aarch64: Add -mbranch-protection=gcs option

This enables Guarded Control Stack (GCS) compatible code generation.

The "standard" branch-protection type enables it, and the default
depends on the compiler default.

gcc/ChangeLog:

	* config/aarch64/aarch64-protos.h (aarch_gcs_enabled): Declare.
	* config/aarch64/aarch64.cc (aarch_gcs_enabled): Define.
	(aarch_handle_no_branch_protection): Handle gcs.
	(aarch_handle_standard_branch_protection): Handle gcs.
	(aarch_handle_gcs_protection): New.
	* config/aarch64/aarch64.opt: Add aarch_enable_gcs.
	* configure: Regenerate.
	* configure.ac: Handle gcs in --enable-standard-branch-protection.
	* doc/invoke.texi: Document -mbranch-protection=gcs.

diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 72df4a575b3278580caf59dade2521774452fa12..0a7a5e10d7a0be4cbb4cfcee29df3af97e2737a7 100644 (file)
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -1219,4 +1219,6 @@ extern void aarch64_adjust_reg_alloc_order ();
 bool aarch64_optimize_mode_switching (aarch64_mode_entity);
 void aarch64_restore_za (rtx);
 
+extern bool aarch64_gcs_enabled ();
+
 #endif /* GCC_AARCH64_PROTOS_H */

diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 00bcf18ae97cea94227c00798b7951daa255d360..68230e1f4c2deebc05560a215f66ebfa360f6400 100644 (file)
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -8562,6 +8562,13 @@ aarch_bti_j_insn_p (rtx_insn *insn)
   return GET_CODE (pat) == UNSPEC_VOLATILE && XINT (pat, 1) == UNSPECV_BTI_J;
 }
 
+/* Return TRUE if Guarded Control Stack is enabled.  */
+bool
+aarch64_gcs_enabled (void)
+{
+  return (aarch64_enable_gcs == 1);
+}
+
 /* Check if X (or any sub-rtx of X) is a PACIASP/PACIBSP instruction.  */
 bool
 aarch_pac_insn_p (rtx x)
@@ -18981,6 +18988,7 @@ aarch64_handle_no_branch_protection (void)
 {
   aarch_ra_sign_scope = AARCH_FUNCTION_NONE;
   aarch_enable_bti = 0;
+  aarch64_enable_gcs = 0;
 }
 
 static void
@@ -18989,6 +18997,7 @@ aarch64_handle_standard_branch_protection (void)
   aarch_ra_sign_scope = AARCH_FUNCTION_NON_LEAF;
   aarch64_ra_sign_key = AARCH64_KEY_A;
   aarch_enable_bti = 1;
+  aarch64_enable_gcs = 1;
 }
 
 static void
@@ -19015,6 +19024,11 @@ aarch64_handle_bti_protection (void)
 {
   aarch_enable_bti = 1;
 }
+static void
+aarch64_handle_gcs_protection (void)
+{
+  aarch64_enable_gcs = 1;
+}
 
 static const struct aarch_branch_protect_type aarch64_pac_ret_subtypes[] = {
   { "leaf", false, aarch64_handle_pac_ret_leaf, NULL, 0 },
@@ -19029,6 +19043,7 @@ static const struct aarch_branch_protect_type aarch64_branch_protect_types[] =
   { "pac-ret", false, aarch64_handle_pac_ret_protection,
     aarch64_pac_ret_subtypes, ARRAY_SIZE (aarch64_pac_ret_subtypes) },
   { "bti", false, aarch64_handle_bti_protection, NULL, 0 },
+  { "gcs", false, aarch64_handle_gcs_protection, NULL, 0 },
   { NULL, false, NULL, NULL, 0 }
 };
 
@@ -19128,6 +19143,15 @@ aarch64_override_options (void)
 #endif
     }
 
+  if (aarch64_enable_gcs == 2)
+    {
+#ifdef TARGET_ENABLE_GCS
+      aarch64_enable_gcs = 1;
+#else
+      aarch64_enable_gcs = 0;
+#endif
+    }
+
   /* Return address signing is currently not supported for ILP32 targets.  For
      LP64 targets use the configured option in the absence of a command-line
      option for -mbranch-protection.  */

diff --git a/gcc/config/aarch64/aarch64.opt b/gcc/config/aarch64/aarch64.opt
index c2c9965b0625ec8f6bb54e8a3fbfcf300a81827d..36bc719b822db6d427170f19f3a00dc65453772c 100644 (file)
--- a/gcc/config/aarch64/aarch64.opt
+++ b/gcc/config/aarch64/aarch64.opt
@@ -45,6 +45,9 @@ uint64_t aarch64_isa_flags_1 = 0
 TargetVariable
 unsigned aarch_enable_bti = 2
 
+TargetVariable
+unsigned aarch64_enable_gcs = 2
+
 TargetVariable
 enum aarch64_key_type aarch64_ra_sign_key = AARCH64_KEY_A
 

diff --git a/gcc/configure b/gcc/configure
index 150ab6164142c2d2b01a2b1ed159ea4561f877db..df64af3af57ec7e88c65b6915a650d55ab6e915d 100755 (executable)
--- a/gcc/configure
+++ b/gcc/configure
@@ -28093,7 +28093,7 @@ if test "${enable_standard_branch_protection+set}" = set; then :
   enableval=$enable_standard_branch_protection;
         case $enableval in
           yes)
-            tm_defines="${tm_defines} TARGET_ENABLE_BTI=1 TARGET_ENABLE_PAC_RET=1"
+            tm_defines="${tm_defines} TARGET_ENABLE_BTI=1 TARGET_ENABLE_PAC_RET=1 TARGET_ENABLE_GCS=1"
             ;;
           no)
             ;;

diff --git a/gcc/configure.ac b/gcc/configure.ac
index bdb22d53e2cafc6e8cbf54808b6ca10268fecf1f..bdd8cb0002f38813614cbffb42a20e32e6464d35 100644 (file)
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4402,14 +4402,14 @@ case "$target" in
     AC_ARG_ENABLE(standard-branch-protection,
     [
 AS_HELP_STRING([--enable-standard-branch-protection],
-        [enable Branch Target Identification Mechanism and Return Address Signing by default for AArch64])
+        [enable Branch Target Identification Mechanism, Return Address Signing, and Guarded Control Stack by default for AArch64])
 AS_HELP_STRING([--disable-standard-branch-protection],
-        [disable Branch Target Identification Mechanism and Return Address Signing by default for AArch64])
+        [disable Branch Target Identification Mechanism, Return Address Signing, and Guarded Control Stack by default for AArch64])
     ],
       [
         case $enableval in
           yes)
-            tm_defines="${tm_defines} TARGET_ENABLE_BTI=1 TARGET_ENABLE_PAC_RET=1"
+            tm_defines="${tm_defines} TARGET_ENABLE_BTI=1 TARGET_ENABLE_PAC_RET=1 TARGET_ENABLE_GCS=1"
             ;;
           no)
             ;;

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e00a04720e05e02ff5095f808a0f1d8c14d9c0a0..93e096bc9d53561455ebf5351b53920e69065d6b 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -814,7 +814,7 @@ Objective-C and Objective-C++ Dialects}.
 -mpc-relative-literal-loads
 -msign-return-address=@var{scope}
 -mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}
-+@var{b-key}]|@var{bti}
++@var{b-key}]|@var{bti}|@var{gcs}
 -mharden-sls=@var{opts}
 -march=@var{name}  -mcpu=@var{name}  -mtune=@var{name}
 -moverride=@var{string}  -mverbose-cost-dump
@@ -21607,7 +21607,7 @@ default value is @samp{none}. This option has been deprecated by
 -mbranch-protection.
 
 @opindex mbranch-protection
-@item -mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}+@var{b-key}]|@var{bti}
+@item -mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}+@var{b-key}]|@var{bti}|@var{gcs}
 Select the branch protection features to use.
 @samp{none} is the default and turns off all types of branch protection.
 @samp{standard} turns on all types of branch protection features.  If a feature
@@ -21620,6 +21620,7 @@ argument @samp{leaf} can be used to extend the signing to include leaf
 functions.  The optional argument @samp{b-key} can be used to sign the functions
 with the B-key instead of the A-key.
 @samp{bti} turns on branch target identification mechanism.
+@samp{gcs} turns on guarded control stack compatible code generation.
 
 @opindex mharden-sls
 @item -mharden-sls=@var{opts}