perf maps: Add remove maps function to remove a map based on callback

Removing maps wasn't being done under the write lock. Similar to
maps__for_each_map(), iterate the entries but in this case remove the
entry based on the result of the callback. If an entry was removed
then maps_by_name() also needs updating, so add missed flush.

In dso__load_kcore(), the test of map to save would always be false with
REFCNT_CHECKING because of a missing RC_CHK_ACCESS/RC_CHK_EQUAL.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Guilherme Amadio <amadio@gentoo.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Li Dong <lidong@vivo.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Wenyu Liu <liuwenyu7@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20231207011722.1220634-15-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 00e6589bba10dcae4a8031f2def6a5239753aaca..f13fd3a9686b1b7d83c19ebd81e84e16e4044549 100644 (file)
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -13,6 +13,10 @@
 #define maps__for_each_entry(maps, map) \
        for (map = maps__first(maps); map; map = map_rb_node__next(map))
 
+#define maps__for_each_entry_safe(maps, map, next) \
+       for (map = maps__first(maps), next = map_rb_node__next(map); map; \
+            map = next, next = map_rb_node__next(map))
+
 static void maps__init(struct maps *maps, struct machine *machine)
 {
        refcount_set(maps__refcnt(maps), 1);
@@ -214,6 +218,26 @@ int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data)
        return ret;
 }
 
+void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data)
+{
+       struct map_rb_node *pos, *next;
+       unsigned int start_nr_maps;
+
+       down_write(maps__lock(maps));
+
+       start_nr_maps = maps__nr_maps(maps);
+       maps__for_each_entry_safe(maps, pos, next)      {
+               if (cb(pos->map, data)) {
+                       __maps__remove(maps, pos);
+                       --RC_CHK_ACCESS(maps)->nr_maps;
+               }
+       }
+       if (maps__maps_by_name(maps) && start_nr_maps != maps__nr_maps(maps))
+               __maps__free_maps_by_name(maps);
+
+       up_write(maps__lock(maps));
+}
+
 struct symbol *maps__find_symbol(struct maps *maps, u64 addr, struct map **mapp)
 {
        struct map *map = maps__find(maps, addr);

diff --git a/tools/perf/util/maps.h b/tools/perf/util/maps.h
index 8ac30cdaf5bd1dc89eb79e75ec4fb6596bdb9059..b94ad5c8fea743817c84bafe6b95594a1f55ea47 100644 (file)
--- a/tools/perf/util/maps.h
+++ b/tools/perf/util/maps.h
@@ -36,10 +36,6 @@ struct map_rb_node *map_rb_node__next(struct map_rb_node *node);
 struct map_rb_node *maps__find_node(struct maps *maps, struct map *map);
 struct map *maps__find(struct maps *maps, u64 addr);
 
-#define maps__for_each_entry_safe(maps, map, next) \
-       for (map = maps__first(maps), next = map_rb_node__next(map); map; \
-            map = next, next = map_rb_node__next(map))
-
 DECLARE_RC_STRUCT(maps) {
        struct rb_root      entries;
        struct rw_semaphore lock;
@@ -80,6 +76,8 @@ static inline void __maps__zput(struct maps **map)
 
 /* Iterate over map calling cb for each entry. */
 int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data), void *data);
+/* Iterate over map removing an entry if cb returns true. */
+void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data);
 
 static inline struct rb_root *maps__entries(struct maps *maps)
 {

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 72f03b875478ac548e6adb56385bdfb603c2ad0d..be212ba157dc321d96534ba6063febbc1ccd5e04 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1239,13 +1239,23 @@ static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
        return 0;
 }
 
+static bool remove_old_maps(struct map *map, void *data)
+{
+       const struct map *map_to_save = data;
+
+       /*
+        * We need to preserve eBPF maps even if they are covered by kcore,
+        * because we need to access eBPF dso for source data.
+        */
+       return !RC_CHK_EQUAL(map, map_to_save) && !__map__is_bpf_prog(map);
+}
+
 static int dso__load_kcore(struct dso *dso, struct map *map,
                           const char *kallsyms_filename)
 {
        struct maps *kmaps = map__kmaps(map);
        struct kcore_mapfn_data md;
        struct map *replacement_map = NULL;
-       struct map_rb_node *old_node, *next;
        struct machine *machine;
        bool is_64_bit;
        int err, fd;
@@ -1292,17 +1302,7 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
        }
 
        /* Remove old maps */
-       maps__for_each_entry_safe(kmaps, old_node, next) {
-               struct map *old_map = old_node->map;
-
-               /*
-                * We need to preserve eBPF maps even if they are
-                * covered by kcore, because we need to access
-                * eBPF dso for source data.
-                */
-               if (old_map != map && !__map__is_bpf_prog(old_map))
-                       maps__remove(kmaps, old_map);
-       }
+       maps__remove_maps(kmaps, remove_old_maps, map);
        machine->trampolines_mapped = false;
 
        /* Find the kernel map using the '_stext' symbol */