diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c
index b171fd53b004..c1a6ce7b0912 100644
--- a/tools/testing/selftests/cachestat/test_cachestat.c
+++ b/tools/testing/selftests/cachestat/test_cachestat.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <stdio.h>
 #include <stdbool.h>
 #include <linux/kernel.h>
diff --git a/tools/testing/selftests/capabilities/test_execve.c b/tools/testing/selftests/capabilities/test_execve.c
index 7cde07a5df78..e3954b88c3ee 100644
--- a/tools/testing/selftests/capabilities/test_execve.c
+++ b/tools/testing/selftests/capabilities/test_execve.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <cap-ng.h>
 #include <linux/capability.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
index 3c9bf0cd82a8..3c5e45dae617 100644
--- a/tools/testing/selftests/clone3/clone3.c
+++ b/tools/testing/selftests/clone3/clone3.c
@@ -1,8 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
 /* Based on Christian Brauner's clone3() example */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <inttypes.h>
 #include <linux/types.h>
diff --git a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
index 31b56d625655..bb99ea20f7d5 100644
--- a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
+++ b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
@@ -7,8 +7,6 @@
  */
 
 /* capabilities related code based on selftests/bpf/test_verifier.c */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <linux/types.h>
 #include <linux/sched.h>
diff --git a/tools/testing/selftests/clone3/clone3_clear_sighand.c b/tools/testing/selftests/clone3/clone3_clear_sighand.c
index 54a8b2445be9..50336d56db6b 100644
--- a/tools/testing/selftests/clone3/clone3_clear_sighand.c
+++ b/tools/testing/selftests/clone3/clone3_clear_sighand.c
@@ -1,6 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <sched.h>
 #include <signal.h>
diff --git a/tools/testing/selftests/clone3/clone3_selftests.h b/tools/testing/selftests/clone3/clone3_selftests.h
index 3d2663fe50ba..172e19d5515f 100644
--- a/tools/testing/selftests/clone3/clone3_selftests.h
+++ b/tools/testing/selftests/clone3/clone3_selftests.h
@@ -3,7 +3,6 @@
 #ifndef _CLONE3_SELFTESTS_H
 #define _CLONE3_SELFTESTS_H
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <linux/sched.h>
 #include <linux/types.h>
diff --git a/tools/testing/selftests/clone3/clone3_set_tid.c b/tools/testing/selftests/clone3/clone3_set_tid.c
index ed785afb6077..8b5ed4484ee6 100644
--- a/tools/testing/selftests/clone3/clone3_set_tid.c
+++ b/tools/testing/selftests/clone3/clone3_set_tid.c
@@ -5,8 +5,6 @@
  * These tests are assuming to be running in the host's
  * PID namespace.
  */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <linux/types.h>
 #include <linux/sched.h>
diff --git a/tools/testing/selftests/core/close_range_test.c b/tools/testing/selftests/core/close_range_test.c
index c59e4adb905d..1c2902bcc913 100644
--- a/tools/testing/selftests/core/close_range_test.c
+++ b/tools/testing/selftests/core/close_range_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/kernel.h>
diff --git a/tools/testing/selftests/drivers/dma-buf/udmabuf.c b/tools/testing/selftests/drivers/dma-buf/udmabuf.c
index c812080e304e..7c8dbab8ac44 100644
--- a/tools/testing/selftests/drivers/dma-buf/udmabuf.c
+++ b/tools/testing/selftests/drivers/dma-buf/udmabuf.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #define __EXPORTED_HEADERS__
 
 #include <stdio.h>
diff --git a/tools/testing/selftests/fchmodat2/fchmodat2_test.c b/tools/testing/selftests/fchmodat2/fchmodat2_test.c
index e0319417124d..6b411859c2cd 100644
--- a/tools/testing/selftests/fchmodat2/fchmodat2_test.c
+++ b/tools/testing/selftests/fchmodat2/fchmodat2_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-
-#define _GNU_SOURCE
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
index 5f362c0fd890..fca693db1b09 100644
--- a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
+++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/filesystems/devpts_pts.c b/tools/testing/selftests/filesystems/devpts_pts.c
index b1fc9b916ace..73766447eeb0 100644
--- a/tools/testing/selftests/filesystems/devpts_pts.c
+++ b/tools/testing/selftests/filesystems/devpts_pts.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <sched.h>
diff --git a/tools/testing/selftests/filesystems/dnotify_test.c b/tools/testing/selftests/filesystems/dnotify_test.c
index c0a9b2d3302d..05367a70b963 100644
--- a/tools/testing/selftests/filesystems/dnotify_test.c
+++ b/tools/testing/selftests/filesystems/dnotify_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE	/* needed to get the defines */
 #include <fcntl.h>	/* in glibc 2.2 this has the needed
 				   values defined */
 #include <signal.h>
diff --git a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
index 65ede506305c..9bc2ddad7e92 100644
--- a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
+++ b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <asm/unistd.h>
 #include <linux/time_types.h>
 #include <poll.h>
diff --git a/tools/testing/selftests/filesystems/eventfd/eventfd_test.c b/tools/testing/selftests/filesystems/eventfd/eventfd_test.c
index f142a137526c..17935f42fbc9 100644
--- a/tools/testing/selftests/filesystems/eventfd/eventfd_test.c
+++ b/tools/testing/selftests/filesystems/eventfd/eventfd_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <asm/unistd.h>
diff --git a/tools/testing/selftests/filesystems/fat/rename_exchange.c b/tools/testing/selftests/filesystems/fat/rename_exchange.c
index e488ad354fce..56cf3ad8640d 100644
--- a/tools/testing/selftests/filesystems/fat/rename_exchange.c
+++ b/tools/testing/selftests/filesystems/fat/rename_exchange.c
@@ -6,8 +6,6 @@
  * Copyright 2022 Red Hat Inc.
  * Author: Javier Martinez Canillas <javierm@redhat.com>
  */
-
-#define _GNU_SOURCE
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
index 759f86e7d263..b58a80bde95a 100644
--- a/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
+++ b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <inttypes.h>
 #include <unistd.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/filesystems/statmount/statmount_test.c b/tools/testing/selftests/filesystems/statmount/statmount_test.c
index 3eafd7da58e2..d1cefd1b7d16 100644
--- a/tools/testing/selftests/filesystems/statmount/statmount_test.c
+++ b/tools/testing/selftests/filesystems/statmount/statmount_test.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-
-#define _GNU_SOURCE
-
 #include <assert.h>
 #include <stdint.h>
 #include <sched.h>
diff --git a/tools/testing/selftests/futex/functional/futex_requeue_pi.c b/tools/testing/selftests/futex/functional/futex_requeue_pi.c
index 7f3ca5c78df1..8e41f9fe784c 100644
--- a/tools/testing/selftests/futex/functional/futex_requeue_pi.c
+++ b/tools/testing/selftests/futex/functional/futex_requeue_pi.c
@@ -16,9 +16,6 @@
  *      2009-Nov-6: futex test adaptation by Darren Hart <dvhart@linux.intel.com>
  *
  *****************************************************************************/
-
-#define _GNU_SOURCE
-
 #include <errno.h>
 #include <limits.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/ipc/msgque.c b/tools/testing/selftests/ipc/msgque.c
index 656c43c24044..291c81d59a9d 100644
--- a/tools/testing/selftests/ipc/msgque.c
+++ b/tools/testing/selftests/ipc/msgque.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
diff --git a/tools/testing/selftests/kcmp/kcmp_test.c b/tools/testing/selftests/kcmp/kcmp_test.c
index 25110c7c0b3e..885c9e943cee 100644
--- a/tools/testing/selftests/kcmp/kcmp_test.c
+++ b/tools/testing/selftests/kcmp/kcmp_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c
index 4eaba83cdcf3..5369959e9fc2 100644
--- a/tools/testing/selftests/kvm/aarch64/arch_timer.c
+++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c
@@ -5,8 +5,6 @@
  *
  * Copyright (c) 2021, Google LLC.
  */
-#define _GNU_SOURCE
-
 #include "arch_timer.h"
 #include "delay.h"
 #include "gic.h"
diff --git a/tools/testing/selftests/kvm/aarch64/page_fault_test.c b/tools/testing/selftests/kvm/aarch64/page_fault_test.c
index 5972905275cf..79e99f47a9fe 100644
--- a/tools/testing/selftests/kvm/aarch64/page_fault_test.c
+++ b/tools/testing/selftests/kvm/aarch64/page_fault_test.c
@@ -7,7 +7,6 @@
  * hugetlbfs with a hole). It checks that the expected handling method is
  * called (e.g., uffd faults with the right address and write/read flag).
  */
-#define _GNU_SOURCE
 #include <linux/bitmap.h>
 #include <fcntl.h>
 #include <test_util.h>
diff --git a/tools/testing/selftests/kvm/aarch64/psci_test.c b/tools/testing/selftests/kvm/aarch64/psci_test.c
index 9b004905d1d3..1c8c6f0c1ca3 100644
--- a/tools/testing/selftests/kvm/aarch64/psci_test.c
+++ b/tools/testing/selftests/kvm/aarch64/psci_test.c
@@ -10,9 +10,6 @@
  *  - A test for KVM's handling of PSCI SYSTEM_SUSPEND and the associated
  *    KVM_SYSTEM_EVENT_SUSPEND UAPI.
  */
-
-#define _GNU_SOURCE
-
 #include <linux/psci.h>
 
 #include "kvm_util.h"
diff --git a/tools/testing/selftests/kvm/aarch64/vgic_init.c b/tools/testing/selftests/kvm/aarch64/vgic_init.c
index ca917c71ff60..b3b5fb0ff0a9 100644
--- a/tools/testing/selftests/kvm/aarch64/vgic_init.c
+++ b/tools/testing/selftests/kvm/aarch64/vgic_init.c
@@ -4,7 +4,6 @@
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
-#define _GNU_SOURCE
 #include <linux/kernel.h>
 #include <sys/syscall.h>
 #include <asm/kvm.h>
diff --git a/tools/testing/selftests/kvm/arch_timer.c b/tools/testing/selftests/kvm/arch_timer.c
index ae1f1a6d8312..fcebd8d81ce4 100644
--- a/tools/testing/selftests/kvm/arch_timer.c
+++ b/tools/testing/selftests/kvm/arch_timer.c
@@ -19,9 +19,6 @@
  *
  * Copyright (c) 2021, Google LLC.
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <pthread.h>
 #include <linux/sizes.h>
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index bf3609f71854..0c4d3b6afbf8 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -6,9 +6,6 @@
  * Copyright (C) 2018, Red Hat, Inc.
  * Copyright (C) 2019, Google, Inc.
  */
-
-#define _GNU_SOURCE /* for pipe2 */
-
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index eaad5b20854c..bf1ebc29f22a 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -4,9 +4,6 @@
  *
  * Copyright (C) 2018, Red Hat, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index 92eae206baa6..309fe84b84ad 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -4,8 +4,6 @@
  *
  * Author: Chao Peng <chao.p.peng@linux.intel.com>
  */
-
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/kvm/hardware_disable_test.c b/tools/testing/selftests/kvm/hardware_disable_test.c
index decc521fc760..bce73bcb973c 100644
--- a/tools/testing/selftests/kvm/hardware_disable_test.c
+++ b/tools/testing/selftests/kvm/hardware_disable_test.c
@@ -4,9 +4,6 @@
  * kvm_arch_hardware_disable is called and it attempts to unregister the user
  * return notifiers.
  */
-
-#define _GNU_SOURCE
-
 #include <fcntl.h>
 #include <pthread.h>
 #include <semaphore.h>
diff --git a/tools/testing/selftests/kvm/include/userfaultfd_util.h b/tools/testing/selftests/kvm/include/userfaultfd_util.h
index 877449c34592..a9d97c213584 100644
--- a/tools/testing/selftests/kvm/include/userfaultfd_util.h
+++ b/tools/testing/selftests/kvm/include/userfaultfd_util.h
@@ -5,9 +5,6 @@
  * Copyright (C) 2018, Red Hat, Inc.
  * Copyright (C) 2019-2022 Google LLC
  */
-
-#define _GNU_SOURCE /* for pipe2 */
-
 #include <inttypes.h>
 #include <time.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/kvm/kvm_binary_stats_test.c b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
index 698c1cfa3111..f02355c3c4c2 100644
--- a/tools/testing/selftests/kvm/kvm_binary_stats_test.c
+++ b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
@@ -6,8 +6,6 @@
  *
  * Test the fd-based interface for KVM statistics.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
index b9e23265e4b3..c78f34699f73 100644
--- a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
+++ b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
@@ -6,8 +6,6 @@
  *
  * Test for KVM_CAP_MAX_VCPUS and KVM_CAP_MAX_VCPU_ID.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
index e0ba97ac1c56..7759c685086b 100644
--- a/tools/testing/selftests/kvm/kvm_page_table_test.c
+++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
@@ -8,9 +8,6 @@
  * page size have been pre-allocated on your system, if you are planning to
  * use hugepages to back the guest memory for testing.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
diff --git a/tools/testing/selftests/kvm/lib/assert.c b/tools/testing/selftests/kvm/lib/assert.c
index 2bd25b191d15..b49690658c60 100644
--- a/tools/testing/selftests/kvm/lib/assert.c
+++ b/tools/testing/selftests/kvm/lib/assert.c
@@ -4,9 +4,6 @@
  *
  * Copyright (C) 2018, Google LLC.
  */
-
-#define _GNU_SOURCE /* for getline(3) and strchrnul(3)*/
-
 #include "test_util.h"
 
 #include <execinfo.h>
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index b2262b5fad9e..1eaf001d0ad4 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -4,8 +4,6 @@
  *
  * Copyright (C) 2018, Google LLC.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"
diff --git a/tools/testing/selftests/kvm/lib/memstress.c b/tools/testing/selftests/kvm/lib/memstress.c
index cf2c73971308..555e3932e529 100644
--- a/tools/testing/selftests/kvm/lib/memstress.c
+++ b/tools/testing/selftests/kvm/lib/memstress.c
@@ -2,8 +2,6 @@
 /*
  * Copyright (C) 2020, Google LLC.
  */
-#define _GNU_SOURCE
-
 #include <inttypes.h>
 #include <linux/bitmap.h>
 
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 5a8f8becb129..8ed0b74ae837 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -4,8 +4,6 @@
  *
  * Copyright (C) 2020, Google LLC.
  */
-
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdarg.h>
 #include <assert.h>
diff --git a/tools/testing/selftests/kvm/lib/userfaultfd_util.c b/tools/testing/selftests/kvm/lib/userfaultfd_util.c
index f4eef6eb2dc2..bd07568a5240 100644
--- a/tools/testing/selftests/kvm/lib/userfaultfd_util.c
+++ b/tools/testing/selftests/kvm/lib/userfaultfd_util.c
@@ -6,9 +6,6 @@
  * Copyright (C) 2018, Red Hat, Inc.
  * Copyright (C) 2019-2022 Google LLC
  */
-
-#define _GNU_SOURCE /* for pipe2 */
-
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/lib/x86_64/sev.c b/tools/testing/selftests/kvm/lib/x86_64/sev.c
index e248d3364b9c..e83809febae1 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/sev.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/sev.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <stdint.h>
 #include <stdbool.h>
 
diff --git a/tools/testing/selftests/kvm/max_guest_memory_test.c b/tools/testing/selftests/kvm/max_guest_memory_test.c
index 1a6da7389bf1..0b9678858b6d 100644
--- a/tools/testing/selftests/kvm/max_guest_memory_test.c
+++ b/tools/testing/selftests/kvm/max_guest_memory_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/kvm/memslot_modification_stress_test.c b/tools/testing/selftests/kvm/memslot_modification_stress_test.c
index 156361966612..05fcf902e067 100644
--- a/tools/testing/selftests/kvm/memslot_modification_stress_test.c
+++ b/tools/testing/selftests/kvm/memslot_modification_stress_test.c
@@ -6,9 +6,6 @@
  * Copyright (C) 2018, Red Hat, Inc.
  * Copyright (C) 2020, Google, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/syscall.h>
diff --git a/tools/testing/selftests/kvm/riscv/arch_timer.c b/tools/testing/selftests/kvm/riscv/arch_timer.c
index 0f9cabd99fd4..4b5004ef9c6b 100644
--- a/tools/testing/selftests/kvm/riscv/arch_timer.c
+++ b/tools/testing/selftests/kvm/riscv/arch_timer.c
@@ -7,9 +7,6 @@
  *
  * Copyright (c) 2024, Intel Corporation.
  */
-
-#define _GNU_SOURCE
-
 #include "arch_timer.h"
 #include "kvm_util.h"
 #include "processor.h"
diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c
index 28f97fb52044..b3536400f9ac 100644
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/kvm/s390x/cmma_test.c b/tools/testing/selftests/kvm/s390x/cmma_test.c
index 626a2b8a2037..84ba79c42ab1 100644
--- a/tools/testing/selftests/kvm/s390x/cmma_test.c
+++ b/tools/testing/selftests/kvm/s390x/cmma_test.c
@@ -7,8 +7,6 @@
  * Authors:
  *  Nico Boehr <nrb@linux.ibm.com>
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
index 43fb25ddc3ec..53def355ccba 100644
--- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
@@ -10,8 +10,6 @@
  *
  * Test expected behavior of the KVM_CAP_SYNC_REGS functionality.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index bd57d991e27d..214ff84f6fdb 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <pthread.h>
 #include <sched.h>
diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index bae0c5026f82..e9231387c589 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -4,7 +4,6 @@
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <time.h>
 #include <sched.h>
diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index eae521f050e0..8e5713e36d4b 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -6,8 +6,6 @@
  *
  * Tests for amx #NM exception and save/restore.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/exit_on_emulation_failure_test.c b/tools/testing/selftests/kvm/x86_64/exit_on_emulation_failure_test.c
index 6c2e5e0ceb1f..9c21b6bccc38 100644
--- a/tools/testing/selftests/kvm/x86_64/exit_on_emulation_failure_test.c
+++ b/tools/testing/selftests/kvm/x86_64/exit_on_emulation_failure_test.c
@@ -4,9 +4,6 @@
  *
  * Test for KVM_CAP_EXIT_ON_EMULATION_FAILURE.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
-
 #include "flds_emulation.h"
 
 #include "test_util.h"
diff --git a/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c b/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c
index df351ae17029..10b1b0ba374e 100644
--- a/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c
+++ b/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c
@@ -2,8 +2,6 @@
 /*
  * Copyright (C) 2023, Google LLC.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <sys/ioctl.h>
 
 #include "test_util.h"
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c b/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
index 5c27efbf405e..4f5881d4ef66 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
@@ -7,8 +7,6 @@
  * This work is licensed under the terms of the GNU GPL, version 2.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_evmcs.c b/tools/testing/selftests/kvm/x86_64/hyperv_evmcs.c
index 4c7257ecd2a6..4f3f3a9b038b 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_evmcs.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_evmcs.c
@@ -4,7 +4,6 @@
  *
  * Tests for Enlightened VMCS, including nested guest state.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c b/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
index f1617762c22f..8206f5ef42dd 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
@@ -5,8 +5,6 @@
  * Copyright (C) 2022, Red Hat, Inc.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <pthread.h>
 #include <inttypes.h>
 
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
index c9b18707edc0..b987a3d79715 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
@@ -4,7 +4,6 @@
  *
  * Tests for Hyper-V extensions to SVM.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_tlb_flush.c b/tools/testing/selftests/kvm/x86_64/hyperv_tlb_flush.c
index 05b56095cf76..077cd0ec3040 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_tlb_flush.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_tlb_flush.c
@@ -5,8 +5,6 @@
  * Copyright (C) 2022, Red Hat, Inc.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <asm/barrier.h>
 #include <pthread.h>
 #include <inttypes.h>
diff --git a/tools/testing/selftests/kvm/x86_64/nested_exceptions_test.c b/tools/testing/selftests/kvm/x86_64/nested_exceptions_test.c
index 3670331adf21..3eb0313ffa39 100644
--- a/tools/testing/selftests/kvm/x86_64/nested_exceptions_test.c
+++ b/tools/testing/selftests/kvm/x86_64/nested_exceptions_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
-
 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"
diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
index 17bbb96fc4df..e7efb2b35f8b 100644
--- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
+++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
@@ -5,9 +5,6 @@
  *
  * Copyright (C) 2022, Google LLC.
  */
-
-#define _GNU_SOURCE
-
 #include <fcntl.h>
 #include <stdint.h>
 #include <time.h>
diff --git a/tools/testing/selftests/kvm/x86_64/platform_info_test.c b/tools/testing/selftests/kvm/x86_64/platform_info_test.c
index 87011965dc41..2165b1ad8b38 100644
--- a/tools/testing/selftests/kvm/x86_64/platform_info_test.c
+++ b/tools/testing/selftests/kvm/x86_64/platform_info_test.c
@@ -9,8 +9,6 @@
  * Verifies expected behavior of controlling guest access to
  * MSR_PLATFORM_INFO.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
index 26c85815f7e9..77f14138594e 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -2,8 +2,6 @@
 /*
  * Copyright (C) 2023, Tencent, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <x86intrin.h>
 
 #include "pmu.h"
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
index 3c85d1ae9893..5ce53b8c46e0 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
@@ -9,9 +9,6 @@
  * Verifies the expected behavior of allow lists and deny lists for
  * virtual PMU events.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
-
 #include "kvm_util.h"
 #include "pmu.h"
 #include "processor.h"
diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c b/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c
index e0f642d2a3c4..82a8d88b5338 100644
--- a/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c
+++ b/tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c
@@ -2,7 +2,6 @@
 /*
  * Copyright (C) 2022, Google LLC.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <limits.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
index 366cf18600bc..d691d86e5bc3 100644
--- a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
+++ b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
@@ -4,7 +4,6 @@
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
-#define _GNU_SOURCE /* for program_invocation_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/set_sregs_test.c b/tools/testing/selftests/kvm/x86_64/set_sregs_test.c
index 3610981d9162..c021c0795a96 100644
--- a/tools/testing/selftests/kvm/x86_64/set_sregs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/set_sregs_test.c
@@ -10,7 +10,6 @@
  * That bug allowed a user-mode program that called the KVM_SET_SREGS
  * ioctl to put a VCPU's local APIC into an invalid state.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
index 416207c38a17..362be40fc00d 100644
--- a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
+++ b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
@@ -5,9 +5,6 @@
  * Test that KVM emulates instructions in response to EPT violations when
  * allow_smaller_maxphyaddr is enabled and guest.MAXPHYADDR < host.MAXPHYADDR.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
-
 #include "flds_emulation.h"
 
 #include "test_util.h"
diff --git a/tools/testing/selftests/kvm/x86_64/smm_test.c b/tools/testing/selftests/kvm/x86_64/smm_test.c
index e18b86666e1f..55c88d664a94 100644
--- a/tools/testing/selftests/kvm/x86_64/smm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/smm_test.c
@@ -4,7 +4,6 @@
  *
  * Tests for SMM.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/state_test.c b/tools/testing/selftests/kvm/x86_64/state_test.c
index 88b58aab7207..1c756db329e5 100644
--- a/tools/testing/selftests/kvm/x86_64/state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/state_test.c
@@ -6,7 +6,6 @@
  *
  * Tests for vCPU state save/restore, including nested guest state.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c
index adb5593daf48..8fa3948b0170 100644
--- a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c
@@ -8,8 +8,6 @@
  * including requesting an invalid register set, updates to/from values
  * in kvm_run.s.regs when kvm_valid_regs and kvm_dirty_regs are toggled.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c b/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c
index dcbb3c29fb8e..abe71946941f 100644
--- a/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c
+++ b/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c
@@ -17,8 +17,6 @@
  * delivered into the guest or not.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <pthread.h>
 #include <inttypes.h>
 #include <string.h>
diff --git a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
index f4f61a2d2464..53afbea4df88 100644
--- a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
+++ b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
@@ -4,8 +4,6 @@
  *
  * Tests for exiting into userspace on registered MSRs
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <sys/ioctl.h>
 
 #include "kvm_test_harness.h"
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c b/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
index 977948fd52e6..fa512d033205 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
@@ -4,9 +4,6 @@
  *
  * Copyright (C) 2018, Red Hat, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <linux/bitmap.h>
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
index ea0cb3cae0f7..3b93f262b797 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
@@ -10,7 +10,6 @@
  * and check it can be retrieved with KVM_GET_MSR, also test
  * the invalid LBR formats are rejected.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <sys/ioctl.h>
 
 #include <linux/bitmap.h>
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
index affc32800158..00dd2ac07a61 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
@@ -9,7 +9,6 @@
  * value instead of partially decayed timer value
  *
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c b/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c
index 725c206ba0b9..c78e5f755116 100644
--- a/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c
@@ -19,8 +19,6 @@
  * Migration is a command line option. When used on non-numa machines will 
  * exit with error. Test is still usefull on non-numa for testing IPIs.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <getopt.h>
 #include <pthread.h>
 #include <inttypes.h>
diff --git a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
index ab75b873a4ad..69849acd95b0 100644
--- a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
index 167c97abff1b..f331a4e9bae3 100644
--- a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
@@ -4,8 +4,6 @@
  *
  * Tests for the IA32_XSS MSR.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <sys/ioctl.h>
 
 #include "test_util.h"
diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index a6f89aaea77d..bdb3955a9452 100644
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -5,8 +5,6 @@
  * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2019-2020 ANSSI
  */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/landlock.h>
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 9a6036fbf289..acec1c82c8b4 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -6,8 +6,6 @@
  * Copyright © 2020 ANSSI
  * Copyright © 2020-2022 Microsoft Corporation
  */
-
-#define _GNU_SOURCE
 #include <fcntl.h>
 #include <linux/landlock.h>
 #include <linux/magic.h>
diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
index f21cfbbc3638..eed040adcbac 100644
--- a/tools/testing/selftests/landlock/net_test.c
+++ b/tools/testing/selftests/landlock/net_test.c
@@ -5,8 +5,6 @@
  * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
  * Copyright © 2023 Microsoft Corporation
  */
-
-#define _GNU_SOURCE
 #include <arpa/inet.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/landlock/ptrace_test.c b/tools/testing/selftests/landlock/ptrace_test.c
index a19db4d0b3bd..c831e6d03b02 100644
--- a/tools/testing/selftests/landlock/ptrace_test.c
+++ b/tools/testing/selftests/landlock/ptrace_test.c
@@ -5,8 +5,6 @@
  * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2019-2020 ANSSI
  */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/landlock.h>
diff --git a/tools/testing/selftests/lsm/common.c b/tools/testing/selftests/lsm/common.c
index 9ad258912646..1b18aac570f1 100644
--- a/tools/testing/selftests/lsm/common.c
+++ b/tools/testing/selftests/lsm/common.c
@@ -4,8 +4,6 @@
  *
  * Copyright © 2023 Casey Schaufler <casey@schaufler-ca.com>
  */
-
-#define _GNU_SOURCE
 #include <linux/lsm.h>
 #include <fcntl.h>
 #include <string.h>
diff --git a/tools/testing/selftests/lsm/lsm_get_self_attr_test.c b/tools/testing/selftests/lsm/lsm_get_self_attr_test.c
index df215e4aa63f..7465bde3f922 100644
--- a/tools/testing/selftests/lsm/lsm_get_self_attr_test.c
+++ b/tools/testing/selftests/lsm/lsm_get_self_attr_test.c
@@ -5,8 +5,6 @@
  *
  * Copyright © 2022 Casey Schaufler <casey@schaufler-ca.com>
  */
-
-#define _GNU_SOURCE
 #include <linux/lsm.h>
 #include <fcntl.h>
 #include <string.h>
diff --git a/tools/testing/selftests/lsm/lsm_list_modules_test.c b/tools/testing/selftests/lsm/lsm_list_modules_test.c
index 06d24d4679a6..a6b44e25c21f 100644
--- a/tools/testing/selftests/lsm/lsm_list_modules_test.c
+++ b/tools/testing/selftests/lsm/lsm_list_modules_test.c
@@ -5,8 +5,6 @@
  *
  * Copyright © 2022 Casey Schaufler <casey@schaufler-ca.com>
  */
-
-#define _GNU_SOURCE
 #include <linux/lsm.h>
 #include <string.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/lsm/lsm_set_self_attr_test.c b/tools/testing/selftests/lsm/lsm_set_self_attr_test.c
index 66dec47e3ca3..110c6a07e74c 100644
--- a/tools/testing/selftests/lsm/lsm_set_self_attr_test.c
+++ b/tools/testing/selftests/lsm/lsm_set_self_attr_test.c
@@ -5,8 +5,6 @@
  *
  * Copyright © 2022 Casey Schaufler <casey@schaufler-ca.com>
  */
-
-#define _GNU_SOURCE
 #include <linux/lsm.h>
 #include <string.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/membarrier/membarrier_test_impl.h b/tools/testing/selftests/membarrier/membarrier_test_impl.h
index af89855adb7b..a8a60b6271a5 100644
--- a/tools/testing/selftests/membarrier/membarrier_test_impl.h
+++ b/tools/testing/selftests/membarrier/membarrier_test_impl.h
@@ -1,5 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-#define _GNU_SOURCE
 #include <linux/membarrier.h>
 #include <syscall.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c b/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c
index a9cc17facfb3..b4651e2ade00 100644
--- a/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c
+++ b/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <linux/membarrier.h>
 #include <syscall.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/membarrier/membarrier_test_single_thread.c b/tools/testing/selftests/membarrier/membarrier_test_single_thread.c
index 4cdc8b1d124c..17ae5199b916 100644
--- a/tools/testing/selftests/membarrier/membarrier_test_single_thread.c
+++ b/tools/testing/selftests/membarrier/membarrier_test_single_thread.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <linux/membarrier.h>
 #include <syscall.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/memfd/common.c b/tools/testing/selftests/memfd/common.c
index 8eb3d75f6e60..879d4f4c66fa 100644
--- a/tools/testing/selftests/memfd/common.c
+++ b/tools/testing/selftests/memfd/common.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #define __EXPORTED_HEADERS__
 
 #include <stdio.h>
diff --git a/tools/testing/selftests/memfd/fuse_test.c b/tools/testing/selftests/memfd/fuse_test.c
index 93798c8c5d54..15bc189bf831 100644
--- a/tools/testing/selftests/memfd/fuse_test.c
+++ b/tools/testing/selftests/memfd/fuse_test.c
@@ -12,8 +12,6 @@
  * the read() syscall with our memory-mapped memfd object as receive buffer to
  * force the kernel to write into our memfd object.
  */
-
-#define _GNU_SOURCE
 #define __EXPORTED_HEADERS__
 
 #include <errno.h>
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index 18f585684e20..5172c27a8748 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #define __EXPORTED_HEADERS__
 
 #include <errno.h>
diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 363bf5f801be..6f1a36d51f19 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -6,7 +6,6 @@
  *
  * Author(s): David Hildenbrand <david@redhat.com>
  */
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/mm/gup_longterm.c b/tools/testing/selftests/mm/gup_longterm.c
index ad168d35b23b..3bfd5a630081 100644
--- a/tools/testing/selftests/mm/gup_longterm.c
+++ b/tools/testing/selftests/mm/gup_longterm.c
@@ -6,7 +6,6 @@
  *
  * Author(s): David Hildenbrand <david@redhat.com>
  */
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/mm/hugepage-mmap.c b/tools/testing/selftests/mm/hugepage-mmap.c
index 267eea2e0e0b..edb46888222f 100644
--- a/tools/testing/selftests/mm/hugepage-mmap.c
+++ b/tools/testing/selftests/mm/hugepage-mmap.c
@@ -16,7 +16,6 @@
  * range.
  * Other architectures, such as ppc64, i386 or x86_64 are not so constrained.
  */
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
index c463d1c09c9b..8e22822bb754 100644
--- a/tools/testing/selftests/mm/hugepage-mremap.c
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
@@ -11,8 +11,6 @@
  * To make sure the test triggers pmd sharing and goes through the 'unshare'
  * path in the mremap code use 1GB (1024) or more.
  */
-
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/mm/hugetlb-madvise.c b/tools/testing/selftests/mm/hugetlb-madvise.c
index e74107185324..70c40c67bc5d 100644
--- a/tools/testing/selftests/mm/hugetlb-madvise.c
+++ b/tools/testing/selftests/mm/hugetlb-madvise.c
@@ -11,8 +11,6 @@
  * filesystem.  Therefore, a hugetlbfs filesystem must be mounted on some
  * directory.
  */
-
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/mm/hugetlb-read-hwpoison.c b/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
index ba6cc6f9cabc..6b8b41b4f754 100644
--- a/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
+++ b/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 829320a519e7..d18bf400dae6 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -1,4 +1,3 @@
-#define _GNU_SOURCE
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index d615767e396b..1deae905c42e 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -6,7 +6,6 @@
  *
  * Author(s): David Hildenbrand <david@redhat.com>
  */
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/mm/madv_populate.c b/tools/testing/selftests/mm/madv_populate.c
index 17bcb07f19f3..d19ad13ffd7e 100644
--- a/tools/testing/selftests/mm/madv_populate.c
+++ b/tools/testing/selftests/mm/madv_populate.c
@@ -6,7 +6,6 @@
  *
  * Author(s): David Hildenbrand <david@redhat.com>
  */
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/mm/map_populate.c b/tools/testing/selftests/mm/map_populate.c
index 5c8a53869b1b..ff4d4079bd0e 100644
--- a/tools/testing/selftests/mm/map_populate.c
+++ b/tools/testing/selftests/mm/map_populate.c
@@ -4,8 +4,6 @@
  *
  * MAP_POPULATE | MAP_PRIVATE should COW VMA pages.
  */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
index 1e01d3ddc11c..200bedcdc32e 100644
--- a/tools/testing/selftests/mm/mdwe_test.c
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -7,7 +7,6 @@
 #include <linux/mman.h>
 #include <linux/prctl.h>
 
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/auxv.h>
diff --git a/tools/testing/selftests/mm/memfd_secret.c b/tools/testing/selftests/mm/memfd_secret.c
index 9b298f6a04b3..750adede2816 100644
--- a/tools/testing/selftests/mm/memfd_secret.c
+++ b/tools/testing/selftests/mm/memfd_secret.c
@@ -4,8 +4,6 @@
  *
  * Author: Mike Rapoport <rppt@linux.ibm.com>
  */
-
-#define _GNU_SOURCE
 #include <sys/uio.h>
 #include <sys/mman.h>
 #include <sys/wait.h>
diff --git a/tools/testing/selftests/mm/mlock2-tests.c b/tools/testing/selftests/mm/mlock2-tests.c
index 26f744188ad0..42574290d728 100644
--- a/tools/testing/selftests/mm/mlock2-tests.c
+++ b/tools/testing/selftests/mm/mlock2-tests.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <sys/mman.h>
 #include <stdint.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/mm/mrelease_test.c b/tools/testing/selftests/mm/mrelease_test.c
index 100370a7111d..d78bf686e99f 100644
--- a/tools/testing/selftests/mm/mrelease_test.c
+++ b/tools/testing/selftests/mm/mrelease_test.c
@@ -2,7 +2,6 @@
 /*
  * Copyright 2022 Google LLC
  */
-#define _GNU_SOURCE
 #include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/mm/mremap_dontunmap.c b/tools/testing/selftests/mm/mremap_dontunmap.c
index 1d75084b9ca5..934fa6b441b2 100644
--- a/tools/testing/selftests/mm/mremap_dontunmap.c
+++ b/tools/testing/selftests/mm/mremap_dontunmap.c
@@ -5,7 +5,6 @@
  *
  * Copyright 2020, Brian Geffon <bgeffon@google.com>
  */
-#define _GNU_SOURCE
 #include <sys/mman.h>
 #include <linux/mman.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c
index 2f8b991f78cb..e057154630e0 100644
--- a/tools/testing/selftests/mm/mremap_test.c
+++ b/tools/testing/selftests/mm/mremap_test.c
@@ -2,8 +2,6 @@
 /*
  * Copyright 2020 Google LLC
  */
-#define _GNU_SOURCE
-
 #include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index d59517ed3d48..2a18b5d276f0 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <fcntl.h>
 #include <string.h>
diff --git a/tools/testing/selftests/mm/pkey-helpers.h b/tools/testing/selftests/mm/pkey-helpers.h
index 1af3156a9db8..37d6b01ce90a 100644
--- a/tools/testing/selftests/mm/pkey-helpers.h
+++ b/tools/testing/selftests/mm/pkey-helpers.h
@@ -1,7 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _PKEYS_HELPER_H
 #define _PKEYS_HELPER_H
-#define _GNU_SOURCE
 #include <string.h>
 #include <stdarg.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
index 48dc151f8fca..9f7de92caeda 100644
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -21,7 +21,6 @@
  *	gcc -mxsave      -o protection_keys    -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm
  *	gcc -mxsave -m32 -o protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm
  */
-#define _GNU_SOURCE
 #define __SANE_USERSPACE_TYPES__
 #include <errno.h>
 #include <linux/elf.h>
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index d3c7f5fb3e7b..ae6ac950d7a1 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -3,8 +3,6 @@
  * A test of splitting PMD THPs and PTE-mapped THPs from a specified virtual
  * address range in a process via <debugfs>/split_huge_pages interface.
  */
-
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
diff --git a/tools/testing/selftests/mm/thuge-gen.c b/tools/testing/selftests/mm/thuge-gen.c
index ea7fd8fe2876..28a5c31bd791 100644
--- a/tools/testing/selftests/mm/thuge-gen.c
+++ b/tools/testing/selftests/mm/thuge-gen.c
@@ -12,8 +12,6 @@
    ipcrm -m by hand, like this
    sudo ipcs | awk '$1 == "0x00000000" {print $2}' | xargs -n1 sudo ipcrm -m
    (warning this will remove all if someone else uses them) */
-
-#define _GNU_SOURCE 1
 #include <sys/mman.h>
 #include <stdlib.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/mm/uffd-common.h b/tools/testing/selftests/mm/uffd-common.h
index cc5629c3d2aa..abb44319264a 100644
--- a/tools/testing/selftests/mm/uffd-common.h
+++ b/tools/testing/selftests/mm/uffd-common.h
@@ -7,7 +7,6 @@
 #ifndef __UFFD_COMMON_H__
 #define __UFFD_COMMON_H__
 
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/mount_setattr/mount_setattr_test.c b/tools/testing/selftests/mount_setattr/mount_setattr_test.c
index c6a8c732b802..d894417134b6 100644
--- a/tools/testing/selftests/mount_setattr/mount_setattr_test.c
+++ b/tools/testing/selftests/mount_setattr/mount_setattr_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c b/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c
index bcf51d785a37..bd975670f61d 100644
--- a/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c
+++ b/tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/af_unix/diag_uid.c b/tools/testing/selftests/net/af_unix/diag_uid.c
index 79a3dd75590e..279d0c5f70d3 100644
--- a/tools/testing/selftests/net/af_unix/diag_uid.c
+++ b/tools/testing/selftests/net/af_unix/diag_uid.c
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright Amazon.com Inc. or its affiliates. */
-
-#define _GNU_SOURCE
 #include <sched.h>
 
 #include <unistd.h>
diff --git a/tools/testing/selftests/net/af_unix/scm_pidfd.c b/tools/testing/selftests/net/af_unix/scm_pidfd.c
index 7e534594167e..2986b8cd0418 100644
--- a/tools/testing/selftests/net/af_unix/scm_pidfd.c
+++ b/tools/testing/selftests/net/af_unix/scm_pidfd.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0 OR MIT
-#define _GNU_SOURCE
 #include <error.h>
 #include <limits.h>
 #include <stddef.h>
diff --git a/tools/testing/selftests/net/af_unix/unix_connect.c b/tools/testing/selftests/net/af_unix/unix_connect.c
index d799fd8f5c7c..34e816862cc7 100644
--- a/tools/testing/selftests/net/af_unix/unix_connect.c
+++ b/tools/testing/selftests/net/af_unix/unix_connect.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <sched.h>
 
 #include <stddef.h>
diff --git a/tools/testing/selftests/net/csum.c b/tools/testing/selftests/net/csum.c
index 90eb06fefa59..8262aa862331 100644
--- a/tools/testing/selftests/net/csum.c
+++ b/tools/testing/selftests/net/csum.c
@@ -58,9 +58,6 @@
  * different seed for each run (and logs this for reproducibility). It
  * is advised to enable this for extra coverage in continuous testing.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <asm/byteorder.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/gro.c b/tools/testing/selftests/net/gro.c
index 353e1e867fbb..f5d7032e6466 100644
--- a/tools/testing/selftests/net/gro.c
+++ b/tools/testing/selftests/net/gro.c
@@ -34,9 +34,6 @@
  * flakiness is to be expected.
  *
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/ip_defrag.c b/tools/testing/selftests/net/ip_defrag.c
index f9ed749fd8c7..80c9e567a3d8 100644
--- a/tools/testing/selftests/net/ip_defrag.c
+++ b/tools/testing/selftests/net/ip_defrag.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/ipsec.c b/tools/testing/selftests/net/ipsec.c
index be4a30a0d02a..04aa06d26b09 100644
--- a/tools/testing/selftests/net/ipsec.c
+++ b/tools/testing/selftests/net/ipsec.c
@@ -3,9 +3,6 @@
  * ipsec.c - Check xfrm on veth inside a net-ns.
  * Copyright (c) 2018 Dmitry Safonov
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <asm/types.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/ipv6_flowlabel.c b/tools/testing/selftests/net/ipv6_flowlabel.c
index 708a9822259d..b7e0c3c02e20 100644
--- a/tools/testing/selftests/net/ipv6_flowlabel.c
+++ b/tools/testing/selftests/net/ipv6_flowlabel.c
@@ -1,8 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Test IPV6_FLOWINFO cmsg on send and recv */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <asm/byteorder.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
index af95b48acea9..ebd219ba386e 100644
--- a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
+++ b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
@@ -1,8 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Test IPV6_FLOWINFO_MGR */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <error.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c
index d2043ec3bf6d..ea93030ed3ec 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <errno.h>
 #include <limits.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/net/mptcp/mptcp_inq.c b/tools/testing/selftests/net/mptcp/mptcp_inq.c
index 218aac467321..c5bf873d76c2 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_inq.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_inq.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
index 926b0be87c99..7203ca9900e9 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c
index bdc03a2097e8..9278bf585c80 100644
--- a/tools/testing/selftests/net/msg_zerocopy.c
+++ b/tools/testing/selftests/net/msg_zerocopy.c
@@ -24,9 +24,6 @@
  * the kernel queues completions on the error queue for all zerocopy
  * transfers.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <error.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c
index cd8a58097448..88e1d3b2ddf1 100644
--- a/tools/testing/selftests/net/nettest.c
+++ b/tools/testing/selftests/net/nettest.c
@@ -3,8 +3,6 @@
  *
  * Copyright (c) 2013-2019 David Ahern <dsahern@gmail.com>. All rights reserved.
  */
-
-#define _GNU_SOURCE
 #include <features.h>
 #include <sys/types.h>
 #include <sys/ioctl.h>
diff --git a/tools/testing/selftests/net/psock_fanout.c b/tools/testing/selftests/net/psock_fanout.c
index 1a736f700be4..5b2d34440ae9 100644
--- a/tools/testing/selftests/net/psock_fanout.c
+++ b/tools/testing/selftests/net/psock_fanout.c
@@ -26,9 +26,6 @@
  * Todo:
  * - functionality: PACKET_FANOUT_FLAG_DEFRAG
  */
-
-#define _GNU_SOURCE		/* for sched_setaffinity */
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index edf1e6f80d41..2f29b513e18f 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/reuseport_addr_any.c b/tools/testing/selftests/net/reuseport_addr_any.c
index b8475cb29be7..9ee6ece52865 100644
--- a/tools/testing/selftests/net/reuseport_addr_any.c
+++ b/tools/testing/selftests/net/reuseport_addr_any.c
@@ -3,9 +3,6 @@
 /* Test that sockets listening on a specific address are preferred
  * over sockets listening on addr_any.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/reuseport_bpf_cpu.c b/tools/testing/selftests/net/reuseport_bpf_cpu.c
index 2d646174729f..e93e38cfb2a8 100644
--- a/tools/testing/selftests/net/reuseport_bpf_cpu.c
+++ b/tools/testing/selftests/net/reuseport_bpf_cpu.c
@@ -11,9 +11,6 @@
  * This entire process is done for several different core id permutations
  * and for each IPv4/IPv6 and TCP/UDP combination.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/reuseport_bpf_numa.c b/tools/testing/selftests/net/reuseport_bpf_numa.c
index c9ba36aa688e..502fdb9ce770 100644
--- a/tools/testing/selftests/net/reuseport_bpf_numa.c
+++ b/tools/testing/selftests/net/reuseport_bpf_numa.c
@@ -3,9 +3,6 @@
  * Test functionality of BPF filters with SO_REUSEPORT. Same test as
  * in reuseport_bpf_cpu, only as one socket per NUMA node.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/reuseport_dualstack.c b/tools/testing/selftests/net/reuseport_dualstack.c
index fb7a59ed759e..d3c3d3f39f8f 100644
--- a/tools/testing/selftests/net/reuseport_dualstack.c
+++ b/tools/testing/selftests/net/reuseport_dualstack.c
@@ -10,9 +10,6 @@
  * This test creates these mixed AF_INET/AF_INET6 sockets and asserts the
  * AF_INET preference for v4 packets.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/so_incoming_cpu.c b/tools/testing/selftests/net/so_incoming_cpu.c
index e9fa14e10732..95bd0cdc3253 100644
--- a/tools/testing/selftests/net/so_incoming_cpu.c
+++ b/tools/testing/selftests/net/so_incoming_cpu.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright Amazon.com Inc. or its affiliates. */
-#define _GNU_SOURCE
 #include <sched.h>
 
 #include <fcntl.h>
diff --git a/tools/testing/selftests/net/so_netns_cookie.c b/tools/testing/selftests/net/so_netns_cookie.c
index b39e87e967cd..18532d564f79 100644
--- a/tools/testing/selftests/net/so_netns_cookie.c
+++ b/tools/testing/selftests/net/so_netns_cookie.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <sched.h>
 #include <unistd.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/net/so_txtime.c b/tools/testing/selftests/net/so_txtime.c
index 8457b7ccbc09..011a24af9786 100644
--- a/tools/testing/selftests/net/so_txtime.c
+++ b/tools/testing/selftests/net/so_txtime.c
@@ -9,9 +9,6 @@
  * the expected stream. Sender will read transmit timestamps from the error
  * queue. The streams can differ due to out-of-order delivery and drops.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <error.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/tap.c b/tools/testing/selftests/net/tap.c
index 247c3b3ac1c9..fa78b92d9740 100644
--- a/tools/testing/selftests/net/tap.c
+++ b/tools/testing/selftests/net/tap.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/net/tcp_fastopen_backup_key.c b/tools/testing/selftests/net/tcp_fastopen_backup_key.c
index c1cb0c75156a..d30f89bb944c 100644
--- a/tools/testing/selftests/net/tcp_fastopen_backup_key.c
+++ b/tools/testing/selftests/net/tcp_fastopen_backup_key.c
@@ -12,7 +12,6 @@
  * there are no cases in which a cookie is not accepted by verifying
  * that TcpExtTCPFastOpenPassiveFail remains 0.
  */
-#define _GNU_SOURCE
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/tcp_inq.c b/tools/testing/selftests/net/tcp_inq.c
index bd6a9c7a3e8a..71ee145f151e 100644
--- a/tools/testing/selftests/net/tcp_inq.c
+++ b/tools/testing/selftests/net/tcp_inq.c
@@ -5,8 +5,6 @@
  *
  * Simple example on how to use TCP_INQ and TCP_CM_INQ.
  */
-#define _GNU_SOURCE
-
 #include <error.h>
 #include <netinet/in.h>
 #include <netinet/tcp.h>
diff --git a/tools/testing/selftests/net/tcp_mmap.c b/tools/testing/selftests/net/tcp_mmap.c
index 4fcce5150850..72d5f1207ee0 100644
--- a/tools/testing/selftests/net/tcp_mmap.c
+++ b/tools/testing/selftests/net/tcp_mmap.c
@@ -46,7 +46,6 @@
  * received 32768 MB (99.9939 % mmap'ed) in 7.43764 s, 36.9577 Gbit
  *   cpu usage user:0.035 sys:3.467, 106.873 usec per MB, 65530 c-switches
  */
-#define _GNU_SOURCE
 #include <pthread.h>
 #include <sys/types.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/net/tls.c b/tools/testing/selftests/net/tls.c
index f27a12d2a2c9..6dbad97d1d0a 100644
--- a/tools/testing/selftests/net/tls.c
+++ b/tools/testing/selftests/net/tls.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/toeplitz.c b/tools/testing/selftests/net/toeplitz.c
index 9ba03164d73a..e2d739892ce4 100644
--- a/tools/testing/selftests/net/toeplitz.c
+++ b/tools/testing/selftests/net/toeplitz.c
@@ -20,9 +20,6 @@
  * 5. Compute the cpu that RPS should select based on rx_hash and $rps_bitmap
  * 6. Compare the cpus from 4 and 5
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c
index fa83918b62d1..a64dcfb242c1 100644
--- a/tools/testing/selftests/net/tun.c
+++ b/tools/testing/selftests/net/tun.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/net/txring_overwrite.c b/tools/testing/selftests/net/txring_overwrite.c
index 7d9ea039450a..96972e0110a0 100644
--- a/tools/testing/selftests/net/txring_overwrite.c
+++ b/tools/testing/selftests/net/txring_overwrite.c
@@ -4,9 +4,6 @@
  * Verify that consecutive sends over packet tx_ring are mirrored
  * with their original content intact.
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <assert.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/txtimestamp.c b/tools/testing/selftests/net/txtimestamp.c
index ec60a16c9307..33dba9e90dea 100644
--- a/tools/testing/selftests/net/txtimestamp.c
+++ b/tools/testing/selftests/net/txtimestamp.c
@@ -16,9 +16,6 @@
  * This test requires a dummy TCP server.
  * A simple `nc6 [-u] -l -p $DESTPORT` will do
  */
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <asm/types.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/udpgso.c b/tools/testing/selftests/net/udpgso.c
index 85b3baa3f7f3..9dc1026a033a 100644
--- a/tools/testing/selftests/net/udpgso.c
+++ b/tools/testing/selftests/net/udpgso.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <stddef.h>
 #include <arpa/inet.h>
 #include <error.h>
diff --git a/tools/testing/selftests/net/udpgso_bench_rx.c b/tools/testing/selftests/net/udpgso_bench_rx.c
index 1cbadd267c96..999df1236320 100644
--- a/tools/testing/selftests/net/udpgso_bench_rx.c
+++ b/tools/testing/selftests/net/udpgso_bench_rx.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <error.h>
 #include <errno.h>
diff --git a/tools/testing/selftests/net/udpgso_bench_tx.c b/tools/testing/selftests/net/udpgso_bench_tx.c
index 477392715a9a..d7632993b354 100644
--- a/tools/testing/selftests/net/udpgso_bench_tx.c
+++ b/tools/testing/selftests/net/udpgso_bench_tx.c
@@ -1,7 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
diff --git a/tools/testing/selftests/perf_events/remove_on_exec.c b/tools/testing/selftests/perf_events/remove_on_exec.c
index 5814611a1dc7..ef4d923f4759 100644
--- a/tools/testing/selftests/perf_events/remove_on_exec.c
+++ b/tools/testing/selftests/perf_events/remove_on_exec.c
@@ -5,8 +5,6 @@
  * Copyright (C) 2021, Google LLC.
  */
 
-#define _GNU_SOURCE
-
 /* We need the latest siginfo from the kernel repo. */
 #include <sys/types.h>
 #include <asm/siginfo.h>
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index d1d8483ac628..14d1a3c8cb5c 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -5,8 +5,6 @@
  * Copyright (C) 2021, Google LLC.
  */
 
-#define _GNU_SOURCE
-
 /* We need the latest siginfo from the kernel repo. */
 #include <sys/types.h>
 #include <asm/siginfo.h>
diff --git a/tools/testing/selftests/pid_namespace/regression_enomem.c b/tools/testing/selftests/pid_namespace/regression_enomem.c
index 7d84097ad45c..54dc8f16d92a 100644
--- a/tools/testing/selftests/pid_namespace/regression_enomem.c
+++ b/tools/testing/selftests/pid_namespace/regression_enomem.c
@@ -1,4 +1,3 @@
-#define _GNU_SOURCE
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h
index 88d6830ee004..e33177b1aa41 100644
--- a/tools/testing/selftests/pidfd/pidfd.h
+++ b/tools/testing/selftests/pidfd/pidfd.h
@@ -3,7 +3,6 @@
 #ifndef __PIDFD_H
 #define __PIDFD_H
 
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <sched.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c b/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c
index 01cc37bf611c..67c9dc436c71 100644
--- a/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_getfd_test.c b/tools/testing/selftests/pidfd/pidfd_getfd_test.c
index cd51d547b751..b6a0e9b3d2f5 100644
--- a/tools/testing/selftests/pidfd/pidfd_getfd_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_getfd_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_open_test.c b/tools/testing/selftests/pidfd/pidfd_open_test.c
index 8a59438ccc78..781a3931fb5a 100644
--- a/tools/testing/selftests/pidfd/pidfd_open_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_open_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_poll_test.c b/tools/testing/selftests/pidfd/pidfd_poll_test.c
index 610811275357..a40fb27a78bb 100644
--- a/tools/testing/selftests/pidfd/pidfd_poll_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_poll_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <linux/types.h>
 #include <poll.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_setns_test.c b/tools/testing/selftests/pidfd/pidfd_setns_test.c
index 6e2f2cd400ca..49d7a78cc4fe 100644
--- a/tools/testing/selftests/pidfd/pidfd_setns_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_setns_test.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c
index c081ae91313a..c3d52406b8fd 100644
--- a/tools/testing/selftests/pidfd/pidfd_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_test.c
@@ -1,6 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/types.h>
diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c
index 0dcb8365ddc3..54beba0983f1 100644
--- a/tools/testing/selftests/pidfd/pidfd_wait.c
+++ b/tools/testing/selftests/pidfd/pidfd_wait.c
@@ -1,6 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <linux/sched.h>
 #include <linux/types.h>
diff --git a/tools/testing/selftests/ptrace/get_set_sud.c b/tools/testing/selftests/ptrace/get_set_sud.c
index 5297b10d25c3..054a78ebe8b5 100644
--- a/tools/testing/selftests/ptrace/get_set_sud.c
+++ b/tools/testing/selftests/ptrace/get_set_sud.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include "../kselftest_harness.h"
 #include <stdio.h>
 #include <string.h>
diff --git a/tools/testing/selftests/ptrace/peeksiginfo.c b/tools/testing/selftests/ptrace/peeksiginfo.c
index a6884f66dc01..1b7b77190f72 100644
--- a/tools/testing/selftests/ptrace/peeksiginfo.c
+++ b/tools/testing/selftests/ptrace/peeksiginfo.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <signal.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/rseq/basic_percpu_ops_test.c b/tools/testing/selftests/rseq/basic_percpu_ops_test.c
index 2348d2c20d0a..5961c24ee1ae 100644
--- a/tools/testing/selftests/rseq/basic_percpu_ops_test.c
+++ b/tools/testing/selftests/rseq/basic_percpu_ops_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: LGPL-2.1
-#define _GNU_SOURCE
 #include <assert.h>
 #include <pthread.h>
 #include <sched.h>
diff --git a/tools/testing/selftests/rseq/basic_test.c b/tools/testing/selftests/rseq/basic_test.c
index 295eea16466f..1fed749b4bd7 100644
--- a/tools/testing/selftests/rseq/basic_test.c
+++ b/tools/testing/selftests/rseq/basic_test.c
@@ -2,8 +2,6 @@
 /*
  * Basic test coverage for critical regions and rseq_current_cpu().
  */
-
-#define _GNU_SOURCE
 #include <assert.h>
 #include <sched.h>
 #include <signal.h>
diff --git a/tools/testing/selftests/rseq/param_test.c b/tools/testing/selftests/rseq/param_test.c
index 2f37961240ca..48a55d94eb72 100644
--- a/tools/testing/selftests/rseq/param_test.c
+++ b/tools/testing/selftests/rseq/param_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: LGPL-2.1
-#define _GNU_SOURCE
 #include <assert.h>
 #include <linux/membarrier.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 96e812bdf8a4..88602889414c 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -14,8 +14,6 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * Lesser General Public License for more details.
  */
-
-#define _GNU_SOURCE
 #include <errno.h>
 #include <sched.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/seccomp/seccomp_benchmark.c b/tools/testing/selftests/seccomp/seccomp_benchmark.c
index b83099160fbc..3632a4890da9 100644
--- a/tools/testing/selftests/seccomp/seccomp_benchmark.c
+++ b/tools/testing/selftests/seccomp/seccomp_benchmark.c
@@ -2,7 +2,6 @@
  * Strictly speaking, this is not a test. But it can report during test
  * runs so relative performace can be measured.
  */
-#define _GNU_SOURCE
 #include <assert.h>
 #include <err.h>
 #include <limits.h>
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 783ebce8c4de..972ccc12553e 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -4,8 +4,6 @@
  *
  * Test code for seccomp bpf.
  */
-
-#define _GNU_SOURCE
 #include <sys/types.h>
 
 /*
diff --git a/tools/testing/selftests/user_events/abi_test.c b/tools/testing/selftests/user_events/abi_test.c
index 7288a05136ba..a1f156dbbd56 100644
--- a/tools/testing/selftests/user_events/abi_test.c
+++ b/tools/testing/selftests/user_events/abi_test.c
@@ -4,8 +4,6 @@
  *
  * Copyright (c) 2022 Beau Belgrave <beaub@linux.microsoft.com>
  */
-
-#define _GNU_SOURCE
 #include <sched.h>
 
 #include <errno.h>
diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c
index d884fd69dd51..9441635fc452 100644
--- a/tools/testing/selftests/x86/amx.c
+++ b/tools/testing/selftests/x86/amx.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-
-#define _GNU_SOURCE
 #include <err.h>
 #include <errno.h>
 #include <pthread.h>
diff --git a/tools/testing/selftests/x86/check_initial_reg_state.c b/tools/testing/selftests/x86/check_initial_reg_state.c
index 3bc95f3ed585..0129cdae8abe 100644
--- a/tools/testing/selftests/x86/check_initial_reg_state.c
+++ b/tools/testing/selftests/x86/check_initial_reg_state.c
@@ -3,9 +3,6 @@
  * check_initial_reg_state.c - check that execve sets the correct state
  * Copyright (c) 2014-2016 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
-
 #include <stdio.h>
 
 unsigned long ax, bx, cx, dx, si, di, bp, sp, flags;
diff --git a/tools/testing/selftests/x86/corrupt_xstate_header.c b/tools/testing/selftests/x86/corrupt_xstate_header.c
index cf9ce8fbb656..d2c746149678 100644
--- a/tools/testing/selftests/x86/corrupt_xstate_header.c
+++ b/tools/testing/selftests/x86/corrupt_xstate_header.c
@@ -4,9 +4,6 @@
  *
  * Based on analysis and a test case from Thomas Gleixner.
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/entry_from_vm86.c b/tools/testing/selftests/x86/entry_from_vm86.c
index d1e919b0c1dc..9fa9d4a847ac 100644
--- a/tools/testing/selftests/x86/entry_from_vm86.c
+++ b/tools/testing/selftests/x86/entry_from_vm86.c
@@ -5,9 +5,6 @@
  *
  * This exercises a few paths that need to special-case vm86 mode.
  */
-
-#define _GNU_SOURCE
-
 #include <assert.h>
 #include <stdlib.h>
 #include <sys/syscall.h>
diff --git a/tools/testing/selftests/x86/fsgsbase.c b/tools/testing/selftests/x86/fsgsbase.c
index 8c780cce941d..348134d2cefc 100644
--- a/tools/testing/selftests/x86/fsgsbase.c
+++ b/tools/testing/selftests/x86/fsgsbase.c
@@ -3,8 +3,6 @@
  * fsgsbase.c, an fsgsbase test
  * Copyright (c) 2014-2016 Andy Lutomirski
  */
-
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/x86/fsgsbase_restore.c b/tools/testing/selftests/x86/fsgsbase_restore.c
index 6fffadc51579..88dce47ab8e6 100644
--- a/tools/testing/selftests/x86/fsgsbase_restore.c
+++ b/tools/testing/selftests/x86/fsgsbase_restore.c
@@ -12,8 +12,6 @@
  *
  * This is not part of fsgsbase.c, because that test is 64-bit only.
  */
-
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/x86/ioperm.c b/tools/testing/selftests/x86/ioperm.c
index 57ec5e99edb9..07b7c10f8d39 100644
--- a/tools/testing/selftests/x86/ioperm.c
+++ b/tools/testing/selftests/x86/ioperm.c
@@ -3,8 +3,6 @@
  * ioperm.c - Test case for ioperm(2)
  * Copyright (c) 2015 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
 #include <err.h>
 #include <stdio.h>
 #include <stdint.h>
diff --git a/tools/testing/selftests/x86/iopl.c b/tools/testing/selftests/x86/iopl.c
index 7e3e09c1abac..baa691154905 100644
--- a/tools/testing/selftests/x86/iopl.c
+++ b/tools/testing/selftests/x86/iopl.c
@@ -3,8 +3,6 @@
  * iopl.c - Test case for a Linux on Xen 64-bit bug
  * Copyright (c) 2015 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
 #include <err.h>
 #include <stdio.h>
 #include <stdint.h>
diff --git a/tools/testing/selftests/x86/lam.c b/tools/testing/selftests/x86/lam.c
index 215b8150b7cc..39edfd7f6037 100644
--- a/tools/testing/selftests/x86/lam.c
+++ b/tools/testing/selftests/x86/lam.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/ldt_gdt.c b/tools/testing/selftests/x86/ldt_gdt.c
index 3a29346e1452..3b4237a85a12 100644
--- a/tools/testing/selftests/x86/ldt_gdt.c
+++ b/tools/testing/selftests/x86/ldt_gdt.c
@@ -3,8 +3,6 @@
  * ldt_gdt.c - Test cases for LDT and GDT access
  * Copyright (c) 2015 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
 #include <err.h>
 #include <stdio.h>
 #include <stdint.h>
diff --git a/tools/testing/selftests/x86/mov_ss_trap.c b/tools/testing/selftests/x86/mov_ss_trap.c
index cc3de6ff9fba..47ecc63220b7 100644
--- a/tools/testing/selftests/x86/mov_ss_trap.c
+++ b/tools/testing/selftests/x86/mov_ss_trap.c
@@ -19,8 +19,6 @@
  *
  * This should mostly cover CVE-2018-1087 and CVE-2018-8897.
  */
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <sys/ptrace.h>
 #include <sys/types.h>
diff --git a/tools/testing/selftests/x86/nx_stack.c b/tools/testing/selftests/x86/nx_stack.c
index ea4a4e246879..97c5b34096cc 100644
--- a/tools/testing/selftests/x86/nx_stack.c
+++ b/tools/testing/selftests/x86/nx_stack.c
@@ -23,8 +23,6 @@
  * Regular stack is completely overwritten before testing.
  * Test doesn't exit SIGSEGV handler after first fault at INT3.
  */
-#undef _GNU_SOURCE
-#define _GNU_SOURCE
 #undef NDEBUG
 #include <assert.h>
 #include <signal.h>
diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
index 12aaa063196e..bdc81c8bd1a7 100644
--- a/tools/testing/selftests/x86/ptrace_syscall.c
+++ b/tools/testing/selftests/x86/ptrace_syscall.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <sys/ptrace.h>
 #include <sys/types.h>
 #include <sys/wait.h>
diff --git a/tools/testing/selftests/x86/sigaltstack.c b/tools/testing/selftests/x86/sigaltstack.c
index f689af75e979..7f41c3a4268b 100644
--- a/tools/testing/selftests/x86/sigaltstack.c
+++ b/tools/testing/selftests/x86/sigaltstack.c
@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-only
-
-#define _GNU_SOURCE
 #include <signal.h>
 #include <stdio.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
index 5d7961a5f7f6..2054f729b2c2 100644
--- a/tools/testing/selftests/x86/sigreturn.c
+++ b/tools/testing/selftests/x86/sigreturn.c
@@ -24,9 +24,6 @@
  *
  * Do not run on outdated, unpatched kernels at risk of nasty crashes.
  */
-
-#define _GNU_SOURCE
-
 #include <sys/time.h>
 #include <time.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/x86/single_step_syscall.c b/tools/testing/selftests/x86/single_step_syscall.c
index 9a30f443e928..375f3b50a0b5 100644
--- a/tools/testing/selftests/x86/single_step_syscall.c
+++ b/tools/testing/selftests/x86/single_step_syscall.c
@@ -9,9 +9,6 @@
  * immediately issues #DB from CPL 0.  This requires special handling in
  * the kernel.
  */
-
-#define _GNU_SOURCE
-
 #include <sys/time.h>
 #include <time.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c
index 461fa41a4d02..10eee1bcd015 100644
--- a/tools/testing/selftests/x86/syscall_arg_fault.c
+++ b/tools/testing/selftests/x86/syscall_arg_fault.c
@@ -3,9 +3,6 @@
  * syscall_arg_fault.c - tests faults 32-bit fast syscall stack args
  * Copyright (c) 2015 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/syscall_numbering.c b/tools/testing/selftests/x86/syscall_numbering.c
index 991591718bb0..c72fc8aaa4d3 100644
--- a/tools/testing/selftests/x86/syscall_numbering.c
+++ b/tools/testing/selftests/x86/syscall_numbering.c
@@ -5,9 +5,6 @@
  *
  * Copyright (c) 2018 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdbool.h>
diff --git a/tools/testing/selftests/x86/sysret_rip.c b/tools/testing/selftests/x86/sysret_rip.c
index 84d74be1d902..24bc219358a5 100644
--- a/tools/testing/selftests/x86/sysret_rip.c
+++ b/tools/testing/selftests/x86/sysret_rip.c
@@ -3,9 +3,6 @@
  * sigreturn.c - tests that x86 avoids Intel SYSRET pitfalls
  * Copyright (c) 2014-2016 Andrew Lutomirski
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/x86/sysret_ss_attrs.c b/tools/testing/selftests/x86/sysret_ss_attrs.c
index 5f3d4fca440f..f8b9e0b2a0c5 100644
--- a/tools/testing/selftests/x86/sysret_ss_attrs.c
+++ b/tools/testing/selftests/x86/sysret_ss_attrs.c
@@ -7,9 +7,6 @@
  * the hidden attributes set to an unusable state.  Make sure the kernel
  * doesn't let this happen.
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
diff --git a/tools/testing/selftests/x86/test_FCMOV.c b/tools/testing/selftests/x86/test_FCMOV.c
index 6b5036fbb735..0c9431ba7d31 100644
--- a/tools/testing/selftests/x86/test_FCMOV.c
+++ b/tools/testing/selftests/x86/test_FCMOV.c
@@ -1,8 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#undef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#undef __USE_GNU
-#define __USE_GNU 1
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/test_FCOMI.c b/tools/testing/selftests/x86/test_FCOMI.c
index aec6692c6dcf..ba186665918d 100644
--- a/tools/testing/selftests/x86/test_FCOMI.c
+++ b/tools/testing/selftests/x86/test_FCOMI.c
@@ -1,8 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#undef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#undef __USE_GNU
-#define __USE_GNU 1
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/test_FISTTP.c b/tools/testing/selftests/x86/test_FISTTP.c
index 09789c0ce3e9..95580cdaaa32 100644
--- a/tools/testing/selftests/x86/test_FISTTP.c
+++ b/tools/testing/selftests/x86/test_FISTTP.c
@@ -1,8 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#undef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#undef __USE_GNU
-#define __USE_GNU 1
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
index f0d876d48277..a8bdba356682 100644
--- a/tools/testing/selftests/x86/test_mremap_vdso.c
+++ b/tools/testing/selftests/x86/test_mremap_vdso.c
@@ -9,7 +9,6 @@
  * Can be built statically:
  * gcc -Os -Wall -static -m32 test_mremap_vdso.c
  */
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
diff --git a/tools/testing/selftests/x86/test_shadow_stack.c b/tools/testing/selftests/x86/test_shadow_stack.c
index 757e6527f67e..0ceca9064cec 100644
--- a/tools/testing/selftests/x86/test_shadow_stack.c
+++ b/tools/testing/selftests/x86/test_shadow_stack.c
@@ -7,9 +7,6 @@
  * special glibc shadow stack support (longjmp(), swapcontext(), etc). Just
  * stick to the basics and hope the compiler doesn't do anything strange.
  */
-
-#define _GNU_SOURCE
-
 #include <sys/syscall.h>
 #include <asm/mman.h>
 #include <sys/mman.h>
diff --git a/tools/testing/selftests/x86/test_syscall_vdso.c b/tools/testing/selftests/x86/test_syscall_vdso.c
index 8965c311bd65..5cd13279bba5 100644
--- a/tools/testing/selftests/x86/test_syscall_vdso.c
+++ b/tools/testing/selftests/x86/test_syscall_vdso.c
@@ -8,10 +8,6 @@
  * Can be built statically:
  * gcc -Os -Wall -static -m32 test_syscall_vdso.c thunks_32.S
  */
-#undef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#undef __USE_GNU
-#define __USE_GNU 1
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c
index 47cab972807c..cbf4e5012005 100644
--- a/tools/testing/selftests/x86/test_vsyscall.c
+++ b/tools/testing/selftests/x86/test_vsyscall.c
@@ -1,7 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-
-#define _GNU_SOURCE
-
 #include <stdio.h>
 #include <sys/time.h>
 #include <time.h>
diff --git a/tools/testing/selftests/x86/unwind_vdso.c b/tools/testing/selftests/x86/unwind_vdso.c
index 4c311e1af4c7..754f5d4d425a 100644
--- a/tools/testing/selftests/x86/unwind_vdso.c
+++ b/tools/testing/selftests/x86/unwind_vdso.c
@@ -5,9 +5,6 @@
  *
  * This tests __kernel_vsyscall's unwind info.
  */
-
-#define _GNU_SOURCE
-
 #include <features.h>
 #include <stdio.h>
 
diff --git a/tools/testing/selftests/x86/vdso_restorer.c b/tools/testing/selftests/x86/vdso_restorer.c
index fe99f2434155..8193de22a390 100644
--- a/tools/testing/selftests/x86/vdso_restorer.c
+++ b/tools/testing/selftests/x86/vdso_restorer.c
@@ -10,9 +10,6 @@
  * 64-bit userspace has never supported sa_restorer == NULL, so this is
  * 32-bit only.
  */
-
-#define _GNU_SOURCE
-
 #include <err.h>
 #include <stdio.h>
 #include <dlfcn.h>
