perf tools: Adjust kallsyms for relocated kernel

[~andy/linux] / tools / perf / util / symbol.c

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 4ac1f871ec273f8a2a1f58d5fffe617848ffac97..a9d758a3b3719a0b8db5d7b5d239c7dea5ceb34e 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -627,7 +627,7 @@ static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map,
  * kernel range is broken in several maps, named [kernel].N, as we don't have
  * the original ELF section names vmlinux have.
  */
-static int dso__split_kallsyms(struct dso *dso, struct map *map,
+static int dso__split_kallsyms(struct dso *dso, struct map *map, u64 delta,
                               symbol_filter_t filter)
 {
        struct map_groups *kmaps = map__kmap(map)->kmaps;
@@ -692,6 +692,12 @@ static int dso__split_kallsyms(struct dso *dso, struct map *map,
                        char dso_name[PATH_MAX];
                        struct dso *ndso;
 
+                       if (delta) {
+                               /* Kernel was relocated at boot time */
+                               pos->start -= delta;
+                               pos->end -= delta;
+                       }
+
                        if (count == 0) {
                                curr_map = map;
                                goto filter_symbol;
@@ -721,6 +727,10 @@ static int dso__split_kallsyms(struct dso *dso, struct map *map,
                        curr_map->map_ip = curr_map->unmap_ip = identity__map_ip;
                        map_groups__insert(kmaps, curr_map);
                        ++kernel_range;
+               } else if (delta) {
+                       /* Kernel was relocated at boot time */
+                       pos->start -= delta;
+                       pos->end -= delta;
                }
 filter_symbol:
                if (filter && filter(curr_map, pos)) {
@@ -1130,15 +1140,41 @@ out_err:
        return -EINVAL;
 }
 
+/*
+ * If the kernel is relocated at boot time, kallsyms won't match.  Compute the
+ * delta based on the relocation reference symbol.
+ */
+static int kallsyms__delta(struct map *map, const char *filename, u64 *delta)
+{
+       struct kmap *kmap = map__kmap(map);
+       u64 addr;
+
+       if (!kmap->ref_reloc_sym || !kmap->ref_reloc_sym->name)
+               return 0;
+
+       addr = kallsyms__get_function_start(filename,
+                                           kmap->ref_reloc_sym->name);
+       if (!addr)
+               return -1;
+
+       *delta = addr - kmap->ref_reloc_sym->addr;
+       return 0;
+}
+
 int dso__load_kallsyms(struct dso *dso, const char *filename,
                       struct map *map, symbol_filter_t filter)
 {
+       u64 delta = 0;
+
        if (symbol__restricted_filename(filename, "/proc/kallsyms"))
                return -1;
 
        if (dso__load_all_kallsyms(dso, filename, map) < 0)
                return -1;
 
+       if (kallsyms__delta(map, filename, &delta))
+               return -1;
+
        symbols__fixup_duplicate(&dso->symbols[map->type]);
        symbols__fixup_end(&dso->symbols[map->type]);
 
@@ -1150,7 +1186,7 @@ int dso__load_kallsyms(struct dso *dso, const char *filename,
        if (!dso__load_kcore(dso, map, filename))
                return dso__split_kallsyms_for_kcore(dso, map, filter);
        else
-               return dso__split_kallsyms(dso, map, filter);
+               return dso__split_kallsyms(dso, map, delta, filter);
 }
 
 static int dso__load_perf_map(struct dso *dso, struct map *map,