From d691a3cf8004784303f0a4c1c036edfaa7d64d0b Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 17 Mar 2017 21:55:13 +0300 Subject: [PATCH] x86/kasan: Prepare clear_pgds() to switch to With folded p4d, pgd_clear() is a nop. Change clear_pgds() to use p4d_clear() instead. Signed-off-by: Kirill A. Shutemov Acked-by: Thomas Gleixner Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Dmitry Vyukov Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Michal Hocko Cc: Peter Zijlstra Cc: linux-arch@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170317185515.8636-5-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/kasan_init_64.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 8d63d7a104c3..7b81f01067f2 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -32,8 +32,19 @@ static int __init map_range(struct range *range) static void __init clear_pgds(unsigned long start, unsigned long end) { - for (; start < end; start += PGDIR_SIZE) - pgd_clear(pgd_offset_k(start)); + pgd_t *pgd; + + for (; start < end; start += PGDIR_SIZE) { + pgd = pgd_offset_k(start); + /* + * With folded p4d, pgd_clear() is nop, use p4d_clear() + * instead. + */ + if (CONFIG_PGTABLE_LEVELS < 5) + p4d_clear(p4d_offset(pgd, start)); + else + pgd_clear(pgd); + } } static void __init kasan_map_early_shadow(pgd_t *pgd) -- 2.39.2