linux-kernel - [tip: x86/boot] x86/bootflag: Replace open-coded parity calculation with parity8()

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Message-ID: <174066211374.10177.8948394435153413345.tip-bot2@tip-bot2>
Date: Thu, 27 Feb 2025 13:15:13 -0000
From: "tip-bot2 for Kuan-Wei Chiu" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Yu-Chun Lin" <eleanor15x@...il.com>,
 "Kuan-Wei Chiu" <visitorckw@...il.com>, Uros Bizjak <ubizjak@...il.com>,
 Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/boot] x86/bootflag: Replace open-coded parity calculation
 with parity8()

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

Commit-ID:     9c94c14ca39577b6324c667d8450ffa19fc1e5c4
Gitweb:        https://git.kernel.org/tip/9c94c14ca39577b6324c667d8450ffa19fc1e5c4
Author:        Kuan-Wei Chiu <visitorckw@...il.com>
AuthorDate:    Thu, 27 Feb 2025 13:55:45 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Thu, 27 Feb 2025 14:00:30 +01:00

x86/bootflag: Replace open-coded parity calculation with parity8()

Refactor parity calculations to use the standard parity8() helper. This
change eliminates redundant implementations and improves code
efficiency.

[ ubizjak: Updated the patch to apply to the latest x86 tree. ]

Co-developed-by: Yu-Chun Lin <eleanor15x@...il.com>
Signed-off-by: Yu-Chun Lin <eleanor15x@...il.com>
Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: "H. Peter Anvin" <hpa@...or.com>
Link: https://lore.kernel.org/r/20250227125616.2253774-1-ubizjak@gmail.com
---
 arch/x86/kernel/bootflag.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/bootflag.c b/arch/x86/kernel/bootflag.c
index b935c3e..73274d7 100644
--- a/arch/x86/kernel/bootflag.c
+++ b/arch/x86/kernel/bootflag.c
@@ -8,6 +8,7 @@
 #include <linux/string.h>
 #include <linux/spinlock.h>
 #include <linux/acpi.h>
+#include <linux/bitops.h>
 #include <asm/io.h>

 #include <linux/mc146818rtc.h>
@@ -20,25 +21,12 @@

 int sbf_port __initdata = -1;	/* set via acpi_boot_init() */

-static bool __init parity(u8 v)
-{
-	int x = 0;
-	int i;
-
-	for (i = 0; i < 8; i++) {
-		x ^= (v & 1);
-		v >>= 1;
-	}
-
-	return !!x;
-}
-
 static void __init sbf_write(u8 v)
 {
 	unsigned long flags;

 	if (sbf_port != -1) {
-		if (!parity(v))
+		if (!parity8(v))
 			v ^= SBF_PARITY;

 		printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n",
@@ -69,7 +57,7 @@ static bool __init sbf_value_valid(u8 v)
 {
 	if (v & SBF_RESERVED)		/* Reserved bits */
 		return false;
-	if (!parity(v))
+	if (!parity8(v))
 		return false;

 	return true;