arm-gcs: add recipe for GDB with GCS support

The GCS support patches are based on GDB 15.
Copy the GDB 14.2 recipe from meta, upgrade to 15.1, and add the patches.

Signed-off-by: James McGregor <james.mcgregor2@arm.com>

.gitlab-ci.yml

@@ -28,6 +28,7 @@ stages:
 
 # Common job fragment to get a worker ready
 .setup:
+  when: manual
   tags:
     - $DEFAULT_TAG
   stage: build
@@ -89,6 +90,7 @@ stages:
 #
 update-repos:
   extends: .setup
+  when: on_success
   stage: prep
   allow_failure:
     exit_codes: 128
@@ -353,3 +355,9 @@ sgi575:
 
 toolchains:
   extends: .build
+
+gcs:
+  when: on_success
+  extends: .setup
+  script:
+    - kas build meta-arm-gcs/gcs-test.yml

meta-arm-gcs/.gitignore

@@ -0,0 +1,3 @@
+build
+meta-arm
+poky

meta-arm-gcs/COPYING.MIT

@@ -0,0 +1,17 @@
+Permission is hereby granted, free of charge, to any person obtaining a copy 
+of this software and associated documentation files (the "Software"), to deal 
+in the Software without restriction, including without limitation the rights 
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
+copies of the Software, and to permit persons to whom the Software is 
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in 
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
+THE SOFTWARE.

meta-arm-gcs/README

@@ -0,0 +1,36 @@
+Guarded Control Stack prototype
+===============================
+
+To build:
+
+First, install Kas if you don't already have it:
+
+$ pip3 install --user kas
+
+Then use Kas to build an image:
+
+$ kas build --update gcs.yml
+
+To run the image inside an FVP:
+
+$ kas shell gcs.yml -c "../../scripts/runfvp --console"
+
+To run the tests automatically, Kas can be used:
+
+$ kas build --update meta-arm-gcs/gcs-test.yml
+
+Verification:
+
+On boot, the kernel should detect that the cores have GCS:
+
+  CPU features: detected: Guarded Control Stack (GCS)
+
+Binaries should be tagged with PAC/BTI/GCS:
+
+  $ readelf  -n /bin/bash | grep AArch
+  Properties: AArch64 feature: BTI, PAC, GCS
+
+Enabling GCS tunables shouldn't cause crashes:
+
+  $ GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_policy=2 ls /
+  bin  boot  dev	etc  home  lib	lost+found  media  mnt	proc  run  sbin  sys  tmp  usr	var

meta-arm-gcs/conf/layer.conf

@@ -0,0 +1,15 @@
+# We have a conf and classes directory, add to BBPATH
+BBPATH .= ":${LAYERDIR}"
+
+# We have recipes-* directories, add to BBFILES
+BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
+            ${LAYERDIR}/recipes-*/*/*.bbappend"
+
+BBFILE_COLLECTIONS += "meta-arm-gcs"
+BBFILE_PATTERN_meta-arm-gcs = "^${LAYERDIR}/"
+BBFILE_PRIORITY_meta-arm-gcs = "5"
+
+LAYERDEPENDS_meta-arm-gcs = "core"
+LAYERSERIES_COMPAT_meta-arm-gcs = " scarthgap"
+
+addpylib ${LAYERDIR}/lib oeqa

meta-arm-gcs/gcs-test.yml

@@ -0,0 +1,8 @@
+header:
+  version: 14
+  includes:
+    - meta-arm-gcs/gcs.yml
+
+local_conf_header:
+  autotestimage: |
+    TESTIMAGE_AUTO = "1"

meta-arm-gcs/gcs.yml

@@ -0,0 +1,62 @@
+header:
+  version: 14
+
+distro: poky
+
+machine: fvp-base
+
+repos:
+  meta-arm:
+    layers:
+      meta-arm:
+      meta-arm-bsp:
+      meta-arm-toolchain:
+      meta-arm-gcs:
+
+  poky:
+    url: https://git.yoctoproject.org/git/poky-contrib
+    branch: ross/gcc14
+    layers:
+      meta:
+      meta-poky:
+
+local_conf_header:
+  setup: |
+    # We accept the FVP EULA
+    LICENSE_FLAGS_ACCEPTED += "Arm-FVP-EULA"
+    # Enable running an image inside a FVP
+    IMAGE_CLASSES += "fvpboot"
+    # Use the -dev patched kernel
+    PREFERRED_PROVIDER_virtual/kernel = "linux-yocto-dev"
+    LINUXLIBCVERSION = "6.11"
+    # No root password for ease
+    EXTRA_IMAGE_FEATURES += "empty-root-password allow-empty-password allow-root-login"
+    # Install a toolchain
+    EXTRA_IMAGE_FEATURES += "tools-sdk"
+    # Install a pre-generated SSH key because key generation in a FVP is tiresome
+    CORE_IMAGE_EXTRA_INSTALL += "ssh-pregen-hostkeys"
+
+  fvp_options: |
+    # Set the instruction set tune to 8.0 to match binary distributions
+    DEFAULTTUNE = "armv8a-crc"
+
+    # Set the cores to v9.4 and turn on more features
+    FVP_CONFIG[cluster0.has_arm_v9-4] = "1"
+    FVP_CONFIG[cluster1.has_arm_v9-4] = "1"
+    FVP_CONFIG[cluster0.has_branch_target_exception] = "1"
+    FVP_CONFIG[cluster1.has_branch_target_exception] = "1"
+    FVP_CONFIG[cluster0.has_gcs] = "1"
+    FVP_CONFIG[cluster1.has_gcs] = "1"
+    FVP_CONFIG[cluster0.has_chkfeat] = "1"
+    FVP_CONFIG[cluster1.has_chkfeat] = "1"
+    FVP_CONFIG[cluster0.has_permission_indirection_s1] = "1"
+    FVP_CONFIG[cluster1.has_permission_indirection_s1] = "1"
+
+  testimage: |
+    IMAGE_CLASSES += "testimage"
+    TEST_SUITES = "ping ssh gcs"
+    IMAGE_FEATURES += "ssh-server-dropbear"
+    CORE_IMAGE_EXTRA_INSTALL += "ssh-pregen-hostkeys binutils kselftest gcs-test"
+
+target:
+  - core-image-full-cmdline

meta-arm-gcs/lib/oeqa/runtime/cases/gcs.py

@@ -0,0 +1,83 @@
+#
+# SPDX-License-Identifier: MIT
+#
+
+import unittest
+
+from oeqa.runtime.case import OERuntimeTestCase
+from oeqa.runtime.decorator.package import OEHasPackage
+
+class GCSTests(OERuntimeTestCase):
+
+    def test_dmesg(self):
+        """
+        Verify that the kernel detected the GCS processor feature.
+
+        If this fails the FVP configuration or kernel is at fault.
+        """
+        status, output = self.target.run("dmesg | grep 'CPU features'")
+        self.assertEqual(status, 0, f"dmesg failed: {output}")
+
+        self.assertIn("CPU features: detected: Guarded Control Stack (GCS)", output)
+
+
+    @OEHasPackage(['binutils'])
+    def test_elf_tags(self):
+        """
+        Verify that ELF binaries have the GCS feature enabled.
+        
+        If this fails the toolchain doesn't have GCS enabled, or the compilation
+        flags don't enable GCS.
+        """
+        status, output = self.target.run("readelf -n /bin/bash | grep 'AArch64 feature'")
+        self.assertEqual(status, 0, f"readelf failed: {output}")
+
+        self.assertIn("Properties: AArch64 feature: BTI, PAC, GCS", output)
+
+
+    def test_execution(self):
+        """
+        Verify that enabling GCS with the glibc tunables doesn't cause a crash.
+
+        This is an incredibly low bar, but if this fails then the GCS patches
+        are at fault.
+        """
+        cmd = "GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_policy=2 ls -d /u*"
+        status, output = self.target.run(cmd)
+        self.assertEqual(status, 0, f"ls failed: {output}")
+        self.assertEqual(output, "/usr")
+
+    def test_chkfeat(self):
+        """
+        Verify that CHKFEAT reports GCS as enabled when running with the tunables.
+
+        If this fails then GCS is not being properly enabled at runtime glibc. The kernel
+        and glibc patches may be out of sync.
+        """
+        cmd = "GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_policy=2 gcs-test"
+        status, output = self.target.run(cmd)
+        self.assertEqual(status, 0, f"gcs-test failed: {output}")
+
+        # gcs-test should return 1 if GCS is not enabled via the tunables
+        cmd = "gcs-test"
+        status, output = self.target.run(cmd)
+        self.assertEqual(status, 1, f"gcs-test failed: {output}")
+
+    @OEHasPackage(['kselftest'])
+    @unittest.expectedFailure
+    def test_kselftest(self):
+        """
+        Run the GCS tests in the kselftest.
+        """
+        cmd = """
+        cd /usr/libexec/kselftest; \
+        ./run_kselftest.sh $(./run_kselftest.sh -l | awk -e '/arm64.*gcs/ { print "-t " $1 }') \
+        """
+        status, output = self.target.run(cmd)
+
+        # kselftest normally returns 0 even if tests fail, so a failure here is serious
+        self.assertEqual(status, 0, f"kselftest failed: {output}")
+
+        # Identify any test failure lines, and assert that the list is empty
+        fails = [l for l in output.splitlines() if "not ok " in l]
+        self.assertFalse(fails)

meta-arm-gcs/recipes-bsp/trusted-firmware-a/trusted-firmware-a_%.bbappend

@@ -0,0 +1 @@
+EXTRA_OEMAKE:append:fvp-base = " CTX_INCLUDE_AARCH32_REGS=0"

meta-arm-gcs/recipes-core/glibc/glibc_2.39.bbappend

@@ -0,0 +1,3 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI += "file://gcs.patch"

meta-arm-gcs/recipes-devtools/binutils/binutils_2.42.bbappend

@@ -0,0 +1,3 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI += "file://gcs.patch"

meta-arm-gcs/recipes-devtools/binutils/files/gcs.patch

@@ -0,0 +1,973 @@
+From afe69c2e274db719e1835ee112150012271b62b7 Mon Sep 17 00:00:00 2001
+From: Srinath Parvathaneni <srinath.parvathaneni@arm.com>
+Date: Tue, 30 Jan 2024 08:59:53 +0000
+Subject: [PATCH] aarch64: Add support for GCS in AArch64 linker.
+
+This patch adds support for GCS in AArch64 linker.
+
+This patch implements the following:
+1) Defines GNU_PROPERTY_AARCH64_FEATURE_1_GCS bit for GCS in
+GNU_PROPERTY_AARCH64_FEATURE_1_AND macro.
+
+2) Adds readelf support to read and print the GNU properties
+in AArch64.
+
+Displaying notes found in: .note.gnu.property
+[      ]+Owner[        ]+Data size[    ]+Description
+  GNU                  0x00000010      NT_GNU_PROPERTY_TYPE_0
+      Properties: AArch64 feature: GCS
+
+3) Adds support for -z experimental-gcs linker option and document
+all the values allowed with option (-z experimental-gcs[=always|never|implicit]).
+-z experimental-gcs is equivalent to -z experimental-gcs=always and
+when option is not passed in the command line, it defaults to implicit.
+
+4) Adds support for -z experimental-gcs-report linker option and document
+all the values allowed with this option (-z experimental-gcs-report[=none|warning|error]).
+-z experimental-gcs-report is equivalent to -z experimental-gcs-report=none
+and when option is not passed in the command line, it defaults to none.
+
+The ABI changes adding GNU_PROPERTY_AARCH64_FEATURE_1_GCS to the
+GNU property GNU_PROPERTY_AARCH64_FEATURE_1_AND is merged into main and
+can be found below.
+https://github.com/ARM-software/abi-aa/blob/main/sysvabi64/sysvabi64.rst
+
+Upstream-Status: Pending [https://sourceware.org/git/?p=binutils-gdb.git;a=shortlog;h=refs/heads/users/ARM/gcs-binutils-gdb-master]
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+---
+ bfd/elfnn-aarch64.c                         | 87 +++++++++++++++++----
+ bfd/elfxx-aarch64.c                         | 37 ++++++++-
+ bfd/elfxx-aarch64.h                         | 36 +++++++--
+ binutils/readelf.c                          |  4 +
+ include/elf/common.h                        |  1 +
+ ld/emultempl/aarch64elf.em                  | 45 ++++++++++-
+ ld/testsuite/ld-aarch64/aarch64-elf.exp     | 23 ++++++
+ ld/testsuite/ld-aarch64/property-bti-pac1.d |  2 +-
+ ld/testsuite/ld-aarch64/property-bti-pac1.s | 14 ++++
+ ld/testsuite/ld-aarch64/property-gcs.s      | 25 ++++++
+ ld/testsuite/ld-aarch64/property-gcs1.d     |  6 ++
+ ld/testsuite/ld-aarch64/property-gcs10.d    |  6 ++
+ ld/testsuite/ld-aarch64/property-gcs11.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs12.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs13.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs14.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs15.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs16.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs17.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs18.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs19.d    |  6 ++
+ ld/testsuite/ld-aarch64/property-gcs2.d     | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs2.s     | 33 ++++++++
+ ld/testsuite/ld-aarch64/property-gcs20.d    |  6 ++
+ ld/testsuite/ld-aarch64/property-gcs21.d    |  6 ++
+ ld/testsuite/ld-aarch64/property-gcs22.d    | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs3.d     | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs4.d     | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs5.d     | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs6.d     | 12 +++
+ ld/testsuite/ld-aarch64/property-gcs7.d     |  6 ++
+ ld/testsuite/ld-aarch64/property-gcs8.d     | 11 +++
+ ld/testsuite/ld-aarch64/property-gcs9.d     | 12 +++
+ 33 files changed, 495 insertions(+), 26 deletions(-)
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs.s
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs1.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs10.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs11.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs12.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs13.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs14.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs15.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs16.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs17.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs18.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs19.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs2.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs2.s
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs20.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs21.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs22.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs3.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs4.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs5.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs6.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs7.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs8.d
+ create mode 100644 ld/testsuite/ld-aarch64/property-gcs9.d
+
+diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
+index 109517db4aa..428f2c3507d 100644
+--- a/bfd/elfnn-aarch64.c
++++ b/bfd/elfnn-aarch64.c
+@@ -2546,6 +2546,12 @@ struct elf_aarch64_obj_tdata
+      GNU_PROPERTY_AARCH64_FEATURE_1_BTI.  */
+   int no_bti_warn;
+ 
++  /* Mark ouput with GCS based on -z experimental-gcs.  */
++  aarch64_gcs_type gcs_type;
++  /* Report linker warning/error for -z experimental-gcs-report based on
++     -z experimental-gcs.  */
++  aarch64_gcs_report gcs_report;
++
+   /* PLT type based on security.  */
+   aarch64_plt_type plt_type;
+ };
+@@ -5011,7 +5017,7 @@ bfd_elfNN_aarch64_set_options (struct bfd *output_bfd,
+ 			       int fix_erratum_835769,
+ 			       erratum_84319_opts fix_erratum_843419,
+ 			       int no_apply_dynamic_relocs,
+-			       aarch64_bti_pac_info bp_info)
++			       aarch64_gnu_prop_info bp_info)
+ {
+   struct elf_aarch64_link_hash_table *globals;
+ 
+@@ -5039,6 +5045,24 @@ bfd_elfNN_aarch64_set_options (struct bfd *output_bfd,
+     default:
+       break;
+     }
++
++  switch (bp_info.gcs_type)
++    {
++    case GCS_ALWAYS:
++      elf_aarch64_tdata (output_bfd)->gnu_and_prop
++	|= GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
++      break;
++    case GCS_NEVER:
++      elf_aarch64_tdata (output_bfd)->gnu_and_prop
++	&= ~GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
++      break;
++
++    default:
++      break;
++    }
++
++  elf_aarch64_tdata (output_bfd)->gcs_type = bp_info.gcs_type;
++  elf_aarch64_tdata (output_bfd)->gcs_report = bp_info.gcs_report;
+   elf_aarch64_tdata (output_bfd)->plt_type = bp_info.plt_type;
+   setup_plt_values (link_info, bp_info.plt_type);
+ }
+@@ -10196,7 +10220,12 @@ static bfd *
+ elfNN_aarch64_link_setup_gnu_properties (struct bfd_link_info *info)
+ {
+   uint32_t prop = elf_aarch64_tdata (info->output_bfd)->gnu_and_prop;
+-  bfd *pbfd = _bfd_aarch64_elf_link_setup_gnu_properties (info, &prop);
++  aarch64_gcs_report gcs_report
++    = elf_aarch64_tdata (info->output_bfd)->gcs_report;
++  aarch64_gcs_report gcs_type
++    = elf_aarch64_tdata (info->output_bfd)->gcs_type;
++  bfd *pbfd = _bfd_aarch64_elf_link_setup_gnu_properties (info, &prop,
++							  gcs_report, gcs_type);
+   elf_aarch64_tdata (info->output_bfd)->gnu_and_prop = prop;
+   elf_aarch64_tdata (info->output_bfd)->plt_type
+     |= (prop & GNU_PROPERTY_AARCH64_FEATURE_1_BTI) ? PLT_BTI : 0;
+@@ -10215,30 +10244,54 @@ elfNN_aarch64_merge_gnu_properties (struct bfd_link_info *info,
+ {
+   uint32_t prop
+     = elf_aarch64_tdata (info->output_bfd)->gnu_and_prop;
++  aarch64_gcs_report gcs_report
++    = elf_aarch64_tdata (info->output_bfd)->gcs_report;
++  aarch64_gcs_type gcs_type
++    = elf_aarch64_tdata (info->output_bfd)->gcs_type;
+ 
+-  /* If output has been marked with BTI using command line argument, give out
+-     warning if necessary.  */
+   /* Properties are merged per type, hence only check for warnings when merging
+      GNU_PROPERTY_AARCH64_FEATURE_1_AND.  */
+-  if (((aprop && aprop->pr_type == GNU_PROPERTY_AARCH64_FEATURE_1_AND)
++  if ((aprop && aprop->pr_type == GNU_PROPERTY_AARCH64_FEATURE_1_AND)
+ 	|| (bprop && bprop->pr_type == GNU_PROPERTY_AARCH64_FEATURE_1_AND))
+-      && (prop & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
+-      && (!elf_aarch64_tdata (info->output_bfd)->no_bti_warn))
+     {
+-      if ((aprop && !(aprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
+-	   || !aprop)
++      /* If output has been marked with BTI using command line argument, give
++	 out warning if necessary.  */
++      if ((prop & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
++	  && (!elf_aarch64_tdata (info->output_bfd)->no_bti_warn))
+ 	{
+-	  _bfd_error_handler (_("%pB: warning: BTI turned on by -z force-bti when "
+-				"all inputs do not have BTI in NOTE section."),
+-			      abfd);
++	  if ((aprop && !(aprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
++	      || !aprop)
++	    {
++	      _bfd_error_handler (_("%pB: warning: BTI turned on by -z "
++				  "force-bti when all inputs do not have BTI "
++				  "in NOTE section."), abfd);
++	    }
++	  if ((bprop && !(bprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
++	      || !bprop)
++	    {
++	      _bfd_error_handler (_("%pB: warning: BTI turned on by -z "
++				  "force-bti when all inputs do not have BTI "
++				  "in NOTE section."), bbfd);
++	    }
+ 	}
+-      if ((bprop && !(bprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
+-	   || !bprop)
++
++      /* If output has been marked with GCS using -z experimental-gcs and input
++	 is missing GCS marking throw warning/error on
++	 -z experimental-gcs-report=warning/error.  */
++      if ((prop & GNU_PROPERTY_AARCH64_FEATURE_1_GCS) && gcs_report != GCS_NONE)
+ 	{
+-	  _bfd_error_handler (_("%pB: warning: BTI turned on by -z force-bti when "
+-				"all inputs do not have BTI in NOTE section."),
+-			      bbfd);
++	  if ((aprop && !(aprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_GCS))
++	      || !aprop)
++	    _bfd_aarch64_elf_check_gcs_report (gcs_report, abfd);
++	  if ((bprop && !(bprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_GCS))
++	      || !bprop)
++	    _bfd_aarch64_elf_check_gcs_report (gcs_report, bbfd);
+ 	}
++
++      if (gcs_type == GCS_NEVER && aprop != NULL)
++	aprop->u.number &= ~GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
++      if (gcs_type == GCS_NEVER && bprop != NULL)
++	bprop->u.number &= ~GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
+     }
+ 
+   return  _bfd_aarch64_elf_merge_gnu_properties (info, abfd, aprop,
+diff --git a/bfd/elfxx-aarch64.c b/bfd/elfxx-aarch64.c
+index d1279adc2e4..dd64f2067ac 100644
+--- a/bfd/elfxx-aarch64.c
++++ b/bfd/elfxx-aarch64.c
+@@ -702,7 +702,9 @@ _bfd_aarch64_elf_write_core_note (bfd *abfd, char *buf, int *bufsiz, int note_ty
+    GPROP accordingly.  */
+ bfd *
+ _bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *info,
+-					    uint32_t *gprop)
++					    uint32_t *gprop,
++					    aarch64_gcs_report gcs_report,
++					    aarch64_gcs_type gcs_type)
+ {
+   asection *sec;
+   bfd *pbfd;
+@@ -738,6 +740,11 @@ _bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *info,
+ 	    _bfd_error_handler (_("%pB: warning: BTI turned on by -z force-bti "
+ 				  "when all inputs do not have BTI in NOTE "
+ 				  "section."), ebfd);
++
++      if ((gnu_prop & GNU_PROPERTY_AARCH64_FEATURE_1_GCS)
++	  && !(prop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_GCS))
++	_bfd_aarch64_elf_check_gcs_report (gcs_report, ebfd);
++
+       prop->u.number |= gnu_prop;
+       prop->pr_kind = property_number;
+ 
+@@ -765,6 +772,14 @@ _bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *info,
+ 	  elf_section_type (sec) = SHT_NOTE;
+ 	}
+     }
++  else if (ebfd != NULL && gcs_type == GCS_NEVER)
++    {
++      prop = _bfd_elf_get_property (ebfd, GNU_PROPERTY_AARCH64_FEATURE_1_AND,
++				    4);
++      prop->u.number &= ~GNU_PROPERTY_AARCH64_FEATURE_1_GCS;
++      if (prop->u.number == 0)
++	prop->pr_kind = property_remove;
++    }
+ 
+   pbfd = _bfd_elf_link_setup_gnu_properties (info);
+ 
+@@ -785,7 +800,8 @@ _bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *info,
+ 	    {
+ 	      gnu_prop = (p->property.u.number
+ 			  & (GNU_PROPERTY_AARCH64_FEATURE_1_PAC
+-			      | GNU_PROPERTY_AARCH64_FEATURE_1_BTI));
++			      | GNU_PROPERTY_AARCH64_FEATURE_1_BTI
++			      | GNU_PROPERTY_AARCH64_FEATURE_1_GCS));
+ 	      break;
+ 	    }
+ 	  else if (GNU_PROPERTY_AARCH64_FEATURE_1_AND < p->property.pr_type)
+@@ -922,3 +938,20 @@ _bfd_aarch64_elf_link_fixup_gnu_properties
+ 	}
+     }
+ }
++
++/* Check AArch64 GCS report.  */
++void
++_bfd_aarch64_elf_check_gcs_report (aarch64_gcs_report gcs_report, bfd *ebfd)
++{
++  if (gcs_report == GCS_WARN)
++    _bfd_error_handler (_("%pB: warning: GCS turned on by -z experimental-gcs "
++			"on the output when all inputs do not have GCS in NOTE "
++			"section."), ebfd);
++  else if (gcs_report == GCS_ERROR)
++    {
++      _bfd_error_handler (_("%pB: error: GCS turned on by -z experimental-gcs "
++			  "on the output when all inputs do not have GCS in "
++			  "NOTE section."), ebfd);
++      _exit (EXIT_FAILURE);
++    }
++}
+diff --git a/bfd/elfxx-aarch64.h b/bfd/elfxx-aarch64.h
+index 6c084f75796..ca523d81df1 100644
+--- a/bfd/elfxx-aarch64.h
++++ b/bfd/elfxx-aarch64.h
+@@ -46,6 +46,27 @@ typedef enum
+   BTI_WARN	= 1,  /* BTI is enabled with -z force-bti.  */
+ } aarch64_enable_bti_type;
+ 
++/* To indicate whether GNU_PROPERTY_AARCH64_FEATURE_1_GCS bit is
++   enabled/disabled on the output when -z experimental-gcs linker
++   command line option is passed.  */
++typedef enum
++{
++  GCS_NEVER	= 0,  /* gcs is disabled on output.  */
++  GCS_IMPLICIT  = 1,  /* gcs is deduced from input object.  */
++  GCS_ALWAYS	= 2,  /* gsc is enabled on output.  */
++} aarch64_gcs_type;
++
++/* To indicate whether to generate linker warning/errors for
++   -z experimental-gcs-report when -z experimental-gcs=always is passed.  */
++typedef enum
++{
++  GCS_NONE	= 0,  /* Does not emit any warning/error messages.  */
++  GCS_WARN	= 1,  /* Emit warning when the input objects are missing gcs
++			 markings and output have gcs marking.  */
++  GCS_ERROR	= 2,  /* Emit error when the input objects are missing gcs
++			 markings and output have gcs marking.  */
++} aarch64_gcs_report;
++
+ /* A structure to encompass all information coming from BTI or PAC
+    related command line options.  This involves the "PLT_TYPE" to determine
+    which version of PLTs to pick and "BTI_TYPE" to determine if
+@@ -54,7 +75,9 @@ typedef struct
+ {
+   aarch64_plt_type plt_type;
+   aarch64_enable_bti_type bti_type;
+-} aarch64_bti_pac_info;
++  aarch64_gcs_type gcs_type;
++  aarch64_gcs_report gcs_report;
++} aarch64_gnu_prop_info;
+ 
+ /* An enum to define what kind of erratum fixes we should apply.  This gives the
+    user a bit more control over the sequences we generate.  */
+@@ -67,11 +90,11 @@ typedef enum
+ 
+ extern void bfd_elf64_aarch64_set_options
+   (bfd *, struct bfd_link_info *, int, int, int, int, erratum_84319_opts, int,
+-   aarch64_bti_pac_info);
++   aarch64_gnu_prop_info);
+ 
+ extern void bfd_elf32_aarch64_set_options
+   (bfd *, struct bfd_link_info *, int, int, int, int, erratum_84319_opts, int,
+-   aarch64_bti_pac_info);
++   aarch64_gnu_prop_info);
+ 
+ /* AArch64 stub generation support for ELF64.  Called from the linker.  */
+ extern int elf64_aarch64_setup_section_lists
+@@ -135,8 +158,9 @@ _bfd_aarch64_elf_write_core_note (bfd *, char *, int *, int, ...);
+ #define elf_backend_write_core_note	_bfd_aarch64_elf_write_core_note
+ 
+ extern bfd *
+-_bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *,
+-					    uint32_t *);
++_bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *, uint32_t *,
++					    aarch64_gcs_report,
++					    aarch64_gcs_type);
+ 
+ extern enum elf_property_kind
+ _bfd_aarch64_elf_parse_gnu_properties (bfd *, unsigned int,
+@@ -146,6 +170,8 @@ extern bool
+ _bfd_aarch64_elf_merge_gnu_properties (struct bfd_link_info *, bfd *,
+ 				       elf_property *, elf_property *,
+ 				       uint32_t);
++extern void
++_bfd_aarch64_elf_check_gcs_report (aarch64_gcs_report, bfd *);
+ 
+ extern void
+ _bfd_aarch64_elf_link_fixup_gnu_properties (struct bfd_link_info *,
+diff --git a/binutils/readelf.c b/binutils/readelf.c
+index 5e4ad6ea6ad..794cbb77a9c 100644
+--- a/binutils/readelf.c
++++ b/binutils/readelf.c
+@@ -20636,6 +20636,10 @@ decode_aarch64_feature_1_and (unsigned int bitmask)
+ 	  printf ("PAC");
+ 	  break;
+ 
++	case GNU_PROPERTY_AARCH64_FEATURE_1_GCS:
++	  printf ("GCS");
++	  break;
++
+ 	default:
+ 	  printf (_("<unknown: %x>"), bit);
+ 	  break;
+diff --git a/include/elf/common.h b/include/elf/common.h
+index 6a66456cd22..289b8821b7d 100644
+--- a/include/elf/common.h
++++ b/include/elf/common.h
+@@ -1001,6 +1001,7 @@
+ 
+ #define GNU_PROPERTY_AARCH64_FEATURE_1_BTI	(1U << 0)
+ #define GNU_PROPERTY_AARCH64_FEATURE_1_PAC	(1U << 1)
++#define GNU_PROPERTY_AARCH64_FEATURE_1_GCS	(1U << 2)
+ 
+ /* Values used in GNU .note.ABI-tag notes (NT_GNU_ABI_TAG).  */
+ #define GNU_ABI_TAG_LINUX	0
+diff --git a/ld/emultempl/aarch64elf.em b/ld/emultempl/aarch64elf.em
+index b647909ae63..fb331e06553 100644
+--- a/ld/emultempl/aarch64elf.em
++++ b/ld/emultempl/aarch64elf.em
+@@ -36,6 +36,12 @@ static erratum_84319_opts fix_erratum_843419 = ERRAT_NONE;
+ static int no_apply_dynamic_relocs = 0;
+ static aarch64_plt_type plt_type = PLT_NORMAL;
+ static aarch64_enable_bti_type bti_type = BTI_NONE;
++static aarch64_gcs_type gcs_type = GCS_IMPLICIT;
++static aarch64_gcs_report gcs_report = GCS_NONE;
++static const char * egr = "experimental-gcs-report";
++static const char * eg = "experimental-gcs";
++#define EGR_LEN strlen (egr)
++#define EG_LEN strlen (eg)
+ 
+ static void
+ gld${EMULATION_NAME}_before_parse (void)
+@@ -321,9 +327,11 @@ aarch64_elf_create_output_section_statements (void)
+       return;
+     }
+ 
+-  aarch64_bti_pac_info bp_info;
++  aarch64_gnu_prop_info bp_info;
+   bp_info.plt_type = plt_type;
+   bp_info.bti_type = bti_type;
++  bp_info.gcs_type = gcs_type;
++  bp_info.gcs_report = gcs_report;
+ 
+   bfd_elf${ELFSIZE}_aarch64_set_options (link_info.output_bfd, &link_info,
+ 				 no_enum_size_warning,
+@@ -408,6 +416,19 @@ PARSE_AND_LIST_OPTIONS='
+   fprintf (file, _("  --no-apply-dynamic-relocs    Do not apply link-time values for dynamic relocations\n"));
+   fprintf (file, _("  -z force-bti                  Turn on Branch Target Identification mechanism and generate PLTs with BTI. Generate warnings for missing BTI on inputs\n"));
+   fprintf (file, _("  -z pac-plt                    Protect PLTs with Pointer Authentication.\n"));
++  fprintf (file, _("\
++  -z experimental-gcs[=always|never|implicit]		Turn on Guarded Control Stack(gcs) mechanism on the output.\n\
++							implicit(default): deduce gcs from input objects.\n\
++							always: always marks the output with gcs.\n\
++							never: never marks the output with gcs.\n"));
++  fprintf (file, _("\
++  -z experimental-gcs-report[=none|warning|error]	Emit warning/error on mismatch of gcs marking between input objects and ouput.\n\
++							none (default): Does not emit any warning/error messages.\n\
++							warning: Emit warning when the input objects are missing gcs markings\n\
++								 and output have gcs marking.\n\
++							error: Emit error when the input objects are missing gcs markings\n\
++							       and output have gcs marking.\n"));
++
+ '
+ 
+ PARSE_AND_LIST_ARGS_CASE_Z_AARCH64='
+@@ -418,6 +439,28 @@ PARSE_AND_LIST_ARGS_CASE_Z_AARCH64='
+ 	}
+       else if (strcmp (optarg, "pac-plt") == 0)
+ 	plt_type |= PLT_PAC;
++     else if (strncmp (optarg, egr, EGR_LEN) == 0)
++	{
++	  if (strlen (optarg) == EGR_LEN || strcmp (optarg + EGR_LEN, "=none") == 0)
++	    gcs_report = GCS_NONE;
++	  else if (strcmp (optarg + EGR_LEN, "=warning") == 0)
++	    gcs_report = GCS_WARN;
++	  else if (strcmp (optarg + EGR_LEN, "=error") == 0)
++	    gcs_report = GCS_ERROR;
++	  else
++	    einfo (_("%P: error: unrecognized: `%s'\''\n"), optarg);
++	}
++     else if (strncmp (optarg, eg, EG_LEN) == 0)
++	{
++	  if (strlen (optarg) == EG_LEN || strcmp (optarg + EG_LEN, "=always") == 0)
++	    gcs_type = GCS_ALWAYS;
++	  else if (strcmp (optarg + EG_LEN, "=never") == 0)
++	    gcs_type = GCS_NEVER;
++	  else if (strcmp (optarg + EG_LEN, "=implicit") == 0)
++	    gcs_type = GCS_IMPLICIT;
++	  else
++	    einfo (_("%P: error: unrecognized: `%s'\''\n"), optarg);
++	}
+ '
+ PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_AARCH64"
+ 
+diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
+index 9ce61579e6c..31abc5a07d8 100644
+--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
++++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
+@@ -471,3 +471,26 @@ run_dump_test_lp64 "bti-far-3"
+ if { ![skip_sframe_tests] } {
+   run_dump_test "sframe-simple-1"
+ }
++
++run_dump_test "property-gcs1"
++run_dump_test "property-gcs2"
++run_dump_test "property-gcs3"
++run_dump_test "property-gcs4"
++run_dump_test "property-gcs5"
++run_dump_test "property-gcs6"
++run_dump_test "property-gcs7"
++run_dump_test "property-gcs8"
++run_dump_test "property-gcs9"
++run_dump_test "property-gcs10"
++run_dump_test "property-gcs11"
++run_dump_test "property-gcs12"
++run_dump_test "property-gcs13"
++run_dump_test "property-gcs14"
++run_dump_test "property-gcs15"
++run_dump_test "property-gcs16"
++run_dump_test "property-gcs17"
++run_dump_test "property-gcs18"
++run_dump_test "property-gcs19"
++run_dump_test "property-gcs20"
++run_dump_test "property-gcs21"
++run_dump_test "property-gcs22"
+diff --git a/ld/testsuite/ld-aarch64/property-bti-pac1.d b/ld/testsuite/ld-aarch64/property-bti-pac1.d
+index 59fa695165a..c28a0cbf850 100644
+--- a/ld/testsuite/ld-aarch64/property-bti-pac1.d
++++ b/ld/testsuite/ld-aarch64/property-bti-pac1.d
+@@ -8,4 +8,4 @@
+ Displaying notes found in: .note.gnu.property
+ [ 	]+Owner[ 	]+Data size[ 	]+Description
+   GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
+-      Properties: AArch64 feature: BTI, PAC
++      Properties: AArch64 feature: BTI, PAC, GCS
+diff --git a/ld/testsuite/ld-aarch64/property-bti-pac1.s b/ld/testsuite/ld-aarch64/property-bti-pac1.s
+index 414c9277f1d..42156917d58 100644
+--- a/ld/testsuite/ld-aarch64/property-bti-pac1.s
++++ b/ld/testsuite/ld-aarch64/property-bti-pac1.s
+@@ -12,6 +12,20 @@ _start:
+ 	.long 5f - 2f		/* data length */
+ 	.long 5			/* note type */
+ 0:	.asciz "GNU"		/* vendor name */
++1:
++	.p2align 3
++2:	.long 0xc0000000	/* pr_type.  */
++	.long 4f - 3f		/* pr_datasz.  */
++3:
++	.long 0x4		/* GCS.  */
++4:
++	.p2align 3
++5:
++	.p2align 3
++	.long 1f - 0f		/* name length */
++	.long 5f - 2f		/* data length */
++	.long 5			/* note type */
++0:	.asciz "GNU"		/* vendor name */
+ 1:
+ 	.p2align 3
+ 2:	.long 0xc0000000	/* pr_type.  */
+diff --git a/ld/testsuite/ld-aarch64/property-gcs.s b/ld/testsuite/ld-aarch64/property-gcs.s
+new file mode 100644
+index 00000000000..bc7e66e8933
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs.s
+@@ -0,0 +1,25 @@
++	.text
++	.globl _start
++	.type _start,@function
++_start:
++	mov x1, #2
++.ifndef __mult__
++	bl foo
++.endif
++.ifdef __property_gcs__
++	.section ".note.gnu.property", "a"
++	.p2align 3
++	.long 1f - 0f		/* name length */
++	.long 5f - 2f		/* data length */
++	.long 5			/* note type */
++0:	.asciz "GNU"		/* vendor name */
++1:
++	.p2align 3
++2:	.long 0xc0000000	/* pr_type.  */
++	.long 4f - 3f		/* pr_datasz.  */
++3:
++	.long 0x4		/* GCS.  */
++4:
++	.p2align 3
++5:
++.endif
+diff --git a/ld/testsuite/ld-aarch64/property-gcs1.d b/ld/testsuite/ld-aarch64/property-gcs1.d
+new file mode 100644
+index 00000000000..c724ac56ca3
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs1.d
+@@ -0,0 +1,6 @@
++#name: GNU Property (input without gcs)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -shared
++#readelf: -n
+diff --git a/ld/testsuite/ld-aarch64/property-gcs10.d b/ld/testsuite/ld-aarch64/property-gcs10.d
+new file mode 100644
+index 00000000000..4b6deedc0c2
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs10.d
+@@ -0,0 +1,6 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs=always experimental-gcs-report=error)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs=always -z experimental-gcs-report=error
++#error: .*property-gcs.*: error: GCS turned on by -z experimental-gcs on the output when all inputs do not have GCS in NOTE section.
+diff --git a/ld/testsuite/ld-aarch64/property-gcs11.d b/ld/testsuite/ld-aarch64/property-gcs11.d
+new file mode 100644
+index 00000000000..8abacf28eb1
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs11.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs output forced with experimental-gcs)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs12.d b/ld/testsuite/ld-aarch64/property-gcs12.d
+new file mode 100644
+index 00000000000..0fe246dfa3a
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs12.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs=always)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs=always
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs13.d b/ld/testsuite/ld-aarch64/property-gcs13.d
+new file mode 100644
+index 00000000000..c6077aeaa5a
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs13.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs experimental-gcs-report=none)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs -z experimental-gcs-report=none
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs14.d b/ld/testsuite/ld-aarch64/property-gcs14.d
+new file mode 100644
+index 00000000000..0f7490ef4a5
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs14.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs experimental-gcs-report=warning)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs -z experimental-gcs-report=warning
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs15.d b/ld/testsuite/ld-aarch64/property-gcs15.d
+new file mode 100644
+index 00000000000..d1e723e0ea6
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs15.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs experimental-gcs-report=error)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs -z experimental-gcs-report=error
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs16.d b/ld/testsuite/ld-aarch64/property-gcs16.d
+new file mode 100644
+index 00000000000..340577f1758
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs16.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs=always experimental-gcs-report=none)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs=always -z experimental-gcs-report=none
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs17.d b/ld/testsuite/ld-aarch64/property-gcs17.d
+new file mode 100644
+index 00000000000..4ba9583ee92
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs17.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs=always experimental-gcs-report=warning)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs=always -z experimental-gcs-report=warning
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs18.d b/ld/testsuite/ld-aarch64/property-gcs18.d
+new file mode 100644
+index 00000000000..f71c10e2523
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs18.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs ouput forced with experimental-gcs=always experimental-gcs-report=error)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs=always -z experimental-gcs-report=error
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs19.d b/ld/testsuite/ld-aarch64/property-gcs19.d
+new file mode 100644
+index 00000000000..468f96edcf1
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs19.d
+@@ -0,0 +1,6 @@
++#name: GNU Property (input without gcs output forced with experimental-gcs=never)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs=never
++#readelf: -n
+diff --git a/ld/testsuite/ld-aarch64/property-gcs2.d b/ld/testsuite/ld-aarch64/property-gcs2.d
+new file mode 100644
+index 00000000000..ed545a180b3
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs2.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -shared
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs2.s b/ld/testsuite/ld-aarch64/property-gcs2.s
+new file mode 100644
+index 00000000000..6db7d8396c8
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs2.s
+@@ -0,0 +1,33 @@
++	.text
++	.global	foo
++	.type	foo, %function
++foo:
++	sub	sp, sp, #16
++	mov	w0, 9
++	str	w0, [sp, 12]
++	ldr	w0, [sp, 12]
++	add	w0, w0, 4
++	str	w0, [sp, 12]
++	nop
++	add	sp, sp, 16
++	ret
++	.size	foo, .-foo
++	.global	bar
++	.type	bar, %function
++.ifdef __property_gcs__
++	.section ".note.gnu.property", "a"
++	.p2align 3
++	.long 1f - 0f		/* name length */
++	.long 5f - 2f		/* data length */
++	.long 5			/* note type */
++0:	.asciz "GNU"		/* vendor name */
++1:
++	.p2align 3
++2:	.long 0xc0000000	/* pr_type.  */
++	.long 4f - 3f		/* pr_datasz.  */
++3:
++	.long 0x4		/* GCS.  */
++4:
++	.p2align 3
++5:
++.endif
+diff --git a/ld/testsuite/ld-aarch64/property-gcs20.d b/ld/testsuite/ld-aarch64/property-gcs20.d
+new file mode 100644
+index 00000000000..2bdff88a27a
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs20.d
+@@ -0,0 +1,6 @@
++#name: GNU Property (input without gcs output forced with experimental-gcs=implicit)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs=implicit
++#readelf: -n
+diff --git a/ld/testsuite/ld-aarch64/property-gcs21.d b/ld/testsuite/ld-aarch64/property-gcs21.d
+new file mode 100644
+index 00000000000..b42b11d14ea
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs21.d
+@@ -0,0 +1,6 @@
++#name: GNU Property (input with gcs output forced with experimental-gcs=never)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs=never
++#readelf: -n
+diff --git a/ld/testsuite/ld-aarch64/property-gcs22.d b/ld/testsuite/ld-aarch64/property-gcs22.d
+new file mode 100644
+index 00000000000..431fc1ed35b
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs22.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input with gcs output forced with experimental-gcs=implicit)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0 -defsym __property_gcs__=1
++#ld: -z experimental-gcs=implicit
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs3.d b/ld/testsuite/ld-aarch64/property-gcs3.d
+new file mode 100644
+index 00000000000..68d50be0823
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs3.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input without gcs output forced with experimental-gcs)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs4.d b/ld/testsuite/ld-aarch64/property-gcs4.d
+new file mode 100644
+index 00000000000..cd5711e3da3
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs4.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs=always)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs=always
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs5.d b/ld/testsuite/ld-aarch64/property-gcs5.d
+new file mode 100644
+index 00000000000..b7a751c0276
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs5.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs experimental-gcs-report=none)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs -z experimental-gcs-report=none
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs6.d b/ld/testsuite/ld-aarch64/property-gcs6.d
+new file mode 100644
+index 00000000000..5abf8126d89
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs6.d
+@@ -0,0 +1,12 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs experimental-gcs-report=warning)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs -z experimental-gcs-report=warning
++#readelf: -n
++#warning: .*property-gcs.*: warning: GCS turned on by -z experimental-gcs on the output when all inputs do not have GCS in NOTE section.
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs7.d b/ld/testsuite/ld-aarch64/property-gcs7.d
+new file mode 100644
+index 00000000000..4df5693a27b
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs7.d
+@@ -0,0 +1,6 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs experimental-gcs-report=error)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs -z experimental-gcs-report=error
++#error: .*property-gcs.*: error: GCS turned on by -z experimental-gcs on the output when all inputs do not have GCS in NOTE section.
+diff --git a/ld/testsuite/ld-aarch64/property-gcs8.d b/ld/testsuite/ld-aarch64/property-gcs8.d
+new file mode 100644
+index 00000000000..463c3ad4197
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs8.d
+@@ -0,0 +1,11 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs=always experimental-gcs-report=none)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs=always -z experimental-gcs-report=none
++#readelf: -n
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+diff --git a/ld/testsuite/ld-aarch64/property-gcs9.d b/ld/testsuite/ld-aarch64/property-gcs9.d
+new file mode 100644
+index 00000000000..c3083675c8f
+--- /dev/null
++++ b/ld/testsuite/ld-aarch64/property-gcs9.d
+@@ -0,0 +1,12 @@
++#name: GNU Property (input without gcs ouput forced with experimental-gcs=always experimental-gcs-report=warning)
++#source: property-gcs.s
++#alltargets: [check_shared_lib_support] *linux*
++#as: -march=armv9.4-a+gcs -defsym __mult__=0
++#ld: -z experimental-gcs=always -z experimental-gcs-report=warning
++#readelf: -n
++#warning: .*property-gcs.*: warning: GCS turned on by -z experimental-gcs on the output when all inputs do not have GCS in NOTE section.
++
++Displaying notes found in: .note.gnu.property
++[ 	]+Owner[ 	]+Data size[ 	]+Description
++  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
++      Properties: AArch64 feature: GCS
+-- 
+2.34.1
+

meta-arm-gcs/recipes-devtools/gcc/gcc-source_14.0.bbappend

@@ -0,0 +1,3 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI += "file://gcs.patch"

meta-arm-gcs/recipes-devtools/gdb/gdb_15.1.bb

@@ -0,0 +1,40 @@
+require recipes-devtools/gdb/gdb-common.inc
+
+inherit gettext pkgconfig
+
+PACKAGES =+ "gdbserver"
+FILES:gdbserver = "${bindir}/gdbserver"
+
+require recipes-devtools/gdb/gdb.inc
+
+FILESEXTRAPATHS:prepend := "${COREBASE}/meta/recipes-devtools/gdb/gdb:"
+
+# This patch doesn't apply to 15.1
+SRC_URI:remove = "file://0005-Change-order-of-CFLAGS.patch"
+SRC_URI[sha256sum] = "38254eacd4572134bca9c5a5aa4d4ca564cbbd30c369d881f733fb6b903354f2"
+
+inherit python3-dir
+
+EXTRA_OEMAKE:append:libc-musl = "\
+                                 gt_cv_func_gnugettext1_libc=yes \
+                                 gt_cv_func_gnugettext2_libc=yes \
+                                 gl_cv_func_working_strerror=yes \
+                                 gl_cv_func_strerror_0_works=yes \
+                                 gl_cv_func_gettimeofday_clobber=no \
+                                "
+
+do_configure:prepend() {
+	if [ "${@bb.utils.filter('PACKAGECONFIG', 'python', d)}" ]; then
+		cat > ${WORKDIR}/python << EOF
+#!/bin/sh
+case "\$2" in
+	--includes) echo "-I${STAGING_INCDIR}/${PYTHON_DIR}${PYTHON_ABI}/" ;;
+	--ldflags) echo "-Wl,-rpath-link,${STAGING_LIBDIR}/.. -Wl,-rpath,${libdir}/.. -lpthread -ldl -lutil -lm -lpython${PYTHON_BASEVERSION}${PYTHON_ABI}" ;;
+	--exec-prefix) echo "${exec_prefix}" ;;
+	*) exit 1 ;;
+esac
+exit 0
+EOF
+		chmod +x ${WORKDIR}/python
+	fi
+}

meta-arm-gcs/recipes-devtools/gdb/gdb_15.1.bbappend

@@ -0,0 +1,3 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI += "file://gcs.patch"

meta-arm-gcs/recipes-kernel/linux-libc-headers/linux-libc-headers_6.11.bb

@@ -0,0 +1,14 @@
+require ${COREBASE}/meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc
+
+FILESEXTRAPATHS:prepend = "${THISDIR}/../linux/files/:"
+
+KBRANCH = "v6.11/standard/base"
+# 6.11-rc3
+SRCREV = "7c626ce4bae1ac14f60076d00eafe71af30450ba"
+
+SRC_URI = "git://git.yoctoproject.org/linux-yocto-dev.git;branch=${KBRANCH};protocol=https"
+SRC_URI += "file://gcs.patch"
+
+LIC_FILES_CHKSUM = "file://COPYING;md5=6bc538ed5bd9a7fc9398086aedcd7e46"
+
+S = "${WORKDIR}/git"

meta-arm-gcs/recipes-kernel/linux/files/disable_uprobe.cfg

@@ -0,0 +1 @@
+CONFIG_UPROBE_EVENTS=n

meta-arm-gcs/recipes-kernel/linux/kselftest.bb

@@ -0,0 +1,51 @@
+SUMMARY = "kselftest, the kernel test suite"
+SECTION = "kernel"
+LICENSE = "GPL-2.0-only"
+
+DEPENDS = "rsync-native alsa-lib libcap libcap-ng numactl popt libmnl"
+
+inherit kernelsrc kernel-arch
+
+PACKAGE_ARCH = "${MACHINE_ARCH}"
+
+B = "${WORKDIR}/build"
+
+do_compile[cleandirs] = "${B}"
+
+CC:remove:aarch64 = "-mbranch-protection=standard"
+SECURITY_CFLAGS = ""
+
+# Disable BPF and HID as they need clang for BPF compilation
+SKIP_TARGETS ?= "bpf hid"
+
+EXTRA_OEMAKE += "\
+    O=${B} \
+    V=1 \
+    ARCH=${ARCH} \
+    CROSS_COMPILE=${TARGET_PREFIX} \
+    CC="${CC}" \
+    AR="${AR}" \
+    LD="${LD}" \
+    KHDR_INCLUDES="-isystem ${STAGING_KERNEL_BUILDDIR}" \
+    SKIP_TARGETS="${SKIP_TARGETS}" \
+"
+
+# Force all tests to build successfully
+#EXTRA_OEMAKE += "FORCE_TARGETS=1"
+
+do_compile() {
+	oe_runmake -C ${S}/tools/testing/selftests
+}
+
+do_install() {
+	oe_runmake -C ${S}/tools/testing/selftests install INSTALL_PATH=${D}/${libexecdir}/kselftest
+	# install uses rsync -a
+	chown -R root:root ${D}/${libexecdir}/kselftest
+}
+
+RDEPENDS:${PN} += "bash python3-core python3 perl perl-module-io-handle"
+
+INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
+INSANE_SKIP:${PN} = "already-stripped buildpaths ldflags textrel"
+
+# TODO test with musl

meta-arm-gcs/recipes-kernel/linux/linux-yocto-dev.bbappend

@@ -0,0 +1,13 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+KBRANCH = "v6.11/standard/base"
+SRCREV_machine = "7c626ce4bae1ac14f60076d00eafe71af30450ba"
+SRCREV_meta = "66aec68f0ba1d15ba0e9c19f1ec0d2b4a75c5333"
+LINUX_VERSION = "6.11.0"
+
+SRC_URI += "file://gcs.patch file://disable_uprobe.cfg"
+
+# TMPDIR references in:
+#  /usr/src/debug/linux-yocto-dev/6.8.0+git/drivers/tty/vt/consolemap_deftbl.c
+#  /usr/src/debug/linux-yocto-dev/6.8.0+git/lib/oid_registry_data.c
+INSANE_SKIP:${PN}-src += "buildpaths"

meta-arm-gcs/recipes-test/gcs-test/files/chkfeat.s

@@ -0,0 +1,22 @@
+/* Copyright (C) 2024 Arm Ltd */
+/* SPDX-License-Identifier: MIT */
+
+.global gcs_enabled
+.type gcs_enabled,@function
+gcs_enabled:
+	mov x16, #0x1
+	hint 40
+	eor x0, x16, #0x1
+	ret
+
+.pushsection .note.gnu.property, "a"
+.balign 8
+.long 4
+.long 0x10
+.long 0x5
+.asciz "GNU"
+.long 0xc0000000
+.long 4
+.long 4
+.long 0
+.popsection

meta-arm-gcs/recipes-test/gcs-test/files/gcs_enabled.c

@@ -0,0 +1,9 @@
+// Copyright (C) 2024 Arm Ltd
+// SPDX-License-Identifier: MIT
+
+extern int gcs_enabled(void);
+
+int main(void)
+{
+	return gcs_enabled() ? 0 : 1;
+}

meta-arm-gcs/recipes-test/gcs-test/gcs-test.bb

@@ -0,0 +1,18 @@
+SUMMARY = "test"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
+
+SRC_URI = "file://chkfeat.s file://gcs_enabled.c"
+
+S = "${WORKDIR}"
+
+LDFLAGS:append = " -z experimental-gcs=always"
+
+do_compile() {
+    ${CC} ${CFLAGS} ${LDFLAGS} ${WORKDIR}/gcs_enabled.c ${WORKDIR}/chkfeat.s -o gcs-test 
+}
+
+do_install() {
+    install -d ${D}${bindir}
+    install -m 0755 gcs-test ${D}${bindir}
+}