diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2017-03-09 21:52:01 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2017-03-23 13:54:19 +0000 |
| commit | 5ea5306c3235a157f06040c59730b1133115ed26 (patch) | |
| tree | 5bc46cf0c5ff286e1a0c8c02ef3f5da9a27efda7 /arch/arm64/include/asm/mmu.h | |
| parent | aa8c09be7a6f58e1b0dd19413d872fffdb054677 (diff) | |
arm64: alternatives: apply boot time fixups via the linear mapping
One important rule of thumb when desiging a secure software system is
that memory should never be writable and executable at the same time.
We mostly adhere to this rule in the kernel, except at boot time, when
regions may be mapped RWX until after we are done applying alternatives
or making other one-off changes.
For the alternative patching, we can improve the situation by applying
the fixups via the linear mapping, which is never mapped with executable
permissions. So map the linear alias of .text with RW- permissions
initially, and remove the write permissions as soon as alternative
patching has completed.
Reviewed-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/mmu.h')
| -rw-r--r-- | arch/arm64/include/asm/mmu.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 47619411f0ff..5468c834b072 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -37,5 +37,6 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot, bool page_mappings_only); extern void *fixmap_remap_fdt(phys_addr_t dt_phys); +extern void mark_linear_text_alias_ro(void); #endif |