From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Subject: arm64/kasan: don't allocate extra shadow memory We used to read several bytes of the shadow memory in advance. Therefore additional shadow memory mapped to prevent crash if speculative load would happen near the end of the mapped shadow memory. Now we don't have such speculative loads, so we no longer need to map additional shadow memory. Link: http://lkml.kernel.org/r/20170601162338.23540-3-aryabinin@xxxxxxxxxxxxx Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Acked-by: Mark Rutland <mark.rutland@xxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm64/mm/kasan_init.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff -puN arch/arm64/mm/kasan_init.c~arm64-kasan-dont-allocate-extra-shadow-memory arch/arm64/mm/kasan_init.c --- a/arch/arm64/mm/kasan_init.c~arm64-kasan-dont-allocate-extra-shadow-memory +++ a/arch/arm64/mm/kasan_init.c @@ -191,14 +191,8 @@ void __init kasan_init(void) if (start >= end) break; - /* - * end + 1 here is intentional. We check several shadow bytes in - * advance to slightly speed up fastpath. In some rare cases - * we could cross boundary of mapped shadow, so we just map - * some more here. - */ vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), - (unsigned long)kasan_mem_to_shadow(end) + 1, + (unsigned long)kasan_mem_to_shadow(end), pfn_to_nid(virt_to_pfn(start))); } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
