From eccc1bff1b0d168a136ecd51c6091cf0ba02151b Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 9 Mar 2017 21:52:05 +0100 Subject: [PATCH] arm64/mmu: ignore debug_pagealloc for kernel segments The debug_pagealloc facility manipulates kernel mappings in the linear region at page granularity to detect out of bounds or use-after-free accesses. Since the kernel segments are not allocated dynamically, there is no point in taking the debug_pagealloc_enabled flag into account for them, and we can use block mappings unconditionally. Note that this applies equally to the linear alias of text/rodata: we will never have dynamic allocations there given that the same memory is statically in use by the kernel image. Reviewed-by: Mark Rutland Tested-by: Mark Rutland Signed-off-by: Ard Biesheuvel Signed-off-by: Catalin Marinas --- arch/arm64/mm/mmu.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index bb9179084217..ec23aec6433f 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -328,8 +328,7 @@ static void update_mapping_prot(phys_addr_t phys, unsigned long virt, return; } - __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, - NULL, debug_pagealloc_enabled()); + __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, false); /* flush the TLBs after updating live kernel mappings */ flush_tlb_kernel_range(virt, virt + size); @@ -381,7 +380,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end */ __create_pgd_mapping(pgd, kernel_start, __phys_to_virt(kernel_start), kernel_end - kernel_start, PAGE_KERNEL, - early_pgtable_alloc, debug_pagealloc_enabled()); + early_pgtable_alloc, false); } void __init mark_linear_text_alias_ro(void) @@ -437,7 +436,7 @@ static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end, BUG_ON(!PAGE_ALIGNED(size)); __create_pgd_mapping(pgd, pa_start, (unsigned long)va_start, size, prot, - early_pgtable_alloc, debug_pagealloc_enabled()); + early_pgtable_alloc, false); vma->addr = va_start; vma->phys_addr = pa_start; -- 2.20.1