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         struct maps *maps = machine__kernel_maps(&vmlinux);
  23         u64 mem_start, mem_end;
  24         bool header_printed;
  25
  26         /*
  27          * Step 1:
  28          *
  29          * Init the machines that will hold kernel, modules obtained from
  30          * both vmlinux + .ko files and from /proc/kallsyms split by modules.
  31          */
  32         machine__init(&kallsyms, "", HOST_KERNEL_ID);
  33         machine__init(&vmlinux, "", HOST_KERNEL_ID);
  34
  35         /*
  36          * Step 2:
  37          *
  38          * Create the kernel maps for kallsyms and the DSO where we will then
  39          * load /proc/kallsyms. Also create the modules maps from /proc/modules
  40          * and find the .ko files that match them in /lib/modules/`uname -r`/.
  41          */
  42         if (machine__create_kernel_maps(&kallsyms) < 0) {
  43                 pr_debug("machine__create_kernel_maps ");
  44                 goto out;
  45         }
  46
  47         /*
  48          * Step 3:
  49          *
  50          * Load and split /proc/kallsyms into multiple maps, one per module.
  51          * Do not use kcore, as this test was designed before kcore support
  52          * and has parts that only make sense if using the non-kcore code.
  53          * XXX: extend it to stress the kcorre code as well, hint: the list
  54          * of modules extracted from /proc/kcore, in its current form, can't
  55          * be compacted against the list of modules found in the "vmlinux"
  56          * code and with the one got from /proc/modules from the "kallsyms" code.
  57          */
  58         if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 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) <= 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         map__for_each_symbol(vmlinux_map, sym, nd) {
 111                 struct symbol *pair, *first_pair;
 112
 113                 sym  = rb_entry(nd, struct symbol, rb_node);
 114
 115                 if (sym->start == sym->end)
 116                         continue;
 117
 118                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
 119                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
 120
 121                 first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
 122                 pair = first_pair;
 123
 124                 if (pair && UM(pair->start) == mem_start) {
 125 next_pair:
 126                         if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
 127                                 /*
 128                                  * kallsyms don't have the symbol end, so we
 129                                  * set that by using the next symbol start - 1,
 130                                  * in some cases we get this up to a page
 131                                  * wrong, trace_kmalloc when I was developing
 132                                  * this code was one such example, 2106 bytes
 133                                  * off the real size. More than that and we
 134                                  * _really_ have a problem.
 135                                  */
 136                                 s64 skew = mem_end - UM(pair->end);
 137                                 if (llabs(skew) >= page_size)
 138                                         pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 139                                                  mem_start, sym->name, mem_end,
 140                                                  UM(pair->end));
 141
 142                                 /*
 143                                  * Do not count this as a failure, because we
 144                                  * could really find a case where it's not
 145                                  * possible to get proper function end from
 146                                  * kallsyms.
 147                                  */
 148                                 continue;
 149                         } else {
 150                                 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
 151                                 if (pair) {
 152                                         if (UM(pair->start) == mem_start)
 153                                                 goto next_pair;
 154
 155                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 156                                                  mem_start, sym->name, pair->name);
 157                                 } else {
 158                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 159                                                  mem_start, sym->name, first_pair->name);
 160                                 }
 161
 162                                 continue;
 163                         }
 164                 } else
 165                         pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
 166                                  mem_start, sym->name);
 167
 168                 err = -1;
 169         }
 170
 171         if (verbose <= 0)
 172                 goto out;
 173
 174         header_printed = false;
 175
 176         for (map = maps__first(maps); map; map = map__next(map)) {
 177                 struct map *
 178                 /*
 179                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 180                  * the kernel will have the path for the vmlinux file being used,
 181                  * so use the short name, less descriptive but the same ("[kernel]" in
 182                  * both cases.
 183                  */
 184                 pair = map_groups__find_by_name(&kallsyms.kmaps,
 185                                                 (map->dso->kernel ?
 186                                                         map->dso->short_name :
 187                                                         map->dso->name));
 188                 if (pair) {
 189                         pair->priv = 1;
 190                 } else {
 191                         if (!header_printed) {
 192                                 pr_info("WARN: Maps only in vmlinux:\n");
 193                                 header_printed = true;
 194                         }
 195                         map__fprintf(map, stderr);
 196                 }
 197         }
 198
 199         header_printed = false;
 200
 201         for (map = maps__first(maps); map; map = map__next(map)) {
 202                 struct map *pair;
 203
 204                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
 205                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
 206
 207                 pair = map_groups__find(&kallsyms.kmaps, mem_start);
 208                 if (pair == NULL || pair->priv)
 209                         continue;
 210
 211                 if (pair->start == mem_start) {
 212                         if (!header_printed) {
 213                                 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
 214                                 header_printed = true;
 215                         }
 216
 217                         pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 218                                 map->start, map->end, map->pgoff, map->dso->name);
 219                         if (mem_end != pair->end)
 220                                 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
 221                                         pair->start, pair->end, pair->pgoff);
 222                         pr_info(" %s\n", pair->dso->name);
 223                         pair->priv = 1;
 224                 }
 225         }
 226
 227         header_printed = false;
 228
 229         maps = machine__kernel_maps(&kallsyms);
 230
 231         for (map = maps__first(maps); map; map = map__next(map)) {
 232                 if (!map->priv) {
 233                         if (!header_printed) {
 234                                 pr_info("WARN: Maps only in kallsyms:\n");
 235                                 header_printed = true;
 236                         }
 237                         map__fprintf(map, stderr);
 238                 }
 239         }
 240 out:
 241         machine__exit(&kallsyms);
 242         machine__exit(&vmlinux);
 243         return err;
 244 }