From 2d6ad925fb2386f3ee1d26f5022f7ea71bbc1541 Mon Sep 17 00:00:00 2001 From: Jens Remus Date: Mon, 8 Dec 2025 17:03:49 +0100 Subject: [PATCH] unwind_user: Enhance comments on get CFA, FP, and RA Move the comment "Get the Canonical Frame Address (CFA)" to the top of the sequence of statements that actually get the CFA. Reword the comment "Find the Return Address (RA)" to "Get ...", as the statements actually get the RA. Add a respective comment to the statements that get the FP. This will be useful once future commits extend the logic to get the RA and FP. While at it align the comment on the "stack going in wrong direction" check to the following one on the "address is word aligned" check. Signed-off-by: Jens Remus Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251208160352.1363040-2-jremus@linux.ibm.com --- kernel/unwind/user.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c index 39e2707894447..0ca434f86e730 100644 --- a/kernel/unwind/user.c +++ b/kernel/unwind/user.c @@ -31,6 +31,7 @@ static int unwind_user_next_common(struct unwind_user_state *state, { unsigned long cfa, fp, ra; + /* Get the Canonical Frame Address (CFA) */ if (frame->use_fp) { if (state->fp < state->sp) return -EINVAL; @@ -38,11 +39,9 @@ static int unwind_user_next_common(struct unwind_user_state *state, } else { cfa = state->sp; } - - /* Get the Canonical Frame Address (CFA) */ cfa += frame->cfa_off; - /* stack going in wrong direction? */ + /* Make sure that stack is not going in wrong direction */ if (cfa <= state->sp) return -EINVAL; @@ -50,10 +49,11 @@ static int unwind_user_next_common(struct unwind_user_state *state, if (cfa & (state->ws - 1)) return -EINVAL; - /* Find the Return Address (RA) */ + /* Get the Return Address (RA) */ if (get_user_word(&ra, cfa, frame->ra_off, state->ws)) return -EINVAL; + /* Get the Frame Pointer (FP) */ if (frame->fp_off && get_user_word(&fp, cfa, frame->fp_off, state->ws)) return -EINVAL; -- 2.47.3