[PATCH v7 10/11] arm64/kasan: explicitly zero kasan shadow memory
From: Pavel Tatashin <hidden>
Date: 2017-08-29 02:03:54
Also in:
linux-mm, linuxppc-dev, lkml, sparclinux
Subsystem:
arm64 port (aarch64 architecture), kasan, the rest · Maintainers:
Catalin Marinas, Will Deacon, Andrey Ryabinin, Linus Torvalds
To optimize the performance of struct page initialization, vmemmap_populate() will no longer zero memory. We must explicitly zero the memory that is allocated by vmemmap_populate() for kasan, as this memory does not go through struct page initialization path. Signed-off-by: Pavel Tatashin <redacted> Reviewed-by: Steven Sistare <redacted> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Bob Picco <redacted> --- arch/arm64/mm/kasan_init.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+)
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 81f03959a4ab..e78a9ecbb687 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c@@ -135,6 +135,41 @@ static void __init clear_pgds(unsigned long start, set_pgd(pgd_offset_k(start), __pgd(0)); } +/* + * Memory that was allocated by vmemmap_populate is not zeroed, so we must + * zero it here explicitly. + */ +static void +zero_vmemmap_populated_memory(void) +{ + struct memblock_region *reg; + u64 start, end; + + for_each_memblock(memory, reg) { + start = __phys_to_virt(reg->base); + end = __phys_to_virt(reg->base + reg->size); + + if (start >= end) + break; + + start = (u64)kasan_mem_to_shadow((void *)start); + end = (u64)kasan_mem_to_shadow((void *)end); + + /* Round to the start end of the mapped pages */ + start = round_down(start, SWAPPER_BLOCK_SIZE); + end = round_up(end, SWAPPER_BLOCK_SIZE); + memset((void *)start, 0, end - start); + } + + start = (u64)kasan_mem_to_shadow(_text); + end = (u64)kasan_mem_to_shadow(_end); + + /* Round to the start end of the mapped pages */ + start = round_down(start, SWAPPER_BLOCK_SIZE); + end = round_up(end, SWAPPER_BLOCK_SIZE); + memset((void *)start, 0, end - start); +} + void __init kasan_init(void) { u64 kimg_shadow_start, kimg_shadow_end;
@@ -205,8 +240,15 @@ void __init kasan_init(void) pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO)); memset(kasan_zero_page, 0, PAGE_SIZE); + cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); + /* + * vmemmap_populate does not zero the memory, so we need to zero it + * explicitly + */ + zero_vmemmap_populated_memory(); + /* At this point kasan is fully initialized. Enable error messages */ init_task.kasan_depth = 0; pr_info("KernelAddressSanitizer initialized\n");
--
2.14.1