| From 56530f5d2ddc9b9fade7ef8db9cb886e9dc689b5 Mon Sep 17 00:00:00 2001 |
| From: Steve Capper <steve.capper@arm.com> |
| Date: Tue, 7 Jun 2016 17:58:06 +0100 |
| Subject: ARM: 8579/1: mm: Fix definition of pmd_mknotpresent |
| |
| From: Steve Capper <steve.capper@arm.com> |
| |
| commit 56530f5d2ddc9b9fade7ef8db9cb886e9dc689b5 upstream. |
| |
| Currently pmd_mknotpresent will use a zero entry to respresent an |
| invalidated pmd. |
| |
| Unfortunately this definition clashes with pmd_none, thus it is |
| possible for a race condition to occur if zap_pmd_range sees pmd_none |
| whilst __split_huge_pmd_locked is running too with pmdp_invalidate |
| just called. |
| |
| This patch fixes the race condition by modifying pmd_mknotpresent to |
| create non-zero faulting entries (as is done in other architectures), |
| removing the ambiguity with pmd_none. |
| |
| [catalin.marinas@arm.com: using L_PMD_SECT_VALID instead of PMD_TYPE_SECT] |
| |
| Fixes: 8d9625070073 ("ARM: mm: Transparent huge page support for LPAE systems.") |
| Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
| Acked-by: Will Deacon <will.deacon@arm.com> |
| Cc: Russell King <linux@armlinux.org.uk> |
| Signed-off-by: Steve Capper <steve.capper@arm.com> |
| Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
| Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm/include/asm/pgtable-3level.h | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/arch/arm/include/asm/pgtable-3level.h |
| +++ b/arch/arm/include/asm/pgtable-3level.h |
| @@ -258,10 +258,10 @@ PMD_BIT_FUNC(mkyoung, |= PMD_SECT_AF); |
| #define pfn_pmd(pfn,prot) (__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))) |
| #define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot) |
| |
| -/* represent a notpresent pmd by zero, this is used by pmdp_invalidate */ |
| +/* represent a notpresent pmd by faulting entry, this is used by pmdp_invalidate */ |
| static inline pmd_t pmd_mknotpresent(pmd_t pmd) |
| { |
| - return __pmd(0); |
| + return __pmd(pmd_val(pmd) & ~L_PMD_SECT_VALID); |
| } |
| |
| static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) |
