The patch titled
Subject: x86/kasan: don't allocate extra shadow memory
has been added to the -mm tree. Its filename is
x86-kasan-dont-allocate-extra-shadow-memory.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-kasan-dont-allocate-extra-shadow-memory.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-kasan-dont-allocate-extra-shadow-memory.patch
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------------------------------------------------------
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxx
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/kasan_init_64.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff -puN arch/x86/mm/kasan_init_64.c~x86-kasan-dont-allocate-extra-shadow-memory arch/x86/mm/kasan_init_64.c
--- a/arch/x86/mm/kasan_init_64.c~x86-kasan-dont-allocate-extra-shadow-memory
+++ a/arch/x86/mm/kasan_init_64.c
@@ -23,12 +23,7 @@ static int __init map_range(struct 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,
_
Patches currently in -mm which might be from aryabinin@xxxxxxxxxxxxx are
mm-kasan-get-rid-of-speculative-shadow-checks.patch
x86-kasan-dont-allocate-extra-shadow-memory.patch
arm64-kasan-dont-allocate-extra-shadow-memory.patch
mm-kasan-add-support-for-memory-hotplug.patch
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