From 4d461333f144456b80d9eabd7cee7ac02fa5d0ee Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin <aryabinin@virtuozzo.com> Date: Mon, 10 Jul 2017 15:50:27 -0700 Subject: [PATCH] x86/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/20170601162338.23540-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alexander Potapenko <glider@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- arch/x86/mm/kasan_init_64.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 88215ac16b24b..02c9d75534091 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -23,12 +23,7 @@ static int __init map_range(struct range *range) start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start)); end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end)); - /* - * 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. - */ - return vmemmap_populate(start, end + 1, NUMA_NO_NODE); + return vmemmap_populate(start, end, NUMA_NO_NODE); } static void __init clear_pgds(unsigned long start, -- GitLab