On Sun, 2021-04-25 at 20:50 -0500, Bill Schmidt via Gcc-patches wrote:
> 2021-03-25 Bill Schmidt <wschm...@linux.ibm.com>
>
> gcc/
> * config/rs6000/rs6000.c (rs6000_option_override_internal):
> Disable shrink wrap when inserting ROP-protect instructions.
> * config/rs6000/rs6000.opt (mrop-protect): New option.
> (mprivileged): Likewise.
> * doc/invoke.texi: Document mrop-protect and mprivileged.
Hi,
> ---
> gcc/config/rs6000/rs6000.c | 7 +++++++
> gcc/config/rs6000/rs6000.opt | 6 ++++++
> gcc/doc/invoke.texi | 19 +++++++++++++++++--
> 3 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 844fee88cf3..d13ed6e7ff4 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -4036,6 +4036,13 @@ rs6000_option_override_internal (bool global_init_p)
> && ((rs6000_isa_flags_explicit & OPTION_MASK_QUAD_MEMORY_ATOMIC) == 0))
> rs6000_isa_flags |= OPTION_MASK_QUAD_MEMORY_ATOMIC;
>
> + /* If we are inserting ROP-protect instructions, disable shrink wrap. */
> + if (rs6000_rop_protect)
> + {
> + flag_shrink_wrap = 0;
> + flag_shrink_wrap_separate = 0;
> + }
Does this (shrink-wrap is disabled if/when ROP-protect is enabled) need
additional commentary somewhere?
> +
> /* If we can shrink-wrap the TOC register save separately, then use
> -msave-toc-indirect unless explicitly disabled. */
> if ((rs6000_isa_flags_explicit & OPTION_MASK_SAVE_TOC_INDIRECT) == 0
> diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
> index 0dbdf753673..d116fd12f7e 100644
> --- a/gcc/config/rs6000/rs6000.opt
> +++ b/gcc/config/rs6000/rs6000.opt
> @@ -619,3 +619,9 @@ Generate (do not generate) MMA instructions.
>
> mrelative-jumptables
> Target Undocumented Var(rs6000_relative_jumptables) Init(1) Save
> +
> +mrop-protect
> +Target Var(rs6000_rop_protect) Init(0)
> +
> +mprivileged
> +Target Var(rs6000_privileged) Init(0)
Most but not all of the entries in rs6000.opt have an additional
description line. I'd wonder about updating this to be stl
> +mrop-protect
> +Target Var(rs6000_rop_protect) Init(0)
Enable ROP protection
> +
> +mprivileged
> +Target Var(rs6000_privileged) Init(0)
Enable privileged instructions for ROP protection.
OK with me either way. :-)
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index e98b0962b9f..36bd0bf9b3b 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -1238,7 +1238,8 @@ See RS/6000 and PowerPC Options.
> -mgnu-attribute -mno-gnu-attribute @gol
> -mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{reg}
> @gol
> -mstack-protector-guard-offset=@var{offset} -mprefixed -mno-prefixed @gol
> --mpcrel -mno-pcrel -mmma -mno-mmma}
> +-mpcrel -mno-pcrel -mmma -mno-mmma -mrop-protect -mno-rop-protect @gol
> +-mprivileged -mno-privileged}
>
> @emph{RX Options}
> @gccoptlist{-m64bit-doubles -m32bit-doubles -fpu -nofpu@gol
> @@ -27019,7 +27020,8 @@ following options:
> -mmulhw -mdlmzb -mmfpgpr -mvsx @gol
> -mcrypto -mhtm -mpower8-fusion -mpower8-vector @gol
> -mquad-memory -mquad-memory-atomic -mfloat128 @gol
> --mfloat128-hardware -mprefixed -mpcrel -mmma}
> +-mfloat128-hardware -mprefixed -mpcrel -mmma @gol
> +-mrop-protect -mprivileged}
>
> The particular options set for any particular CPU varies between
> compiler versions, depending on what setting seems to produce optimal
> @@ -28024,6 +28026,19 @@ store instructions when the option
> @option{-mcpu=future} is used.
> Generate (do not generate) the MMA instructions when the option
> @option{-mcpu=future} is used.
>
> +@item -mrop-protect
> +@itemx -mno-rop-protect
> +@opindex mrop-protect
> +@opindex mno-rop-protect
> +Generate (do not generate) ROP protection instructions when the option
> +@option{-mcpu=power10} is used.
Is the option on by default? if so, may want another testcase to
verify ROP instructions are generated with just -mcpu=power10.
if not,
perhaps the "-mcpu=power10" reference here instead be "-mrop-protect".
> +
> +@item -mprivileged
> +@itemx -mno-privileged
> +@opindex mprivileged
> +@opindex mno-privileged
> +Generate (do not generate) instructions for privileged state.
> +
> @item -mblock-ops-unaligned-vsx
> @itemx -mno-block-ops-unaligned-vsx
> @opindex block-ops-unaligned-vsx
lgtm
thanks,
-Will
