Commit 6f606ffd authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

bpf: Move insn_buf[16] to bpf_verifier_env 



This patch moves the 'struct bpf_insn insn_buf[16]' stack usage
to the bpf_verifier_env. A '#define INSN_BUF_SIZE 16' is also added
to replace the ARRAY_SIZE(insn_buf) usages.

Both convert_ctx_accesses() and do_misc_fixup() are changed
to use the env->insn_buf.

It is a refactoring work for adding the epilogue_buf[16] in a later patch.

With this patch, the stack size usage decreased.

Before:
./kernel/bpf/verifier.c:22133:5: warning: stack frame size (2584)

After:
./kernel/bpf/verifier.c:22184:5: warning: stack frame size (2264)

Reviewed-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240829210833.388152-2-martin.lau@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent c6d9dafb

include/linux/bpf_verifier.h

+3 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
 * (in the "-8,-16,...,-512" form)

 */

#define TMP_STR_BUF_LEN 320

/* Patch buffer size */

#define INSN_BUF_SIZE 16



/* Liveness marks, used for registers and spilled-regs (in stack slots).

 * Read marks propagate upwards until they find a write mark; they record that
@@ -780,6 +782,7 @@ struct bpf_verifier_env { 
	 * e.g., in reg_type_str() to generate reg_type string

	 */

	char tmp_str_buf[TMP_STR_BUF_LEN];

	struct bpf_insn insn_buf[INSN_BUF_SIZE];

};



static inline struct bpf_func_info_aux *subprog_aux(struct bpf_verifier_env *env, int subprog)

kernel/bpf/verifier.c

+8 −7
Original line number Diff line number Diff line
@@ -19677,7 +19677,8 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) 
	const struct bpf_verifier_ops *ops = env->ops;

	int i, cnt, size, ctx_field_size, delta = 0;

	const int insn_cnt = env->prog->len;

	struct bpf_insn insn_buf[16], *insn;

	struct bpf_insn *insn_buf = env->insn_buf;

	struct bpf_insn *insn;

	u32 target_size, size_default, off;

	struct bpf_prog *new_prog;

	enum bpf_access_type type;
@@ -19690,7 +19691,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) 
		}

		cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,

					env->prog);

		if (cnt >= ARRAY_SIZE(insn_buf)) {

		if (cnt >= INSN_BUF_SIZE) {

			verbose(env, "bpf verifier is misconfigured\n");

			return -EINVAL;

		} else if (cnt) {
@@ -19837,7 +19838,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) 
		target_size = 0;

		cnt = convert_ctx_access(type, insn, insn_buf, env->prog,

					 &target_size);

		if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||

		if (cnt == 0 || cnt >= INSN_BUF_SIZE ||

		    (ctx_field_size && !target_size)) {

			verbose(env, "bpf verifier is misconfigured\n");

			return -EINVAL;
@@ -19846,7 +19847,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) 
		if (is_narrower_load && size < target_size) {

			u8 shift = bpf_ctx_narrow_access_offset(

				off, size, size_default) * 8;

			if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) {

			if (shift && cnt + 1 >= INSN_BUF_SIZE) {

				verbose(env, "bpf verifier narrow ctx load misconfigured\n");

				return -EINVAL;

			}
@@ -20391,7 +20392,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) 
	const int insn_cnt = prog->len;

	const struct bpf_map_ops *ops;

	struct bpf_insn_aux_data *aux;

	struct bpf_insn insn_buf[16];

	struct bpf_insn *insn_buf = env->insn_buf;

	struct bpf_prog *new_prog;

	struct bpf_map *map_ptr;

	int i, ret, cnt, delta = 0, cur_subprog = 0;
@@ -20510,7 +20511,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) 
		    (BPF_MODE(insn->code) == BPF_ABS ||

		     BPF_MODE(insn->code) == BPF_IND)) {

			cnt = env->ops->gen_ld_abs(insn, insn_buf);

			if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {

			if (cnt == 0 || cnt >= INSN_BUF_SIZE) {

				verbose(env, "bpf verifier is misconfigured\n");

				return -EINVAL;

			}
@@ -20803,7 +20804,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) 
				cnt = ops->map_gen_lookup(map_ptr, insn_buf);

				if (cnt == -EOPNOTSUPP)

					goto patch_map_ops_generic;

				if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) {

				if (cnt <= 0 || cnt >= INSN_BUF_SIZE) {

					verbose(env, "bpf verifier is misconfigured\n");

					return -EINVAL;

				}