux_matches_kallsyms(int subtest __maybe_unused)
  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
 114                 sym  = rb_entry(nd, struct symbol, rb_node);
 115
 116                 if (sym->start == sym->end)
 117                         continue;
 118
 119                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
 120                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
 121
 122                 first_pair = machine__find_kernel_symbol(&kallsyms, type,
 123                                                          mem_start, NULL, NULL);
 124                 pair = first_pair;
 125
 126                 if (pair && UM(pair->start) == mem_start) {
 127 next_pair:
 128                         if (strcmp(sym->name, pair->name) == 0) {
 129                                 /*
 130                                  * kallsyms don't have the symbol end, so we
 131                                  * set that by using the next symbol start - 1,
 132                                  * in some cases we get this up to a page
 133                                  * wrong, trace_kmalloc when I was developing
 134                                  * this code was one such example, 2106 bytes
 135                                  * off the real size. More than that and we
 136                                  * _really_ have a problem.
 137                                  */
 138                                 s64 skew = mem_end - UM(pair->end);
 139                                 if (llabs(skew) >= page_size)
 140                                         pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 141                                                  mem_start, sym->name, mem_end,
 142                                                  UM(pair->end));
 143
 144                                 /*
 145                                  * Do not count this as a failure, because we
 146                                  * could really find a case where it's not
 147                                  * possible to get proper function end from
 148                                  * kallsyms.
 149                                  */
 150                                 continue;
 151
 152                         } else {
 153                                 pair = machine__find_kernel_symbol_by_name(&kallsyms, type, sym->name, NULL, NULL);
 154                                 if (pair) {
 155                                         if (UM(pair->start) == mem_start)
 156                                                 goto next_pair;
 157
 158                                         pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
 159                                                  mem_start, sym->name, pair->name);
 160                                 }
 161                         }
 162                 } else
 163                         pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
 164                                  mem_start, sym->name);
 165
 166                 err = -1;
 167         }
 168
 169         if (!verbose)
 170                 goto out;
 171
 172         pr_info("Maps only in vmlinux:\n");
 173
 174         for (map = maps__first(maps); map; map = map__next(map)) {
 175                 struct map *
 176                 /*
 177                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 178                  * the kernel will have the path for the vmlinux file being used,
 179                  * so use the short name, less descriptive but the same ("[kernel]" in
 180                  * both cases.
 181                  */
 182                 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
 183                                                 (map->dso->kernel ?
 184                                                         map->dso->short_name :
 185                                                         map->dso->name));
 186                 if (pair)
 187                         pair->priv = 1;
 188                 else
 189                         map__fprintf(map, stderr);
 190         }
 191
 192         pr_info("Maps in vmlinux with a different name in kallsyms:\n");
 193
 194         for (map = maps__first(maps); map; map = map__next(map)) {
 195                 struct map *pair;
 196
 197                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
 198                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
 199
 200                 pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
 201                 if (pair == NULL || pair->priv)
 202                         continue;
 203
 204                 if (pair->start == mem_start) {
 205                         pair->priv = 1;
 206                         pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 207                                 map->start, map->end, map->pgoff, map->dso->name);
 208                         if (mem_end != pair->end)
 209                                 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
 210                                         pair->start, pair->end, pair->pgoff);
 211                         pr_info(" %s\n", pair->dso->name);
 212                         pair->priv = 1;
 213                 }
 214         }
 215
 216         pr_info("Maps only in kallsyms:\n");
 217
 218         maps = &kallsyms.kmaps.maps[type];
 219
 220         for (map = maps__first(maps); map; map = map__next(map)) {
 221                 if (!map->priv)
 222                         map__fprintf(map, stderr);
 223         }
 224 out:
 225         machine__exit(&kallsyms);
 226         machine__exit(&vmlinux);
 227         return err;
 228 }