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| author | Will Deacon <will.deacon@arm.com> | 2012-09-01 05:22:12 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2012-11-09 14:13:20 +0000 |
| commit | 26ffd0d43b186b0d5186354da8714a1c2d360df0 (patch) | |
| tree | 405c83d298530b65bb64630da52cfb368927691a /arch/arm/mm/proc-macros.S | |
| parent | dbf62d50067e55a782583fe53c3d2a3d98b1f6f3 (diff) | |
| download | talos-obmc-linux-26ffd0d43b186b0d5186354da8714a1c2d360df0.tar.gz talos-obmc-linux-26ffd0d43b186b0d5186354da8714a1c2d360df0.zip | |
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 <will.deacon@arm.com>
Diffstat (limited to 'arch/arm/mm/proc-macros.S')
| -rw-r--r-- | arch/arm/mm/proc-macros.S | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S index b29a2265af01..eb6aa73bc8b7 100644 --- a/arch/arm/mm/proc-macros.S +++ b/arch/arm/mm/proc-macros.S @@ -167,6 +167,10 @@ tst r1, #L_PTE_YOUNG tstne r1, #L_PTE_PRESENT moveq r3, #0 +#ifndef CONFIG_CPU_USE_DOMAINS + tstne r1, #L_PTE_NONE + movne r3, #0 +#endif str r3, [r0] mcr p15, 0, r0, c7, c10, 1 @ flush_pte |
