On Wed, Sep 09, 2020 at 07:46:51AM -0500, Josh Poimboeuf wrote: > On Wed, Sep 09, 2020 at 08:20:07AM +0000, David Laight wrote: > > From: Josh Poimboeuf <jpoim...@redhat.com> > > > Sent: 08 September 2020 18:43 > > > Hi x86 maintainers, > > ... > > > > --- a/arch/x86/lib/putuser.S > > > > +++ b/arch/x86/lib/putuser.S > > > > @@ -38,6 +38,8 @@ SYM_FUNC_START(__put_user_1) > > > > ENTER > > > > cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX > > > > jae .Lbad_put_user > > > > + sbb %_ASM_BX, %_ASM_BX /* uaccess_mask_ptr() */ > > > > + and %_ASM_BX, %_ASM_CX > > > > ASM_STAC > > > > 1: movb %al,(%_ASM_CX) > > > > xor %eax,%eax > > > > For 64bit the sbb+and pattern can be replaced by an instruction > > that clears the high bit (eg btr $63, %rcx). > > This isn't dependant on the earlier instructions so can execute > > in parallel with them. > > Wouldn't that break with KERNEL_DS?
Looks like the set_fs() removal patches are now in the vfs tree for -next. I doubt this is going in an -rc so I'll rework the patch based on top of Christoph's changes. -- Josh
