From 1d4d37159d013a4c54d785407dd8902f901d7bc5 Mon Sep 17 00:00:00 2001 From: Jungseung Lee Date: Sat, 29 Nov 2014 02:33:30 +0100 Subject: ARM: 8235/1: Support for the PXN CPU feature on ARMv7 Modern ARMv7-A/R cores optionally implement below new hardware feature: - PXN: Privileged execute-never(PXN) is a security feature. PXN bit determines whether the processor can execute software from the region. This is effective solution against ret2usr attack. On an implementation that does not include the LPAE, PXN is optionally supported. This patch set PXN bit on user page table for preventing user code execution with privilege mode. Reviewed-by: Catalin Marinas Signed-off-by: Jungseung Lee Signed-off-by: Russell King --- arch/arm/include/asm/pgalloc.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'arch/arm/include/asm/pgalloc.h') diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h index 78a779361682..19cfab526d13 100644 --- a/arch/arm/include/asm/pgalloc.h +++ b/arch/arm/include/asm/pgalloc.h @@ -157,7 +157,15 @@ pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep) static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtable_t ptep) { - __pmd_populate(pmdp, page_to_phys(ptep), _PAGE_USER_TABLE); + extern pmdval_t user_pmd_table; + pmdval_t prot; + + if (__LINUX_ARM_ARCH__ >= 6 && !IS_ENABLED(CONFIG_ARM_LPAE)) + prot = user_pmd_table; + else + prot = _PAGE_USER_TABLE; + + __pmd_populate(pmdp, page_to_phys(ptep), prot); } #define pmd_pgtable(pmd) pmd_page(pmd) -- cgit v1.2.1