Re: [PATCH 05/23] x86, kaiser: unmap kernel from userspace page tables (core patch)

Dave Hansen
2018-01-05T19:03:59Z

On 01/05/2018 10:19 AM, Jiri Kosina wrote:
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -95,6 +95,12 @@ 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;
> }
> __flush_tlb_all();

Wait a sec... Where does the _PAGE_USER come from? Shouldn't we see
the &init_mm in there and *not* set _PAGE_USER?