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perf tools: Preserve eBPF maps when loading kcore
We need to preserve eBPF maps even if they are covered by kcore, because we need to access eBPF dso for source data. Add the map_groups__merge_in function to do that. It merges a map into map_groups by splitting the new map within the existing map regions. Suggested-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stanislav Fomichev <sdf@google.com> Link: http://lkml.kernel.org/r/20190508132010.14512-9-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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1 changed files with 93 additions and 4 deletions
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@ -1166,6 +1166,85 @@ static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
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return 0;
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}
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/*
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* Merges map into map_groups by splitting the new map
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* within the existing map regions.
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*/
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static int map_groups__merge_in(struct map_groups *kmaps, struct map *new_map)
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{
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struct map *old_map;
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LIST_HEAD(merged);
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for (old_map = map_groups__first(kmaps); old_map;
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old_map = map_groups__next(old_map)) {
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/* no overload with this one */
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if (new_map->end < old_map->start ||
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new_map->start >= old_map->end)
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continue;
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if (new_map->start < old_map->start) {
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/*
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* |new......
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* |old....
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*/
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if (new_map->end < old_map->end) {
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/*
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* |new......| -> |new..|
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* |old....| -> |old....|
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*/
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new_map->end = old_map->start;
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} else {
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/*
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* |new.............| -> |new..| |new..|
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* |old....| -> |old....|
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*/
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struct map *m = map__clone(new_map);
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if (!m)
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return -ENOMEM;
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m->end = old_map->start;
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list_add_tail(&m->node, &merged);
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new_map->start = old_map->end;
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}
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} else {
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/*
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* |new......
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* |old....
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*/
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if (new_map->end < old_map->end) {
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/*
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* |new..| -> x
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* |old.........| -> |old.........|
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*/
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map__put(new_map);
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new_map = NULL;
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break;
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} else {
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/*
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* |new......| -> |new...|
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* |old....| -> |old....|
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*/
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new_map->start = old_map->end;
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}
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}
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}
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while (!list_empty(&merged)) {
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old_map = list_entry(merged.next, struct map, node);
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list_del_init(&old_map->node);
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map_groups__insert(kmaps, old_map);
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map__put(old_map);
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}
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if (new_map) {
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map_groups__insert(kmaps, new_map);
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map__put(new_map);
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}
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return 0;
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}
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static int dso__load_kcore(struct dso *dso, struct map *map,
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const char *kallsyms_filename)
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{
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@ -1222,7 +1301,12 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
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while (old_map) {
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struct map *next = map_groups__next(old_map);
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if (old_map != map)
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/*
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* We need to preserve eBPF maps even if they are
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* covered by kcore, because we need to access
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* eBPF dso for source data.
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*/
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if (old_map != map && !__map__is_bpf_prog(old_map))
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map_groups__remove(kmaps, old_map);
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old_map = next;
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}
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@ -1256,11 +1340,16 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
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map_groups__remove(kmaps, map);
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map_groups__insert(kmaps, map);
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map__put(map);
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map__put(new_map);
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} else {
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map_groups__insert(kmaps, new_map);
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/*
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* Merge kcore map into existing maps,
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* and ensure that current maps (eBPF)
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* stay intact.
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*/
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if (map_groups__merge_in(kmaps, new_map))
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goto out_err;
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}
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map__put(new_map);
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}
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if (machine__is(machine, "x86_64")) {
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