linux-kernel - [PATCH 22/41] x86/alternatives: Use non-inverted logic instead of 'tp_order

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Message-ID: <20250327205355.378659-23-mingo@kernel.org>
Date: Thu, 27 Mar 2025 21:53:35 +0100
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 22/41] x86/alternatives: Use non-inverted logic instead of 'tp_order_fail()'

tp_order_fail() uses inverted logic: it returns true in case something
is false, which is only a plus at the IOCCC.

Instead rename it to regular parity as 'tp_addr_ordered()',
and adjust the code accordingly.

Also add a comment explaining how the address ordering should be
understood.

No change in functionality intended.

Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/alternative.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 883c2146ce54..938e8e70a379 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2843,28 +2843,34 @@ static void text_poke_int3_loc_init(struct text_poke_int3_loc *tp, void *addr,
  * We hard rely on the tp_vec being ordered; ensure this is so by flushing
  * early if needed.
  */
-static bool tp_order_fail(void *addr)
+static bool tp_addr_ordered(void *addr)
 {
 	struct text_poke_int3_loc *tp;
 
 	if (!tp_vec_nr)
-		return false;
+		return true;
 
 	if (!addr) /* force */
-		return true;
+		return false;
 
-	tp = &tp_vec[tp_vec_nr - 1];
+	/*
+	 * If the last current entry's address is higher than the
+	 * new entry's address we'd like to add, then ordering
+	 * is violated and we must first flush all pending patching
+	 * requests:
+	 */
+	tp = &tp_vec[tp_vec_nr-1];
 	if ((unsigned long)text_poke_int3_addr(tp) > (unsigned long)addr)
-		return true;
+		return false;
 
-	return false;
+	return true;
 }
 
 static void text_poke_int3_flush(void *addr)
 {
 	lockdep_assert_held(&text_mutex);
 
-	if (tp_vec_nr == TP_VEC_MAX || tp_order_fail(addr)) {
+	if (tp_vec_nr == TP_VEC_MAX || !tp_addr_ordered(addr)) {
 		text_poke_int3_batch(tp_vec, tp_vec_nr);
 		tp_vec_nr = 0;
 	}
-- 
2.45.2