rs6000: Error on CPUs and ABIs that don't support the ROP protection insns [PR114759]

We currently silently ignore the -mrop-protect option for old CPUs we don't
support with the ROP hash insns, but we throw an error for unsupported ABIs.
This patch treats unsupported CPUs and ABIs similarly by throwing an error
both both.  This matches clang behavior and allows us to simplify our tests
in the code that generates our prologue and epilogue code.

2024-06-26  Peter Bergner  <bergner@linux.ibm.com>

gcc/
	PR target/114759
	* config/rs6000/rs6000.cc (rs6000_option_override_internal): Disallow
	CPUs and ABIs that do no support the ROP protection insns.
	* config/rs6000/rs6000-logue.cc (rs6000_stack_info): Remove now
	unneeded tests.
	(rs6000_emit_prologue): Likewise.
	Remove unneeded gcc_assert.
	(rs6000_emit_epilogue): Likewise.
	* config/rs6000/rs6000.md: Likewise.

gcc/testsuite/
	PR target/114759
	* gcc.target/powerpc/pr114759-3.c: New test.

diff --git a/gcc/config/rs6000/rs6000-logue.cc b/gcc/config/rs6000/rs6000-logue.cc
index 48f406330714f01e6d96f2037af7d015c8b68597..edc0d6c8f520b34f7f88f62bd6f1c8330ef2eb66 100644 (file)
--- a/gcc/config/rs6000/rs6000-logue.cc
+++ b/gcc/config/rs6000/rs6000-logue.cc
@@ -716,17 +716,11 @@ rs6000_stack_info (void)
   info->calls_p = (!crtl->is_leaf || cfun->machine->ra_needs_full_frame);
   info->rop_hash_size = 0;
 
-  if (TARGET_POWER8
-      && info->calls_p
-      && DEFAULT_ABI == ABI_ELFv2
-      && rs6000_rop_protect)
+  /* If we want ROP protection and this function makes a call, indicate
+     we need to create a stack slot to save the hashed return address in.  */
+  if (rs6000_rop_protect
+      && info->calls_p)
     info->rop_hash_size = 8;
-  else if (rs6000_rop_protect && DEFAULT_ABI != ABI_ELFv2)
-    {
-      /* We can't check this in rs6000_option_override_internal since
-        DEFAULT_ABI isn't established yet.  */
-      error ("%qs requires the ELFv2 ABI", "-mrop-protect");
-    }
 
   /* Determine if we need to save the condition code registers.  */
   if (save_reg_p (CR2_REGNO)
@@ -3272,9 +3266,8 @@ 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_POWER8 && rs6000_rop_protect && info->rop_hash_size != 0)
+  if (info->rop_hash_size)
     {
-      gcc_assert (DEFAULT_ABI == ABI_ELFv2);
       rtx stack_ptr = gen_rtx_REG (Pmode, STACK_POINTER_REGNUM);
       rtx addr = gen_rtx_PLUS (Pmode, stack_ptr,
                               GEN_INT (info->rop_hash_save_offset));
@@ -5051,12 +5044,9 @@ 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_POWER8
-      && rs6000_rop_protect
-      && info->rop_hash_size != 0
+  if (info->rop_hash_size
       && epilogue_type != EPILOGUE_TYPE_SIBCALL)
     {
-      gcc_assert (DEFAULT_ABI == ABI_ELFv2);
       rtx stack_ptr = gen_rtx_REG (Pmode, STACK_POINTER_REGNUM);
       rtx addr = gen_rtx_PLUS (Pmode, stack_ptr,
                               GEN_INT (info->rop_hash_save_offset));

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 195f2af9062ea9322118c3f109dd026f31935d67..d4eec5c472f8ae76cbceae76132993c303d6027b 100644 (file)
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -4844,6 +4844,18 @@ rs6000_option_override_internal (bool global_init_p)
        }
     }
 
+  /* We only support ROP protection on certain targets.  */
+  if (rs6000_rop_protect)
+    {
+      /* Disallow CPU targets we don't support.  */
+      if (!TARGET_POWER8)
+       error ("%<-mrop-protect%> requires %<-mcpu=power8%> or later");
+
+      /* Disallow ABI targets we don't support.  */
+      if (DEFAULT_ABI != ABI_ELFv2)
+       error ("%<-mrop-protect%> requires the ELFv2 ABI");
+    }
+
   /* Initialize all of the registers.  */
   rs6000_init_hard_regno_mode_ok (global_init_p);
 

diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 679aac5a10d573f338681b4bfaa00e7b31a77b19..45a4a8cfb907981f8fcdcf2a030149252dbceb8c 100644 (file)
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -15810,7 +15810,7 @@
   [(set (match_operand:DI 0 "simple_offsettable_mem_operand" "=m")
        (unspec_volatile:DI [(match_operand:DI 1 "int_reg_operand" "r")]
                            UNSPEC_HASHST))]
-  "TARGET_POWER8 && rs6000_rop_protect"
+  "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_POWER8 && rs6000_rop_protect"
+  "rs6000_rop_protect"
 {
   static char templ[32];
   const char *p = rs6000_privileged ? "p" : "";

diff --git a/gcc/testsuite/gcc.target/powerpc/pr114759-3.c b/gcc/testsuite/gcc.target/powerpc/pr114759-3.c
new file mode 100644 (file)
index 0000000..6770a9a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr114759-3.c
@@ -0,0 +1,19 @@
+/* PR target/114759 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mdejagnu-cpu=power7 -mrop-protect" } */
+
+/* Verify we emit an error if we use -mrop-protect with an unsupported cpu.  */
+
+extern void foo (void);
+
+int
+bar (void)
+{
+  foo ();
+  return 5;
+}
+
+/* The correct line number is in the preamble to the error message, not
+   in the final line (which is all that dg-error inspects). Hence, we have
+   to tell dg-error to ignore the line number.  */
+/* { dg-error "'-mrop-protect' requires '-mcpu=power8'" "PR114759" { target *-*-* } 0 } */