From: Jiri Kosina <[email protected]> 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. Signed-off-by: Jiri Kosina <[email protected]> Signed-off-by: Pavel Tatashin <[email protected]> --- arch/x86/platform/efi/efi_64.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 18dfaad71c99..12118bae3caf 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -90,6 +90,12 @@ pgd_t * __init efi_call_phys_prolog(void) save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE); vaddress = (unsigned long)__va(pgd * PGDIR_SIZE); set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress)); + /* + * pgprot API doesn't clear it for PGD + * + * Will be brought back automatically in _epilog() + */ + pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX; } out: __flush_tlb_all(); -- 2.16.2
