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          * Do not use kcore, as this test was designed before kcore support
  58          * and has parts that only make sense if using the non-kcore code.
  59          * XXX: extend it to stress the kcorre code as well, hint: the list
  60          * of modules extracted from /proc/kcore, in its current form, can't
  61          * be compacted against the list of modules found in the "vmlinux"
  62          * code and with the one got from /proc/modules from the "kallsyms" code.
  63          */
  64         if (__machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, true, NULL) <= 0) {
  65                 pr_debug("dso__load_kallsyms ");
  66                 goto out;
  67         }
  68
  69         /*
  70          * Step 4:
  71          *
  72          * kallsyms will be internally on demand sorted by name so that we can
  73          * find the reference relocation * symbol, i.e. the symbol we will use
  74          * to see if the running kernel was relocated by checking if it has the
  75          * same value in the vmlinux file we load.
  76          */
  77         kallsyms_map = machine__kernel_map(&kallsyms);
  78
  79         /*
  80          * Step 5:
  81          *
  82          * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
  83          */
  84         if (machine__create_kernel_maps(&vmlinux) < 0) {
  85                 pr_debug("machine__create_kernel_maps ");
  86                 goto out;
  87         }
  88
  89         vmlinux_map = machine__kernel_map(&vmlinux);
  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
 120                 sym  = rb_entry(nd, struct symbol, rb_node);
 121
 122                 if (sym->start == sym->end)
 123                         continue;
 124
 125                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
 126                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
 127
 128                 first_pair = machine__find_kernel_symbol(&kallsyms, type,
 129                                                          mem_start, NULL, NULL);
 130                 pair = first_pair;
 131
 132                 if (pair && UM(pair->start) == mem_start) {
 133 next_pair:
 134                         if (strcmp(sym->name, pair->name) == 0) {
 135                                 /*
 136                                  * kallsyms don't have the symbol end, so we
 137                                  * set that by using the next symbol start - 1,
 138                                  * in some cases we get this up to a page
 139                                  * wrong, trace_kmalloc when I was developing
 140                                  * this code was one such example, 2106 bytes
 141                                  * off the real size. More than that and we
 142                                  * _really_ have a problem.
 143                                  */
 144                                 s64 skew = mem_end - UM(pair->end);
 145                                 if (llabs(skew) >= page_size)
 146                                         pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 147                                                  mem_start, sym->name, mem_end,
 148                                                  UM(pair->end));
 149
 150                                 /*
 151                                  * Do not count this as a failure, because we
 152                                  * could really find a case where it's not
 153                                  * possible to get proper function end from
 154                                  * kallsyms.
 155                                  */
 156                                 continue;
 157
 158                         } else {
 159                                 pair = machine__find_kernel_symbol_by_name(&kallsyms, type, sym->name, NULL, NULL);
 160                                 if (pair) {
 161                                         if (UM(pair->start) == mem_start)
 162                                                 goto next_pair;
 163
 164                                         pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
 165                                                  mem_start, sym->name, pair->name);
 166                                 } else {
 167                                         pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
 168                                                  mem_start, sym->name, first_pair->name);
 169                                 }
 170                         }
 171                 } else
 172                         pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
 173                                  mem_start, sym->name);
 174
 175                 err = -1;
 176         }
 177
 178         if (!verbose)
 179                 goto out;
 180
 181         pr_info("Maps only in vmlinux:\n");
 182
 183         for (map = maps__first(maps); map; map = map__next(map)) {
 184                 struct map *
 185                 /*
 186                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 187                  * the kernel will have the path for the vmlinux file being used,
 188                  * so use the short name, less descriptive but the same ("[kernel]" in
 189                  * both cases.
 190                  */
 191                 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
 192                                                 (map->dso->kernel ?
 193                                                         map->dso->short_name :
 194                                                         map->dso->name));
 195                 if (pair)
 196                         pair->priv = 1;
 197                 else
 198                         map__fprintf(map, stderr);
 199         }
 200
 201         pr_info("Maps in vmlinux with a different name in kallsyms:\n");
 202
 203         for (map = maps__first(maps); map; map = map__next(map)) {
 204                 struct map *pair;
 205
 206                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
 207                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
 208
 209                 pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
 210                 if (pair == NULL || pair->priv)
 211                         continue;
 212
 213                 if (pair->start == mem_start) {
 214                         pair->priv = 1;
 215                         pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 216                                 map->start, map->end, map->pgoff, map->dso->name);
 217                         if (mem_end != pair->end)
 218                                 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
 219                                         pair->start, pair->end, pair->pgoff);
 220                         pr_info(" %s\n", pair->dso->name);
 221                         pair->priv = 1;
 222                 }
 223         }
 224
 225         pr_info("Maps only in kallsyms:\n");
 226
 227         maps = &kallsyms.kmaps.maps[type];
 228
 229         for (map = maps__first(maps); map; map = map__next(map)) {
 230                 if (!map->priv)
 231                         map__fprintf(map, stderr);
 232         }
 233 out:
 234         machine__exit(&kallsyms);
 235         machine__exit(&vmlinux);
 236         return err;
 237 }