linux-kernel - [PATCH v1] mm/contpte: Optimize loop to reduce redundant operations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250407092243.2207837-1-xavier_qy@163.com>
Date: Mon,  7 Apr 2025 17:22:43 +0800
From: Xavier <xavier_qy@....com>
To: catalin.marinas@....com,
	will@...nel.org,
	akpm@...ux-foundation.org,
	baohua@...nel.org,
	ryan.roberts@....com,
	ioworker0@...il.com
Cc: xavier_qy@....com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1] mm/contpte: Optimize loop to reduce redundant operations

This commit optimizes the contpte_ptep_get function by adding early
 termination logic. It checks if the dirty and young bits of orig_pte
 are already set and skips redundant bit-setting operations during
 the loop. This reduces unnecessary iterations and improves performance.

Signed-off-by: Xavier <xavier_qy@....com>
---
 arch/arm64/mm/contpte.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
index bcac4f55f9c1..ca15d8f52d14 100644
--- a/arch/arm64/mm/contpte.c
+++ b/arch/arm64/mm/contpte.c
@@ -163,17 +163,26 @@ pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte)
 
 	pte_t pte;
 	int i;
+	bool dirty = false;
+	bool young = false;
 
 	ptep = contpte_align_down(ptep);
 
 	for (i = 0; i < CONT_PTES; i++, ptep++) {
 		pte = __ptep_get(ptep);
 
-		if (pte_dirty(pte))
+		if (!dirty && pte_dirty(pte)) {
+			dirty = true;
 			orig_pte = pte_mkdirty(orig_pte);
+		}
 
-		if (pte_young(pte))
+		if (!young && pte_young(pte)) {
+			young = true;
 			orig_pte = pte_mkyoung(orig_pte);
+		}
+
+		if (dirty && young)
+			break;
 	}
 
 	return orig_pte;
-- 
2.34.1