linux-kernel - [tip:x86/urgent] x86/efi: Fix efi_call_phys_epilog() with CONFIG_X86

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Message-ID: <tip-cfe19577047e74cdac5826adbdc2337d8437f8fb@git.kernel.org>
Date:   Wed, 27 Jun 2018 02:08:48 -0700
From:   "tip-bot for Kirill A. Shutemov" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ard.biesheuvel@...aro.org, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        matt@...eblueprint.co.uk, bhe@...hat.com, hpa@...or.com,
        peterz@...radead.org, aryabinin@...tuozzo.com, mingo@...nel.org,
        kirill.shutemov@...ux.intel.com
Subject: [tip:x86/urgent] x86/efi: Fix efi_call_phys_epilog() with
 CONFIG_X86_5LEVEL=y

Commit-ID:  cfe19577047e74cdac5826adbdc2337d8437f8fb
Gitweb:     https://git.kernel.org/tip/cfe19577047e74cdac5826adbdc2337d8437f8fb
Author:     Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
AuthorDate: Mon, 25 Jun 2018 15:08:52 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 27 Jun 2018 09:52:52 +0200

x86/efi: Fix efi_call_phys_epilog() with CONFIG_X86_5LEVEL=y

Open-coded page table entry checks don't work correctly when we fold the
page table level at runtime.

pgd_present() on 4-level paging machine always returns true, but
open-coded version of the check may return false-negative result and
we silently skip the rest of the loop body in efi_call_phys_epilog().

Replace open-coded checks with proper helpers.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: stable@...r.kernel.org # v4.12+
Fixes: 94133e46a0f5 ("x86/efi: Correct EFI identity mapping under 'efi=old_map' when KASLR is enabled")
Link: http://lkml.kernel.org/r/20180625120852.18300-1-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/platform/efi/efi_64.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index e01f7ceb9e7a..77873ce700ae 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -166,14 +166,14 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
 		pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE);
 		set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);
 
-		if (!(pgd_val(*pgd) & _PAGE_PRESENT))
+		if (!pgd_present(*pgd))
 			continue;
 
 		for (i = 0; i < PTRS_PER_P4D; i++) {
 			p4d = p4d_offset(pgd,
 					 pgd_idx * PGDIR_SIZE + i * P4D_SIZE);
 
-			if (!(p4d_val(*p4d) & _PAGE_PRESENT))
+			if (!p4d_present(*p4d))
 				continue;
 
 			pud = (pud_t *)p4d_page_vaddr(*p4d);