bpf: Simplify do_check_insn()

Move env->insn_idx++ to the caller, so that most of
check_*() calls in do_check_insn() tail call into the next helper.

Link: https://lore.kernel.org/r/20260411230001.71664-1-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 974e46f04f186988f5d648758bf03a8e9a7f42a1..967e132f26626f6c910022fb79154352b5cc077a 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -14541,6 +14541,8 @@ static int check_special_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_ca
 }
 
 static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name);
+static int process_bpf_exit_full(struct bpf_verifier_env *env,
+                                bool *do_print_state, bool exception_exit);
 
 static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                            int *insn_idx_p)
@@ -14921,6 +14923,9 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
        if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie])
                env->prog->call_session_cookie = true;
 
+       if (is_bpf_throw_kfunc(insn))
+               return process_bpf_exit_full(env, NULL, true);
+
        return 0;
 }
 
@@ -21371,7 +21376,8 @@ static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type typ
 }
 
 enum {
-       PROCESS_BPF_EXIT = 1
+       PROCESS_BPF_EXIT = 1,
+       INSN_IDX_UPDATED = 2,
 };
 
 static int process_bpf_exit_full(struct bpf_verifier_env *env,
@@ -21411,7 +21417,7 @@ static int process_bpf_exit_full(struct bpf_verifier_env *env,
                if (err)
                        return err;
                *do_print_state = true;
-               return 0;
+               return INSN_IDX_UPDATED;
        }
 
        /*
@@ -21521,7 +21527,7 @@ static int check_indirect_jump(struct bpf_verifier_env *env, struct bpf_insn *in
                        return PTR_ERR(other_branch);
        }
        env->insn_idx = env->gotox_tmp_buf->items[n-1];
-       return 0;
+       return INSN_IDX_UPDATED;
 }
 
 static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
@@ -21530,49 +21536,40 @@ static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
        struct bpf_insn *insn = &env->prog->insnsi[env->insn_idx];
        u8 class = BPF_CLASS(insn->code);
 
-       if (class == BPF_ALU || class == BPF_ALU64) {
-               err = check_alu_op(env, insn);
-               if (err)
-                       return err;
-       } else if (class == BPF_LDX) {
-               bool is_ldsx = BPF_MODE(insn->code) == BPF_MEMSX;
+       switch (class) {
+       case BPF_ALU:
+       case BPF_ALU64:
+               return check_alu_op(env, insn);
 
-               err = check_load_mem(env, insn, false, is_ldsx, true, "ldx");
-               if (err)
-                       return err;
-       } else if (class == BPF_STX) {
-               if (BPF_MODE(insn->code) == BPF_ATOMIC) {
-                       err = check_atomic(env, insn);
-                       if (err)
-                               return err;
-                       env->insn_idx++;
-                       return 0;
-               }
+       case BPF_LDX:
+               return check_load_mem(env, insn, false,
+                                     BPF_MODE(insn->code) == BPF_MEMSX,
+                                     true, "ldx");
 
-               err = check_store_reg(env, insn, false);
-               if (err)
-                       return err;
-       } else if (class == BPF_ST) {
+       case BPF_STX:
+               if (BPF_MODE(insn->code) == BPF_ATOMIC)
+                       return check_atomic(env, insn);
+               return check_store_reg(env, insn, false);
+
+       case BPF_ST: {
                enum bpf_reg_type dst_reg_type;
 
-               /* check src operand */
                err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                if (err)
                        return err;
 
                dst_reg_type = cur_regs(env)[insn->dst_reg].type;
 
-               /* check that memory (dst_reg + off) is writeable */
                err = check_mem_access(env, env->insn_idx, insn->dst_reg,
                                       insn->off, BPF_SIZE(insn->code),
                                       BPF_WRITE, -1, false, false);
                if (err)
                        return err;
 
-               err = save_aux_ptr_type(env, dst_reg_type, false);
-               if (err)
-                       return err;
-       } else if (class == BPF_JMP || class == BPF_JMP32) {
+               return save_aux_ptr_type(env, dst_reg_type, false);
+       }
+       case BPF_JMP:
+       case BPF_JMP32: {
                u8 opcode = BPF_OP(insn->code);
 
                env->jmps_processed++;
@@ -21588,19 +21585,12 @@ static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
                                        return -EINVAL;
                                }
                        }
-                       if (insn->src_reg == BPF_PSEUDO_CALL) {
-                               err = check_func_call(env, insn, &env->insn_idx);
-                       } else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
-                               err = check_kfunc_call(env, insn, &env->insn_idx);
-                               if (!err && is_bpf_throw_kfunc(insn))
-                                       return process_bpf_exit_full(env, do_print_state, true);
-                       } else {
-                               err = check_helper_call(env, insn, &env->insn_idx);
-                       }
-                       if (err)
-                               return err;
-
                        mark_reg_scratched(env, BPF_REG_0);
+                       if (insn->src_reg == BPF_PSEUDO_CALL)
+                               return check_func_call(env, insn, &env->insn_idx);
+                       if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL)
+                               return check_kfunc_call(env, insn, &env->insn_idx);
+                       return check_helper_call(env, insn, &env->insn_idx);
                } else if (opcode == BPF_JA) {
                        if (BPF_SRC(insn->code) == BPF_X)
                                return check_indirect_jump(env, insn);
@@ -21609,23 +21599,19 @@ static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
                                env->insn_idx += insn->off + 1;
                        else
                                env->insn_idx += insn->imm + 1;
-                       return 0;
+                       return INSN_IDX_UPDATED;
                } else if (opcode == BPF_EXIT) {
                        return process_bpf_exit_full(env, do_print_state, false);
-               } else {
-                       err = check_cond_jmp_op(env, insn, &env->insn_idx);
-                       if (err)
-                               return err;
                }
-       } else if (class == BPF_LD) {
+               return check_cond_jmp_op(env, insn, &env->insn_idx);
+       }
+       case BPF_LD: {
                u8 mode = BPF_MODE(insn->code);
 
-               if (mode == BPF_ABS || mode == BPF_IND) {
-                       err = check_ld_abs(env, insn);
-                       if (err)
-                               return err;
+               if (mode == BPF_ABS || mode == BPF_IND)
+                       return check_ld_abs(env, insn);
 
-               } else if (mode == BPF_IMM) {
+               if (mode == BPF_IMM) {
                        err = check_ld_imm(env, insn);
                        if (err)
                                return err;
@@ -21633,10 +21619,11 @@ static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
                        env->insn_idx++;
                        sanitize_mark_insn_seen(env);
                }
+               return 0;
        }
-
-       env->insn_idx++;
-       return 0;
+       }
+       /* all class values are handled above. silence compiler warning */
+       return -EFAULT;
 }
 
 static int do_check(struct bpf_verifier_env *env)
@@ -21780,8 +21767,10 @@ static int do_check(struct bpf_verifier_env *env)
                        return err;
                } else if (err == PROCESS_BPF_EXIT) {
                        goto process_bpf_exit;
+               } else if (err == INSN_IDX_UPDATED) {
+               } else if (err == 0) {
+                       env->insn_idx++;
                }
-               WARN_ON_ONCE(err);
 
                if (state->speculative && insn_aux->nospec_result) {
                        /* If we are on a path that performed a jump-op, this