From: Szabolcs Nagy <szabolcs.n...@arm.com>
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.
---
gcc/config/aarch64/aarch64-protos.h | 2 ++
gcc/config/aarch64/aarch64.cc | 24 ++++++++++++++++++++++++
gcc/config/aarch64/aarch64.opt | 3 +++
gcc/configure | 2 +-
gcc/configure.ac | 6 +++---
gcc/doc/invoke.texi | 5 +++--
6 files changed, 36 insertions(+), 6 deletions(-)
diff --git a/gcc/config/aarch64/aarch64-protos.h
b/gcc/config/aarch64/aarch64-protos.h
index 9be64913091..80c4de0ce60 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -1121,4 +1121,6 @@ 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 0fa7927d821..f87ec2e43b5 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -8531,6 +8531,13 @@ 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)
@@ -18911,6 +18918,7 @@ aarch64_handle_no_branch_protection (void)
{
aarch_ra_sign_scope = AARCH_FUNCTION_NONE;
aarch_enable_bti = 0;
+ aarch64_enable_gcs = 0;
}
static void
@@ -18919,6 +18927,7 @@ 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
@@ -18945,6 +18954,11 @@ 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 },
@@ -18959,6 +18973,7 @@ 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 }
};
@@ -19058,6 +19073,15 @@ 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 c2c9965b062..36bc719b822 100644
--- 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 47c58036530..142bfa82694 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -28044,7 +28044,7 @@ 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="${tm_defines} TARGET_ENABLE_BTI=1
TARGET_ENABLE_PAC_RET=1 TARGET_ENABLE_GCS=1"
;;
no)
;;
diff --git a/gcc/configure.ac b/gcc/configure.ac
index dc8346a7b82..8319e8e5e11 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4392,14 +4392,14 @@ case "$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 19c148a7d6f..43b96bb5e07 100644
--- 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
@@ -21589,7 +21589,7 @@ 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
@@ -21602,6 +21602,7 @@ 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}
--
2.39.5
