From b7301f20105a27112f7ca8040cfb0b0505a32fbd Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 30 Nov 2020 12:21:25 +0100 Subject: [PATCH] x86/mm/pae: Be consistent with pXXp_get_and_clear() Given that ptep_get_and_clear() uses cmpxchg8b, and that should be by far the most common case, there's no point in having an optimized variant for pmd/pud. Introduce the pxx_xchg64() helper to implement the common logic once. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20221022114425.103392961%40infradead.org --- arch/x86/include/asm/pgtable-3level.h | 71 +++++++-------------------- 1 file changed, 19 insertions(+), 52 deletions(-) diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h index d3a24929ddff..93c82c6ce6e3 100644 --- a/arch/x86/include/asm/pgtable-3level.h +++ b/arch/x86/include/asm/pgtable-3level.h @@ -90,34 +90,33 @@ static inline void pud_clear(pud_t *pudp) */ } + +#define pxx_xchg64(_pxx, _ptr, _val) ({ \ + _pxx##val_t *_p = (_pxx##val_t *)_ptr; \ + _pxx##val_t _o = *_p; \ + do { } while (!try_cmpxchg64(_p, &_o, (_val))); \ + native_make_##_pxx(_o); \ +}) + #ifdef CONFIG_SMP static inline pte_t native_ptep_get_and_clear(pte_t *ptep) { - pte_t old = *ptep; + return pxx_xchg64(pte, ptep, 0ULL); +} - do { - } while (!try_cmpxchg64(&ptep->pte, &old.pte, 0ULL)); +static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp) +{ + return pxx_xchg64(pmd, pmdp, 0ULL); +} - return old; +static inline pud_t native_pudp_get_and_clear(pud_t *pudp) +{ + return pxx_xchg64(pud, pudp, 0ULL); } #else #define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp) -#endif - -#ifdef CONFIG_SMP -static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp) -{ - pmd_t res; - - /* xchg acts as a barrier before setting of the high bits */ - res.pmd_low = xchg(&pmdp->pmd_low, 0); - res.pmd_high = READ_ONCE(pmdp->pmd_high); - WRITE_ONCE(pmdp->pmd_high, 0); - - return res; -} -#else #define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp) +#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp) #endif #ifndef pmdp_establish @@ -141,42 +140,10 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, return old; } - do { - old = *pmdp; - } while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd); - - return old; + return pxx_xchg64(pmd, pmdp, pmd.pmd); } #endif -#ifdef CONFIG_SMP -union split_pud { - struct { - u32 pud_low; - u32 pud_high; - }; - pud_t pud; -}; - -static inline pud_t native_pudp_get_and_clear(pud_t *pudp) -{ - union split_pud res, *orig = (union split_pud *)pudp; - -#ifdef CONFIG_PAGE_TABLE_ISOLATION - pti_set_user_pgtbl(&pudp->p4d.pgd, __pgd(0)); -#endif - - /* xchg acts as a barrier before setting of the high bits */ - res.pud_low = xchg(&orig->pud_low, 0); - res.pud_high = orig->pud_high; - orig->pud_high = 0; - - return res.pud; -} -#else -#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp) -#endif - /* Encode and de-code a swap entry */ #define SWP_TYPE_BITS 5