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

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Date:   Mon, 25 Jun 2018 15:08:52 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        stable@...r.kernel.org, Baoquan He <bhe@...hat.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: [PATCH] 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>
Fixes: 94133e46a0f5 ("x86/efi: Correct EFI identity mapping under 'efi=old_map' when KASLR is enabled")
Cc: stable@...r.kernel.org # 4.12+
Cc: Baoquan He <bhe@...hat.com>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
---
 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);
-- 
2.18.0