perf kmaps: Check kmaps to make code more robust

This patch add checks in places where map__kmap is used to get kmaps
from struct kmap.

Error messages are added at map__kmap to warn invalid accessing of kmap
(for the case of !map->dso->kernel, kmap(map) does not exists at all).

Also, introduces map__kmaps() to warn uninitialized kmaps.

Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: pi3orama@163.com
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1428394966-131044-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

7 files changed, 70 insertions, 16 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index e45c8f33a8fd..9c380a2caa54 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -679,6 +679,9 @@ int __machine__create_kernel_maps(struct machine *machine, struct dso *kernel)
                         machine->vmlinux_maps[type]->unmap_ip =
                                 identity__map_ip;
                 kmap = map__kmap(machine->vmlinux_maps[type]);
+                if (!kmap)
+                        return -1;
+
                 kmap->kmaps = &machine->kmaps;
                 map_groups__insert(&machine->kmaps,
                                    machine->vmlinux_maps[type]);
@@ -700,7 +703,7 @@ void machine__destroy_kernel_maps(struct machine *machine)
                 kmap = map__kmap(machine->vmlinux_maps[type]);
                 map_groups__remove(&machine->kmaps,
                                    machine->vmlinux_maps[type]);
-                if (kmap->ref_reloc_sym) {
+                if (kmap && kmap->ref_reloc_sym) {
                         /*
                          * ref_reloc_sym is shared among all maps, so free just
                          * on one of them.
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 62ca9f2607d5..a14f08f41686 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -778,3 +778,23 @@ struct map *maps__next(struct map *map)
                 return rb_entry(next, struct map, rb_node);
         return NULL;
 }
+
+struct kmap *map__kmap(struct map *map)
+{
+        if (!map->dso || !map->dso->kernel) {
+                pr_err("Internal error: map__kmap with a non-kernel map\n");
+                return NULL;
+        }
+        return (struct kmap *)(map + 1);
+}
+
+struct map_groups *map__kmaps(struct map *map)
+{
+        struct kmap *kmap = map__kmap(map);
+
+        if (!kmap || !kmap->kmaps) {
+                pr_err("Internal error: map__kmaps with a non-kernel map\n");
+                return NULL;
+        }
+        return kmap->kmaps;
+}
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index 0e42438b1e59..ec19c59ca38e 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -76,10 +76,8 @@ static inline struct map_groups *map_groups__get(struct map_groups *mg)
 
 void map_groups__put(struct map_groups *mg);
 
-static inline struct kmap *map__kmap(struct map *map)
-{
-        return (struct kmap *)(map + 1);
-}
+struct kmap *map__kmap(struct map *map);
+struct map_groups *map__kmaps(struct map *map);
 
 static inline u64 map__map_ip(struct map *map, u64 ip)
 {
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 8feac0774c41..4fd49f021073 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -135,6 +135,8 @@ static struct ref_reloc_sym *kernel_get_ref_reloc_sym(void)
                 return NULL;
 
         kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
+        if (!kmap)
+                return NULL;
         return kmap->ref_reloc_sym;
 }
 
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index dfacf1d50162..0c74012575ac 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1466,6 +1466,9 @@ int maps__set_kallsyms_ref_reloc_sym(struct map **maps,
 
         for (i = 0; i < MAP__NR_TYPES; ++i) {
                 struct kmap *kmap = map__kmap(maps[i]);
+
+                if (!kmap)
+                        continue;
                 kmap->ref_reloc_sym = ref;
         }
 
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 476268c99431..a7ab6063e038 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -776,6 +776,7 @@ int dso__load_sym(struct dso *dso, struct map *map,
                   symbol_filter_t filter, int kmodule)
 {
         struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
+        struct map_groups *kmaps = kmap ? map__kmaps(map) : NULL;
         struct map *curr_map = map;
         struct dso *curr_dso = dso;
         Elf_Data *symstrs, *secstrs;
@@ -791,6 +792,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
         int nr = 0;
         bool remap_kernel = false, adjust_kernel_syms = false;
 
+        if (kmap && !kmaps)
+                return -1;
+
         dso->symtab_type = syms_ss->type;
         dso->is_64_bit = syms_ss->is_64_bit;
         dso->rel = syms_ss->ehdr.e_type == ET_REL;
@@ -958,8 +962,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
                                         map->map_ip = map__map_ip;
                                         map->unmap_ip = map__unmap_ip;
                                         /* Ensure maps are correctly ordered */
-                                        map_groups__remove(kmap->kmaps, map);
-                                        map_groups__insert(kmap->kmaps, map);
+                                        if (kmaps) {
+                                                map_groups__remove(kmaps, map);
+                                                map_groups__insert(kmaps, map);
+                                        }
                                 }
 
                                 /*
@@ -983,7 +989,7 @@ int dso__load_sym(struct dso *dso, struct map *map,
                         snprintf(dso_name, sizeof(dso_name),
                                  "%s%s", dso->short_name, section_name);
 
-                        curr_map = map_groups__find_by_name(kmap->kmaps, map->type, dso_name);
+                        curr_map = map_groups__find_by_name(kmaps, map->type, dso_name);
                         if (curr_map == NULL) {
                                 u64 start = sym.st_value;
 
@@ -1013,7 +1019,7 @@ int dso__load_sym(struct dso *dso, struct map *map,
                                         curr_map->unmap_ip = identity__map_ip;
                                 }
                                 curr_dso->symtab_type = dso->symtab_type;
-                                map_groups__insert(kmap->kmaps, curr_map);
+                                map_groups__insert(kmaps, curr_map);
                                 /*
                                  * The new DSO should go to the kernel DSOS
                                  */
@@ -1075,7 +1081,7 @@ new_symbol:
                          * We need to fixup this here too because we create new
                          * maps here, for things like vsyscall sections.
                          */
-                        __map_groups__fixup_end(kmap->kmaps, map->type);
+                        __map_groups__fixup_end(kmaps, map->type);
                 }
         }
         err = nr;
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index fddeb9073039..201f6c4ca738 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -630,13 +630,16 @@ static int dso__load_all_kallsyms(struct dso *dso, const char *filename,
 static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map,
                                          symbol_filter_t filter)
 {
-        struct map_groups *kmaps = map__kmap(map)->kmaps;
+        struct map_groups *kmaps = map__kmaps(map);
         struct map *curr_map;
         struct symbol *pos;
         int count = 0, moved = 0;
         struct rb_root *root = &dso->symbols[map->type];
         struct rb_node *next = rb_first(root);
 
+        if (!kmaps)
+                return -1;
+
         while (next) {
                 char *module;
 
@@ -682,8 +685,8 @@ static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map,
 static int dso__split_kallsyms(struct dso *dso, struct map *map, u64 delta,
                                symbol_filter_t filter)
 {
-        struct map_groups *kmaps = map__kmap(map)->kmaps;
-        struct machine *machine = kmaps->machine;
+        struct map_groups *kmaps = map__kmaps(map);
+        struct machine *machine;
         struct map *curr_map = map;
         struct symbol *pos;
         int count = 0, moved = 0;
@@ -691,6 +694,11 @@ static int dso__split_kallsyms(struct dso *dso, struct map *map, u64 delta,
         struct rb_node *next = rb_first(root);
         int kernel_range = 0;
 
+        if (!kmaps)
+                return -1;
+
+        machine = kmaps->machine;
+
         while (next) {
                 char *module;
 
@@ -1025,9 +1033,12 @@ static bool filename_from_kallsyms_filename(char *filename,
 static int validate_kcore_modules(const char *kallsyms_filename,
                                   struct map *map)
 {
-        struct map_groups *kmaps = map__kmap(map)->kmaps;
+        struct map_groups *kmaps = map__kmaps(map);
         char modules_filename[PATH_MAX];
 
+        if (!kmaps)
+                return -EINVAL;
+
         if (!filename_from_kallsyms_filename(modules_filename, "modules",
                                              kallsyms_filename))
                 return -EINVAL;
@@ -1043,6 +1054,9 @@ static int validate_kcore_addresses(const char *kallsyms_filename,
 {
         struct kmap *kmap = map__kmap(map);
 
+        if (!kmap)
+                return -EINVAL;
+
         if (kmap->ref_reloc_sym && kmap->ref_reloc_sym->name) {
                 u64 start;
 
@@ -1081,8 +1095,8 @@ static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
 static int dso__load_kcore(struct dso *dso, struct map *map,
                            const char *kallsyms_filename)
 {
-        struct map_groups *kmaps = map__kmap(map)->kmaps;
-        struct machine *machine = kmaps->machine;
+        struct map_groups *kmaps = map__kmaps(map);
+        struct machine *machine;
         struct kcore_mapfn_data md;
         struct map *old_map, *new_map, *replacement_map = NULL;
         bool is_64_bit;
@@ -1090,6 +1104,11 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
         char kcore_filename[PATH_MAX];
         struct symbol *sym;
 
+        if (!kmaps)
+                return -EINVAL;
+
+        machine = kmaps->machine;
+
         /* This function requires that the map is the kernel map */
         if (map != machine->vmlinux_maps[map->type])
                 return -EINVAL;
@@ -1202,6 +1221,9 @@ static int kallsyms__delta(struct map *map, const char *filename, u64 *delta)
         struct kmap *kmap = map__kmap(map);
         u64 addr;
 
+        if (!kmap)
+                return -1;
+
         if (!kmap->ref_reloc_sym || !kmap->ref_reloc_sym->name)
                 return 0;