Directly call mark_stack_slot_obj_read() from function processing
iter, dynptr and irq_flag. To prepare for unifying dynptr handling,
dynptr_get_spi() will be moved out of mark_dynptr_read(),
As mark_dynptr_read() would join mark_iter_read() as a thin wrapper of
mark_stack_slot_obj_read(), just open code the helpers.

In addition, since 6762e3a0bce5 ("bpf: simplify liveness to use
(callsite, depth) keyed func_instances") has made
mark_stack_slot_obj_read() always succeed. Return void and drop the now
unused bpf_reg_state argument.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 kernel/bpf/verifier.c | 69 +++++++++++++------------------------------
 1 file changed, 21 insertions(+), 48 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 11054ad89c14..6931012d3ee2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2972,50 +2972,13 @@ static int sort_subprogs_topo(struct bpf_verifier_env *env)
 	return ret;
 }
 
-static int mark_stack_slot_obj_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
-				    int spi, int nr_slots)
+static void mark_stack_slot_obj_read(struct bpf_verifier_env *env,
+				     int spi, int nr_slots)
 {
 	int i;
 
 	for (i = 0; i < nr_slots; i++)
 		mark_stack_slot_scratched(env, spi - i);
-	return 0;
-}
-
-static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
-{
-	int spi;
-
-	/* For CONST_PTR_TO_DYNPTR, it must have already been done by
-	 * check_reg_arg in check_helper_call and mark_btf_func_reg_size in
-	 * check_kfunc_call.
-	 */
-	if (reg->type == CONST_PTR_TO_DYNPTR)
-		return 0;
-	spi = dynptr_get_spi(env, reg);
-	if (spi < 0)
-		return spi;
-	/* Caller ensures dynptr is valid and initialized, which means spi is in
-	 * bounds and spi is the first dynptr slot. Simply mark stack slot as
-	 * read.
-	 */
-	return mark_stack_slot_obj_read(env, reg, spi, BPF_DYNPTR_NR_SLOTS);
-}
-
-static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
-			  int spi, int nr_slots)
-{
-	return mark_stack_slot_obj_read(env, reg, spi, nr_slots);
-}
-
-static int mark_irq_flag_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
-{
-	int spi;
-
-	spi = irq_flag_get_spi(env, reg);
-	if (spi < 0)
-		return spi;
-	return mark_stack_slot_obj_read(env, reg, spi, 1);
 }
 
 /* This function is supposed to be used by the following 32-bit optimization
@@ -7078,7 +7041,7 @@ static int process_kptr_func(struct bpf_verifier_env *env, int regno,
 static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno, int insn_idx,
 			       enum bpf_arg_type arg_type, int clone_ref_obj_id)
 {
-	int err;
+	int spi, err = 0;
 
 	if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) {
 		verbose(env,
@@ -7140,7 +7103,17 @@ static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_stat
 			return -EINVAL;
 		}
 
-		err = mark_dynptr_read(env, reg);
+		if (reg->type != CONST_PTR_TO_DYNPTR) {
+			spi = dynptr_get_spi(env, reg);
+			if (spi < 0)
+				return spi;
+
+			/*
+			 * For CONST_PTR_TO_DYNPTR, reg is already scratched by check_reg_arg
+			 * in check_helper_call and mark_btf_func_reg_size in check_kfunc_call.
+			 */
+			mark_stack_slot_obj_read(env, spi, BPF_DYNPTR_NR_SLOTS);
+		}
 	}
 	return err;
 }
@@ -7250,9 +7223,7 @@ static int process_iter_arg(struct bpf_verifier_env *env, struct bpf_reg_state *
 		if (spi < 0)
 			return spi;
 
-		err = mark_iter_read(env, reg, spi, nr_slots);
-		if (err)
-			return err;
+		mark_stack_slot_obj_read(env, spi, nr_slots);
 
 		/* remember meta->iter info for process_iter_next_call() */
 		meta->iter.spi = spi;
@@ -11150,7 +11121,7 @@ static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env,
 static int process_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno,
 			     struct bpf_kfunc_call_arg_meta *meta)
 {
-	int err, kfunc_class = IRQ_NATIVE_KFUNC;
+	int err, spi, kfunc_class = IRQ_NATIVE_KFUNC;
 	bool irq_save;
 
 	if (meta->func_id == special_kfunc_list[KF_bpf_local_irq_save] ||
@@ -11191,9 +11162,11 @@ static int process_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *
 			return err;
 		}
 
-		err = mark_irq_flag_read(env, reg);
-		if (err)
-			return err;
+		spi = irq_flag_get_spi(env, reg);
+		if (spi < 0)
+			return spi;
+
+		mark_stack_slot_obj_read(env, spi, 1);
 
 		err = unmark_stack_slot_irq_flag(env, reg, kfunc_class);
 		if (err)
-- 
2.52.0