diff mbox series

[1/4] rs6000: Add -mrop-protect and -mprivileged flags

Message ID 443cb100cf5a27c6724ee69adaec375843927d27.1620958221.git.wschmidt@linux.ibm.com
State New
Headers show
Series ROP support | expand

Commit Message

Bill Schmidt May 14, 2021, 3:34 a.m. UTC 
2021-05-13  Bill Schmidt  <wschmidt@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.
---
 gcc/config/rs6000/rs6000.c   |  4 ++++
 gcc/config/rs6000/rs6000.opt |  8 ++++++++
 gcc/doc/invoke.texi          | 20 ++++++++++++++++++--
 3 files changed, 30 insertions(+), 2 deletions(-)

Comments

Segher Boessenkool May 14, 2021, 3:55 p.m. UTC | #1 
On Thu, May 13, 2021 at 10:34:54PM -0500, Bill Schmidt via Gcc-patches wrote:
> +mprivileged
> +Target Var(rs6000_privileged) Init(0)
> +Enable generation of instructions that require privileged state.

That isn't quite it -- it will generate "p" insns instead of the usual
ones, it isn't just that it is allowed to generate the "p" insns.

> +@item -mprivileged
> +@itemx -mno-privileged
> +@opindex mprivileged
> +@opindex mno-privileged
> +Generate (do not generate) instructions for privileged state.

That is better.  But may I suggest:

"Generate code that will run in privileged state."

Okay for trunk and 11 with whatever you end up with.  Thanks!


Segher
Li, Pan2 via Gcc-patches May 15, 2021, 7:06 p.m. UTC | #2 
Series pushed with recommended changes.  Thank you!

Bill

On 5/14/21 10:55 AM, Segher Boessenkool wrote:
> On Thu, May 13, 2021 at 10:34:54PM -0500, Bill Schmidt via Gcc-patches wrote:
>> +mprivileged
>> +Target Var(rs6000_privileged) Init(0)
>> +Enable generation of instructions that require privileged state.
> That isn't quite it -- it will generate "p" insns instead of the usual
> ones, it isn't just that it is allowed to generate the "p" insns.
>
>> +@item -mprivileged
>> +@itemx -mno-privileged
>> +@opindex mprivileged
>> +@opindex mno-privileged
>> +Generate (do not generate) instructions for privileged state.
> That is better.  But may I suggest:
>
> "Generate code that will run in privileged state."
>
> Okay for trunk and 11 with whatever you end up with.  Thanks!
>
>
> Segher
diff mbox series

Patch

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index d1b76f6ec41..53a9f5411c7 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4040,6 +4040,10 @@  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;
+
   /* 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..f66ef20a102 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -619,3 +619,11 @@  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)
+Enable instructions that guard against return-oriented programming attacks.
+
+mprivileged
+Target Var(rs6000_privileged) Init(0)
+Enable generation of instructions that require privileged state.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 519881509a6..92549524583 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1240,7 +1240,8 @@  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
@@ -27029,7 +27030,8 @@  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}
 
 The particular options set for any particular CPU varies between
 compiler versions, depending on what setting seems to produce optimal
@@ -28034,6 +28036,20 @@  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 target
+processor supports them.  Currently this option disables the shrink-wrap
+optimization (@option{-fshrink-wrap}).
+
+@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