4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jiri Kosina jkosina@suse.cz
commit de53c3786a3ce162a1c815d0c04c766c23ec9c0a upstream.
EFI_OLD_MEMMAP's efi_call_phys_prolog() calls set_pgd() with swapper PGD that has PAGE_USER set, which makes PTI set NX on it, and therefore EFI can't execute it's code.
Fix that by forcefully clearing _PAGE_NX from the PGD (this can't be done by the pgprot API).
_PAGE_NX will be automatically reintroduced in efi_call_phys_epilog(), as _set_pgd() will again notice that this is _PAGE_USER, and set _PAGE_NX on it.
Tested-by: Dimitri Sivanich sivanich@hpe.com Signed-off-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Dave Hansen dave.hansen@linux.intel.com Cc: Andrea Arcangeli aarcange@redhat.com Cc: Ard Biesheuvel ard.biesheuvel@linaro.org 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: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1801052215460.11852@cbobk.fhfr.pm Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/platform/efi/efi_64.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -134,7 +134,9 @@ pgd_t * __init efi_call_phys_prolog(void pud[j] = *pud_offset(p4d_k, vaddr); } } + pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX; } + out: __flush_tlb_all();