1 files changed, 833 insertions, 473 deletions

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 0334fc18d9c65..ce13145a9f8e8 100644
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -6,81 +6,285 @@
 #include "dso.h"
 #include "map.h"
 #include "maps.h"
+#include "rwsem.h"
 #include "thread.h"
 #include "ui/ui.h"
 #include "unwind.h"
+#include <internal/rc_check.h>
 
-struct map_rb_node {
-	struct rb_node rb_node;
-	struct map *map;
+/*
+ * Locking/sorting note:
+ *
+ * Sorting is done with the write lock, iteration and binary searching happens
+ * under the read lock requiring being sorted. There is a race between sorting
+ * releasing the write lock and acquiring the read lock for iteration/searching
+ * where another thread could insert and break the sorting of the maps. In
+ * practice inserting maps should be rare meaning that the race shouldn't lead
+ * to live lock. Removal of maps doesn't break being sorted.
+ */
+
+DECLARE_RC_STRUCT(maps) {
+	struct rw_semaphore lock;
+	/**
+	 * @maps_by_address: array of maps sorted by their starting address if
+	 * maps_by_address_sorted is true.
+	 */
+	struct map	 **maps_by_address;
+	/**
+	 * @maps_by_name: optional array of maps sorted by their dso name if
+	 * maps_by_name_sorted is true.
+	 */
+	struct map	 **maps_by_name;
+	struct machine	 *machine;
+#ifdef HAVE_LIBUNWIND_SUPPORT
+	void		*addr_space;
+	const struct unwind_libunwind_ops *unwind_libunwind_ops;
+#endif
+	refcount_t	 refcnt;
+	/**
+	 * @nr_maps: number of maps_by_address, and possibly maps_by_name,
+	 * entries that contain maps.
+	 */
+	unsigned int	 nr_maps;
+	/**
+	 * @nr_maps_allocated: number of entries in maps_by_address and possibly
+	 * maps_by_name.
+	 */
+	unsigned int	 nr_maps_allocated;
+	/**
+	 * @last_search_by_name_idx: cache of last found by name entry's index
+	 * as frequent searches for the same dso name are common.
+	 */
+	unsigned int	 last_search_by_name_idx;
+	/** @maps_by_address_sorted: is maps_by_address sorted. */
+	bool		 maps_by_address_sorted;
+	/** @maps_by_name_sorted: is maps_by_name sorted. */
+	bool		 maps_by_name_sorted;
+	/** @ends_broken: does the map contain a map where end values are unset/unsorted? */
+	bool		 ends_broken;
 };
 
-#define maps__for_each_entry(maps, map) \
-	for (map = maps__first(maps); map; map = map_rb_node__next(map))
+static void check_invariants(const struct maps *maps __maybe_unused)
+{
+#ifndef NDEBUG
+	assert(RC_CHK_ACCESS(maps)->nr_maps <= RC_CHK_ACCESS(maps)->nr_maps_allocated);
+	for (unsigned int i = 0; i < RC_CHK_ACCESS(maps)->nr_maps; i++) {
+		struct map *map = RC_CHK_ACCESS(maps)->maps_by_address[i];
+
+		/* Check map is well-formed. */
+		assert(map__end(map) == 0 || map__start(map) <= map__end(map));
+		/* Expect at least 1 reference count. */
+		assert(refcount_read(map__refcnt(map)) > 0);
+
+		if (map__dso(map) && map__dso(map)->kernel)
+			assert(RC_CHK_EQUAL(map__kmap(map)->kmaps, maps));
+
+		if (i > 0) {
+			struct map *prev = RC_CHK_ACCESS(maps)->maps_by_address[i - 1];
+
+			/* If addresses are sorted... */
+			if (RC_CHK_ACCESS(maps)->maps_by_address_sorted) {
+				/* Maps should be in start address order. */
+				assert(map__start(prev) <= map__start(map));
+				/*
+				 * If the ends of maps aren't broken (during
+				 * construction) then they should be ordered
+				 * too.
+				 */
+				if (!RC_CHK_ACCESS(maps)->ends_broken) {
+					assert(map__end(prev) <= map__end(map));
+					assert(map__end(prev) <= map__start(map) ||
+					       map__start(prev) == map__start(map));
+				}
+			}
+		}
+	}
+	if (RC_CHK_ACCESS(maps)->maps_by_name) {
+		for (unsigned int i = 0; i < RC_CHK_ACCESS(maps)->nr_maps; i++) {
+			struct map *map = RC_CHK_ACCESS(maps)->maps_by_name[i];
 
-#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))
+			/*
+			 * Maps by name maps should be in maps_by_address, so
+			 * the reference count should be higher.
+			 */
+			assert(refcount_read(map__refcnt(map)) > 1);
+		}
+	}
+#endif
+}
 
-static struct rb_root *maps__entries(struct maps *maps)
+static struct map **maps__maps_by_address(const struct maps *maps)
 {
-	return &RC_CHK_ACCESS(maps)->entries;
+	return RC_CHK_ACCESS(maps)->maps_by_address;
 }
 
-static struct rw_semaphore *maps__lock(struct maps *maps)
+static void maps__set_maps_by_address(struct maps *maps, struct map **new)
 {
-	return &RC_CHK_ACCESS(maps)->lock;
+	RC_CHK_ACCESS(maps)->maps_by_address = new;
+
+}
+
+static struct map ***maps__maps_by_name_addr(struct maps *maps)
+{
+	return &RC_CHK_ACCESS(maps)->maps_by_name;
+}
+
+static void maps__set_nr_maps_allocated(struct maps *maps, unsigned int nr_maps_allocated)
+{
+	RC_CHK_ACCESS(maps)->nr_maps_allocated = nr_maps_allocated;
+}
+
+static void maps__set_nr_maps(struct maps *maps, unsigned int nr_maps)
+{
+	RC_CHK_ACCESS(maps)->nr_maps = nr_maps;
 }
 
-static struct map **maps__maps_by_name(struct maps *maps)
+/* Not in the header, to aid reference counting. */
+static struct map **maps__maps_by_name(const struct maps *maps)
 {
 	return RC_CHK_ACCESS(maps)->maps_by_name;
+
 }
 
-static struct map_rb_node *maps__first(struct maps *maps)
+static void maps__set_maps_by_name(struct maps *maps, struct map **new)
 {
-	struct rb_node *first = rb_first(maps__entries(maps));
+	RC_CHK_ACCESS(maps)->maps_by_name = new;
 
-	if (first)
-		return rb_entry(first, struct map_rb_node, rb_node);
-	return NULL;
 }
 
-static struct map_rb_node *map_rb_node__next(struct map_rb_node *node)
+static bool maps__maps_by_address_sorted(const struct maps *maps)
+{
+	return RC_CHK_ACCESS(maps)->maps_by_address_sorted;
+}
+
+static void maps__set_maps_by_address_sorted(struct maps *maps, bool value)
 {
-	struct rb_node *next;
+	RC_CHK_ACCESS(maps)->maps_by_address_sorted = value;
+}
 
-	if (!node)
-		return NULL;
+static bool maps__maps_by_name_sorted(const struct maps *maps)
+{
+	return RC_CHK_ACCESS(maps)->maps_by_name_sorted;
+}
 
-	next = rb_next(&node->rb_node);
+static void maps__set_maps_by_name_sorted(struct maps *maps, bool value)
+{
+	RC_CHK_ACCESS(maps)->maps_by_name_sorted = value;
+}
 
-	if (!next)
-		return NULL;
+struct machine *maps__machine(const struct maps *maps)
+{
+	return RC_CHK_ACCESS(maps)->machine;
+}
 
-	return rb_entry(next, struct map_rb_node, rb_node);
+unsigned int maps__nr_maps(const struct maps *maps)
+{
+	return RC_CHK_ACCESS(maps)->nr_maps;
 }
 
-static struct map_rb_node *maps__find_node(struct maps *maps, struct map *map)
+refcount_t *maps__refcnt(struct maps *maps)
 {
-	struct map_rb_node *rb_node;
+	return &RC_CHK_ACCESS(maps)->refcnt;
+}
 
-	maps__for_each_entry(maps, rb_node) {
-		if (rb_node->RC_CHK_ACCESS(map) == RC_CHK_ACCESS(map))
-			return rb_node;
-	}
-	return NULL;
+#ifdef HAVE_LIBUNWIND_SUPPORT
+void *maps__addr_space(const struct maps *maps)
+{
+	return RC_CHK_ACCESS(maps)->addr_space;
+}
+
+void maps__set_addr_space(struct maps *maps, void *addr_space)
+{
+	RC_CHK_ACCESS(maps)->addr_space = addr_space;
+}
+
+const struct unwind_libunwind_ops *maps__unwind_libunwind_ops(const struct maps *maps)
+{
+	return RC_CHK_ACCESS(maps)->unwind_libunwind_ops;
+}
+
+void maps__set_unwind_libunwind_ops(struct maps *maps, const struct unwind_libunwind_ops *ops)
+{
+	RC_CHK_ACCESS(maps)->unwind_libunwind_ops = ops;
+}
+#endif
+
+static struct rw_semaphore *maps__lock(struct maps *maps)
+{
+	/*
+	 * When the lock is acquired or released the maps invariants should
+	 * hold.
+	 */
+	check_invariants(maps);
+	return &RC_CHK_ACCESS(maps)->lock;
 }
 
 static void maps__init(struct maps *maps, struct machine *machine)
 {
-	refcount_set(maps__refcnt(maps), 1);
 	init_rwsem(maps__lock(maps));
-	RC_CHK_ACCESS(maps)->entries = RB_ROOT;
+	RC_CHK_ACCESS(maps)->maps_by_address = NULL;
+	RC_CHK_ACCESS(maps)->maps_by_name = NULL;
 	RC_CHK_ACCESS(maps)->machine = machine;
-	RC_CHK_ACCESS(maps)->last_search_by_name = NULL;
+#ifdef HAVE_LIBUNWIND_SUPPORT
+	RC_CHK_ACCESS(maps)->addr_space = NULL;
+	RC_CHK_ACCESS(maps)->unwind_libunwind_ops = NULL;
+#endif
+	refcount_set(maps__refcnt(maps), 1);
 	RC_CHK_ACCESS(maps)->nr_maps = 0;
-	RC_CHK_ACCESS(maps)->maps_by_name = NULL;
+	RC_CHK_ACCESS(maps)->nr_maps_allocated = 0;
+	RC_CHK_ACCESS(maps)->last_search_by_name_idx = 0;
+	RC_CHK_ACCESS(maps)->maps_by_address_sorted = true;
+	RC_CHK_ACCESS(maps)->maps_by_name_sorted = false;
+}
+
+static void maps__exit(struct maps *maps)
+{
+	struct map **maps_by_address = maps__maps_by_address(maps);
+	struct map **maps_by_name = maps__maps_by_name(maps);
+
+	for (unsigned int i = 0; i < maps__nr_maps(maps); i++) {
+		map__zput(maps_by_address[i]);
+		if (maps_by_name)
+			map__zput(maps_by_name[i]);
+	}
+	zfree(&maps_by_address);
+	zfree(&maps_by_name);
+	unwind__finish_access(maps);
+}
+
+struct maps *maps__new(struct machine *machine)
+{
+	struct maps *result;
+	RC_STRUCT(maps) *maps = zalloc(sizeof(*maps));
+
+	if (ADD_RC_CHK(result, maps))
+		maps__init(result, machine);
+
+	return result;
+}
+
+static void maps__delete(struct maps *maps)
+{
+	maps__exit(maps);
+	RC_CHK_FREE(maps);
+}
+
+struct maps *maps__get(struct maps *maps)
+{
+	struct maps *result;
+
+	if (RC_CHK_GET(result, maps))
+		refcount_inc(maps__refcnt(maps));
+
+	return result;
+}
+
+void maps__put(struct maps *maps)
+{
+	if (maps && refcount_dec_and_test(maps__refcnt(maps)))
+		maps__delete(maps);
+	else
+		RC_CHK_PUT(maps);
 }
 
 static void __maps__free_maps_by_name(struct maps *maps)
@@ -92,219 +296,330 @@ static void __maps__free_maps_by_name(struct maps *maps)
 		map__put(maps__maps_by_name(maps)[i]);
 
 	zfree(&RC_CHK_ACCESS(maps)->maps_by_name);
-	RC_CHK_ACCESS(maps)->nr_maps_allocated = 0;
 }
 
-static int __maps__insert(struct maps *maps, struct map *map)
+static int map__start_cmp(const void *a, const void *b)
 {
-	struct rb_node **p = &maps__entries(maps)->rb_node;
-	struct rb_node *parent = NULL;
-	const u64 ip = map__start(map);
-	struct map_rb_node *m, *new_rb_node;
-
-	new_rb_node = malloc(sizeof(*new_rb_node));
-	if (!new_rb_node)
-		return -ENOMEM;
-
-	RB_CLEAR_NODE(&new_rb_node->rb_node);
-	new_rb_node->map = map__get(map);
-
-	while (*p != NULL) {
-		parent = *p;
-		m = rb_entry(parent, struct map_rb_node, rb_node);
-		if (ip < map__start(m->map))
-			p = &(*p)->rb_left;
-		else
-			p = &(*p)->rb_right;
+	const struct map *map_a = *(const struct map * const *)a;
+	const struct map *map_b = *(const struct map * const *)b;
+	u64 map_a_start = map__start(map_a);
+	u64 map_b_start = map__start(map_b);
+
+	if (map_a_start == map_b_start) {
+		u64 map_a_end = map__end(map_a);
+		u64 map_b_end = map__end(map_b);
+
+		if  (map_a_end == map_b_end) {
+			/* Ensure maps with the same addresses have a fixed order. */
+			if (RC_CHK_ACCESS(map_a) == RC_CHK_ACCESS(map_b))
+				return 0;
+			return (intptr_t)RC_CHK_ACCESS(map_a) > (intptr_t)RC_CHK_ACCESS(map_b)
+				? 1 : -1;
+		}
+		return map_a_end > map_b_end ? 1 : -1;
 	}
-
-	rb_link_node(&new_rb_node->rb_node, parent, p);
-	rb_insert_color(&new_rb_node->rb_node, maps__entries(maps));
-	return 0;
+	return map_a_start > map_b_start ? 1 : -1;
 }
 
-int maps__insert(struct maps *maps, struct map *map)
+static void __maps__sort_by_address(struct maps *maps)
 {
-	int err;
-	const struct dso *dso = map__dso(map);
+	if (maps__maps_by_address_sorted(maps))
+		return;
+
+	qsort(maps__maps_by_address(maps),
+		maps__nr_maps(maps),
+		sizeof(struct map *),
+		map__start_cmp);
+	maps__set_maps_by_address_sorted(maps, true);
+}
 
+static void maps__sort_by_address(struct maps *maps)
+{
 	down_write(maps__lock(maps));
-	err = __maps__insert(maps, map);
-	if (err)
-		goto out;
-
-	++RC_CHK_ACCESS(maps)->nr_maps;
+	__maps__sort_by_address(maps);
+	up_write(maps__lock(maps));
+}
 
-	if (dso && dso->kernel) {
-		struct kmap *kmap = map__kmap(map);
+static int map__strcmp(const void *a, const void *b)
+{
+	const struct map *map_a = *(const struct map * const *)a;
+	const struct map *map_b = *(const struct map * const *)b;
+	const struct dso *dso_a = map__dso(map_a);
+	const struct dso *dso_b = map__dso(map_b);
+	int ret = strcmp(dso_a->short_name, dso_b->short_name);
 
-		if (kmap)
-			kmap->kmaps = maps;
-		else
-			pr_err("Internal error: kernel dso with non kernel map\n");
+	if (ret == 0 && RC_CHK_ACCESS(map_a) != RC_CHK_ACCESS(map_b)) {
+		/* Ensure distinct but name equal maps have an order. */
+		return map__start_cmp(a, b);
 	}
+	return ret;
+}
 
+static int maps__sort_by_name(struct maps *maps)
+{
+	int err = 0;
+	down_write(maps__lock(maps));
+	if (!maps__maps_by_name_sorted(maps)) {
+		struct map **maps_by_name = maps__maps_by_name(maps);
 
-	/*
-	 * If we already performed some search by name, then we need to add the just
-	 * inserted map and resort.
-	 */
-	if (maps__maps_by_name(maps)) {
-		if (maps__nr_maps(maps) > RC_CHK_ACCESS(maps)->nr_maps_allocated) {
-			int nr_allocate = maps__nr_maps(maps) * 2;
-			struct map **maps_by_name = realloc(maps__maps_by_name(maps),
-							    nr_allocate * sizeof(map));
-
-			if (maps_by_name == NULL) {
-				__maps__free_maps_by_name(maps);
+		if (!maps_by_name) {
+			maps_by_name = malloc(RC_CHK_ACCESS(maps)->nr_maps_allocated *
+					sizeof(*maps_by_name));
+			if (!maps_by_name)
 				err = -ENOMEM;
-				goto out;
-			}
+			else {
+				struct map **maps_by_address = maps__maps_by_address(maps);
+				unsigned int n = maps__nr_maps(maps);
 
-			RC_CHK_ACCESS(maps)->maps_by_name = maps_by_name;
-			RC_CHK_ACCESS(maps)->nr_maps_allocated = nr_allocate;
+				maps__set_maps_by_name(maps, maps_by_name);
+				for (unsigned int i = 0; i < n; i++)
+					maps_by_name[i] = map__get(maps_by_address[i]);
+			}
+		}
+		if (!err) {
+			qsort(maps_by_name,
+				maps__nr_maps(maps),
+				sizeof(struct map *),
+				map__strcmp);
+			maps__set_maps_by_name_sorted(maps, true);
 		}
-		maps__maps_by_name(maps)[maps__nr_maps(maps) - 1] = map__get(map);
-		__maps__sort_by_name(maps);
 	}
- out:
 	up_write(maps__lock(maps));
 	return err;
 }
 
-static void __maps__remove(struct maps *maps, struct map_rb_node *rb_node)
+static unsigned int maps__by_address_index(const struct maps *maps, const struct map *map)
 {
-	rb_erase_init(&rb_node->rb_node, maps__entries(maps));
-	map__put(rb_node->map);
-	free(rb_node);
+	struct map **maps_by_address = maps__maps_by_address(maps);
+
+	if (maps__maps_by_address_sorted(maps)) {
+		struct map **mapp =
+			bsearch(&map, maps__maps_by_address(maps), maps__nr_maps(maps),
+				sizeof(*mapp), map__start_cmp);
+
+		if (mapp)
+			return mapp - maps_by_address;
+	} else {
+		for (unsigned int i = 0; i < maps__nr_maps(maps); i++) {
+			if (RC_CHK_ACCESS(maps_by_address[i]) == RC_CHK_ACCESS(map))
+				return i;
+		}
+	}
+	pr_err("Map missing from maps");
+	return -1;
 }
 
-void maps__remove(struct maps *maps, struct map *map)
+static unsigned int maps__by_name_index(const struct maps *maps, const struct map *map)
 {
-	struct map_rb_node *rb_node;
-
-	down_write(maps__lock(maps));
-	if (RC_CHK_ACCESS(maps)->last_search_by_name == map)
-		RC_CHK_ACCESS(maps)->last_search_by_name = NULL;
-
-	rb_node = maps__find_node(maps, map);
-	assert(rb_node->RC_CHK_ACCESS(map) == RC_CHK_ACCESS(map));
-	__maps__remove(maps, rb_node);
-	if (maps__maps_by_name(maps))
-		__maps__free_maps_by_name(maps);
-	--RC_CHK_ACCESS(maps)->nr_maps;
-	up_write(maps__lock(maps));
+	struct map **maps_by_name = maps__maps_by_name(maps);
+
+	if (maps__maps_by_name_sorted(maps)) {
+		struct map **mapp =
+			bsearch(&map, maps_by_name, maps__nr_maps(maps),
+				sizeof(*mapp), map__strcmp);
+
+		if (mapp)
+			return mapp - maps_by_name;
+	} else {
+		for (unsigned int i = 0; i < maps__nr_maps(maps); i++) {
+			if (RC_CHK_ACCESS(maps_by_name[i]) == RC_CHK_ACCESS(map))
+				return i;
+		}
+	}
+	pr_err("Map missing from maps");
+	return -1;
 }
 
-static void __maps__purge(struct maps *maps)
+static int __maps__insert(struct maps *maps, struct map *new)
 {
-	struct map_rb_node *pos, *next;
+	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;
+
+	if (nr_maps + 1 > nr_allocate) {
+		nr_allocate = !nr_allocate ? 32 : nr_allocate * 2;
+
+		maps_by_address = realloc(maps_by_address, nr_allocate * sizeof(new));
+		if (!maps_by_address)
+			return -ENOMEM;
+
+		maps__set_maps_by_address(maps, maps_by_address);
+		if (maps_by_name) {
+			maps_by_name = realloc(maps_by_name, nr_allocate * sizeof(new));
+			if (!maps_by_name) {
+				/*
+				 * If by name fails, just disable by name and it will
+				 * recompute next time it is required.
+				 */
+				__maps__free_maps_by_name(maps);
+			}
+			maps__set_maps_by_name(maps, maps_by_name);
+		}
+		RC_CHK_ACCESS(maps)->nr_maps_allocated = nr_allocate;
+	}
+	/* Insert the value at the end. */
+	maps_by_address[nr_maps] = map__get(new);
+	if (maps_by_name)
+		maps_by_name[nr_maps] = map__get(new);
 
-	if (maps__maps_by_name(maps))
-		__maps__free_maps_by_name(maps);
+	nr_maps++;
+	RC_CHK_ACCESS(maps)->nr_maps = nr_maps;
 
-	maps__for_each_entry_safe(maps, pos, next) {
-		rb_erase_init(&pos->rb_node,  maps__entries(maps));
-		map__put(pos->map);
-		free(pos);
+	/*
+	 * Recompute if things are sorted. If things are inserted in a sorted
+	 * manner, for example by processing /proc/pid/maps, then no
+	 * sorting/resorting will be necessary.
+	 */
+	if (nr_maps == 1) {
+		/* If there's just 1 entry then maps are sorted. */
+		maps__set_maps_by_address_sorted(maps, true);
+		maps__set_maps_by_name_sorted(maps, maps_by_name != NULL);
+	} else {
+		/* Sorted if maps were already sorted and this map starts after the last one. */
+		maps__set_maps_by_address_sorted(maps,
+			maps__maps_by_address_sorted(maps) &&
+			map__end(maps_by_address[nr_maps - 2]) <= map__start(new));
+		maps__set_maps_by_name_sorted(maps, false);
 	}
+	if (map__end(new) < map__start(new))
+		RC_CHK_ACCESS(maps)->ends_broken = true;
+	if (dso && dso->kernel) {
+		struct kmap *kmap = map__kmap(new);
+
+		if (kmap)
+			kmap->kmaps = maps;
+		else
+			pr_err("Internal error: kernel dso with non kernel map\n");
+	}
+	return 0;
 }
 
-static void maps__exit(struct maps *maps)
+int maps__insert(struct maps *maps, struct map *map)
 {
+	int ret;
+
 	down_write(maps__lock(maps));
-	__maps__purge(maps);
+	ret = __maps__insert(maps, map);
 	up_write(maps__lock(maps));
+	return ret;
 }
 
-bool maps__empty(struct maps *maps)
-{
-	return !maps__first(maps);
-}
-
-struct maps *maps__new(struct machine *machine)
+static void __maps__remove(struct maps *maps, struct map *map)
 {
-	struct maps *result;
-	RC_STRUCT(maps) *maps = zalloc(sizeof(*maps));
-
-	if (ADD_RC_CHK(result, maps))
-		maps__init(result, machine);
+	struct map **maps_by_address = maps__maps_by_address(maps);
+	struct map **maps_by_name = maps__maps_by_name(maps);
+	unsigned int nr_maps = maps__nr_maps(maps);
+	unsigned int address_idx;
+
+	/* Slide later mappings over the one to remove */
+	address_idx = maps__by_address_index(maps, map);
+	map__put(maps_by_address[address_idx]);
+	memmove(&maps_by_address[address_idx],
+		&maps_by_address[address_idx + 1],
+		(nr_maps - address_idx - 1) * sizeof(*maps_by_address));
+
+	if (maps_by_name) {
+		unsigned int name_idx = maps__by_name_index(maps, map);
+
+		map__put(maps_by_name[name_idx]);
+		memmove(&maps_by_name[name_idx],
+			&maps_by_name[name_idx + 1],
+			(nr_maps - name_idx - 1) *  sizeof(*maps_by_name));
+	}
 
-	return result;
+	--RC_CHK_ACCESS(maps)->nr_maps;
 }
 
-static void maps__delete(struct maps *maps)
+void maps__remove(struct maps *maps, struct map *map)
 {
-	maps__exit(maps);
-	unwind__finish_access(maps);
-	RC_CHK_FREE(maps);
+	down_write(maps__lock(maps));
+	__maps__remove(maps, map);
+	up_write(maps__lock(maps));
 }
 
-struct maps *maps__get(struct maps *maps)
+bool maps__empty(struct maps *maps)
 {
-	struct maps *result;
+	bool res;
 
-	if (RC_CHK_GET(result, maps))
-		refcount_inc(maps__refcnt(maps));
+	down_read(maps__lock(maps));
+	res = maps__nr_maps(maps) == 0;
+	up_read(maps__lock(maps));
 
-	return result;
+	return res;
 }
 
-void maps__put(struct maps *maps)
+bool maps__equal(struct maps *a, struct maps *b)
 {
-	if (maps && refcount_dec_and_test(maps__refcnt(maps)))
-		maps__delete(maps);
-	else
-		RC_CHK_PUT(maps);
+	return RC_CHK_EQUAL(a, b);
 }
 
 int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data), void *data)
 {
-	struct map_rb_node *pos;
+	bool done = false;
 	int ret = 0;
 
-	down_read(maps__lock(maps));
-	maps__for_each_entry(maps, pos)	{
-		ret = cb(pos->map, data);
-		if (ret)
-			break;
+	/* See locking/sorting note. */
+	while (!done) {
+		down_read(maps__lock(maps));
+		if (maps__maps_by_address_sorted(maps)) {
+			/*
+			 * maps__for_each_map callbacks may buggily/unsafely
+			 * insert into maps_by_address. Deliberately reload
+			 * maps__nr_maps and maps_by_address on each iteration
+			 * to avoid using memory freed by maps__insert growing
+			 * the array - this may cause maps to be skipped or
+			 * repeated.
+			 */
+			for (unsigned int i = 0; i < maps__nr_maps(maps); i++) {
+				struct map **maps_by_address = maps__maps_by_address(maps);
+				struct map *map = maps_by_address[i];
+
+				ret = cb(map, data);
+				if (ret)
+					break;
+			}
+			done = true;
+		}
+		up_read(maps__lock(maps));
+		if (!done)
+			maps__sort_by_address(maps);
 	}
-	up_read(maps__lock(maps));
 	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;
+	struct map **maps_by_address;
 
 	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;
-		}
+	maps_by_address = maps__maps_by_address(maps);
+	for (unsigned int i = 0; i < maps__nr_maps(maps);) {
+		if (cb(maps_by_address[i], data))
+			__maps__remove(maps, maps_by_address[i]);
+		else
+			i++;
 	}
-	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);
+	struct symbol *result = NULL;
 
 	/* Ensure map is loaded before using map->map_ip */
-	if (map != NULL && map__load(map) >= 0) {
-		if (mapp != NULL)
-			*mapp = map;
-		return map__find_symbol(map, map__map_ip(map, addr));
-	}
+	if (map != NULL && map__load(map) >= 0)
+		result = map__find_symbol(map, map__map_ip(map, addr));
+
+	if (mapp)
+		*mapp = map;
+	else
+		map__put(map);
 
-	return NULL;
+	return result;
 }
 
 struct maps__find_symbol_by_name_args {
@@ -393,24 +708,28 @@ size_t maps__fprintf(struct maps *maps, FILE *fp)
  * Find first map where end > map->start.
  * Same as find_vma() in kernel.
  */
-static struct rb_node *first_ending_after(struct maps *maps, const struct map *map)
+static unsigned int first_ending_after(struct maps *maps, const struct map *map)
 {
-	struct rb_root *root;
-	struct rb_node *next, *first;
+	struct map **maps_by_address = maps__maps_by_address(maps);
+	int low = 0, high = (int)maps__nr_maps(maps) - 1, first = high + 1;
+
+	assert(maps__maps_by_address_sorted(maps));
+	if (low <= high && map__end(maps_by_address[0]) > map__start(map))
+		return 0;
 
-	root = maps__entries(maps);
-	next = root->rb_node;
-	first = NULL;
-	while (next) {
-		struct map_rb_node *pos = rb_entry(next, struct map_rb_node, rb_node);
+	while (low <= high) {
+		int mid = (low + high) / 2;
+		struct map *pos = maps_by_address[mid];
 
-		if (map__end(pos->map) > map__start(map)) {
-			first = next;
-			if (map__start(pos->map) <= map__start(map))
+		if (map__end(pos) > map__start(map)) {
+			first = mid;
+			if (map__start(pos) <= map__start(map)) {
+				/* Entry overlaps map. */
 				break;
-			next = next->rb_left;
+			}
+			high = mid - 1;
 		} else
-			next = next->rb_right;
+			low = mid + 1;
 	}
 	return first;
 }
@@ -419,171 +738,249 @@ static struct rb_node *first_ending_after(struct maps *maps, const struct map *m
  * Adds new to maps, if new overlaps existing entries then the existing maps are
  * adjusted or removed so that new fits without overlapping any entries.
  */
-int maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
+static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 {
-
-	struct rb_node *next;
+	struct map **maps_by_address;
 	int err = 0;
 	FILE *fp = debug_file();
 
-	down_write(maps__lock(maps));
+sort_again:
+	if (!maps__maps_by_address_sorted(maps))
+		__maps__sort_by_address(maps);
 
-	next = first_ending_after(maps, new);
-	while (next && !err) {
-		struct map_rb_node *pos = rb_entry(next, struct map_rb_node, rb_node);
-		next = rb_next(&pos->rb_node);
+	maps_by_address = maps__maps_by_address(maps);
+	/*
+	 * Iterate through entries where the end of the existing entry is
+	 * greater-than the new map's start.
+	 */
+	for (unsigned int i = first_ending_after(maps, new); i < maps__nr_maps(maps); ) {
+		struct map *pos = maps_by_address[i];
+		struct map *before = NULL, *after = NULL;
 
 		/*
 		 * Stop if current map starts after map->end.
 		 * Maps are ordered by start: next will not overlap for sure.
 		 */
-		if (map__start(pos->map) >= map__end(new))
+		if (map__start(pos) >= map__end(new))
 			break;
 
-		if (verbose >= 2) {
-
-			if (use_browser) {
-				pr_debug("overlapping maps in %s (disable tui for more info)\n",
-					 map__dso(new)->name);
-			} else {
-				pr_debug("overlapping maps:\n");
-				map__fprintf(new, fp);
-				map__fprintf(pos->map, fp);
-			}
+		if (use_browser) {
+			pr_debug("overlapping maps in %s (disable tui for more info)\n",
+				map__dso(new)->name);
+		} else if (verbose >= 2) {
+			pr_debug("overlapping maps:\n");
+			map__fprintf(new, fp);
+			map__fprintf(pos, fp);
 		}
 
-		rb_erase_init(&pos->rb_node, maps__entries(maps));
 		/*
 		 * Now check if we need to create new maps for areas not
 		 * overlapped by the new map:
 		 */
-		if (map__start(new) > map__start(pos->map)) {
-			struct map *before = map__clone(pos->map);
+		if (map__start(new) > map__start(pos)) {
+			/* Map starts within existing map. Need to shorten the existing map. */
+			before = map__clone(pos);
 
 			if (before == NULL) {
 				err = -ENOMEM;
-				goto put_map;
+				goto out_err;
 			}
-
 			map__set_end(before, map__start(new));
-			err = __maps__insert(maps, before);
-			if (err) {
-				map__put(before);
-				goto put_map;
-			}
 
 			if (verbose >= 2 && !use_browser)
 				map__fprintf(before, fp);
-			map__put(before);
 		}
-
-		if (map__end(new) < map__end(pos->map)) {
-			struct map *after = map__clone(pos->map);
+		if (map__end(new) < map__end(pos)) {
+			/* The new map isn't as long as the existing map. */
+			after = map__clone(pos);
 
 			if (after == NULL) {
+				map__zput(before);
 				err = -ENOMEM;
-				goto put_map;
+				goto out_err;
 			}
 
 			map__set_start(after, map__end(new));
-			map__add_pgoff(after, map__end(new) - map__start(pos->map));
-			assert(map__map_ip(pos->map, map__end(new)) ==
-				map__map_ip(after, map__end(new)));
-			err = __maps__insert(maps, after);
-			if (err) {
-				map__put(after);
-				goto put_map;
-			}
+			map__add_pgoff(after, map__end(new) - map__start(pos));
+			assert(map__map_ip(pos, map__end(new)) ==
+			       map__map_ip(after, map__end(new)));
+
 			if (verbose >= 2 && !use_browser)
 				map__fprintf(after, fp);
-			map__put(after);
 		}
-put_map:
-		map__put(pos->map);
-		free(pos);
+		/*
+		 * If adding one entry, for `before` or `after`, we can replace
+		 * the existing entry. If both `before` and `after` are
+		 * necessary than an insert is needed. If the existing entry
+		 * entirely overlaps the existing entry it can just be removed.
+		 */
+		if (before) {
+			map__put(maps_by_address[i]);
+			maps_by_address[i] = before;
+			/* Maps are still ordered, go to next one. */
+			i++;
+			if (after) {
+				__maps__insert(maps, after);
+				map__put(after);
+				if (!maps__maps_by_address_sorted(maps)) {
+					/*
+					 * Sorting broken so invariants don't
+					 * hold, sort and go again.
+					 */
+					goto sort_again;
+				}
+				/*
+				 * Maps are still ordered, skip after and go to
+				 * next one (terminate loop).
+				 */
+				i++;
+			}
+		} else if (after) {
+			map__put(maps_by_address[i]);
+			maps_by_address[i] = after;
+			/* Maps are ordered, go to next one. */
+			i++;
+		} else {
+			__maps__remove(maps, pos);
+			/*
+			 * Maps are ordered but no need to increase `i` as the
+			 * later maps were moved down.
+			 */
+		}
+		check_invariants(maps);
 	}
 	/* Add the map. */
-	err = __maps__insert(maps, new);
-	up_write(maps__lock(maps));
+	__maps__insert(maps, new);
+out_err:
 	return err;
 }
 
-int maps__copy_from(struct maps *maps, struct maps *parent)
+int maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 {
 	int err;
-	struct map_rb_node *rb_node;
 
+	down_write(maps__lock(maps));
+	err =  __maps__fixup_overlap_and_insert(maps, new);
+	up_write(maps__lock(maps));
+	return err;
+}
+
+int maps__copy_from(struct maps *dest, struct maps *parent)
+{
+	/* Note, if struct map were immutable then cloning could use ref counts. */
+	struct map **parent_maps_by_address;
+	int err = 0;
+	unsigned int n;
+
+	down_write(maps__lock(dest));
 	down_read(maps__lock(parent));
 
-	maps__for_each_entry(parent, rb_node) {
-		struct map *new = map__clone(rb_node->map);
+	parent_maps_by_address = maps__maps_by_address(parent);
+	n = maps__nr_maps(parent);
+	if (maps__nr_maps(dest) == 0) {
+		/* No existing mappings so just copy from parent to avoid reallocs in insert. */
+		unsigned int nr_maps_allocated = RC_CHK_ACCESS(parent)->nr_maps_allocated;
+		struct map **dest_maps_by_address =
+			malloc(nr_maps_allocated * sizeof(struct map *));
+		struct map **dest_maps_by_name = NULL;
 
-		if (new == NULL) {
+		if (!dest_maps_by_address)
 			err = -ENOMEM;
-			goto out_unlock;
+		else {
+			if (maps__maps_by_name(parent)) {
+				dest_maps_by_name =
+					malloc(nr_maps_allocated * sizeof(struct map *));
+			}
+
+			RC_CHK_ACCESS(dest)->maps_by_address = dest_maps_by_address;
+			RC_CHK_ACCESS(dest)->maps_by_name = dest_maps_by_name;
+			RC_CHK_ACCESS(dest)->nr_maps_allocated = nr_maps_allocated;
 		}
 
-		err = unwind__prepare_access(maps, new, NULL);
-		if (err)
-			goto out_unlock;
+		for (unsigned int i = 0; !err && i < n; i++) {
+			struct map *pos = parent_maps_by_address[i];
+			struct map *new = map__clone(pos);
 
-		err = maps__insert(maps, new);
-		if (err)
-			goto out_unlock;
+			if (!new)
+				err = -ENOMEM;
+			else {
+				err = unwind__prepare_access(dest, new, NULL);
+				if (!err) {
+					dest_maps_by_address[i] = new;
+					if (dest_maps_by_name)
+						dest_maps_by_name[i] = map__get(new);
+					RC_CHK_ACCESS(dest)->nr_maps = i + 1;
+				}
+			}
+			if (err)
+				map__put(new);
+		}
+		maps__set_maps_by_address_sorted(dest, maps__maps_by_address_sorted(parent));
+		if (!err) {
+			RC_CHK_ACCESS(dest)->last_search_by_name_idx =
+				RC_CHK_ACCESS(parent)->last_search_by_name_idx;
+			maps__set_maps_by_name_sorted(dest,
+						dest_maps_by_name &&
+						maps__maps_by_name_sorted(parent));
+		} else {
+			RC_CHK_ACCESS(dest)->last_search_by_name_idx = 0;
+			maps__set_maps_by_name_sorted(dest, false);
+		}
+	} else {
+		/* Unexpected copying to a maps containing entries. */
+		for (unsigned int i = 0; !err && i < n; i++) {
+			struct map *pos = parent_maps_by_address[i];
+			struct map *new = map__clone(pos);
 
-		map__put(new);
+			if (!new)
+				err = -ENOMEM;
+			else {
+				err = unwind__prepare_access(dest, new, NULL);
+				if (!err)
+					err = __maps__insert(dest, new);
+			}
+			map__put(new);
+		}
 	}
-
-	err = 0;
-out_unlock:
 	up_read(maps__lock(parent));
+	up_write(maps__lock(dest));
 	return err;
 }
 
-struct map *maps__find(struct maps *maps, u64 ip)
+static int map__addr_cmp(const void *key, const void *entry)
 {
-	struct rb_node *p;
-	struct map_rb_node *m;
-
+	const u64 ip = *(const u64 *)key;
+	const struct map *map = *(const struct map * const *)entry;
 
-	down_read(maps__lock(maps));
-
-	p = maps__entries(maps)->rb_node;
-	while (p != NULL) {
-		m = rb_entry(p, struct map_rb_node, rb_node);
-		if (ip < map__start(m->map))
-			p = p->rb_left;
-		else if (ip >= map__end(m->map))
-			p = p->rb_right;
-		else
-			goto out;
-	}
-
-	m = NULL;
-out:
-	up_read(maps__lock(maps));
-	return m ? m->map : NULL;
+	if (ip < map__start(map))
+		return -1;
+	if (ip >= map__end(map))
+		return 1;
+	return 0;
 }
 
-static int map__strcmp(const void *a, const void *b)
+struct map *maps__find(struct maps *maps, u64 ip)
 {
-	const struct map *map_a = *(const struct map **)a;
-	const struct map *map_b = *(const struct map **)b;
-	const struct dso *dso_a = map__dso(map_a);
-	const struct dso *dso_b = map__dso(map_b);
-	int ret = strcmp(dso_a->short_name, dso_b->short_name);
-
-	if (ret == 0 && map_a != map_b) {
-		/*
-		 * Ensure distinct but name equal maps have an order in part to
-		 * aid reference counting.
-		 */
-		ret = (int)map__start(map_a) - (int)map__start(map_b);
-		if (ret == 0)
-			ret = (int)((intptr_t)map_a - (intptr_t)map_b);
+	struct map *result = NULL;
+	bool done = false;
+
+	/* See locking/sorting note. */
+	while (!done) {
+		down_read(maps__lock(maps));
+		if (maps__maps_by_address_sorted(maps)) {
+			struct map **mapp =
+				bsearch(&ip, maps__maps_by_address(maps), maps__nr_maps(maps),
+					sizeof(*mapp), map__addr_cmp);
+
+			if (mapp)
+				result = map__get(*mapp);
+			done = true;
+		}
+		up_read(maps__lock(maps));
+		if (!done)
+			maps__sort_by_address(maps);
 	}
-
-	return ret;
+	return result;
 }
 
 static int map__strcmp_name(const void *name, const void *b)
@@ -593,126 +990,113 @@ static int map__strcmp_name(const void *name, const void *b)
 	return strcmp(name, dso->short_name);
 }
 
-void __maps__sort_by_name(struct maps *maps)
-{
-	qsort(maps__maps_by_name(maps), maps__nr_maps(maps), sizeof(struct map *), map__strcmp);
-}
-
-static int map__groups__sort_by_name_from_rbtree(struct maps *maps)
-{
-	struct map_rb_node *rb_node;
-	struct map **maps_by_name = realloc(maps__maps_by_name(maps),
-					    maps__nr_maps(maps) * sizeof(struct map *));
-	int i = 0;
-
-	if (maps_by_name == NULL)
-		return -1;
-
-	up_read(maps__lock(maps));
-	down_write(maps__lock(maps));
-
-	RC_CHK_ACCESS(maps)->maps_by_name = maps_by_name;
-	RC_CHK_ACCESS(maps)->nr_maps_allocated = maps__nr_maps(maps);
-
-	maps__for_each_entry(maps, rb_node)
-		maps_by_name[i++] = map__get(rb_node->map);
-
-	__maps__sort_by_name(maps);
-
-	up_write(maps__lock(maps));
-	down_read(maps__lock(maps));
-
-	return 0;
-}
-
-static struct map *__maps__find_by_name(struct maps *maps, const char *name)
+struct map *maps__find_by_name(struct maps *maps, const char *name)
 {
-	struct map **mapp;
-
-	if (maps__maps_by_name(maps) == NULL &&
-	    map__groups__sort_by_name_from_rbtree(maps))
-		return NULL;
+	struct map *result = NULL;
+	bool done = false;
 
-	mapp = bsearch(name, maps__maps_by_name(maps), maps__nr_maps(maps),
-		       sizeof(*mapp), map__strcmp_name);
-	if (mapp)
-		return *mapp;
-	return NULL;
-}
+	/* See locking/sorting note. */
+	while (!done) {
+		unsigned int i;
 
-struct map *maps__find_by_name(struct maps *maps, const char *name)
-{
-	struct map_rb_node *rb_node;
-	struct map *map;
+		down_read(maps__lock(maps));
 
-	down_read(maps__lock(maps));
+		/* First check last found entry. */
+		i = RC_CHK_ACCESS(maps)->last_search_by_name_idx;
+		if (i < maps__nr_maps(maps) && maps__maps_by_name(maps)) {
+			struct dso *dso = map__dso(maps__maps_by_name(maps)[i]);
 
+			if (dso && strcmp(dso->short_name, name) == 0) {
+				result = map__get(maps__maps_by_name(maps)[i]);
+				done = true;
+			}
+		}
 
-	if (RC_CHK_ACCESS(maps)->last_search_by_name) {
-		const struct dso *dso = map__dso(RC_CHK_ACCESS(maps)->last_search_by_name);
+		/* Second search sorted array. */
+		if (!done && maps__maps_by_name_sorted(maps)) {
+			struct map **mapp =
+				bsearch(name, maps__maps_by_name(maps), maps__nr_maps(maps),
+					sizeof(*mapp), map__strcmp_name);
 
-		if (strcmp(dso->short_name, name) == 0) {
-			map = RC_CHK_ACCESS(maps)->last_search_by_name;
-			goto out_unlock;
+			if (mapp) {
+				result = map__get(*mapp);
+				i = mapp - maps__maps_by_name(maps);
+				RC_CHK_ACCESS(maps)->last_search_by_name_idx = i;
+			}
+			done = true;
 		}
-	}
-	/*
-	 * If we have maps->maps_by_name, then the name isn't in the rbtree,
-	 * as maps->maps_by_name mirrors the rbtree when lookups by name are
-	 * made.
-	 */
-	map = __maps__find_by_name(maps, name);
-	if (map || maps__maps_by_name(maps) != NULL)
-		goto out_unlock;
-
-	/* Fallback to traversing the rbtree... */
-	maps__for_each_entry(maps, rb_node) {
-		struct dso *dso;
-
-		map = rb_node->map;
-		dso = map__dso(map);
-		if (strcmp(dso->short_name, name) == 0) {
-			RC_CHK_ACCESS(maps)->last_search_by_name = map;
-			goto out_unlock;
+		up_read(maps__lock(maps));
+		if (!done) {
+			/* Sort and retry binary search. */
+			if (maps__sort_by_name(maps)) {
+				/*
+				 * Memory allocation failed do linear search
+				 * through address sorted maps.
+				 */
+				struct map **maps_by_address;
+				unsigned int n;
+
+				down_read(maps__lock(maps));
+				maps_by_address =  maps__maps_by_address(maps);
+				n = maps__nr_maps(maps);
+				for (i = 0; i < n; i++) {
+					struct map *pos = maps_by_address[i];
+					struct dso *dso = map__dso(pos);
+
+					if (dso && strcmp(dso->short_name, name) == 0) {
+						result = map__get(pos);
+						break;
+					}
+				}
+				up_read(maps__lock(maps));
+				done = true;
+			}
 		}
 	}
-	map = NULL;
-
-out_unlock:
-	up_read(maps__lock(maps));
-	return map;
+	return result;
 }
 
 struct map *maps__find_next_entry(struct maps *maps, struct map *map)
 {
-	struct map_rb_node *rb_node = maps__find_node(maps, map);
-	struct map_rb_node *next = map_rb_node__next(rb_node);
+	unsigned int i;
+	struct map *result = NULL;
 
-	if (next)
-		return next->map;
+	down_read(maps__lock(maps));
+	i = maps__by_address_index(maps, map);
+	if (i < maps__nr_maps(maps))
+		result = map__get(maps__maps_by_address(maps)[i]);
 
-	return NULL;
+	up_read(maps__lock(maps));
+	return result;
 }
 
 void maps__fixup_end(struct maps *maps)
 {
-	struct map_rb_node *prev = NULL, *curr;
+	struct map **maps_by_address;
+	unsigned int n;
 
 	down_write(maps__lock(maps));
+	if (!maps__maps_by_address_sorted(maps))
+		__maps__sort_by_address(maps);
 
-	maps__for_each_entry(maps, curr) {
-		if (prev && (!map__end(prev->map) || map__end(prev->map) > map__start(curr->map)))
-			map__set_end(prev->map, map__start(curr->map));
+	maps_by_address = maps__maps_by_address(maps);
+	n = maps__nr_maps(maps);
+	for (unsigned int i = 1; i < n; i++) {
+		struct map *prev = maps_by_address[i - 1];
+		struct map *curr = maps_by_address[i];
 
-		prev = curr;
+		if (!map__end(prev) || map__end(prev) > map__start(curr))
+			map__set_end(prev, map__start(curr));
 	}
 
 	/*
 	 * We still haven't the actual symbols, so guess the
 	 * last map final address.
 	 */
-	if (curr && !map__end(curr->map))
-		map__set_end(curr->map, ~0ULL);
+	if (n > 0 && !map__end(maps_by_address[n - 1]))
+		map__set_end(maps_by_address[n - 1], ~0ULL);
+
+	RC_CHK_ACCESS(maps)->ends_broken = false;
 
 	up_write(maps__lock(maps));
 }
@@ -723,117 +1107,93 @@ void maps__fixup_end(struct maps *maps)
  */
 int maps__merge_in(struct maps *kmaps, struct map *new_map)
 {
-	struct map_rb_node *rb_node;
-	struct rb_node *first;
-	bool overlaps;
-	LIST_HEAD(merged);
-	int err = 0;
-
-	down_read(maps__lock(kmaps));
-	first = first_ending_after(kmaps, new_map);
-	rb_node = first ? rb_entry(first, struct map_rb_node, rb_node) : NULL;
-	overlaps = rb_node && map__start(rb_node->map) < map__end(new_map);
-	up_read(maps__lock(kmaps));
+	unsigned int first_after_, kmaps__nr_maps;
+	struct map **kmaps_maps_by_address;
+	struct map **merged_maps_by_address;
+	unsigned int merged_nr_maps_allocated;
+
+	/* First try under a read lock. */
+	while (true) {
+		down_read(maps__lock(kmaps));
+		if (maps__maps_by_address_sorted(kmaps))
+			break;
 
-	if (!overlaps)
-		return maps__insert(kmaps, new_map);
+		up_read(maps__lock(kmaps));
 
-	maps__for_each_entry(kmaps, rb_node) {
-		struct map *old_map = rb_node->map;
+		/* First after binary search requires sorted maps. Sort and try again. */
+		maps__sort_by_address(kmaps);
+	}
+	first_after_ = first_ending_after(kmaps, new_map);
+	kmaps_maps_by_address = maps__maps_by_address(kmaps);
 
-		/* no overload with this one */
-		if (map__end(new_map) < map__start(old_map) ||
-		    map__start(new_map) >= map__end(old_map))
-			continue;
+	if (first_after_ >= maps__nr_maps(kmaps) ||
+	    map__start(kmaps_maps_by_address[first_after_]) >= map__end(new_map)) {
+		/* No overlap so regular insert suffices. */
+		up_read(maps__lock(kmaps));
+		return maps__insert(kmaps, new_map);
+	}
+	up_read(maps__lock(kmaps));
 
-		if (map__start(new_map) < map__start(old_map)) {
-			/*
-			 * |new......
-			 *       |old....
-			 */
-			if (map__end(new_map) < map__end(old_map)) {
-				/*
-				 * |new......|     -> |new..|
-				 *       |old....| ->       |old....|
-				 */
-				map__set_end(new_map, map__start(old_map));
-			} else {
-				/*
-				 * |new.............| -> |new..|       |new..|
-				 *       |old....|    ->       |old....|
-				 */
-				struct map_list_node *m = map_list_node__new();
+	/* Plain insert with a read-lock failed, try again now with the write lock. */
+	down_write(maps__lock(kmaps));
+	if (!maps__maps_by_address_sorted(kmaps))
+		__maps__sort_by_address(kmaps);
+
+	first_after_ = first_ending_after(kmaps, new_map);
+	kmaps_maps_by_address = maps__maps_by_address(kmaps);
+	kmaps__nr_maps = maps__nr_maps(kmaps);
+
+	if (first_after_ >= kmaps__nr_maps ||
+	    map__start(kmaps_maps_by_address[first_after_]) >= map__end(new_map)) {
+		/* No overlap so regular insert suffices. */
+		int ret = __maps__insert(kmaps, new_map);
+		up_write(maps__lock(kmaps));
+		return ret;
+	}
+	/* Array to merge into, possibly 1 more for the sake of new_map. */
+	merged_nr_maps_allocated = RC_CHK_ACCESS(kmaps)->nr_maps_allocated;
+	if (kmaps__nr_maps + 1 == merged_nr_maps_allocated)
+		merged_nr_maps_allocated++;
+
+	merged_maps_by_address = malloc(merged_nr_maps_allocated * sizeof(*merged_maps_by_address));
+	if (!merged_maps_by_address) {
+		up_write(maps__lock(kmaps));
+		return -ENOMEM;
+	}
+	maps__set_maps_by_address(kmaps, merged_maps_by_address);
+	maps__set_maps_by_address_sorted(kmaps, true);
+	zfree(maps__maps_by_name_addr(kmaps));
+	maps__set_maps_by_name_sorted(kmaps, true);
+	maps__set_nr_maps_allocated(kmaps, merged_nr_maps_allocated);
 
-				if (!m) {
-					err = -ENOMEM;
-					goto out;
-				}
+	/* Copy entries before the new_map that can't overlap. */
+	for (unsigned int i = 0; i < first_after_; i++)
+		merged_maps_by_address[i] = map__get(kmaps_maps_by_address[i]);
 
-				m->map = map__clone(new_map);
-				if (!m->map) {
-					free(m);
-					err = -ENOMEM;
-					goto out;
-				}
+	maps__set_nr_maps(kmaps, first_after_);
 
-				map__set_end(m->map, map__start(old_map));
-				list_add_tail(&m->node, &merged);
-				map__add_pgoff(new_map, map__end(old_map) - map__start(new_map));
-				map__set_start(new_map, map__end(old_map));
-			}
-		} else {
-			/*
-			 *      |new......
-			 * |old....
-			 */
-			if (map__end(new_map) < map__end(old_map)) {
-				/*
-				 *      |new..|   -> x
-				 * |old.........| -> |old.........|
-				 */
-				map__put(new_map);
-				new_map = NULL;
-				break;
-			} else {
-				/*
-				 *      |new......| ->         |new...|
-				 * |old....|        -> |old....|
-				 */
-				map__add_pgoff(new_map, map__end(old_map) - map__start(new_map));
-				map__set_start(new_map, map__end(old_map));
-			}
-		}
-	}
+	/* Add the new map, it will be split when the later overlapping mappings are added. */
+	__maps__insert(kmaps, new_map);
 
-out:
-	while (!list_empty(&merged)) {
-		struct map_list_node *old_node;
+	/* Insert mappings after new_map, splitting new_map in the process. */
+	for (unsigned int i = first_after_; i < kmaps__nr_maps; i++)
+		__maps__fixup_overlap_and_insert(kmaps, kmaps_maps_by_address[i]);
 
-		old_node = list_entry(merged.next, struct map_list_node, node);
-		list_del_init(&old_node->node);
-		if (!err)
-			err = maps__insert(kmaps, old_node->map);
-		map__put(old_node->map);
-		free(old_node);
-	}
+	/* Copy the maps from merged into kmaps. */
+	for (unsigned int i = 0; i < kmaps__nr_maps; i++)
+		map__zput(kmaps_maps_by_address[i]);
 
-	if (new_map) {
-		if (!err)
-			err = maps__insert(kmaps, new_map);
-		map__put(new_map);
-	}
-	return err;
+	free(kmaps_maps_by_address);
+	up_write(maps__lock(kmaps));
+	return 0;
 }
 
 void maps__load_first(struct maps *maps)
 {
-	struct map_rb_node *first;
-
 	down_read(maps__lock(maps));
 
-	first = maps__first(maps);
-	if (first)
-		map__load(first->map);
+	if (maps__nr_maps(maps) > 0)
+		map__load(maps__maps_by_address(maps)[0]);
 
 	up_read(maps__lock(maps));
 }