Date: Fri, 11 Nov 2016 20:31:23 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r308557 - stable/11/sys/i386/i386 Message-ID: <201611112031.uABKVNpg026998@repo.freebsd.org>
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Author: kib Date: Fri Nov 11 20:31:23 2016 New Revision: 308557 URL: https://svnweb.freebsd.org/changeset/base/308557 Log: MFC r308029: Handle pmap_enter() over an existing 4/2M page in KVA on i386. Modified: stable/11/sys/i386/i386/pmap.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/i386/i386/pmap.c ============================================================================== --- stable/11/sys/i386/i386/pmap.c Fri Nov 11 20:27:00 2016 (r308556) +++ stable/11/sys/i386/i386/pmap.c Fri Nov 11 20:31:23 2016 (r308557) @@ -3466,11 +3466,14 @@ pmap_enter(pmap_t pmap, vm_offset_t va, PMAP_LOCK(pmap); sched_pin(); - /* - * In the case that a page table page is not - * resident, we are creating it here. - */ + pde = pmap_pde(pmap, va); if (va < VM_MAXUSER_ADDRESS) { + /* + * va is for UVA. + * In the case that a page table page is not resident, + * we are creating it here. pmap_allocpte() handles + * demotion. + */ mpte = pmap_allocpte(pmap, va, flags); if (mpte == NULL) { KASSERT((flags & PMAP_ENTER_NOSLEEP) != 0, @@ -3480,19 +3483,28 @@ pmap_enter(pmap_t pmap, vm_offset_t va, PMAP_UNLOCK(pmap); return (KERN_RESOURCE_SHORTAGE); } + } else { + /* + * va is for KVA, so pmap_demote_pde() will never fail + * to install a page table page. PG_V is also + * asserted by pmap_demote_pde(). + */ + KASSERT(pde != NULL && (*pde & PG_V) != 0, + ("KVA %#x invalid pde pdir %#jx", va, + (uintmax_t)pmap->pm_pdir[PTDPTDI])); + if ((*pde & PG_PS) != 0) + pmap_demote_pde(pmap, pde, va); } - - pde = pmap_pde(pmap, va); - if ((*pde & PG_PS) != 0) - panic("pmap_enter: attempted pmap_enter on 4MB page"); pte = pmap_pte_quick(pmap, va); /* - * Page Directory table entry not valid, we need a new PT page + * Page Directory table entry is not valid, which should not + * happen. We should have either allocated the page table + * page or demoted the existing mapping above. */ if (pte == NULL) { panic("pmap_enter: invalid page directory pdir=%#jx, va=%#x", - (uintmax_t)pmap->pm_pdir[PTDPTDI], va); + (uintmax_t)pmap->pm_pdir[PTDPTDI], va); } pa = VM_PAGE_TO_PHYS(m);
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