From owner-svn-src-all@freebsd.org Fri Jan 4 17:33:08 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 44A5E1433252; Fri, 4 Jan 2019 17:33:08 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DF66872EC4; Fri, 4 Jan 2019 17:33:07 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id D181040A7; Fri, 4 Jan 2019 17:33:07 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x04HX7uD042892; Fri, 4 Jan 2019 17:33:07 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x04HX7nD042891; Fri, 4 Jan 2019 17:33:07 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201901041733.x04HX7nD042891@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Fri, 4 Jan 2019 17:33:07 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r342769 - head/sys/i386/include X-SVN-Group: head X-SVN-Commit-Author: kib X-SVN-Commit-Paths: head/sys/i386/include X-SVN-Commit-Revision: 342769 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: DF66872EC4 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.96 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.997,0]; NEURAL_HAM_SHORT(-0.97)[-0.966,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-0.999,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 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: Fri, 04 Jan 2019 17:33:08 -0000 Author: kib Date: Fri Jan 4 17:33:07 2019 New Revision: 342769 URL: https://svnweb.freebsd.org/changeset/base/342769 Log: i386: Use atomic 64bit load to read PDE value from PAE pagetables in pmap_kextract(). pmap_kextract() can race with promotion/demotion on the kernel page table, in which case current non-atomic 64bit read would see torn value, breaking pmap_kextract(). pmap_kextract() would correctly handle either promoted or demoted PDE, but not a mix where one word is from a different state. It requires PAE and > 4G memory to reproduce. We observed this in real loads, both for intensive use of malloc(9)/free(9) where vtoslab() returned invalid pointer to the slab, and with the use of busdma_bounce, where incorrect page was bounced. In collaboration with: pho Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D18714 Modified: head/sys/i386/include/pmap.h Modified: head/sys/i386/include/pmap.h ============================================================================== --- head/sys/i386/include/pmap.h Fri Jan 4 17:31:50 2019 (r342768) +++ head/sys/i386/include/pmap.h Fri Jan 4 17:33:07 2019 (r342769) @@ -234,6 +234,32 @@ extern pd_entry_t *IdlePTD; /* physical address of "Id */ extern pt_entry_t *KPTmap; +#if (defined(PAE) || defined(PAE_TABLES)) + +#define pde_cmpset(pdep, old, new) atomic_cmpset_64_i586(pdep, old, new) +#define pte_load_store(ptep, pte) atomic_swap_64_i586(ptep, pte) +#define pte_load_clear(ptep) atomic_swap_64_i586(ptep, 0) +#define pte_store(ptep, pte) atomic_store_rel_64_i586(ptep, pte) +#define pte_load(ptep) atomic_load_acq_64_i586(ptep) + +extern pt_entry_t pg_nx; + +#else /* !(PAE || PAE_TABLES) */ + +#define pde_cmpset(pdep, old, new) atomic_cmpset_int(pdep, old, new) +#define pte_load_store(ptep, pte) atomic_swap_int(ptep, pte) +#define pte_load_clear(ptep) atomic_swap_int(ptep, 0) +#define pte_store(ptep, pte) do { \ + *(u_int *)(ptep) = (u_int)(pte); \ +} while (0) +#define pte_load(ptep) atomic_load_acq_int(ptep) + +#endif /* !(PAE || PAE_TABLES) */ + +#define pte_clear(ptep) pte_store(ptep, 0) + +#define pde_store(pdep, pde) pte_store(pdep, pde) + /* * Extract from the kernel page table the physical address that is mapped by * the given virtual address "va". @@ -245,7 +271,7 @@ pmap_kextract(vm_offset_t va) { vm_paddr_t pa; - if ((pa = PTD[va >> PDRSHIFT]) & PG_PS) { + if ((pa = pte_load(&PTD[va >> PDRSHIFT])) & PG_PS) { pa = (pa & PG_PS_FRAME) | (va & PDRMASK); } else { /* @@ -260,30 +286,6 @@ pmap_kextract(vm_offset_t va) } return (pa); } - -#if (defined(PAE) || defined(PAE_TABLES)) - -#define pde_cmpset(pdep, old, new) atomic_cmpset_64_i586(pdep, old, new) -#define pte_load_store(ptep, pte) atomic_swap_64_i586(ptep, pte) -#define pte_load_clear(ptep) atomic_swap_64_i586(ptep, 0) -#define pte_store(ptep, pte) atomic_store_rel_64_i586(ptep, pte) - -extern pt_entry_t pg_nx; - -#else /* !(PAE || PAE_TABLES) */ - -#define pde_cmpset(pdep, old, new) atomic_cmpset_int(pdep, old, new) -#define pte_load_store(ptep, pte) atomic_swap_int(ptep, pte) -#define pte_load_clear(ptep) atomic_swap_int(ptep, 0) -#define pte_store(ptep, pte) do { \ - *(u_int *)(ptep) = (u_int)(pte); \ -} while (0) - -#endif /* !(PAE || PAE_TABLES) */ - -#define pte_clear(ptep) pte_store(ptep, 0) - -#define pde_store(pdep, pde) pte_store(pdep, pde) #endif /* _KERNEL */