[gcc r12-811] rs6000: Add -mrop-protect and -mprivileged flags

[gcc r12-811] rs6000: Add -mrop-protect and -mprivileged flags

[William Schmidt]

https://gcc.gnu.org/g:0df864ed1d24bbb0cf7504814e2f48e496ea5669

commit r12-811-g0df864ed1d24bbb0cf7504814e2f48e496ea5669
Author: Bill Schmidt <wschmidt@linux.ibm.com>
Date:   Fri May 14 14:15:55 2021 -0500

    rs6000: Add -mrop-protect and -mprivileged flags
    
    2021-05-14  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.

Diff:
---
 gcc/config/rs6000/rs6000.c   |  4 ++++
 gcc/config/rs6000/rs6000.opt |  8 ++++++++
 gcc/doc/invoke.texi          | 20 ++++++++++++++++++--
 3 files changed, 30 insertions(+), 2 deletions(-)

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..2685fa71517 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)
+Generate code that will run in privileged state.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 519881509a6..9cb84210cd0 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) code that will run in privileged state.
+
 @item -mblock-ops-unaligned-vsx
 @itemx -mno-block-ops-unaligned-vsx
 @opindex block-ops-unaligned-vsx