[PATCH bpf-next] bpf: Comment on check_mem_size_reg

[Andrei Matei <andreimatei1@gmail.com>]

This patch adds a comment to check_mem_size_reg -- a function whose
meaning is not very transparent. The function implicitly deals with two
registers connected by convention, which is not obvious.

Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
---
 kernel/bpf/verifier.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index fb690539d5f6..8b2f29d8e0b1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7252,6 +7252,12 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 	}
 }
 
+/* verify arguments to helpers or kfuncs consisting of a pointer and an access
+ * size.
+ *
+ * @regno is the register containing the access size. regno-1 is the register
+ * containing the pointer.
+ */
 static int check_mem_size_reg(struct bpf_verifier_env *env,
 			      struct bpf_reg_state *reg, u32 regno,
 			      bool zero_size_allowed,
-- 
2.40.1