Commit cfe19577 authored Jun 25, 2018 by Kirill A. Shutemov Committed by Ingo Molnar Jun 27, 2018

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@linux.intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # v4.12+
Fixes: 94133e46 ("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@kernel.org>

parent e8a445de

arch/x86/platform/efi/efi_64.c

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -166,14 +166,14 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
	pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE);		pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE);
	set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);		set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);

	if (!(pgd_val(*pgd) & _PAGE_PRESENT))		if (!pgd_present(*pgd))
	continue;		continue;

	for (i = 0; i < PTRS_PER_P4D; i++) {		for (i = 0; i < PTRS_PER_P4D; i++) {
	p4d = p4d_offset(pgd,		p4d = p4d_offset(pgd,
	pgd_idx * PGDIR_SIZE + i * P4D_SIZE);		pgd_idx * PGDIR_SIZE + i * P4D_SIZE);

	if (!(p4d_val(*p4d) & _PAGE_PRESENT))		if (!p4d_present(*p4d))
	continue;		continue;

	pud = (pud_t )p4d_page_vaddr(p4d);		pud = (pud_t )p4d_page_vaddr(p4d);