linux-kernel - [tip: x86/mm] x86/mm/pae: Use WRITE

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Message-ID: <166738035739.7716.310533349085902628.tip-bot2@tip-bot2>
Date:   Wed, 02 Nov 2022 09:12:37 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/mm] x86/mm/pae: Use WRITE_ONCE()

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

Commit-ID:     56a91588395af386a55bd2fee6304a161e7c766f
Gitweb:        https://git.kernel.org/tip/56a91588395af386a55bd2fee6304a161e7c766f
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Thu, 26 Nov 2020 17:40:12 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 01 Nov 2022 13:44:03 +01:00

x86/mm/pae: Use WRITE_ONCE()

Disallow write-tearing, that would be really unfortunate.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20221022114425.038102604%40infradead.org
---
 arch/x86/include/asm/pgtable-3level.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index 0a1b81d..d3a2492 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -27,9 +27,9 @@
  */
 static inline void native_set_pte(pte_t *ptep, pte_t pte)
 {
-	ptep->pte_high = pte.pte_high;
+	WRITE_ONCE(ptep->pte_high, pte.pte_high);
 	smp_wmb();
-	ptep->pte_low = pte.pte_low;
+	WRITE_ONCE(ptep->pte_low, pte.pte_low);
 }
 
 static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
@@ -58,16 +58,16 @@ static inline void native_set_pud(pud_t *pudp, pud_t pud)
 static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
 				    pte_t *ptep)
 {
-	ptep->pte_low = 0;
+	WRITE_ONCE(ptep->pte_low, 0);
 	smp_wmb();
-	ptep->pte_high = 0;
+	WRITE_ONCE(ptep->pte_high, 0);
 }
 
 static inline void native_pmd_clear(pmd_t *pmdp)
 {
-	pmdp->pmd_low = 0;
+	WRITE_ONCE(pmdp->pmd_low, 0);
 	smp_wmb();
-	pmdp->pmd_high = 0;
+	WRITE_ONCE(pmdp->pmd_high, 0);
 }
 
 static inline void native_pud_clear(pud_t *pudp)