tools/perf/tests/vmlinux-kallsyms.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/compiler.h>
   3 #include <linux/rbtree.h>
   4 #include <inttypes.h>
   5 #include <string.h>
   6 #include "map.h"
   7 #include "symbol.h"
   8 #include "util.h"
   9 #include "tests.h"
  10 #include "debug.h"
  11 #include "machine.h"
  12
  13 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
  14
  15 int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest __maybe_unused)
  16 {
  17         int err = -1;
  18         struct rb_node *nd;
  19         struct symbol *sym;
  20         struct map *kallsyms_map, *vmlinux_map, *map;
  21         struct machine kallsyms, vmlinux;
  22         enum map_type type = MAP__FUNCTION;
  23         struct maps *maps = &vmlinux.kmaps.maps[type];
  24         u64 mem_start, mem_end;
  25         bool header_printed;
  26
  27         /*
  28          * Step 1:
  29          *
  30          * Init the machines that will hold kernel, modules obtained from
  31          * both vmlinux + .ko files and from /proc/kallsyms split by modules.
  32          */
  33         machine__init(&kallsyms, "", HOST_KERNEL_ID);
  34         machine__init(&vmlinux, "", HOST_KERNEL_ID);
  35
  36         /*
  37          * Step 2:
  38          *
  39          * Create the kernel maps for kallsyms and the DSO where we will then
  40          * load /proc/kallsyms. Also create the modules maps from /proc/modules
  41          * and find the .ko files that match them in /lib/modules/`uname -r`/.
  42          */
  43         if (machine__create_kernel_maps(&kallsyms) < 0) {
  44                 pr_debug("machine__create_kernel_maps ");
  45                 goto out;
  46         }
  47
  48         /*
  49          * Step 3:
  50          *
  51          * Load and split /proc/kallsyms into multiple maps, one per module.
  52          * Do not use kcore, as this test was designed before kcore support
  53          * and has parts that only make sense if using the non-kcore code.
  54          * XXX: extend it to stress the kcorre code as well, hint: the list
  55          * of modules extracted from /proc/kcore, in its current form, can't
  56          * be compacted against the list of modules found in the "vmlinux"
  57          * code and with the one got from /proc/modules from the "kallsyms" code.
  58          */
  59         if (__machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, true) <= 0) {
  60                 pr_debug("dso__load_kallsyms ");
  61                 goto out;
  62         }
  63
  64         /*
  65          * Step 4:
  66          *
  67          * kallsyms will be internally on demand sorted by name so that we can
  68          * find the reference relocation * symbol, i.e. the symbol we will use
  69          * to see if the running kernel was relocated by checking if it has the
  70          * same value in the vmlinux file we load.
  71          */
  72         kallsyms_map = machine__kernel_map(&kallsyms);
  73
  74         /*
  75          * Step 5:
  76          *
  77          * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
  78          */
  79         if (machine__create_kernel_maps(&vmlinux) < 0) {
  80                 pr_debug("machine__create_kernel_maps ");
  81                 goto out;
  82         }
  83
  84         vmlinux_map = machine__kernel_map(&vmlinux);
  85
  86         /*
  87          * Step 6:
  88          *
  89          * Locate a vmlinux file in the vmlinux path that has a buildid that
  90          * matches the one of the running kernel.
  91          *
  92          * While doing that look if we find the ref reloc symbol, if we find it
  93          * we'll have its ref_reloc_symbol.unrelocated_addr and then
  94          * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
  95          * to fixup the symbols.
  96          */
  97         if (machine__load_vmlinux_path(&vmlinux, type) <= 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);
 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("WARN: %#" 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                         } else {
 152                                 pair = machine__find_kernel_symbol_by_name(&kallsyms, type, sym->name, NULL);
 153                                 if (pair) {
 154                                         if (UM(pair->start) == mem_start)
 155                                                 goto next_pair;
 156
 157                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 158                                                  mem_start, sym->name, pair->name);
 159                                 } else {
 160                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 161                                                  mem_start, sym->name, first_pair->name);
 162                                 }
 163
 164                                 continue;
 165                         }
 166                 } else
 167                         pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
 168                                  mem_start, sym->name);
 169
 170                 err = -1;
 171         }
 172
 173         if (verbose <= 0)
 174                 goto out;
 175
 176         header_printed = false;
 177
 178         for (map = maps__first(maps); map; map = map__next(map)) {
 179                 struct map *
 180                 /*
 181                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 182                  * the kernel will have the path for the vmlinux file being used,
 183                  * so use the short name, less descriptive but the same ("[kernel]" in
 184                  * both cases.
 185                  */
 186                 pair = map_groups__find_by_name(&kallsyms.kmaps, type,
 187                                                 (map->dso->kernel ?
 188                                                         map->dso->short_name :
 189                                                         map->dso->name));
 190                 if (pair) {
 191                         pair->priv = 1;
 192                 } else {
 193                         if (!header_printed) {
 194                                 pr_info("WARN: Maps only in vmlinux:\n");
 195                                 header_printed = true;
 196                         }
 197                         map__fprintf(map, stderr);
 198                 }
 199         }
 200
 201         header_printed = false;
 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                         if (!header_printed) {
 215                                 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
 216                                 header_printed = true;
 217                         }
 218
 219                         pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 220                                 map->start, map->end, map->pgoff, map->dso->name);
 221                         if (mem_end != pair->end)
 222                                 pr_info(":\nWARN: *%" 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         header_printed = false;
 230
 231         maps = &kallsyms.kmaps.maps[type];
 232
 233         for (map = maps__first(maps); map; map = map__next(map)) {
 234                 if (!map->priv) {
 235                         if (!header_printed) {
 236                                 pr_info("WARN: Maps only in kallsyms:\n");
 237                                 header_printed = true;
 238                         }
 239                         map__fprintf(map, stderr);
 240                 }
 241         }
 242 out:
 243         machine__exit(&kallsyms);
 244         machine__exit(&vmlinux);
 245         return err;
 246 }