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powerpc64/pmap: Simplify the code path for moea64_pte_replace_native()

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Summary:
MOEA64_PTE_REPLACE() is called often with the pmap lock held, and
sometimes with the page pv lock held.  The less work done while holding
a lock, the better.  Since we are intending to replace the same PTE
(same hash index), we don't need to recalculate anything, just flat
replace the PTE.  This cuts more than 200 instructions off the
invalidating code path.  In addition, we don't need to replace a PTE
that's not occupied by this PVO.

Reviewed by:	luporl
Differential Revision:	https://reviews.freebsd.org/D21515
This commit is contained in:
Justin Hibbits 2019-09-06 02:45:46 +00:00
parent 2f6823d4c1
commit 197a7e48c9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=351921
1 changed files with 40 additions and 2 deletions
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42
sys/powerpc/aim/moea64_native.c
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@ -357,6 +357,45 @@ moea64_pte_unset_native(mmu_t mmu, struct pvo_entry *pvo)
return (ptelo & (LPTE_CHG | LPTE_REF));
}
static int64_t
moea64_pte_replace_inval_native(mmu_t mmu, struct pvo_entry *pvo,
volatile struct lpte *pt)
{
struct lpte properpt;
uint64_t ptelo;
moea64_pte_from_pvo(pvo, &properpt);
rw_rlock(&moea64_eviction_lock);
if ((be64toh(pt->pte_hi & LPTE_AVPN_MASK)) !=
(properpt.pte_hi & LPTE_AVPN_MASK)) {
/* Evicted */
STAT_MOEA64(moea64_pte_overflow--);
rw_runlock(&moea64_eviction_lock);
return (-1);
}
/*
* Replace the pte, briefly locking it to collect RC bits. No
* atomics needed since this is protected against eviction by the lock.
*/
isync();
critical_enter();
pt->pte_hi = be64toh((pt->pte_hi & ~LPTE_VALID) | LPTE_LOCKED);
PTESYNC();
TLBIE(pvo->pvo_vpn);
ptelo = be64toh(pt->pte_lo);
EIEIO();
pt->pte_lo = htobe64(properpt.pte_lo);
EIEIO();
pt->pte_hi = htobe64(properpt.pte_hi); /* Release lock */
PTESYNC();
critical_exit();
rw_runlock(&moea64_eviction_lock);
return (ptelo & (LPTE_CHG | LPTE_REF));
}
static int64_t
moea64_pte_replace_native(mmu_t mmu, struct pvo_entry *pvo, int flags)
{
@ -379,8 +418,7 @@ moea64_pte_replace_native(mmu_t mmu, struct pvo_entry *pvo, int flags)
rw_runlock(&moea64_eviction_lock);
} else {
/* Otherwise, need reinsertion and deletion */
ptelo = moea64_pte_unset_native(mmu, pvo);
moea64_pte_insert_native(mmu, pvo);
ptelo = moea64_pte_replace_inval_native(mmu, pvo, pt);
}
return (ptelo);