Re: [PATCH 0/4] [rs6000] ROP support

[will schmidt <will_schmidt@vnet.ibm.com>]

On Sun, 2021-04-25 at 20:50 -0500, Bill Schmidt via Gcc-patches wrote:
> Add POWER10 support for hashst[p] and hashchk[p] operations.  When
> the -mrop-protect option is selected, any function that loads the
> link
> register from memory before returning must have protection in the
> prologue and epilogue to ensure the link register save location has
> not been compromised.  If -mprivileged is also specified, the
> protection instructions generated require supervisor privilege.

Hi,

Is -mprivileged tied directly to ROP, or is it a 'generic' option?

As
is, it looks like it can be considered generic, so could be also used
for other cases where we would want to generate instructions that
require supervisor privilege.

Additional comments on the subsequent patches.. 
thanks
-Will

> 
> The patches are broken up into logical chunks:
>  - Option handling
>  - Instruction generation
>  - Predefined macro handling
>  - Test cases
> 
> Bootstrapped and tested on a POWER10 system with no regressions.
> Tests on a kernel that enables user-space ROP mitigation were
> successful.  Is this series ok for trunk?  I would also like to later
> backport these patches to GCC for the 11.2 release.
> 
> Thanks!
> Bill
> 
> Bill Schmidt (4):
>   rs6000: Add -mrop-protect and -mprivileged flags
>   rs6000: Emit ROP-protect instructions in prologue and epilogue
>   rs6000: Conditionally define __ROP_PROTECT__
>   rs6000: Add ROP tests
> 
>  gcc/config/rs6000/rs6000-c.c             |  3 +
>  gcc/config/rs6000/rs6000-internal.h      |  2 +
>  gcc/config/rs6000/rs6000-logue.c         | 86 +++++++++++++++++++++-
> --
>  gcc/config/rs6000/rs6000.c               |  7 ++
>  gcc/config/rs6000/rs6000.md              | 39 +++++++++++
>  gcc/config/rs6000/rs6000.opt             |  6 ++
>  gcc/doc/invoke.texi                      | 19 +++++-
>  gcc/testsuite/gcc.target/powerpc/rop-1.c | 16 +++++
>  gcc/testsuite/gcc.target/powerpc/rop-2.c | 16 +++++
>  gcc/testsuite/gcc.target/powerpc/rop-3.c | 19 ++++++
>  gcc/testsuite/gcc.target/powerpc/rop-4.c | 14 ++++
>  gcc/testsuite/gcc.target/powerpc/rop-5.c | 17 +++++
>  12 files changed, 231 insertions(+), 13 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/rop-1.c
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/rop-2.c
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/rop-3.c
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/rop-4.c
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/rop-5.c
>