tracing/cfi: Fix cmp_entries_* functions signature mismatch

[ Upstream commit 7ce1bb83a14019f8c396d57ec704d19478747716 ]

If CONFIG_CFI_CLANG=y, attempting to read an event histogram will cause
the kernel to panic due to failed CFI check.

    1. echo 'hist:keys=common_pid' >> events/sched/sched_switch/trigger
    2. cat events/sched/sched_switch/hist
    3. kernel panics on attempting to read hist

This happens because the sort() function expects a generic
int (*)(const void *, const void *) pointer for the compare function.
To prevent this CFI failure, change tracing map cmp_entries_* function
signatures to match this.

Also, fix the build error reported by the kernel test robot [1].

[1] https://lore.kernel.org/r/202110141140.zzi4dRh4-lkp@intel.com/

Link: https://lkml.kernel.org/r/20211014045217.3265162-1-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index 4b50fc0..d63e51d 100644 (file)
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -834,29 +834,35 @@ int tracing_map_init(struct tracing_map *map)
        return err;
 }
 
-static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
-                          const struct tracing_map_sort_entry **b)
+static int cmp_entries_dup(const void *A, const void *B)
 {
+       const struct tracing_map_sort_entry *a, *b;
        int ret = 0;
 
-       if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
+       a = *(const struct tracing_map_sort_entry **)A;
+       b = *(const struct tracing_map_sort_entry **)B;
+
+       if (memcmp(a->key, b->key, a->elt->map->key_size))
                ret = 1;
 
        return ret;
 }
 
-static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
-                          const struct tracing_map_sort_entry **b)
+static int cmp_entries_sum(const void *A, const void *B)
 {
        const struct tracing_map_elt *elt_a, *elt_b;
+       const struct tracing_map_sort_entry *a, *b;
        struct tracing_map_sort_key *sort_key;
        struct tracing_map_field *field;
        tracing_map_cmp_fn_t cmp_fn;
        void *val_a, *val_b;
        int ret = 0;
 
-       elt_a = (*a)->elt;
-       elt_b = (*b)->elt;
+       a = *(const struct tracing_map_sort_entry **)A;
+       b = *(const struct tracing_map_sort_entry **)B;
+
+       elt_a = a->elt;
+       elt_b = b->elt;
 
        sort_key = &elt_a->map->sort_key;
 
@@ -873,18 +879,21 @@ static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
        return ret;
 }
 
-static int cmp_entries_key(const struct tracing_map_sort_entry **a,
-                          const struct tracing_map_sort_entry **b)
+static int cmp_entries_key(const void *A, const void *B)
 {
        const struct tracing_map_elt *elt_a, *elt_b;
+       const struct tracing_map_sort_entry *a, *b;
        struct tracing_map_sort_key *sort_key;
        struct tracing_map_field *field;
        tracing_map_cmp_fn_t cmp_fn;
        void *val_a, *val_b;
        int ret = 0;
 
-       elt_a = (*a)->elt;
-       elt_b = (*b)->elt;
+       a = *(const struct tracing_map_sort_entry **)A;
+       b = *(const struct tracing_map_sort_entry **)B;
+
+       elt_a = a->elt;
+       elt_b = b->elt;
 
        sort_key = &elt_a->map->sort_key;
 
@@ -989,10 +998,8 @@ static void sort_secondary(struct tracing_map *map,
                           struct tracing_map_sort_key *primary_key,
                           struct tracing_map_sort_key *secondary_key)
 {
-       int (*primary_fn)(const struct tracing_map_sort_entry **,
-                         const struct tracing_map_sort_entry **);
-       int (*secondary_fn)(const struct tracing_map_sort_entry **,
-                           const struct tracing_map_sort_entry **);
+       int (*primary_fn)(const void *, const void *);
+       int (*secondary_fn)(const void *, const void *);
        unsigned i, start = 0, n_sub = 1;
 
        if (is_key(map, primary_key->field_idx))
@@ -1061,8 +1068,7 @@ int tracing_map_sort_entries(struct tracing_map *map,
                             unsigned int n_sort_keys,
                             struct tracing_map_sort_entry ***sort_entries)
 {
-       int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
-                             const struct tracing_map_sort_entry **);
+       int (*cmp_entries_fn)(const void *, const void *);
        struct tracing_map_sort_entry *sort_entry, **entries;
        int i, n_entries, ret;