lkml.org 
[lkml]   [2015]   [Nov]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCHv2] arm64: Fix R/O permissions in mark_rodata_ro
From
On 12 November 2015 at 21:21, Laura Abbott <labbott@fedoraproject.org> wrote:
> The permissions in mark_rodata_ro trigger a build error
> with STRICT_MM_TYPECHECKS. Fix this by introducing
> PAGE_KERNEL_ROX for the same reasons as PAGE_KERNEL_RO.

Forgive the bikeshedding but perhaps PAGE_KERNEL_EXEC_RO is more consistent?

> From Ard:
>
> "PAGE_KERNEL_EXEC has PTE_WRITE set as well, making the range
> writeable under the ARMv8.1 DBM feature, that manages the
> dirty bit in hardware (writing to a page with the PTE_RDONLY
> and PTE_WRITE bits both set will clear the PTE_RDONLY bit in that case)"
>
> Signed-off-by: Laura Abbott <labbott@fedoraproject.org>

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> ---
> arch/arm64/include/asm/pgtable.h | 1 +
> arch/arm64/mm/mmu.c | 2 +-
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 9819a94..7e074f9 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -81,6 +81,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
>
> #define PAGE_KERNEL __pgprot(_PAGE_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE)
> #define PAGE_KERNEL_RO __pgprot(_PAGE_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_RDONLY)
> +#define PAGE_KERNEL_ROX __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_RDONLY)
> #define PAGE_KERNEL_EXEC __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_WRITE)
> #define PAGE_KERNEL_EXEC_CONT __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_CONT)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9ca5996..6598c48 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -475,7 +475,7 @@ void mark_rodata_ro(void)
> {
> create_mapping_late(__pa(_stext), (unsigned long)_stext,
> (unsigned long)_etext - (unsigned long)_stext,
> - PAGE_KERNEL_EXEC | PTE_RDONLY);
> + PAGE_KERNEL_ROX);
>
> }
> #endif
> --
> 2.5.0
>


\
 
 \ /
  Last update: 2015-11-15 09:01    [W:0.196 / U:0.456 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site