On Tue, Jan 16, 2018 at 8:36 AM, Joerg Roedel <j...@8bytes.org> wrote: > From: Joerg Roedel <jroe...@suse.de> > > Allocate a kernel and a user page-table root when PTI is > enabled. Also allocate a full page per root for PAEm because > otherwise the bit to flip in cr3 to switch between them > would be non-constant, which creates a lot of hassle. > Keep that for a later optimization. > > Signed-off-by: Joerg Roedel <jroe...@suse.de> > --- > arch/x86/kernel/head_32.S | 23 ++++++++++++++++++----- > arch/x86/mm/pgtable.c | 11 ++++++----- > 2 files changed, 24 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S > index c29020907886..fc550559bf58 100644 > --- a/arch/x86/kernel/head_32.S > +++ b/arch/x86/kernel/head_32.S > @@ -512,28 +512,41 @@ ENTRY(initial_code) > ENTRY(setup_once_ref) > .long setup_once > > +#ifdef CONFIG_PAGE_TABLE_ISOLATION > +#define PGD_ALIGN (2 * PAGE_SIZE) > +#define PTI_USER_PGD_FILL 1024 > +#else > +#define PGD_ALIGN (PAGE_SIZE) > +#define PTI_USER_PGD_FILL 0 > +#endif > /* > * BSS section > */ > __PAGE_ALIGNED_BSS > - .align PAGE_SIZE > + .align PGD_ALIGN > #ifdef CONFIG_X86_PAE > .globl initial_pg_pmd > initial_pg_pmd: > .fill 1024*KPMDS,4,0 > + .fill PTI_USER_PGD_FILL,4,0
Couldn't this be simplified to just .align PGD_ALIGN, 0 without the .fill?
