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authorLorenz Bauer2021-04-29 14:46:56 +0100
committerAlexei Starovoitov2021-05-10 16:13:01 -0700
commitc9e73e3d2b1eb1ea7ff068e05007eec3bd8ef1c9 (patch)
tree4a7faeae5e95b86efce632ff25f08a15b725dea9 /kernel
parent06ab6a505583f9adbf5e1f05d86e7bdd7b02248e (diff)
bpf: verifier: Allocate idmap scratch in verifier env
func_states_equal makes a very short lived allocation for idmap, probably because it's too large to fit on the stack. However the function is called quite often, leading to a lot of alloc / free churn. Replace the temporary allocation with dedicated scratch space in struct bpf_verifier_env. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Edward Cree <ecree.xilinx@gmail.com> Link: https://lore.kernel.org/bpf/20210429134656.122225-4-lmb@cloudflare.com
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c46
1 files changed, 15 insertions, 31 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 380c8ad49b7f..bdfdb54676ea 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9748,13 +9748,6 @@ static bool range_within(struct bpf_reg_state *old,
old->s32_max_value >= cur->s32_max_value;
}
-/* Maximum number of register states that can exist at once */
-#define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE)
-struct idpair {
- u32 old;
- u32 cur;
-};
-
/* If in the old state two registers had the same id, then they need to have
* the same id in the new state as well. But that id could be different from
* the old state, so we need to track the mapping from old to new ids.
@@ -9765,11 +9758,11 @@ struct idpair {
* So we look through our idmap to see if this old id has been seen before. If
* so, we require the new id to match; otherwise, we add the id pair to the map.
*/
-static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap)
+static bool check_ids(u32 old_id, u32 cur_id, struct bpf_id_pair *idmap)
{
unsigned int i;
- for (i = 0; i < ID_MAP_SIZE; i++) {
+ for (i = 0; i < BPF_ID_MAP_SIZE; i++) {
if (!idmap[i].old) {
/* Reached an empty slot; haven't seen this id before */
idmap[i].old = old_id;
@@ -9882,7 +9875,7 @@ next:
/* Returns true if (rold safe implies rcur safe) */
static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
- struct idpair *idmap)
+ struct bpf_id_pair *idmap)
{
bool equal;
@@ -10000,7 +9993,7 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
static bool stacksafe(struct bpf_func_state *old,
struct bpf_func_state *cur,
- struct idpair *idmap)
+ struct bpf_id_pair *idmap)
{
int i, spi;
@@ -10097,32 +10090,23 @@ static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur)
* whereas register type in current state is meaningful, it means that
* the current state will reach 'bpf_exit' instruction safely
*/
-static bool func_states_equal(struct bpf_func_state *old,
+static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old,
struct bpf_func_state *cur)
{
- struct idpair *idmap;
- bool ret = false;
int i;
- idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL);
- /* If we failed to allocate the idmap, just say it's not safe */
- if (!idmap)
- return false;
-
- for (i = 0; i < MAX_BPF_REG; i++) {
- if (!regsafe(&old->regs[i], &cur->regs[i], idmap))
- goto out_free;
- }
+ memset(env->idmap_scratch, 0, sizeof(env->idmap_scratch));
+ for (i = 0; i < MAX_BPF_REG; i++)
+ if (!regsafe(&old->regs[i], &cur->regs[i], env->idmap_scratch))
+ return false;
- if (!stacksafe(old, cur, idmap))
- goto out_free;
+ if (!stacksafe(old, cur, env->idmap_scratch))
+ return false;
if (!refsafe(old, cur))
- goto out_free;
- ret = true;
-out_free:
- kfree(idmap);
- return ret;
+ return false;
+
+ return true;
}
static bool states_equal(struct bpf_verifier_env *env,
@@ -10149,7 +10133,7 @@ static bool states_equal(struct bpf_verifier_env *env,
for (i = 0; i <= old->curframe; i++) {
if (old->frame[i]->callsite != cur->frame[i]->callsite)
return false;
- if (!func_states_equal(old->frame[i], cur->frame[i]))
+ if (!func_states_equal(env, old->frame[i], cur->frame[i]))
return false;
}
return true;