aarch64: Add support for GCS extension.

This patch adds for Guarded Control Stack Extension (GCS) extension. GCS feature is
optional from Armv9.4-A architecture and enabled by passing +gcs option to -march
(eg: -march=armv9.4-a+gcs) or using ".arch_extension gcs" directive in the assembly file.

Also this patch adds support for GCS instructions gcspushx, gcspopcx, gcspopx,
gcsss1, gcsss2, gcspushm, gcspopm, gcsstr and gcssttr.

7 files changed, 126 insertions, 0 deletions

diff --git a/gas/NEWS b/gas/NEWS
index 2b593c1..a6ac839 100644
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -1,5 +1,7 @@
 -*- text -*-
 
+* Add support for Guarded Control Stack (GCS) for AArch64.
+
 * Add support for AArch64 Check Feature Status Extension (CHK).
 
 * Add support for 'armv8.9-a' and 'armv9.4-a' for -march in AArch64 GAS.
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index f5b7b42..6d20400 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -10325,6 +10325,7 @@ static const struct aarch64_option_cpu_value_table aarch64_features[] = {
   {"hbc",		AARCH64_FEATURE (HBC), AARCH64_NO_FEATURES},
   {"cssc",		AARCH64_FEATURE (CSSC), AARCH64_NO_FEATURES},
   {"chk",		AARCH64_FEATURE (CHK), AARCH64_NO_FEATURES},
+  {"gcs",		AARCH64_FEATURE (GCS), AARCH64_NO_FEATURES},
   {NULL,		AARCH64_NO_FEATURES, AARCH64_NO_FEATURES},
 };
 
diff --git a/gas/doc/c-aarch64.texi b/gas/doc/c-aarch64.texi
index 0cabf72e..a3ca714 100644
--- a/gas/doc/c-aarch64.texi
+++ b/gas/doc/c-aarch64.texi
@@ -261,6 +261,8 @@ automatically cause those extensions to be disabled.
  @tab Enable Transactional Memory Extensions.
 @item @code{chk} @tab ARMv8-A @tab ARMv8-A
  @tab Enable Check Feature Status Extension.
+@item @code{gcs} @tab N/A @tab No
+ @tab Enable Guarded Control Stack Extension.
 @end multitable
 
 @node AArch64 Syntax
diff --git a/gas/testsuite/gas/aarch64/gcs-1-bad.d b/gas/testsuite/gas/aarch64/gcs-1-bad.d
new file mode 100644
index 0000000..7c3a7ae
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/gcs-1-bad.d
@@ -0,0 +1,3 @@
+#as: -march=armv9.2-a
+#source: gcs-1.s
+#error_output: gcs-1-bad.l
diff --git a/gas/testsuite/gas/aarch64/gcs-1-bad.l b/gas/testsuite/gas/aarch64/gcs-1-bad.l
new file mode 100644
index 0000000..ca8d17a
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/gcs-1-bad.l
@@ -0,0 +1,45 @@
+[^ :]+: Assembler messages:
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspushx'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopcx'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopx'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopm'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspushm x0'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspushm x15'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspushm x30'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspushm xzr'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss1 x0'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss1 x15'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss1 x30'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss1 xzr'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss2 x0'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss2 x15'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss2 x30'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsss2 xzr'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopm x0'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopm x15'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopm x30'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcspopm xzr'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x0,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x0,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x0,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x15,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x15,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x15,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x30,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x30,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr x30,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr xzr,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr xzr,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcsstr xzr,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x0,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x0,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x0,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x15,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x15,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x15,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x30,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x30,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr x30,sp'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr xzr,x1'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr xzr,x16'
+[^ :]+:[0-9]+: Error: selected processor does not support `gcssttr xzr,sp'
diff --git a/gas/testsuite/gas/aarch64/gcs-1.d b/gas/testsuite/gas/aarch64/gcs-1.d
new file mode 100644
index 0000000..51f9dd6
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/gcs-1.d
@@ -0,0 +1,54 @@
+#name: Test of Guarded Control Stack Instructions.
+#as: -march=armv9.3-a+gcs
+#objdump: -dr
+
+[^:]+:     file format .*
+
+
+[^:]+:
+
+[^:]+:
+.*:	d508779f 	gcspushx
+.*:	d50877bf 	gcspopcx
+.*:	d50877df 	gcspopx
+.*:	d52b773f 	gcspopm
+.*:	d50b7700 	gcspushm	x0
+.*:	d50b770f 	gcspushm	x15
+.*:	d50b771e 	gcspushm	x30
+.*:	d50b771f 	gcspushm	xzr
+.*:	d50b7740 	gcsss1	x0
+.*:	d50b774f 	gcsss1	x15
+.*:	d50b775e 	gcsss1	x30
+.*:	d50b775f 	gcsss1	xzr
+.*:	d52b7760 	gcsss2	x0
+.*:	d52b776f 	gcsss2	x15
+.*:	d52b777e 	gcsss2	x30
+.*:	d52b777f 	gcsss2	xzr
+.*:	d52b7720 	gcspopm	x0
+.*:	d52b772f 	gcspopm	x15
+.*:	d52b773e 	gcspopm	x30
+.*:	d52b773f 	gcspopm
+.*:	d91f0c20 	gcsstr	x0, x1
+.*:	d91f0e00 	gcsstr	x0, x16
+.*:	d91f0fe0 	gcsstr	x0, sp
+.*:	d91f0c2f 	gcsstr	x15, x1
+.*:	d91f0e0f 	gcsstr	x15, x16
+.*:	d91f0fef 	gcsstr	x15, sp
+.*:	d91f0c3e 	gcsstr	x30, x1
+.*:	d91f0e1e 	gcsstr	x30, x16
+.*:	d91f0ffe 	gcsstr	x30, sp
+.*:	d91f0c3f 	gcsstr	xzr, x1
+.*:	d91f0e1f 	gcsstr	xzr, x16
+.*:	d91f0fff 	gcsstr	xzr, sp
+.*:	d91f1c20 	gcssttr	x0, x1
+.*:	d91f1e00 	gcssttr	x0, x16
+.*:	d91f1fe0 	gcssttr	x0, sp
+.*:	d91f1c2f 	gcssttr	x15, x1
+.*:	d91f1e0f 	gcssttr	x15, x16
+.*:	d91f1fef 	gcssttr	x15, sp
+.*:	d91f1c3e 	gcssttr	x30, x1
+.*:	d91f1e1e 	gcssttr	x30, x16
+.*:	d91f1ffe 	gcssttr	x30, sp
+.*:	d91f1c3f 	gcssttr	xzr, x1
+.*:	d91f1e1f 	gcssttr	xzr, x16
+.*:	d91f1fff 	gcssttr	xzr, sp
diff --git a/gas/testsuite/gas/aarch64/gcs-1.s b/gas/testsuite/gas/aarch64/gcs-1.s
new file mode 100644
index 0000000..9706587
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/gcs-1.s
@@ -0,0 +1,19 @@
+	.text
+	gcspushx
+	gcspopcx
+	gcspopx
+	gcspopm
+
+	.irp op gcspushm, gcsss1, gcsss2, gcspopm
+        .irp reg1 x0, x15, x30, xzr
+	\op \reg1
+	.endr
+	.endr
+
+	.irp op gcsstr, gcssttr
+        .irp reg1 x0, x15, x30, xzr
+	.irp reg2 x1, x16, sp
+	\op \reg1, \reg2
+	.endr
+	.endr
+	.endr