| Message ID | 1435659443-17625-2-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 30 June 2015 at 16:50, Mark Salter <msalter@redhat.com> wrote: > 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 <ard.biesheuvel@linaro.org> >> --- >> 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))) { > Yes, good point, I will change that. >> + >> + 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) > Actually, I had 'prot |= PTE_RDONLY' but then changed it to the above thinking that it would pass the strict type checks, but apparently not :-) I will fix that up as well. Thanks, Ard. >> >> create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot); >> } >
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)) { + + 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'); create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot); }
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 <ard.biesheuvel@linaro.org> --- arch/arm64/kernel/efi.c | 32 +++++++++++++------- 1 file changed, 21 insertions(+), 11 deletions(-)