linux-kernel - [tip:x86/mm] x86/kasan: Prepare clear_pgds() to switch to <asm-generic/pgtable-nop4d.h>

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Message-ID: <tip-d691a3cf8004784303f0a4c1c036edfaa7d64d0b@git.kernel.org>
Date:   Mon, 27 Mar 2017 03:24:37 -0700
From:   "tip-bot for Kirill A. Shutemov" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     kirill.shutemov@...ux.intel.com, tglx@...utronix.de,
        luto@...nel.org, dvlasenk@...hat.com, arnd@...db.de, bp@...en8.de,
        mhocko@...e.com, mingo@...nel.org, linux-kernel@...r.kernel.org,
        dave.hansen@...el.com, luto@...capital.net, jpoimboe@...hat.com,
        akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
        dvyukov@...gle.com, peterz@...radead.org, hpa@...or.com,
        brgerst@...il.com
Subject: [tip:x86/mm] x86/kasan: Prepare clear_pgds() to switch to
 <asm-generic/pgtable-nop4d.h>

Commit-ID:  d691a3cf8004784303f0a4c1c036edfaa7d64d0b
Gitweb:     http://git.kernel.org/tip/d691a3cf8004784303f0a4c1c036edfaa7d64d0b
Author:     Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
AuthorDate: Fri, 17 Mar 2017 21:55:13 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 27 Mar 2017 08:56:41 +0200

x86/kasan: Prepare clear_pgds() to switch to <asm-generic/pgtable-nop4d.h>

With folded p4d, pgd_clear() is a nop. Change clear_pgds() to use
p4d_clear() instead.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: linux-arch@...r.kernel.org
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/20170317185515.8636-5-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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 8d63d7a..7b81f01 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)