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(void)
  22 {
  23         int err = -1;
  24         struct rb_node *nd;
  25         struct symbol *sym;
  26         struct map *kallsyms_map, *vmlinux_map;
  27         struct machine kallsyms, vmlinux;
  28         enum map_type type = MAP__FUNCTION;
  29         u64 mem_start, mem_end;
  30
  31         /*
  32          * Step 1:
  33          *
  34          * Init the machines that will hold kernel, modules obtained from
  35          * both vmlinux + .ko files and from /proc/kallsyms split by modules.
  36          */
  37         machine__init(&kallsyms, "", HOST_KERNEL_ID);
  38         machine__init(&vmlinux, "", HOST_KERNEL_ID);
  39
  40         /*
  41          * Step 2:
  42          *
  43          * Create the kernel maps for kallsyms and the DSO where we will then
  44          * load /proc/kallsyms. Also create the modules maps from /proc/modules
  45          * and find the .ko files that match them in /lib/modules/`uname -r`/.
  46          */
  47         if (machine__create_kernel_maps(&kallsyms) < 0) {
  48                 pr_debug("machine__create_kernel_maps ");
  49                 goto out;
  50         }
  51
  52         /*
  53          * Step 3:
  54          *
  55          * Load and split /proc/kallsyms into multiple maps, one per module.
  56          */
  57         if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, NULL) <= 0) {
  58                 pr_debug("dso__load_kallsyms ");
  59                 goto out;
  60         }
  61
  62         /*
  63          * Step 4:
  64          *
  65          * kallsyms will be internally on demand sorted by name so that we can
  66          * find the reference relocation * symbol, i.e. the symbol we will use
  67          * to see if the running kernel was relocated by checking if it has the
  68          * same value in the vmlinux file we load.
  69          */
  70         kallsyms_map = machine__kernel_map(&kallsyms, type);
  71
  72         /*
  73          * Step 5:
  74          *
  75          * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
  76          */
  77         if (machine__create_kernel_maps(&vmlinux) < 0) {
  78                 pr_debug("machine__create_kernel_maps ");
  79                 goto out;
  80         }
  81
  82         vmlinux_map = machine__kernel_map(&vmlinux, type);
  83
  84         /*
  85          * Step 6:
  86          *
  87          * Locate a vmlinux file in the vmlinux path that has a buildid that
  88          * matches the one of the running kernel.
  89          *
  90          * While doing that look if we find the ref reloc symbol, if we find it
  91          * we'll have its ref_reloc_symbol.unrelocated_addr and then
  92          * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
  93          * to fixup the symbols.
  94          */
  95         if (machine__load_vmlinux_path(&vmlinux, type,
  96                                        vmlinux_matches_kallsyms_filter) <= 0) {
  97                 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
  98                 err = TEST_SKIP;
  99                 goto out;
 100         }
 101
 102         err = 0;
 103         /*
 104          * Step 7:
 105          *
 106          * Now look at the symbols in the vmlinux DSO and check if we find all of them
 107          * in the kallsyms dso. For the ones that are in both, check its names and
 108          * end addresses too.
 109          */
 110         for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
 111                 struct symbol *pair, *first_pair;
 112                 bool backwards = true;
 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                                 struct rb_node *nnd;
 154 detour:
 155                                 nnd = backwards ? rb_prev(&pair->rb_node) :
 156                                                   rb_next(&pair->rb_node);
 157                                 if (nnd) {
 158                                         struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
 159
 160                                         if (UM(next->start) == mem_start) {
 161                                                 pair = next;
 162                                                 goto next_pair;
 163                                         }
 164                                 }
 165
 166                                 if (backwards) {
 167                                         backwards = false;
 168                                         pair = first_pair;
 169                                         goto detour;
 170                                 }
 171
 172                                 pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
 173                                          mem_start, sym->name, pair->name);
 174                         }
 175                 } else
 176                         pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
 177                                  mem_start, sym->name);
 178
 179                 err = -1;
 180         }
 181
 182         if (!verbose)
 183                 goto out;
 184
 185         pr_info("Maps only in vmlinux:\n");
 186
 187         for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
 188                 struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
 189                 /*
 190                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 191                  * the kernel will have the path for the vmlinux file being used,
 192                  * so use the short name, less descriptive but the same ("[kernel]" in
 193                  * both cases.
 194                  */
 195                 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
 196                                                 (pos->dso->kernel ?
 197                                                         pos->dso->short_name :
 198                                                         pos->dso->name));
 199                 if (pair)
 200                         pair->priv = 1;
 201                 else
 202                         map__fprintf(pos, stderr);
 203         }
 204
 205         pr_info("Maps in vmlinux with a different name in kallsyms:\n");
 206
 207         for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
 208                 struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
 209
 210                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, pos->start);
 211                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, pos->end);
 212
 213                 pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
 214                 if (pair == NULL || pair->priv)
 215                         continue;
 216
 217                 if (pair->start == mem_start) {
 218                         pair->priv = 1;
 219                         pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 220                                 pos->start, pos->end, pos->pgoff, pos->dso->name);
 221                         if (mem_end != pair->end)
 222                                 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
 223                                         pair->start, pair->end, pair->pgoff);
 224                         pr_info(" %s\n", pair->dso->name);
 225                         pair->priv = 1;
 226                 }
 227         }
 228
 229         pr_info("Maps only in kallsyms:\n");
 230
 231         for (nd = rb_first(&kallsyms.kmaps.maps[type]);
 232              nd; nd = rb_next(nd)) {
 233                 struct map *pos = rb_entry(nd, struct map, rb_node);
 234
 235                 if (!pos->priv)
 236                         map__fprintf(pos, stderr);
 237         }
 238 out:
 239         machine__exit(&kallsyms);
 240         machine__exit(&vmlinux);
 241         return err;
 242 }