bpf: extract __check_reg_arg() utility function

Split check_reg_arg() into two utility functions:
- check_reg_arg() operating on registers from current verifier state;
- __check_reg_arg() operating on a specific set of registers passed as
  a parameter;

The __check_reg_arg() function would be used by a follow-up change for
callbacks handling.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-5-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6da370a047feb90c4866310b57cff4c4d9eafe84..e6e1bcfe00f549d389571adb7e6567e976592bcf 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3439,13 +3439,11 @@ static void mark_insn_zext(struct bpf_verifier_env *env,
        reg->subreg_def = DEF_NOT_SUBREG;
 }
 
-static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
-                        enum reg_arg_type t)
+static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno,
+                          enum reg_arg_type t)
 {
-       struct bpf_verifier_state *vstate = env->cur_state;
-       struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
-       struct bpf_reg_state *reg, *regs = state->regs;
+       struct bpf_reg_state *reg;
        bool rw64;
 
        if (regno >= MAX_BPF_REG) {
@@ -3486,6 +3484,15 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
        return 0;
 }
 
+static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
+                        enum reg_arg_type t)
+{
+       struct bpf_verifier_state *vstate = env->cur_state;
+       struct bpf_func_state *state = vstate->frame[vstate->curframe];
+
+       return __check_reg_arg(env, state->regs, regno, t);
+}
+
 static void mark_jmp_point(struct bpf_verifier_env *env, int idx)
 {
        env->insn_aux_data[idx].jmp_point = true;
@@ -9350,7 +9357,7 @@ static void clear_caller_saved_regs(struct bpf_verifier_env *env,
        /* after the call registers r0 - r5 were scratched */
        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                mark_reg_not_init(env, regs, caller_saved[i]);
-               check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
+               __check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK);
        }
 }