On Tue, 2015-06-30 at 12:17 +0200, Ard Biesheuvel wrote:
> Currently, we infer the UEFI memory region mapping permissions
> from the memory region type (i.e., runtime services code are
> mapped RWX and runtime services data mapped RW-). This appears to
> work fine but is not entirely UEFI spec compliant. So instead, use
> the designated permission attributes to decide how these regions
> should be mapped.
>
> Since UEFIv2.5 introduces a new EFI_MEMORY_RO permission attribute,
> and redefines EFI_MEMORY_WP as a cacheability attribute, use only
> the former as a read-only attribute. For setting the PXN bit, the
> corresponding EFI_MEMORY_XP attribute is used.
>
> Signed-off-by: Ard Biesheuvel <[email protected]>
> ---
> arch/arm64/kernel/efi.c | 32 +++++++++++++-------
> 1 file changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index ab21e0d58278..5dcab58d5d30 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -247,20 +247,30 @@ static bool __init efi_virtmap_init(void)
> memrange_efi_to_native(&paddr, &npages);
> size = npages << PAGE_SHIFT;
>
> - pr_info(" EFI remap 0x%016llx => %p\n",
> - md->phys_addr, (void *)md->virt_addr);
> -
> - /*
> - * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
> - * executable, everything else can be mapped with the XN bits
> - * set.
> - */
> if (!is_normal_ram(md))
> prot = __pgprot(PROT_DEVICE_nGnRE);
> - else if (md->type == EFI_RUNTIME_SERVICES_CODE)
> - prot = PAGE_KERNEL_EXEC;
> else
> - prot = PAGE_KERNEL;
> + prot = PAGE_KERNEL_EXEC;
> +
> + /*
> + * On 64 KB granule kernels, only use strict permissions when
> + * the region does not share a 64 KB page frame with another
> + * region at either end.
> + */
> + if (!IS_ENABLED(CONFIG_ARM64_64K_PAGES) ||
> + !(md->virt_addr % PAGE_SIZE ||
> + (md->phys_addr + md->num_pages * EFI_PAGE_SIZE) %
> PAGE_SIZE)) {
I think this would read easier with:
(PAGE_ALIGNED(md->virt_addr) &&
PAGE_ALIGNED(md->phys_addr + md->num_pages *
EFI_PAGE_SIZE))) {
> +
> + if (md->attribute & EFI_MEMORY_RO)
> + prot |= __pgprot(PTE_RDONLY);
> + if (md->attribute & EFI_MEMORY_XP)
> + prot |= __pgprot(PTE_PXN);
> + }
> +
> + pr_info(" EFI remap 0x%016llx => %p (R%c%c)\n",
> + md->phys_addr, (void *)md->virt_addr,
> + prot & __pgprot(PTE_RDONLY) ? '-' : 'W',
> + prot & __pgprot(PTE_PXN) ? '-' : 'X');
You can't maninulate pgprot_t directly like that. It will
break STRICT_MM_TYPECHECKS. You need to use __pgprot_modify()
and/or pgprot_val().
arch/arm64/kernel/efi.c: In function ‘efi_virtmap_init’:
arch/arm64/kernel/efi.c:266:10: error: invalid operands to binary | (have
‘pgprot_t’ and ‘pgprot_t’)
prot |= __pgprot(PTE_RDONLY);
^
...
(In trying that, I see there are a number of other places which
need some STRICT_MM_TYPECHECKS fixing)
>
> create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
> }
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