linux-kernel - [PATCH 4.17 217/220] x86/efi: Fix efi_call_phys_epilog() with CONFIG_X86

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Message-Id: <20180701160917.204993240@linuxfoundation.org>
Date:   Sun,  1 Jul 2018 18:24:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Baoquan He <bhe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.17 217/220] x86/efi: Fix efi_call_phys_epilog() with CONFIG_X86_5LEVEL=y

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

commit cfe19577047e74cdac5826adbdc2337d8437f8fb upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/platform/efi/efi_64.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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 *
 		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);