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arm64: Distinguish between user and kernel XN bits

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On AArch64, the meaning of the XN bit has changed to UXN (user). The PXN
(privileged) bit must be set to prevent kernel execution. Without the
PXN bit set, the CPU may speculatively access device memory. This patch
ensures that all the mappings that the kernel must not execute from
(including user mappings) have the PXN bit set.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas
2012-11-15 17:21:16 +00:00
parent 77b67063bb
commit 8e620b0476
3 changed files with 24 additions and 22 deletions
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2
arch/arm64/include/asm/io.h
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@@ -222,7 +222,7 @@ extern void __iomem *__ioremap(phys_addr_t phys_addr, size_t size, pgprot_t prot
extern void __iounmap(volatile void __iomem *addr);
#define PROT_DEFAULT (PTE_TYPE_PAGE | PTE_AF | PTE_DIRTY)
#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_XN | PTE_ATTRINDX(MT_DEVICE_nGnRE))
#define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_DEVICE_nGnRE))
#define PROT_NORMAL_NC (PROT_DEFAULT | PTE_ATTRINDX(MT_NORMAL_NC))
#define ioremap(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE))