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) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221022114425.103392961%40infradead.org
This commit is contained in:
Peter Zijlstra 2020-11-30 12:21:25 +01:00 committed by Dave Hansen
parent f7bcd4617d
commit b7301f2010
1 changed files with 19 additions and 52 deletions

View File

@ -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