RE: 0001-Part-1.-Add-generic-part-for-Intel-CET-enabling

["Tsimbalist, Igor V" <igor dot v dot tsimbalist at intel dot com>]

Here is an updated patch (version #2). The main differences are:

- Change attribute and option names;
- Add additional parameter to gimple_build_call_from_tree by adding a type parameter and
  use it 'nocf_check' attribute propagation;
- Reimplement fixes in expand_call_stmt to propagate 'nocf_check' attribute;
- Consider 'nocf_check' attribute in Identical Code Folding (ICF) optimization;
- Add warning for type inconsistency regarding 'nocf_check' attribute;
- Many small fixes;

gcc/c-family/
	* c-attribs.c (handle_nocf_check_attribute): New function.
	(c_common_attribute_table): Add 'nocf_check' handling.
	* c-common.c (check_missing_format_attribute): New function.
	* c-common.h: Likewise.

gcc/c/
	* c-typeck.c (convert_for_assignment): Add check for nocf_check
	attribute.
	* gimple-parser.c: Add second argument NULL to
	gimple_build_call_from_tree.

gcc/cp/
	* typeck.c (convert_for_assignment): Add check for nocf_check
	attribute.

gcc/
	* cfgexpand.c (expand_call_stmt): Set REG_CALL_NOCF_CHECK for
	call insn.
	* combine.c (distribute_notes): Add REG_CALL_NOCF_CHECK handling.
	* common.opt: Add fcf-protection flag.
	* emit-rtl.c (try_split): Add REG_CALL_NOCF_CHECK handling.
	* flag-types.h: Add enum cf_protection_level.
	* gimple.c (gimple_build_call_from_tree): Add second parameter.
	Add 'nocf_check' attribute propagation to gimple call.
	* gimple.h (gf_mask): Add GF_CALL_NOCF_CHECK.
	(gimple_call_nocf_check_p): New function.
	(gimple_call_set_nocf_check): Likewise.
	* gimplify.c: Add second argument to gimple_build_call_from_tree.
	* ipa-icf.c: Add nocf_check attribute in statement hash.
	* recog.c (peep2_attempt): Add REG_CALL_NOCF_CHECK handling.
	* reg-notes.def: Add REG_NOTE (CALL_NOCF_CHECK).
	* toplev.c (process_options): Add flag_cf_protection handling.

Is it ok for trunk?

Thanks,
Igor


> -----Original Message-----
> From: Richard Biener [mailto:richard.guenther@gmail.com]
> Sent: Friday, September 15, 2017 2:14 PM
> To: Tsimbalist, Igor V <igor.v.tsimbalist@intel.com>
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: 0001-Part-1.-Add-generic-part-for-Intel-CET-enabling
> 
> On Fri, Sep 15, 2017 at 1:12 PM, Tsimbalist, Igor V
> <igor.v.tsimbalist@intel.com> wrote:
> >> -----Original Message-----
> >> From: Tsimbalist, Igor V
> >> Sent: Tuesday, September 12, 2017 5:35 PM
> >> To: 'Richard Biener' <richard.guenther@gmail.com>
> >> Cc: 'gcc-patches@gcc.gnu.org' <gcc-patches@gcc.gnu.org>; Tsimbalist,
> >> Igor V <igor.v.tsimbalist@intel.com>
> >> Subject: RE: 0001-Part-1.-Add-generic-part-for-Intel-CET-enabling
> >>
> >> > -----Original Message-----
> >> > From: Tsimbalist, Igor V
> >> > Sent: Friday, August 18, 2017 4:43 PM
> >> > To: 'Richard Biener' <richard.guenther@gmail.com>
> >> > Cc: gcc-patches@gcc.gnu.org; Tsimbalist, Igor V
> >> > <igor.v.tsimbalist@intel.com>
> >> > Subject: RE: 0001-Part-1.-Add-generic-part-for-Intel-CET-enabling
> >> >
> >> > > -----Original Message-----
> >> > > From: Richard Biener [mailto:richard.guenther@gmail.com]
> >> > > Sent: Friday, August 18, 2017 3:53 PM
> >> > > To: Tsimbalist, Igor V <igor.v.tsimbalist@intel.com>
> >> > > Cc: gcc-patches@gcc.gnu.org
> >> > > Subject: Re: 0001-Part-1.-Add-generic-part-for-Intel-CET-enabling
> >> > >
> >> > > On Fri, Aug 18, 2017 at 3:11 PM, Tsimbalist, Igor V
> >> > > <igor.v.tsimbalist@intel.com> wrote:
> >> > > >> -----Original Message-----
> >> > > >> From: Richard Biener [mailto:richard.guenther@gmail.com]
> >> > > >> Sent: Tuesday, August 15, 2017 3:43 PM
> >> > > >> To: Tsimbalist, Igor V <igor.v.tsimbalist@intel.com>
> >> > > >> Cc: gcc-patches@gcc.gnu.org
> >> > > >> Subject: Re:
> >> > > >> 0001-Part-1.-Add-generic-part-for-Intel-CET-enabling
> >> > > >>
> >> > > >> On Tue, Aug 1, 2017 at 10:56 AM, Tsimbalist, Igor V
> >> > > >> <igor.v.tsimbalist@intel.com> wrote:
> >> > > >> > Part#1. Add generic part for Intel CET enabling.
> >> > > >> >
> >> > > >> > The spec is available at
> >> > > >> >
> >> > > >> > https://software.intel.com/sites/default/files/managed/4d/2a
> >> > > >> > /co nt ro l-f low-enforcement-technology-preview.pdf
> >
> > <..skipped..>
> >
> >> > > >> I think 'notrack' is somewhat unspecific of a name, what
> >> > > >> prevented you to use 'nocet'?
> >> > > >
> >> > > > Actually it's specific. The HW will have a prefix with exactly
> >> > > > this name and
> >> > > the same meaning. And I think, what is more important,
> 'track/notrack'
> >> > > gives better semantic for a user. CET is a name bound with Intel
> >> > > specific technology.
> >> > >
> >> > > But 'tracking' something is quite unspecific.  Tracking for what?
> >> > > 'no_verify_cf' (aka do not verify control flow) maybe?
> >> >
> >> > The name just  has to suggest the right semantic. 'no_verify_cf' is
> >> > good, let's use it unless different name appears.
> >> I have renamed all newly introduced function and macro names to use
> >> 'noverify_cf'. But I still keep the attribute name as 'notrack'.
> >> Historically the attribute name follows the public CET specification,
> >> which uses 'no-track prefix' wording. Is it ok to keep such attribute name?
> >
> > Here is an updated proposal about option name and attribute name.
> >
> > The new option has values to let a user to choose what control-flow
> protection to activate.
> >
> > -fcf-protection=[full|branch|return|none]
> >   branch - do control-flow protection for indirect jumps and calls
> >   return - do control-flow protection for function returns
> >   full - alias to specify both branch + return
> >   none - turn off protection. This value is needed when/if
> > cf-protection is turned on by default by driver in future
> >
> > Attribute name is the most tough one. Here are several names to evaluate:
> 'nocf_verify' or 'nocf_check', or to be more specific and to mimic option
> name 'nocf_branch_verify' or 'nocf_branch_check'. I would prefer
> 'nocf_check' as it applies to functions and function pointers so it's definitely
> related to a branch and it's a smaller one.
> >
> > If you ok with the new proposal I'll implement it in a general parts (code,
> documentation and tests) and resend these patches for review.
> 
> nocf_check sounds fine to me.
> 
> Richard.
> 
> > Thanks,
> > Igor
> >

Attachment: 0001-Add-generic-part-for-Intel-CET-enabling-fcf-protecti.patch
Description: 0001-Add-generic-part-for-Intel-CET-enabling-fcf-protecti.patch