From 26ffd0d43b186b0d5186354da8714a1c2d360df0 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Sat, 1 Sep 2012 05:22:12 +0100 Subject: ARM: mm: introduce present, faulting entries for PAGE_NONE PROT_NONE mappings apply the page protection attributes defined by _P000 which translate to PAGE_NONE for ARM. These attributes specify an XN, RDONLY pte that is inaccessible to userspace. However, on kernels configured without support for domains, such a pte *is* accessible to the kernel and can be read via get_user, allowing tasks to read PROT_NONE pages via syscalls such as read/write over a pipe. This patch introduces a new software pte flag, L_PTE_NONE, that is set to identify faulting, present entries. Signed-off-by: Will Deacon --- arch/arm/mm/proc-v7-2level.S | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/arm/mm/proc-v7-2level.S') diff --git a/arch/arm/mm/proc-v7-2level.S b/arch/arm/mm/proc-v7-2level.S index e755e9f8d1b4..6d98c13ab827 100644 --- a/arch/arm/mm/proc-v7-2level.S +++ b/arch/arm/mm/proc-v7-2level.S @@ -101,6 +101,10 @@ ENTRY(cpu_v7_set_pte_ext) tst r1, #L_PTE_YOUNG tstne r1, #L_PTE_VALID +#ifndef CONFIG_CPU_USE_DOMAINS + eorne r1, r1, #L_PTE_NONE + tstne r1, #L_PTE_NONE +#endif moveq r3, #0 ARM( str r3, [r0, #2048]! ) -- cgit v1.2.3