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         struct ref_reloc_sym ref_reloc_sym = { .name = "_stext", };
  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, type);
  72
  73         sym = map__find_symbol_by_name(kallsyms_map, ref_reloc_sym.name, NULL);
  74         if (sym == NULL) {
  75                 pr_debug("dso__find_symbol_by_name ");
  76                 goto out;
  77         }
  78
  79         ref_reloc_sym.addr = UM(sym->start);
  80
  81         /*
  82          * Step 5:
  83          *
  84          * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
  85          */
  86         if (machine__create_kernel_maps(&vmlinux) < 0) {
  87                 pr_debug("machine__create_kernel_maps ");
  88                 goto out;
  89         }
  90
  91         vmlinux_map = machine__kernel_map(&vmlinux, type);
  92         map__kmap(vmlinux_map)->ref_reloc_sym = &ref_reloc_sym;
  93
  94         /*
  95          * Step 6:
  96          *
  97          * Locate a vmlinux file in the vmlinux path that has a buildid that
  98          * matches the one of the running kernel.
  99          *
 100          * While doing that look if we find the ref reloc symbol, if we find it
 101          * we'll have its ref_reloc_symbol.unrelocated_addr and then
 102          * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
 103          * to fixup the symbols.
 104          */
 105         if (machine__load_vmlinux_path(&vmlinux, type,
 106                                        vmlinux_matches_kallsyms_filter) <= 0) {
 107                 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
 108                 err = TEST_SKIP;
 109                 goto out;
 110         }
 111
 112         err = 0;
 113         /*
 114          * Step 7:
 115          *
 116          * Now look at the symbols in the vmlinux DSO and check if we find all of them
 117          * in the kallsyms dso. For the ones that are in both, check its names and
 118          * end addresses too.
 119          */
 120         for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
 121                 struct symbol *pair, *first_pair;
 122                 bool backwards = true;
 123
 124                 sym  = rb_entry(nd, struct symbol, rb_node);
 125
 126                 if (sym->start == sym->end)
 127                         continue;
 128
 129                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
 130                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
 131
 132                 first_pair = machine__find_kernel_symbol(&kallsyms, type,
 133                                                          mem_start, NULL, NULL);
 134                 pair = first_pair;
 135
 136                 if (pair && UM(pair->start) == mem_start) {
 137 next_pair:
 138                         if (strcmp(sym->name, pair->name) == 0) {
 139                                 /*
 140                                  * kallsyms don't have the symbol end, so we
 141                                  * set that by using the next symbol start - 1,
 142                                  * in some cases we get this up to a page
 143                                  * wrong, trace_kmalloc when I was developing
 144                                  * this code was one such example, 2106 bytes
 145                                  * off the real size. More than that and we
 146                                  * _really_ have a problem.
 147                                  */
 148                                 s64 skew = mem_end - UM(pair->end);
 149                                 if (llabs(skew) >= page_size)
 150                                         pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 151                                                  mem_start, sym->name, mem_end,
 152                                                  UM(pair->end));
 153
 154                                 /*
 155                                  * Do not count this as a failure, because we
 156                                  * could really find a case where it's not
 157                                  * possible to get proper function end from
 158                                  * kallsyms.
 159                                  */
 160                                 continue;
 161
 162                         } else {
 163                                 struct rb_node *nnd;
 164 detour:
 165                                 nnd = backwards ? rb_prev(&pair->rb_node) :
 166                                                   rb_next(&pair->rb_node);
 167                                 if (nnd) {
 168                                         struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
 169
 170                                         if (UM(next->start) == mem_start) {
 171                                                 pair = next;
 172                                                 goto next_pair;
 173                                         }
 174                                 }
 175
 176                                 if (backwards) {
 177                                         backwards = false;
 178                                         pair = first_pair;
 179                                         goto detour;
 180                                 }
 181
 182                                 pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
 183                                          mem_start, sym->name, pair->name);
 184                         }
 185                 } else
 186                         pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
 187                                  mem_start, sym->name);
 188
 189                 err = -1;
 190         }
 191
 192         if (!verbose)
 193                 goto out;
 194
 195         pr_info("Maps only in vmlinux:\n");
 196
 197         for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
 198                 struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
 199                 /*
 200                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 201                  * the kernel will have the path for the vmlinux file being used,
 202                  * so use the short name, less descriptive but the same ("[kernel]" in
 203                  * both cases.
 204                  */
 205                 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
 206                                                 (pos->dso->kernel ?
 207                                                         pos->dso->short_name :
 208                                                         pos->dso->name));
 209                 if (pair)
 210                         pair->priv = 1;
 211                 else
 212                         map__fprintf(pos, stderr);
 213         }
 214
 215         pr_info("Maps in vmlinux with a different name in kallsyms:\n");
 216
 217         for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
 218                 struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
 219
 220                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, pos->start);
 221                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, pos->end);
 222
 223                 pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
 224                 if (pair == NULL || pair->priv)
 225                         continue;
 226
 227                 if (pair->start == mem_start) {
 228                         pair->priv = 1;
 229                         pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 230                                 pos->start, pos->end, pos->pgoff, pos->dso->name);
 231                         if (mem_end != pair->end)
 232                                 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
 233                                         pair->start, pair->end, pair->pgoff);
 234                         pr_info(" %s\n", pair->dso->name);
 235                         pair->priv = 1;
 236                 }
 237         }
 238
 239         pr_info("Maps only in kallsyms:\n");
 240
 241         for (nd = rb_first(&kallsyms.kmaps.maps[type]);
 242              nd; nd = rb_next(nd)) {
 243                 struct map *pos = rb_entry(nd, struct map, rb_node);
 244
 245                 if (!pos->priv)
 246                         map__fprintf(pos, stderr);
 247         }
 248 out:
 249         machine__exit(&kallsyms);
 250         machine__exit(&vmlinux);
 251         return err;
 252 }