Refine the fix from r312954. Specifically, add a new PDE-only flag,
PG_PROMOTED, that indicates whether lingering 4KB page mappings might need to be flushed on a PDE change that restricts or destroys a 2MB page mapping. This flag allows the pmap to avoid range invalidations that are both unnecessary and costly. Reviewed by: kib, markj MFC after: 6 weeks Differential Revision: https://reviews.freebsd.org/D9665
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@ -613,6 +613,8 @@ static vm_page_t pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va,
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vm_page_t m, vm_prot_t prot, vm_page_t mpte, struct rwlock **lockp);
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static void pmap_fill_ptp(pt_entry_t *firstpte, pt_entry_t newpte);
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static int pmap_insert_pt_page(pmap_t pmap, vm_page_t mpte);
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static void pmap_invalidate_pde_page(pmap_t pmap, vm_offset_t va,
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pd_entry_t pde);
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static void pmap_kenter_attr(vm_offset_t va, vm_paddr_t pa, int mode);
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static void pmap_pde_attr(pd_entry_t *pde, int cache_bits, int mask);
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static void pmap_promote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va,
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@ -1838,6 +1840,27 @@ pmap_update_pde(pmap_t pmap, vm_offset_t va, pd_entry_t *pde, pd_entry_t newpde)
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}
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#endif /* !SMP */
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static void
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pmap_invalidate_pde_page(pmap_t pmap, vm_offset_t va, pd_entry_t pde)
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{
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/*
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* When the PDE has PG_PROMOTED set, the 2MB page mapping was created
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* by a promotion that did not invalidate the 512 4KB page mappings
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* that might exist in the TLB. Consequently, at this point, the TLB
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* may hold both 4KB and 2MB page mappings for the address range [va,
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* va + NBPDR). Therefore, the entire range must be invalidated here.
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* In contrast, when PG_PROMOTED is clear, the TLB will not hold any
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* 4KB page mappings for the address range [va, va + NBPDR), and so a
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* single INVLPG suffices to invalidate the 2MB page mapping from the
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* TLB.
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*/
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if ((pde & PG_PROMOTED) != 0)
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pmap_invalidate_range(pmap, va, va + NBPDR - 1);
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else
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pmap_invalidate_page(pmap, va);
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}
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#define PMAP_CLFLUSH_THRESHOLD (2 * 1024 * 1024)
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void
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@ -3472,7 +3495,8 @@ pmap_demote_pde_locked(pmap_t pmap, pd_entry_t *pde, vm_offset_t va,
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SLIST_INIT(&free);
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sva = trunc_2mpage(va);
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pmap_remove_pde(pmap, pde, sva, &free, lockp);
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pmap_invalidate_range(pmap, sva, sva + NBPDR - 1);
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if ((oldpde & PG_G) == 0)
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pmap_invalidate_pde_page(pmap, sva, oldpde);
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pmap_free_zero_pages(&free);
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CTR2(KTR_PMAP, "pmap_demote_pde: failure for va %#lx"
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" in pmap %p", va, pmap);
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@ -3612,25 +3636,8 @@ pmap_remove_pde(pmap_t pmap, pd_entry_t *pdq, vm_offset_t sva,
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oldpde = pte_load_clear(pdq);
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if (oldpde & PG_W)
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pmap->pm_stats.wired_count -= NBPDR / PAGE_SIZE;
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/*
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* When workaround_erratum383 is false, a promotion to a 2M
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* page mapping does not invalidate the 512 4K page mappings
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* from the TLB. Consequently, at this point, the TLB may
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* hold both 4K and 2M page mappings. Therefore, the entire
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* range of addresses must be invalidated here. In contrast,
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* when workaround_erratum383 is true, a promotion does
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* invalidate the 512 4K page mappings, and so a single INVLPG
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* suffices to invalidate the 2M page mapping.
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*/
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if ((oldpde & PG_G) != 0) {
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if (workaround_erratum383)
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pmap_invalidate_page(kernel_pmap, sva);
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else
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pmap_invalidate_range(kernel_pmap, sva,
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sva + NBPDR - 1);
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}
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if ((oldpde & PG_G) != 0)
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pmap_invalidate_pde_page(kernel_pmap, sva, oldpde);
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pmap_resident_count_dec(pmap, NBPDR / PAGE_SIZE);
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if (oldpde & PG_MANAGED) {
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CHANGE_PV_LIST_LOCK_TO_PHYS(lockp, oldpde & PG_PS_FRAME);
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@ -4010,16 +4017,16 @@ pmap_protect_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t sva, vm_prot_t prot)
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if ((prot & VM_PROT_EXECUTE) == 0)
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newpde |= pg_nx;
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if (newpde != oldpde) {
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if (!atomic_cmpset_long(pde, oldpde, newpde))
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/*
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* As an optimization to future operations on this PDE, clear
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* PG_PROMOTED. The impending invalidation will remove any
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* lingering 4KB page mappings from the TLB.
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*/
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if (!atomic_cmpset_long(pde, oldpde, newpde & ~PG_PROMOTED))
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goto retry;
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if (oldpde & PG_G) {
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/* See pmap_remove_pde() for explanation. */
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if (workaround_erratum383)
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pmap_invalidate_page(kernel_pmap, sva);
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else
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pmap_invalidate_range(kernel_pmap, sva,
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sva + NBPDR - 1);
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} else
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if ((oldpde & PG_G) != 0)
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pmap_invalidate_pde_page(kernel_pmap, sva, oldpde);
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else
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anychanged = TRUE;
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}
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return (anychanged);
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@ -4272,7 +4279,7 @@ pmap_promote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va,
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if (workaround_erratum383)
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pmap_update_pde(pmap, va, pde, PG_PS | newpde);
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else
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pde_store(pde, PG_PS | newpde);
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pde_store(pde, PG_PROMOTED | PG_PS | newpde);
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atomic_add_long(&pmap_pde_promotions, 1);
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CTR2(KTR_PMAP, "pmap_promote_pde: success for va %#lx"
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@ -4585,7 +4592,8 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
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pmap_resident_count_inc(pmap, NBPDR / PAGE_SIZE);
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/*
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* Map the superpage.
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* Map the superpage. (This is not a promoted mapping; there will not
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* be any lingering 4KB page mappings in the TLB.)
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*/
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pde_store(pde, newpde);
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@ -109,6 +109,7 @@
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#define PG_MANAGED X86_PG_AVAIL2
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#define EPT_PG_EMUL_V X86_PG_AVAIL(52)
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#define EPT_PG_EMUL_RW X86_PG_AVAIL(53)
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#define PG_PROMOTED X86_PG_AVAIL(54) /* PDE only */
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#define PG_FRAME (0x000ffffffffff000ul)
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#define PG_PS_FRAME (0x000fffffffe00000ul)
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@ -301,6 +301,8 @@ static vm_page_t pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va,
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vm_page_t m, vm_prot_t prot, vm_page_t mpte);
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static void pmap_flush_page(vm_page_t m);
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static int pmap_insert_pt_page(pmap_t pmap, vm_page_t mpte);
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static void pmap_invalidate_pde_page(pmap_t pmap, vm_offset_t va,
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pd_entry_t pde);
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static void pmap_fill_ptp(pt_entry_t *firstpte, pt_entry_t newpte);
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static boolean_t pmap_is_modified_pvh(struct md_page *pvh);
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static boolean_t pmap_is_referenced_pvh(struct md_page *pvh);
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@ -1259,6 +1261,27 @@ pmap_update_pde(pmap_t pmap, vm_offset_t va, pd_entry_t *pde, pd_entry_t newpde)
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}
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#endif /* !SMP */
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static void
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pmap_invalidate_pde_page(pmap_t pmap, vm_offset_t va, pd_entry_t pde)
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{
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/*
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* When the PDE has PG_PROMOTED set, the 2- or 4MB page mapping was
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* created by a promotion that did not invalidate the 512 or 1024 4KB
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* page mappings that might exist in the TLB. Consequently, at this
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* point, the TLB may hold both 4KB and 2- or 4MB page mappings for
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* the address range [va, va + NBPDR). Therefore, the entire range
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* must be invalidated here. In contrast, when PG_PROMOTED is clear,
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* the TLB will not hold any 4KB page mappings for the address range
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* [va, va + NBPDR), and so a single INVLPG suffices to invalidate the
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* 2- or 4MB page mapping from the TLB.
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*/
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if ((pde & PG_PROMOTED) != 0)
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pmap_invalidate_range(pmap, va, va + NBPDR - 1);
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else
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pmap_invalidate_page(pmap, va);
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}
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#define PMAP_CLFLUSH_THRESHOLD (2 * 1024 * 1024)
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void
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@ -2649,7 +2672,8 @@ pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
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SLIST_INIT(&free);
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sva = trunc_4mpage(va);
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pmap_remove_pde(pmap, pde, sva, &free);
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pmap_invalidate_range(pmap, sva, sva + NBPDR - 1);
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if ((oldpde & PG_G) == 0)
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pmap_invalidate_pde_page(pmap, sva, oldpde);
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pmap_free_zero_pages(&free);
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CTR2(KTR_PMAP, "pmap_demote_pde: failure for va %#x"
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" in pmap %p", va, pmap);
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@ -2819,23 +2843,9 @@ pmap_remove_pde(pmap_t pmap, pd_entry_t *pdq, vm_offset_t sva,
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/*
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* Machines that don't support invlpg, also don't support
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* PG_G.
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*
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* When workaround_erratum383 is false, a promotion to a 2M/4M
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* page mapping does not invalidate the 512/1024 4K page mappings
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* from the TLB. Consequently, at this point, the TLB may
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* hold both 4K and 2M/4M page mappings. Therefore, the entire
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* range of addresses must be invalidated here. In contrast,
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* when workaround_erratum383 is true, a promotion does
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* invalidate the 512/1024 4K page mappings, and so a single INVLPG
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* suffices to invalidate the 2M/4M page mapping.
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*/
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if ((oldpde & PG_G) != 0) {
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if (workaround_erratum383)
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pmap_invalidate_page(kernel_pmap, sva);
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else
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pmap_invalidate_range(kernel_pmap, sva,
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sva + NBPDR - 1);
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}
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if ((oldpde & PG_G) != 0)
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pmap_invalidate_pde_page(kernel_pmap, sva, oldpde);
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pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
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if (oldpde & PG_MANAGED) {
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@ -3143,16 +3153,16 @@ pmap_protect_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t sva, vm_prot_t prot)
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newpde |= pg_nx;
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#endif
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if (newpde != oldpde) {
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if (!pde_cmpset(pde, oldpde, newpde))
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/*
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* As an optimization to future operations on this PDE, clear
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* PG_PROMOTED. The impending invalidation will remove any
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* lingering 4KB page mappings from the TLB.
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*/
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if (!pde_cmpset(pde, oldpde, newpde & ~PG_PROMOTED))
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goto retry;
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if (oldpde & PG_G) {
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/* See pmap_remove_pde() for explanation. */
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if (workaround_erratum383)
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pmap_invalidate_page(kernel_pmap, sva);
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else
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pmap_invalidate_range(kernel_pmap, sva,
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sva + NBPDR - 1);
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} else
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if ((oldpde & PG_G) != 0)
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pmap_invalidate_pde_page(kernel_pmap, sva, oldpde);
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else
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anychanged = TRUE;
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}
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return (anychanged);
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@ -3437,9 +3447,9 @@ pmap_promote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
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if (workaround_erratum383)
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pmap_update_pde(pmap, va, pde, PG_PS | newpde);
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else if (pmap == kernel_pmap)
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pmap_kenter_pde(va, PG_PS | newpde);
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pmap_kenter_pde(va, PG_PROMOTED | PG_PS | newpde);
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else
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pde_store(pde, PG_PS | newpde);
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pde_store(pde, PG_PROMOTED | PG_PS | newpde);
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pmap_pde_promotions++;
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CTR2(KTR_PMAP, "pmap_promote_pde: success for va %#x"
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@ -3722,7 +3732,8 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot)
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pmap->pm_stats.resident_count += NBPDR / PAGE_SIZE;
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/*
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* Map the superpage.
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* Map the superpage. (This is not a promoted mapping; there will not
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* be any lingering 4KB page mappings in the TLB.)
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*/
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pde_store(pde, newpde);
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@ -71,6 +71,7 @@
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/* Our various interpretations of the above */
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#define PG_W PG_AVAIL1 /* "Wired" pseudoflag */
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#define PG_MANAGED PG_AVAIL2
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#define PG_PROMOTED PG_AVAIL3 /* PDE only */
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#if defined(PAE) || defined(PAE_TABLES)
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#define PG_FRAME (0x000ffffffffff000ull)
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#define PG_PS_FRAME (0x000fffffffe00000ull)
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