rs6000: ROP - Emit hashst and hashchk insns on Power8 and later [PR114759]

We currently only emit the ROP-protect hash* insns for Power10, where the
insns were added to the architecture.  We want to emit them for earlier
cpus (where they operate as NOPs), so that if those older binaries are
ever executed on a Power10, then they'll be protected from ROP attacks.
Binutils accepts hashst and hashchk back to Power8, so change GCC to emit
them for Power8 and later.  This matches clang's behavior.

2024-06-19  Peter Bergner  <bergner@linux.ibm.com>

gcc/
	PR target/114759
	* config/rs6000/rs6000-logue.cc (rs6000_stack_info): Use TARGET_POWER8.
	(rs6000_emit_prologue): Likewise.
	* config/rs6000/rs6000.md (hashchk): Likewise.
	(hashst): Likewise.
	Fix whitespace.

gcc/testsuite/
	PR target/114759
	* gcc.target/powerpc/pr114759-2.c: New test.
	* lib/target-supports.exp (rop_ok): Use
	check_effective_target_has_arch_pwr8.

4 files changed, 24 insertions, 7 deletions

diff --git a/gcc/config/rs6000/rs6000-logue.cc b/gcc/config/rs6000/rs6000-logue.cc
index 193e212..48f4063 100644
--- a/gcc/config/rs6000/rs6000-logue.cc
+++ b/gcc/config/rs6000/rs6000-logue.cc
@@ -716,7 +716,7 @@ rs6000_stack_info (void)
   info->calls_p = (!crtl->is_leaf || cfun->machine->ra_needs_full_frame);
   info->rop_hash_size = 0;
 
-  if (TARGET_POWER10
+  if (TARGET_POWER8
       && info->calls_p
       && DEFAULT_ABI == ABI_ELFv2
       && rs6000_rop_protect)
@@ -3272,7 +3272,7 @@ rs6000_emit_prologue (void)
   /* NOTE: The hashst isn't needed if we're going to do a sibcall,
      but there's no way to know that here.  Harmless except for
      performance, of course.  */
-  if (TARGET_POWER10 && rs6000_rop_protect && info->rop_hash_size != 0)
+  if (TARGET_POWER8 && rs6000_rop_protect && info->rop_hash_size != 0)
     {
       gcc_assert (DEFAULT_ABI == ABI_ELFv2);
       rtx stack_ptr = gen_rtx_REG (Pmode, STACK_POINTER_REGNUM);
@@ -5051,7 +5051,7 @@ rs6000_emit_epilogue (enum epilogue_type epilogue_type)
 
   /* The ROP hash check must occur after the stack pointer is restored
      (since the hash involves r1), and is not performed for a sibcall.  */
-  if (TARGET_POWER10
+  if (TARGET_POWER8
       && rs6000_rop_protect
       && info->rop_hash_size != 0
       && epilogue_type != EPILOGUE_TYPE_SIBCALL)
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 276a5c9..679aac5 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -15808,9 +15808,9 @@
 
 (define_insn "hashst"
   [(set (match_operand:DI 0 "simple_offsettable_mem_operand" "=m")
-        (unspec_volatile:DI [(match_operand:DI 1 "int_reg_operand" "r")]
+	(unspec_volatile:DI [(match_operand:DI 1 "int_reg_operand" "r")]
 			    UNSPEC_HASHST))]
-  "TARGET_POWER10 && rs6000_rop_protect"
+  "TARGET_POWER8 && rs6000_rop_protect"
 {
   static char templ[32];
   const char *p = rs6000_privileged ? "p" : "";
@@ -15823,7 +15823,7 @@
   [(unspec_volatile [(match_operand:DI 0 "int_reg_operand" "r")
 		     (match_operand:DI 1 "simple_offsettable_mem_operand" "m")]
 		    UNSPEC_HASHCHK)]
-  "TARGET_POWER10 && rs6000_rop_protect"
+  "TARGET_POWER8 && rs6000_rop_protect"
 {
   static char templ[32];
   const char *p = rs6000_privileged ? "p" : "";
diff --git a/gcc/testsuite/gcc.target/powerpc/pr114759-2.c b/gcc/testsuite/gcc.target/powerpc/pr114759-2.c
new file mode 100644
index 0000000..3881ebd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr114759-2.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mdejagnu-cpu=power8 -mrop-protect" } */
+/* { dg-require-effective-target rop_ok } Only enable on supported ABIs.  */
+
+/* Verify we generate ROP-protect hash insns when compiling for Power8.  */
+
+extern void foo (void);
+
+int
+bar (void)
+{
+  foo ();
+  return 5;
+}
+
+/* { dg-final { scan-assembler-times {\mhashst\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mhashchk\M} 1 } } */
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index f001c28..daa0c75 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -7452,7 +7452,7 @@ proc check_effective_target_powerpc_elfv2 { } {
 # Return 1 if this is a PowerPC target supporting -mrop-protect
 
 proc check_effective_target_rop_ok { } {
-    return [check_effective_target_power10_ok] && [check_effective_target_powerpc_elfv2]
+    return [check_effective_target_has_arch_pwr8] && [check_effective_target_powerpc_elfv2]
 }
 
 # The VxWorks SPARC simulator accepts only EM_SPARC executables and