diff options
| author | Jungseung Lee | 2014-11-29 02:33:30 +0100 |
|---|---|---|
| committer | Russell King | 2014-12-03 15:57:45 +0000 |
| commit | 1d4d37159d013a4c54d785407dd8902f901d7bc5 (patch) | |
| tree | 9d70738fee982093c907f004b2b834e32c86c8d8 /arch/arm/mm | |
| parent | 44cb09c23f8e5838f24ef47d43dd2804b71b3a65 (diff) | |
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 <catalin.marinas@arm.com>
Signed-off-by: Jungseung Lee <js07.lee@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm')
| -rw-r--r-- | arch/arm/mm/mmu.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index d028dc74a9d5..b590a4c92462 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -52,6 +52,8 @@ EXPORT_SYMBOL(empty_zero_page); */ pmd_t *top_pmd; +pmdval_t user_pmd_table = _PAGE_USER_TABLE; + #define CPOLICY_UNCACHED 0 #define CPOLICY_BUFFERED 1 #define CPOLICY_WRITETHROUGH 2 @@ -528,14 +530,23 @@ static void __init build_mem_type_table(void) hyp_device_pgprot = mem_types[MT_DEVICE].prot_pte; s2_device_pgprot = mem_types[MT_DEVICE].prot_pte_s2; +#ifndef CONFIG_ARM_LPAE /* * We don't use domains on ARMv6 (since this causes problems with * v6/v7 kernels), so we must use a separate memory type for user * r/o, kernel r/w to map the vectors page. */ -#ifndef CONFIG_ARM_LPAE if (cpu_arch == CPU_ARCH_ARMv6) vecs_pgprot |= L_PTE_MT_VECTORS; + + /* + * Check is it with support for the PXN bit + * in the Short-descriptor translation table format descriptors. + */ + if (cpu_arch == CPU_ARCH_ARMv7 && + (read_cpuid_ext(CPUID_EXT_MMFR0) & 0xF) == 4) { + user_pmd_table |= PMD_PXNTABLE; + } #endif /* @@ -605,6 +616,11 @@ static void __init build_mem_type_table(void) } kern_pgprot |= PTE_EXT_AF; vecs_pgprot |= PTE_EXT_AF; + + /* + * Set PXN for user mappings + */ + user_pgprot |= PTE_EXT_PXN; #endif for (i = 0; i < 16; i++) { |