Date: Tue, 29 Jul 2014 13:08:56 +0000 (UTC) From: Marius Strobl <marius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r269237 - stable/8/sys/i386/i386 Message-ID: <201407291308.s6TD8uFM067036@svn.freebsd.org>
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Author: marius Date: Tue Jul 29 13:08:56 2014 New Revision: 269237 URL: http://svnweb.freebsd.org/changeset/base/269237 Log: MFC: r269050 (partial) Copying and zeroing pages via temporary mappings involves updating the corresponding page tables followed by accesses to the pages in question. This sequence is subject to the situation exactly described in the "AMD64 Architecture Programmer's Manual Volume 2: System Programming" rev. 3.23, "7.3.1 Special Coherency Considerations" [1, p. 171 f.]. Therefore, issuing the INVLPG right after modifying the PTE bits is crucial. For pmap_copy_page(), this has been broken in r124956. 1: http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/24593_APM_v21.pdf Reviewed by: alc, kib Sponsored by: Bally Wulff Games & Entertainment GmbH Modified: stable/8/sys/i386/i386/pmap.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/i386/ (props changed) Modified: stable/8/sys/i386/i386/pmap.c ============================================================================== --- stable/8/sys/i386/i386/pmap.c Tue Jul 29 13:08:46 2014 (r269236) +++ stable/8/sys/i386/i386/pmap.c Tue Jul 29 13:08:56 2014 (r269237) @@ -1263,6 +1263,13 @@ pmap_pte_release(pt_entry_t *pte) mtx_unlock(&PMAP2mutex); } +/* + * NB: The sequence of updating a page table followed by accesses to the + * corresponding pages is subject to the situation described in the "AMD64 + * Architecture Programmer's Manual Volume 2: System Programming" rev. 3.23, + * "7.3.1 Special Coherency Considerations". Therefore, issuing the INVLPG + * right after modifying the PTE bits is crucial. + */ static __inline void invlcaddr(void *caddr) { @@ -4096,12 +4103,12 @@ pmap_copy_page(vm_page_t src, vm_page_t if (*sysmaps->CMAP2) panic("pmap_copy_page: CMAP2 busy"); sched_pin(); - invlpg((u_int)sysmaps->CADDR1); - invlpg((u_int)sysmaps->CADDR2); *sysmaps->CMAP1 = PG_V | VM_PAGE_TO_PHYS(src) | PG_A | pmap_cache_bits(src->md.pat_mode, 0); + invlcaddr(sysmaps->CADDR1); *sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(dst) | PG_A | PG_M | pmap_cache_bits(dst->md.pat_mode, 0); + invlcaddr(sysmaps->CADDR2); bcopy(sysmaps->CADDR1, sysmaps->CADDR2, PAGE_SIZE); *sysmaps->CMAP1 = 0; *sysmaps->CMAP2 = 0;
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