Commit de53c378 authored by Jiri Kosina's avatar Jiri Kosina Committed by Thomas Gleixner

x86/pti: Unbreak EFI old_memmap

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: default avatarDimitri Sivanich <sivanich@hpe.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarDave 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
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1801052215460.11852@cbobk.fhfr.pm
parent de791821
......@@ -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();
......
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