linux-kernel - [PATCH 3/4] x86/alternatives: Optimize optimize

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Date: Tue, 30 Jan 2024 11:59:40 +0100
From: Borislav Petkov <bp@...en8.de>
To: X86 ML <x86@...nel.org>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/4] x86/alternatives: Optimize optimize_nops()

From: "Borislav Petkov (AMD)" <bp@...en8.de>

Return early if NOPs have already been optimized.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.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 2dd1c7fe0949..68ee46c379c1 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -233,6 +233,10 @@ static void __init_or_module noinline optimize_nops(const u8 * const instr, u8 *
 		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);
-- 
2.43.0