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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@infradead.org>
AuthorDate: Thu, 26 Nov 2020 17:40:12 +01:00
Committer: Peter Zijlstra <peterz@infradead.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@infradead.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)
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