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.

(cherry picked from commit 6f2bab9b5d1ce1914c748b7dcd8638dafaa98df7)

diff --git a/gcc/config/rs6000/rs6000-logue.cc b/gcc/config/rs6000/rs6000-logue.cc
index 9817ce78639a7361df2dc76f5f99eddc1a126d20..d891d43c074e673cdc358252faeb3682e2636326 100644 (file)
--- a/gcc/config/rs6000/rs6000-logue.cc
+++ b/gcc/config/rs6000/rs6000-logue.cc
@@ -720,17 +720,11 @@ 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)
@@ -3279,9 +3273,8 @@ 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));
@@ -5026,12 +5019,9 @@ 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 03893b2cf8bd1b321a7f96a99fb49740c84a66f4..cf0d089d06ba127b0625460726141172d0ad22d1 100644 (file)
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -4888,6 +4888,18 @@ rs6000_option_override_internal (bool global_init_p)
     rs6000_print_builtin_options (stderr, 0, "builtin mask",
                                  rs6000_builtin_mask);
 
+  /* 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 d1ae5be96d44a329f779e7ca073ead6e9fc20ee5..b0614868f942d02545be992afd31c52a980456b9 100644 (file)
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -15559,7 +15559,7 @@
   [(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" : "";
@@ -15572,7 +15572,7 @@
   [(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 } */