On Mon, Nov 16, 2015 at 06:34:27PM +0300, Andrey Ryabinin wrote: > On 11/16/2015 02:16 PM, Suzuki K. Poulose wrote: > > On 13/10/15 09:34, Catalin Marinas wrote: > >> On Mon, Oct 12, 2015 at 06:52:56PM +0300, Andrey Ryabinin wrote: > >>> Andrey Ryabinin (3): > >>> arm64: move PGD_SIZE definition to pgalloc.h > >>> arm64: add KASAN support > >>> Documentation/features/KASAN: arm64 supports KASAN now > >>> > >>> Linus Walleij (1): > >>> ARM64: kasan: print memory assignment > >> > >> Patches queued for 4.4. Thanks. > > > > I get the following failure with KASAN + 16K_PAGES + 48BIT_VA, with 4.4-rc1: > > > > arch/arm64/mm/kasan_init.c: In function ‘kasan_early_init’: > > include/linux/compiler.h:484:38: error: call to ‘__compiletime_assert_95’ declared with attribute error: BUILD_BUG_ON failed: !IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE) > > _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > ^ > > include/linux/compiler.h:467:4: note: in definition of macro ‘__compiletime_assert’ > > prefix ## suffix(); \ > > ^ > > include/linux/compiler.h:484:2: note: in expansion of macro ‘_compiletime_assert’ > > _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > ^ > > include/linux/bug.h:50:37: note: in expansion of macro ‘compiletime_assert’ > > #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > ^ > > include/linux/bug.h:74:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’ > > BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > ^ > > arch/arm64/mm/kasan_init.c:95:2: note: in expansion of macro ‘BUILD_BUG_ON’ > > BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); > > > > The problem is that the PGDIR_SIZE is (1UL << 47) with 16K+48bit, which makes > > the KASAN_SHADOW_END unaligned(which is aligned to (1UL << (48 - 3)) ). Is the > > alignment really needed ? Thoughts on how best we could fix this ? > > Yes, it's really needed, because some code relies on this (e.g. > clear_pgs() and kasan_init()). But it should be possible to get rid of > this requirement. I don't think clear_pgds() and kasan_init() are the only problems. IIUC, kasan_populate_zero_shadow() also assumes that KASan shadow covers multiple pgds. You need some kind of recursive writing which avoids populating an entry which is not empty (like kasan_early_pud_populate). -- Catalin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>