From fb226c3d7c77b4f99cee675795cc0e70937c56ee Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 9 Nov 2015 09:55:46 +0100 Subject: [PATCH] arm64: fix R/O permissions of FDT mapping The mapping permissions of the FDT are set to 'PAGE_KERNEL | PTE_RDONLY' in an attempt to map the FDT as read-only. However, not only does this break at build time under STRICT_MM_TYPECHECKS (since the two terms are of different types in that case), it also results in both the PTE_WRITE and PTE_RDONLY attributes to be set, which means the region is still writable under ARMv8.1 DBM (and an attempted write will simply clear the PT_RDONLY bit). So instead, define PAGE_KERNEL_RO (which already has an established meaning across architectures) and use that instead. Signed-off-by: Ard Biesheuvel Signed-off-by: Catalin Marinas --- 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 c3d22a507648..1c99d5610bc7 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -78,6 +78,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val); #define _PAGE_DEFAULT (PROT_DEFAULT | PTE_ATTRINDX(MT_NORMAL)) #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_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 2784f052df5e..5e23de53b747 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -691,7 +691,7 @@ void __set_fixmap(enum fixed_addresses idx, void *__init fixmap_remap_fdt(phys_addr_t dt_phys) { const u64 dt_virt_base = __fix_to_virt(FIX_FDT); - pgprot_t prot = PAGE_KERNEL | PTE_RDONLY; + pgprot_t prot = PAGE_KERNEL_RO; int size, offset; void *dt_virt;