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| author | Will Deacon <will.deacon@arm.com> | 2012-09-01 06:22:12 +0200 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2012-11-09 15:13:20 +0100 |
| commit | 26ffd0d43b186b0d5186354da8714a1c2d360df0 (patch) | |
| tree | 405c83d298530b65bb64630da52cfb368927691a /arch/arm/include/asm | |
| parent | ARM: mm: introduce L_PTE_VALID for page table entries (diff) | |
| download | linux-26ffd0d43b186b0d5186354da8714a1c2d360df0.tar.xz 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/include/asm')
| -rw-r--r-- | arch/arm/include/asm/pgtable-2level.h | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/pgtable-3level.h | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/pgtable.h | 6 |
3 files changed, 5 insertions, 3 deletions
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h index c44a1ecfc28a..f97ee02386ee 100644 --- a/arch/arm/include/asm/pgtable-2level.h +++ b/arch/arm/include/asm/pgtable-2level.h @@ -124,6 +124,7 @@ #define L_PTE_USER (_AT(pteval_t, 1) << 8) #define L_PTE_XN (_AT(pteval_t, 1) << 9) #define L_PTE_SHARED (_AT(pteval_t, 1) << 10) /* shared(v6), coherent(xsc3) */ +#define L_PTE_NONE (_AT(pteval_t, 1) << 11) /* * These are the memory types, defined to be compatible with diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index e32311a9abca..a3f37929940a 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -77,6 +77,7 @@ #define L_PTE_XN (_AT(pteval_t, 1) << 54) /* XN */ #define L_PTE_DIRTY (_AT(pteval_t, 1) << 55) /* unused */ #define L_PTE_SPECIAL (_AT(pteval_t, 1) << 56) /* unused */ +#define L_PTE_NONE (_AT(pteval_t, 1) << 57) /* PROT_NONE */ /* * To be used in assembly code with the upper page attributes. diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index ccf34b6e9903..9c82f988c0e3 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -73,7 +73,7 @@ extern pgprot_t pgprot_kernel; #define _MOD_PROT(p, b) __pgprot(pgprot_val(p) | (b)) -#define PAGE_NONE _MOD_PROT(pgprot_user, L_PTE_XN | L_PTE_RDONLY) +#define PAGE_NONE _MOD_PROT(pgprot_user, L_PTE_XN | L_PTE_RDONLY | L_PTE_NONE) #define PAGE_SHARED _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_XN) #define PAGE_SHARED_EXEC _MOD_PROT(pgprot_user, L_PTE_USER) #define PAGE_COPY _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY | L_PTE_XN) @@ -83,7 +83,7 @@ extern pgprot_t pgprot_kernel; #define PAGE_KERNEL _MOD_PROT(pgprot_kernel, L_PTE_XN) #define PAGE_KERNEL_EXEC pgprot_kernel -#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN) +#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | L_PTE_NONE) #define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN) #define __PAGE_SHARED_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER) #define __PAGE_COPY __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_RDONLY | L_PTE_XN) @@ -240,7 +240,7 @@ static inline pte_t pte_mkspecial(pte_t pte) { return pte; } static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { - const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER; + const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER | L_PTE_NONE; pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask); return pte; } |