Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 7 May 2024 21:10:54 -0700 | Subject | Re: [PATCH 3/4] perf symbols: Update kcore map before merging in remaining symbols |
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On Tue, May 7, 2024 at 7:13 AM James Clark <james.clark@arm.com> wrote: > > When loading kcore, the main vmlinux map is updated in the same loop > that merges the remaining maps. If a map that overlaps is merged in > before kcore, the list can become unsortable when the main map addresses > are updated. This will later trigger the check_invariants() assert: > > $ perf record > $ perf report > > util/maps.c:96: check_invariants: Assertion `map__end(prev) <= > map__start(map) || map__start(prev) == map__start(map)' failed. > Aborted > > Fix it by moving the main map update prior to the loop so that > maps__merge_in() can split it if necessary.
Looks like you and Leo are working on the same problem.
https://lore.kernel.org/r/20240505202805.583253-1-leo.yan@arm.com/
> > Fixes: 659ad3492b91 ("perf maps: Switch from rbtree to lazily sorted array for addresses") > Signed-off-by: James Clark <james.clark@arm.com> > --- > tools/perf/util/symbol.c | 40 +++++++++++++++++++++------------------- > 1 file changed, 21 insertions(+), 19 deletions(-) > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index 2d95f22d713d..e98dfe766da3 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -1289,7 +1289,7 @@ static int dso__load_kcore(struct dso *dso, struct map *map, > { > struct maps *kmaps = map__kmaps(map); > struct kcore_mapfn_data md; > - struct map *replacement_map = NULL; > + struct map *map_ref, *replacement_map = NULL; > struct machine *machine; > bool is_64_bit; > int err, fd; > @@ -1367,6 +1367,24 @@ static int dso__load_kcore(struct dso *dso, struct map *map, > if (!replacement_map) > replacement_map = list_entry(md.maps.next, struct map_list_node, node)->map; > > + /* > + * Update addresses of vmlinux map. Re-insert it to ensure maps are > + * correctly ordered. Do this before using maps__merge_in() for the > + * remaining maps so vmlinux gets split if necessary. > + */ > + map_ref = map__get(map); > + maps__remove(kmaps, map_ref);
A nitpick. It'd be natural to use 'map' instead of 'map_ref' (even if they are the same) since IIUC we want to remove the old 'map' and update 'map_ref' then add it back.
> + > + map__set_start(map_ref, map__start(replacement_map)); > + map__set_end(map_ref, map__end(replacement_map)); > + map__set_pgoff(map_ref, map__pgoff(replacement_map)); > + map__set_mapping_type(map_ref, map__mapping_type(replacement_map));
So here, replacement_map should not be NULL right?
Thanks, Namhyung
> + > + err = maps__insert(kmaps, map_ref); > + map__put(map_ref); > + if (err) > + goto out_err; > + > /* Add new maps */ > while (!list_empty(&md.maps)) { > struct map_list_node *new_node = list_entry(md.maps.next, struct map_list_node, node); > @@ -1374,24 +1392,8 @@ static int dso__load_kcore(struct dso *dso, struct map *map, > > list_del_init(&new_node->node); > > - if (RC_CHK_EQUAL(new_map, replacement_map)) { > - struct map *map_ref; > - > - /* Ensure maps are correctly ordered */ > - map_ref = map__get(map); > - maps__remove(kmaps, map_ref); > - > - map__set_start(map_ref, map__start(new_map)); > - map__set_end(map_ref, map__end(new_map)); > - map__set_pgoff(map_ref, map__pgoff(new_map)); > - map__set_mapping_type(map_ref, map__mapping_type(new_map)); > - > - err = maps__insert(kmaps, map_ref); > - map__put(map_ref); > - map__put(new_map); > - if (err) > - goto out_err; > - } else { > + /* skip if replacement_map, already inserted above */ > + if (!RC_CHK_EQUAL(new_map, replacement_map)) { > /* > * Merge kcore map into existing maps, > * and ensure that current maps (eBPF) > -- > 2.34.1 >
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