[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[dwmw2 at infradead dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

David Woodhouse <dwmw2 at infradead dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dwmw2 at infradead dot org

--- Comment #1 from David Woodhouse <dwmw2 at infradead dot org> ---
Indeed. We even changed the ABI of the thunk to be CET-compatible and allow the
'jmp *reg' form instead of being ret-equivalent.

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl.tools at gmail dot com

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 48394
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48394&action=edit
A proposal to support retpoline and CET

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
Please DO disable -fcf-protection in the kernel build.  We are enabling
CET for the user space first.   The kernel CET will be the next.

I am enclosing a proposal to make -fcf-protection compatible with retpoline.
It targets user space.  It can be made compatible with kernel.

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-04-28
           Assignee|unassigned at gcc dot gnu.org      |hjl.tools at gmail dot com

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 48396
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48396&action=edit
A patch

Please try this.

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[andrew.cooper3 at citrix dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

--- Comment #5 from Andrew Cooper <andrew.cooper3 at citrix dot com> ---
Thanks.  Just compiling the patch.

As a note however, https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html will
need adjusting to remove the final note for -mindirect-branch=choice

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #48396|0                           |1
        is obsolete|                            |

--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 48401
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48401&action=edit
A patch

I am testing this.

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[andrew.cooper3 at citrix dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

--- Comment #7 from Andrew Cooper <andrew.cooper3 at citrix dot com> ---
Yes - that works.  Confirmed that I have both retpolines and endbr64
instructions, and the resulting hypervisor boots.

(I don't have CET capable hardware, but that is fine.  There is at minimum
there is MSR setup to do, so any other issues can be addressed at that time.)

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.0
                URL|                            |https://gcc.gnu.org/piperma
                   |                            |il/gcc-patches/2020-April/5
                   |                            |44804.html
           Keywords|                            |patch

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> ---
A patch is posted at

https://gcc.gnu.org/pipermail/gcc-patches/2020-April/544804.html

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by H.J. Lu <hjl@gcc.gnu.org>:

https://gcc.gnu.org/g:9be3bb2c0a258fd6a7d3d05d232a21930c757d3c

commit r10-8047-g9be3bb2c0a258fd6a7d3d05d232a21930c757d3c
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Apr 29 04:52:46 2020 -0700

    x86: Allow -fcf-protection with external thunk

    Allow -fcf-protection with external thunk since the external thunk can be
    made compatible with -fcf-protection.

    gcc/

            PR target/93654
            * config/i386/i386-options.c (ix86_set_indirect_branch_type):
            Allow -fcf-protection with -mindirect-branch=thunk-extern and
            -mfunction-return=thunk-extern.
            * doc/invoke.texi: Update notes for -fcf-protection=branch with
            -mindirect-branch=thunk-extern and -mindirect-return=thunk-extern.

    gcc/testsuite/

            PR target/93654
            * gcc.target/i386/pr93654.c: New test.

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by H.J. Lu <hjl@gcc.gnu.org>:

https://gcc.gnu.org/g:a03efb266fcbf4a01285fff871a5bfe5caac4944

commit r9-8552-ga03efb266fcbf4a01285fff871a5bfe5caac4944
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Apr 29 04:52:46 2020 -0700

    x86: Allow -fcf-protection with external thunk

    Allow -fcf-protection with external thunk since the external thunk can be
    made compatible with -fcf-protection.

    gcc/

            Backport from master
            PR target/93654
            * config/i386/i386-options.c (ix86_set_indirect_branch_type):
            Allow -fcf-protection with -mindirect-branch=thunk-extern and
            -mfunction-return=thunk-extern.
            * doc/invoke.texi: Update notes for -fcf-protection=branch with
            -mindirect-branch=thunk-extern and -mindirect-return=thunk-extern.

    gcc/testsuite/

            Backport from master
            PR target/93654
            * gcc.target/i386/pr93654.c: New test.

    (cherry picked from commit 9be3bb2c0a258fd6a7d3d05d232a21930c757d3c)

[Bug target/93654] Inappropriate "-fcf-protection and -mindirect-branch=thunk are incompatible on x86_64" restriction

[andrew.cooper3 at citrix dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

--- Comment #11 from Andrew Cooper <andrew.cooper3 at citrix dot com> ---
Thankyou very much for your help

[Bug target/93654] [9/10 Regression] Inappropriate "-fcf-protection and -mindirect-branch=thunk-extern are incompatible" restriction

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.0                        |9.4
            Summary|Inappropriate               |[9/10 Regression]
                   |"-fcf-protection and        |Inappropriate
                   |-mindirect-branch=thunk are |"-fcf-protection and
                   |incompatible on x86_64"     |-mindirect-branch=thunk-ext
                   |restriction                 |ern are incompatible"
                   |                            |restriction
             Status|NEW                         |RESOLVED
             Target|x86_64-*-*                  |i386, x86_64
         Resolution|---                         |FIXED

--- Comment #12 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed for GCC 10 and GCC 9.4.