Re: [PATCH bpf-next v3 2/2] selftests/bpf: Match tests against regular expres

[Eduard Zingerman <eddyz87@gmail.com>]

On Tue, 2024-06-11 at 18:40 +0100, Cupertino Miranda wrote:
> This patch changes a few tests to make use of reg
> would otherwise fail when compiled with GCC.
> 
> Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
> Cc: jose.marchesi@oracle.com
> Cc: david.faust@oracle.com
> Cc: Yonghong Song <yonghong.song@linux.dev>
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> ---

Looks good, but I think that changes for 'off' for three cases below
are not necessary.

[...]

> diff --git a/tools/testing/selftests/bpf/progs/rbtree_fail.c b/tools/testing/selftests/bpf/progs/rbtree_fail.c
> index 3fecf1c6dfe5..8399304eca72 100644
> --- a/tools/testing/selftests/bpf/progs/rbtree_fail.c
> +++ b/tools/testing/selftests/bpf/progs/rbtree_fail.c
> @@ -29,7 +29,7 @@ static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
>  }
>  
>  SEC("?tc")
> -__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
> +__failure __regex("bpf_spin_lock at off=[0-9]+ must be held for bpf_rb_root")

This error message is reported in a single place in
verifier.c:__process_kf_arg_ptr_to_graph_root():

	if (check_reg_allocation_locked(env, reg)) {
		verbose(env, "bpf_spin_lock at off=%d must be held for %s\n",
			rec->spin_lock_off, head_type_name);
		return -EINVAL;
	}

Where `rec` is a description of the BTF type, `off` is an offset
inside the structure, why do you need to change it to regex?

>  long rbtree_api_nolock_add(void *ctx)
>  {
>  	struct node_data *n;
> @@ -43,7 +43,7 @@ long rbtree_api_nolock_add(void *ctx)
>  }
>  
>  SEC("?tc")
> -__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
> +__failure __regex("bpf_spin_lock at off=[0-9]+ must be held for bpf_rb_root")
>  long rbtree_api_nolock_remove(void *ctx)
>  {
>  	struct node_data *n;
> @@ -61,7 +61,7 @@ long rbtree_api_nolock_remove(void *ctx)
>  }
>  
>  SEC("?tc")
> -__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
> +__failure __regex("bpf_spin_lock at off=[0-9]+ must be held for bpf_rb_root")
>  long rbtree_api_nolock_first(void *ctx)
>  {
>  	bpf_rbtree_first(&groot);

[...]