arm64/mmu: ignore debug_pagealloc for kernel segments (eccc1bff) · Commits · 戴 / test

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 <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>

arch/arm64/mm/mmu.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -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;

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