perf maps: Introduce map__set_kmap_maps() for kernel maps

JIRA: https://issues.redhat.com/browse/RHEL-77936

upstream
========
commit 99deaf5
Author: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri Feb 28 18:17:29 2025 -0300

description
===========
We need to set it in other places than __maps__insert(), so that we can
have access to the 'struct maps' from a kernel 'struct map'.

When building perf with 'DEBUG=1' we can notice it failing a consistency
check done in the check_invariants() function:

  root@number:~# perf record -- perf test -w offcpu
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.040 MB perf.data (23 samples) ]
  perf: util/maps.c:95: check_invariants: Assertion `map__end(prev) <= map__end(map)' failed.
  Aborted (core dumped)
  root@number:~#

The investigation on that was happening bisected to 876e80c
("perf tools: Fixup end address of modules"), and the following patches
will plug the problems found, this patch is just legwork on that
direction.

Use the map__set_kmap_maps() name as per a review comment from Ian
Rogers, later there are further suggestions from him on getting rid of
the kmaps variable, see the thread referenced in the Link below.

    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Acked-by: Namhyung Kim <namhyung@kernel.org>
    Reviewed-by: Ian Rogers <irogers@google.com>
    Link: https://lore.kernel.org/lkml/Z74V0hZXrTLM6VIJ@x1
    Link: https://lore.kernel.org/r/20250228211734.33781-2-acme@kernel.org
    Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Signed-off-by: Michael Petlan <mpetlan@redhat.com>

Author: rfmvh

tools/perf/util/maps.c

@@ -428,11 +428,29 @@ static unsigned int maps__by_name_index(const struct maps *maps, const struct ma
 	return -1;
 }
 
+static void map__set_kmap_maps(struct map *map, struct maps *maps)
+{
+	struct dso *dso;
+
+	if (map == NULL)
+		return;
+
+	dso = map__dso(map);
+
+	if (dso && dso__kernel(dso)) {
+                struct kmap *kmap = map__kmap(map);
+
+                if (kmap)
+                        kmap->kmaps = maps;
+                else
+                        pr_err("Internal error: kernel dso with non kernel map\n");
+        }
+}
+
 static int __maps__insert(struct maps *maps, struct map *new)
 {
 	struct map **maps_by_address = maps__maps_by_address(maps);
 	struct map **maps_by_name = maps__maps_by_name(maps);
-	const struct dso *dso = map__dso(new);
 	unsigned int nr_maps = maps__nr_maps(maps);
 	unsigned int nr_allocate = RC_CHK_ACCESS(maps)->nr_maps_allocated;
 
@@ -483,14 +501,9 @@ static int __maps__insert(struct maps *maps, struct map *new)
 	}
 	if (map__end(new) < map__start(new))
 		RC_CHK_ACCESS(maps)->ends_broken = true;
-	if (dso && dso__kernel(dso)) {
-		struct kmap *kmap = map__kmap(new);
 
-		if (kmap)
-			kmap->kmaps = maps;
-		else
-			pr_err("Internal error: kernel dso with non kernel map\n");
-	}
+	map__set_kmap_maps(new, maps);
+
 	return 0;
 }