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Date: Tue, 10 Nov 2015 17:57:36 -0800
From: Laura Abbott <labbott@...oraproject.org>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Zhong Jiang <zhongjiang@...wei.com>
Cc: Laura Abbott <labbott@...oraproject.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Kees Cook <keescook@...omium.org>,
Xishi Qiu <qiuxishi@...wei.com>,
Mark Rutland <mark.rutland@....com>
Subject: [PATCHv2 1/2] arm64: Get existing page protections in split_pmd
Rather than always putting the least restrictived permissions
(PAGE_KERNEL_EXEC) when spliting a pmd into pages, use
the existing permissions from the pmd for the page.
Signed-off-by: Laura Abbott <labbott@...oraproject.org>
---
v2: Typo and typechecking fixed
I chose not to add the Reviewed-by from Ard here because of the addition of
the contiguous bit in split_pmd. Not sure if I should be explicitly carrying
it over.
---
arch/arm64/mm/mmu.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index c2fa6b5..496c3fd 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -76,15 +76,13 @@ static void __init *early_alloc(unsigned long sz)
static void split_pmd(pmd_t *pmd, pte_t *pte)
{
unsigned long pfn = pmd_pfn(*pmd);
+ unsigned long addr = pfn << PAGE_SHIFT;
+ pgprot_t prot = __pgprot((pmd_val(*pmd) ^ addr) | PTE_TYPE_PAGE);
+
int i = 0;
do {
- /*
- * Need to have the least restrictive permissions available
- * permissions will be fixed up later. Default the new page
- * range as contiguous ptes.
- */
- set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT));
+ set_pte(pte, pfn_pte(pfn, prot));
pfn++;
} while (pte++, i++, i < PTRS_PER_PTE);
}
--
2.5.0
--
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