[tip: x86/alternatives] x86/alternatives: Use non-inverted logic instead of 'tp_order_fail()'

[tip-bot2 for Ingo Molnar]

The following commit has been merged into the x86/alternatives branch of tip:

Commit-ID:     2d0cf10a1eb60deded109c2357326a5ca44e3845
Gitweb:        https://git.kernel.org/tip/2d0cf10a1eb60deded109c2357326a5ca44e3845
Author:        Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate:    Fri, 11 Apr 2025 07:40:34 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 11 Apr 2025 11:01:34 +02:00

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 'text_poke_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@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250411054105.2341982-23-mingo@xxxxxxxxxx
---
 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 c53eb3b..c5801b4 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2841,28 +2841,34 @@ static void text_poke_int3_loc_init(struct smp_text_poke_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 text_poke_addr_ordered(void *addr)
 {
 	struct smp_text_poke_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_addr(tp) > (unsigned long)addr)
-		return true;
+		return false;
 
-	return false;
+	return true;
 }
 
 static void smp_text_poke_batch_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 || !text_poke_addr_ordered(addr)) {
 		smp_text_poke_batch_process(tp_vec, tp_vec_nr);
 		tp_vec_nr = 0;
 	}