[PATCH 09/13] x86/mm/pae: Use WRITE_ONCE()

Peter Zijlstra
2022-10-22T11:49:34Z

Disallow write-tearing, that would be really unfortunate.

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

--- 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
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)