[PATCH bpf-next v1 05/14] bpf: Use canonical stack argument names in diagnostics

The main diagnostic identifies the first outgoing stack slot as stack
argument 1 and the sixth function argument. The causal history instead
labels the same value as stack arg6, making it look like a different slot.

Render causal-history targets in the verifier's canonical stack-argument
location form. The first outgoing slot is now shown as *(R11-8), matching
reg_arg_name(), while the main diagnostic retains its fuller slot and
ordinal description.

Link: https://lore.kernel.org/bpf/[email protected]/
Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>
---
 kernel/bpf/diagnostics.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 37ed22a764e0..2c475174a640 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -2163,7 +2163,7 @@ static const char *diag_mod_target_desc(struct bpf_verifier_env *env,
 	case BPF_DIAG_MOD_TARGET_REG:
 		return bpf_diag_fmt(env, "R%u", target->regno);
 	case BPF_DIAG_MOD_TARGET_STACK_ARG:
-		return bpf_diag_fmt(env, "stack arg%d", diag_stack_argno(target->stack_arg));
+		return bpf_diag_fmt(env, "*(R11-%u)", (target->stack_arg + 1) * BPF_REG_SIZE);
 	case BPF_DIAG_MOD_TARGET_STACK_SLOT:
 		return bpf_diag_fmt(env, "stack slot fp%d", -(target->spi + 1) * BPF_REG_SIZE);
 	default:
-- 
2.53.0