From 37657ad5fb97ca298c2f66fe815b99e2f42188e8 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 13 Jul 2018 17:12:50 +0000 Subject: Invalidate the mapping before updating its physical address. Doing so ensures that all threads sharing the pmap have a consistent view of the mapping. This fixes the problem described in the commit log message for r329254 without the overhead of an extra fault in the common case. (Once the riscv pmap_enter() implementation is similarly modified, the workaround added in r329254 can be removed, reducing the overhead of CoW faults.) See also r335784 for amd64. The mips implementation of pmap_enter() already reused the PV entry from the old mapping. Reviewed by: kib, markj MFC after: 3 weeks Differential Revision: https://reviews.freebsd.org/D16199 --- sys/mips/mips/pmap.c | 56 ++++++++++++++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 26 deletions(-) diff --git a/sys/mips/mips/pmap.c b/sys/mips/mips/pmap.c index 387661d429a6..012362f11f7a 100644 --- a/sys/mips/mips/pmap.c +++ b/sys/mips/mips/pmap.c @@ -2037,6 +2037,8 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot, if (is_kernel_pmap(pmap)) newpte |= PTE_G; PMAP_PTE_SET_CACHE_BITS(newpte, pa, m); + if ((m->oflags & VPO_UNMANAGED) == 0) + newpte |= PTE_MANAGED; mpte = NULL; @@ -2066,8 +2068,11 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot, panic("pmap_enter: invalid page directory, pdir=%p, va=%p", (void *)pmap->pm_segtab, (void *)va); } - om = NULL; + origpte = *pte; + KASSERT(!pte_test(&origpte, PTE_D | PTE_RO | PTE_V), + ("pmap_enter: modified page not writable: va: %p, pte: %#jx", + (void *)va, (uintmax_t)origpte)); opa = TLBLO_PTE_TO_PA(origpte); /* @@ -2086,10 +2091,6 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot, PTE_W)) pmap->pm_stats.wired_count--; - KASSERT(!pte_test(&origpte, PTE_D | PTE_RO), - ("%s: modified page not writable: va: %p, pte: %#jx", - __func__, (void *)va, (uintmax_t)origpte)); - /* * Remove extra pte reference */ @@ -2098,8 +2099,6 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot, if (pte_test(&origpte, PTE_MANAGED)) { m->md.pv_flags |= PV_TABLE_REF; - om = m; - newpte |= PTE_MANAGED; if (!pte_test(&newpte, PTE_RO)) vm_page_aflag_set(m, PGA_WRITEABLE); } @@ -2113,13 +2112,29 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot, * handle validating new mapping. */ if (opa) { + if (is_kernel_pmap(pmap)) + *pte = PTE_G; + else + *pte = 0; if (pte_test(&origpte, PTE_W)) pmap->pm_stats.wired_count--; - if (pte_test(&origpte, PTE_MANAGED)) { om = PHYS_TO_VM_PAGE(opa); + if (pte_test(&origpte, PTE_D)) + vm_page_dirty(om); + if ((om->md.pv_flags & PV_TABLE_REF) != 0) { + om->md.pv_flags &= ~PV_TABLE_REF; + vm_page_aflag_set(om, PGA_REFERENCED); + } pv = pmap_pvh_remove(&om->md, pmap, va); + if (!pte_test(&newpte, PTE_MANAGED)) + free_pv_entry(pmap, pv); + if ((om->aflags & PGA_WRITEABLE) != 0 && + TAILQ_EMPTY(&om->md.pv_list)) + vm_page_aflag_clear(om, PGA_WRITEABLE); } + pmap_invalidate_page(pmap, va); + origpte = 0; if (mpte != NULL) { mpte->wire_count--; KASSERT(mpte->wire_count > 0, @@ -2132,17 +2147,16 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot, /* * Enter on the PV list if part of our managed memory. */ - if ((m->oflags & VPO_UNMANAGED) == 0) { + if (pte_test(&newpte, PTE_MANAGED)) { m->md.pv_flags |= PV_TABLE_REF; - if (pv == NULL) + if (pv == NULL) { pv = get_pv_entry(pmap, FALSE); - pv->pv_va = va; + pv->pv_va = va; + } TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list); - newpte |= PTE_MANAGED; if (!pte_test(&newpte, PTE_RO)) vm_page_aflag_set(m, PGA_WRITEABLE); - } else if (pv != NULL) - free_pv_entry(pmap, pv); + } /* * Increment counters @@ -2163,21 +2177,11 @@ validate: if (origpte != newpte) { *pte = newpte; if (pte_test(&origpte, PTE_V)) { - if (pte_test(&origpte, PTE_MANAGED) && opa != pa) { - if (om->md.pv_flags & PV_TABLE_REF) - vm_page_aflag_set(om, PGA_REFERENCED); - om->md.pv_flags &= ~PV_TABLE_REF; - } + KASSERT(opa == pa, ("pmap_enter: invalid update")); if (pte_test(&origpte, PTE_D)) { - KASSERT(!pte_test(&origpte, PTE_RO), - ("pmap_enter: modified page not writable:" - " va: %p, pte: %#jx", (void *)va, (uintmax_t)origpte)); if (pte_test(&origpte, PTE_MANAGED)) - vm_page_dirty(om); + vm_page_dirty(m); } - if (pte_test(&origpte, PTE_MANAGED) && - TAILQ_EMPTY(&om->md.pv_list)) - vm_page_aflag_clear(om, PGA_WRITEABLE); pmap_update_page(pmap, va, newpte); } } -- cgit v1.2.3