From owner-svn-src-all@FreeBSD.ORG Sat Jan 30 06:23:29 2010 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DF945106566B; Sat, 30 Jan 2010 06:23:28 +0000 (UTC) (envelope-from alc@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id CDFA68FC19; Sat, 30 Jan 2010 06:23:28 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id o0U6NSQn008512; Sat, 30 Jan 2010 06:23:28 GMT (envelope-from alc@svn.freebsd.org) Received: (from alc@localhost) by svn.freebsd.org (8.14.3/8.14.3/Submit) id o0U6NSD2008509; Sat, 30 Jan 2010 06:23:28 GMT (envelope-from alc@svn.freebsd.org) Message-Id: <201001300623.o0U6NSD2008509@svn.freebsd.org> From: Alan Cox Date: Sat, 30 Jan 2010 06:23:28 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org X-SVN-Group: stable-8 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r203182 - in stable/8/sys/i386: i386 include X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 30 Jan 2010 06:23:29 -0000 Author: alc Date: Sat Jan 30 06:23:28 2010 New Revision: 203182 URL: http://svn.freebsd.org/changeset/base/203182 Log: MFC r202894 Handle a race between pmap_kextract() and pmap_promote_pde(). Modified: stable/8/sys/i386/i386/pmap.c stable/8/sys/i386/include/pmap.h Directory Properties: stable/8/sys/ (props changed) stable/8/sys/amd64/include/xen/ (props changed) stable/8/sys/cddl/contrib/opensolaris/ (props changed) stable/8/sys/contrib/dev/acpica/ (props changed) stable/8/sys/contrib/pf/ (props changed) stable/8/sys/dev/xen/xenpci/ (props changed) Modified: stable/8/sys/i386/i386/pmap.c ============================================================================== --- stable/8/sys/i386/i386/pmap.c Sat Jan 30 04:24:03 2010 (r203181) +++ stable/8/sys/i386/i386/pmap.c Sat Jan 30 06:23:28 2010 (r203182) @@ -243,8 +243,9 @@ struct sysmaps { caddr_t CADDR2; }; static struct sysmaps sysmaps_pcpu[MAXCPU]; -pt_entry_t *CMAP1 = 0; +pt_entry_t *CMAP1 = 0, *KPTmap; static pt_entry_t *CMAP3; +static pd_entry_t *KPTD; caddr_t CADDR1 = 0, ptvmmap = 0; static caddr_t CADDR3; struct msgbuf *msgbufp = 0; @@ -440,6 +441,21 @@ pmap_bootstrap(vm_paddr_t firstaddr) SYSMAP(struct msgbuf *, unused, msgbufp, atop(round_page(MSGBUF_SIZE))) /* + * KPTmap is used by pmap_kextract(). + */ + SYSMAP(pt_entry_t *, KPTD, KPTmap, KVA_PAGES) + + for (i = 0; i < NKPT; i++) + KPTD[i] = (KPTphys + (i << PAGE_SHIFT)) | PG_RW | PG_V; + + /* + * Adjust the start of the KPTD and KPTmap so that the implementation + * of pmap_kextract() and pmap_growkernel() can be made simpler. + */ + KPTD -= KPTDI; + KPTmap -= i386_btop(KPTDI << PDRSHIFT); + + /* * ptemap is used for pmap_pte_quick */ SYSMAP(pt_entry_t *, PMAP1, PADDR1, 1); @@ -1829,6 +1845,7 @@ pmap_growkernel(vm_offset_t addr) vm_page_t nkpg; pd_entry_t newpdir; pt_entry_t *pde; + boolean_t updated_PTD; mtx_assert(&kernel_map->system_mtx, MA_OWNED); if (kernel_vm_end == 0) { @@ -1868,14 +1885,20 @@ pmap_growkernel(vm_offset_t addr) pmap_zero_page(nkpg); ptppaddr = VM_PAGE_TO_PHYS(nkpg); newpdir = (pd_entry_t) (ptppaddr | PG_V | PG_RW | PG_A | PG_M); - pdir_pde(PTD, kernel_vm_end) = newpdir; + pdir_pde(KPTD, kernel_vm_end) = newpdir; + updated_PTD = FALSE; mtx_lock_spin(&allpmaps_lock); LIST_FOREACH(pmap, &allpmaps, pm_list) { + if ((pmap->pm_pdir[PTDPTDI] & PG_FRAME) == (PTDpde[0] & + PG_FRAME)) + updated_PTD = TRUE; pde = pmap_pde(pmap, kernel_vm_end); pde_store(pde, newpdir); } mtx_unlock_spin(&allpmaps_lock); + KASSERT(updated_PTD, + ("pmap_growkernel: current page table is not in allpmaps")); kernel_vm_end = (kernel_vm_end + PAGE_SIZE * NPTEPG) & ~(PAGE_SIZE * NPTEPG - 1); if (kernel_vm_end - 1 >= kernel_map->max_offset) { kernel_vm_end = kernel_map->max_offset; Modified: stable/8/sys/i386/include/pmap.h ============================================================================== --- stable/8/sys/i386/include/pmap.h Sat Jan 30 04:24:03 2010 (r203181) +++ stable/8/sys/i386/include/pmap.h Sat Jan 30 06:23:28 2010 (r203182) @@ -265,6 +265,16 @@ pte_load_store_ma(pt_entry_t *ptep, pt_e #define pde_store_ma(ptep, pte) pte_load_store_ma((ptep), (pt_entry_t)pte) #elif !defined(XEN) + +/* + * KPTmap is a linear mapping of the kernel page table. It differs from the + * recursive mapping in two ways: (1) it only provides access to kernel page + * table pages, and not user page table pages, and (2) it provides access to + * a kernel page table page after the corresponding virtual addresses have + * been promoted to a 2/4MB page mapping. + */ +extern pt_entry_t *KPTmap; + /* * Routine: pmap_kextract * Function: @@ -279,10 +289,17 @@ pmap_kextract(vm_offset_t va) if ((pa = PTD[va >> PDRSHIFT]) & PG_PS) { pa = (pa & PG_PS_FRAME) | (va & PDRMASK); } else { - pa = *vtopte(va); + /* + * Beware of a concurrent promotion that changes the PDE at + * this point! For example, vtopte() must not be used to + * access the PTE because it would use the new PDE. It is, + * however, safe to use the old PDE because the page table + * page is preserved by the promotion. + */ + pa = KPTmap[i386_btop(va)]; pa = (pa & PG_FRAME) | (va & PAGE_MASK); } - return pa; + return (pa); } #define PT_UPDATES_FLUSH()