On Mon, Apr 23, 2018 at 8:47 AM, Joerg Roedel <[email protected]> wrote: > From: Joerg Roedel <[email protected]> > > Keeping the kernel text mapped with G bit set keeps its > entries in the TLB across kernel entry/exit and improved the > performance. The 64 bit x86 kernels already do this when > there is no PCID, so do this in 32 bit as well since PCID is > not even supported there.
I think this should keep at least part of the logic as 64-bit since there are other reasons to turn off the Global flag: https://lkml.kernel.org/r/[email protected] -Kees > > Signed-off-by: Joerg Roedel <[email protected]> > --- > arch/x86/mm/init_32.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c > index c893c6a..8299b98 100644 > --- a/arch/x86/mm/init_32.c > +++ b/arch/x86/mm/init_32.c > @@ -956,4 +956,10 @@ void mark_rodata_ro(void) > mark_nxdata_nx(); > if (__supported_pte_mask & _PAGE_NX) > debug_checkwx(); > + > + /* > + * Do this after all of the manipulation of the > + * kernel text page tables are complete. > + */ > + pti_clone_kernel_text(); > } > -- > 2.7.4 > -- Kees Cook Pixel Security
