linux-kernel - [tip: x86/alternatives] x86/alternatives: Optimize optimize

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Date: Tue, 09 Apr 2024 17:11:29 -0000
From: "tip-bot2 for Borislav Petkov (AMD)" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/alternatives] x86/alternatives: Optimize optimize_nops()

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

Commit-ID:     c3a3cb5c3d893d7ca75c773ddd107832f13e7b57
Gitweb:        https://git.kernel.org/tip/c3a3cb5c3d893d7ca75c773ddd107832f13e7b57
Author:        Borislav Petkov (AMD) <bp@...en8.de>
AuthorDate:    Tue, 30 Jan 2024 11:59:40 +01:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Tue, 09 Apr 2024 18:15:03 +02:00

x86/alternatives: Optimize optimize_nops()

Return early if NOPs have already been optimized.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20240130105941.19707-4-bp@alien8.de
---
 arch/x86/kernel/alternative.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4b3378c..67dd7c3 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -233,6 +233,10 @@ static void noinline optimize_nops(const u8 * const instr, u8 *buf, size_t len)
 		if (insn_is_nop(&insn)) {
 			int nop = i;
 
+			/* Has the NOP already been optimized? */
+			if (i + insn.length == len)
+				return;
+
 			next = skip_nops(buf, next, len);
 
 			add_nop(buf + nop, next - nop);