linux-kernel - [tip: x86/alternatives] x86/alternatives: Remove the 'addr == NULL means forced-flush' hack from smp_text_poke_batch_finish()/smp_text_poke_batch_flush()/text_poke_addr

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Message-ID: <174436572515.31282.14486079052605438703.tip-bot2@tip-bot2>
Date: Fri, 11 Apr 2025 10:02:05 -0000
From: "tip-bot2 for Ingo Molnar" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>, Juergen Gross <jgross@...e.com>,
 "H . Peter Anvin" <hpa@...or.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/alternatives] x86/alternatives: Remove the 'addr == NULL
 means forced-flush' hack from smp_text_poke_batch_finish()/smp_text_poke_batch_flush()/text_poke_addr_ordered()

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

Commit-ID:     eaa24c9177c8c765ec9b9ccab392ac07ae8acda0
Gitweb:        https://git.kernel.org/tip/eaa24c9177c8c765ec9b9ccab392ac07ae8acda0
Author:        Ingo Molnar <mingo@...nel.org>
AuthorDate:    Fri, 11 Apr 2025 07:40:35 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 11 Apr 2025 11:01:34 +02:00

x86/alternatives: Remove the 'addr == NULL means forced-flush' hack from smp_text_poke_batch_finish()/smp_text_poke_batch_flush()/text_poke_addr_ordered()

There's this weird hack used by smp_text_poke_batch_finish() to indicate
a 'forced flush':

	smp_text_poke_batch_flush(NULL);

Just open-code the vector-flush in a straightforward fashion:

	smp_text_poke_batch_process(tp_vec, tp_vec_nr);
	tp_vec_nr = 0;

And get rid of !addr hack from text_poke_addr_ordered().

Leave a WARN_ON_ONCE(), just in case some external code learned
to rely on this behavior.

Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Juergen Gross <jgross@...e.com>
Cc: "H . Peter Anvin" <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: https://lore.kernel.org/r/20250411054105.2341982-24-mingo@kernel.org
---
 arch/x86/kernel/alternative.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index c5801b4..16a41e2 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2845,12 +2845,11 @@ static bool text_poke_addr_ordered(void *addr)
 {
 	struct smp_text_poke_loc *tp;

+	WARN_ON_ONCE(!addr);
+
 	if (!tp_vec_nr)
 		return true;

-	if (!addr) /* force */
-		return false;
-
 	/*
 	 * If the last current entry's address is higher than the
 	 * new entry's address we'd like to add, then ordering
@@ -2864,6 +2863,14 @@ static bool text_poke_addr_ordered(void *addr)
 	return true;
 }

+void smp_text_poke_batch_finish(void)
+{
+	if (tp_vec_nr) {
+		smp_text_poke_batch_process(tp_vec, tp_vec_nr);
+		tp_vec_nr = 0;
+	}
+}
+
 static void smp_text_poke_batch_flush(void *addr)
 {
 	lockdep_assert_held(&text_mutex);
@@ -2874,11 +2881,6 @@ static void smp_text_poke_batch_flush(void *addr)
 	}
 }

-void smp_text_poke_batch_finish(void)
-{
-	smp_text_poke_batch_flush(NULL);
-}
-
 void __ref smp_text_poke_batch_add(void *addr, const void *opcode, size_t len, const void *emulate)
 {
 	struct smp_text_poke_loc *tp;