[tip: x86/mm] x86/mm/pae: Use WRITE_ONCE()

[tip-bot2 for Peter Zijlstra]

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

Commit-ID:     f7bcd4617de67a4700a7bd7dc56808b57f1c8748
Gitweb:        https://git.kernel.org/tip/f7bcd4617de67a4700a7bd7dc56808b57f1c8748
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Thu, 26 Nov 2020 17:40:12 +01:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Thu, 15 Dec 2022 10:37:27 -08:00

x86/mm/pae: Use WRITE_ONCE()

Disallow write-tearing, that would be really unfortunate.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
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)