KVM: selftests: Define _GNU_SOURCE for all selftests code

Define _GNU_SOURCE is the base CFLAGS instead of relying on selftests to
manually #define _GNU_SOURCE, which is repetitive and error prone. E.g.
kselftest_harness.h requires _GNU_SOURCE for asprintf(), but if a selftest
includes kvm_test_harness.h after stdio.h, the include guards result in
the effective version of stdio.h consumed by kvm_test_harness.h not
defining asprintf():

In file included from x86_64/fix_hypercall_test.c:12:
In file included from include/kvm_test_harness.h:11:
../kselftest_harness.h:1169:2: error: call to undeclared function
'asprintf'; ISO C99 and later do not support implicit function declarations
[-Wimplicit-function-declaration]
1169 | asprintf(&test_name, "%s%s%s.%s", f->name,
| ^

When including the rseq selftest's "library" code, #undef _GNU_SOURCE so
that rseq.c controls whether or not it wants to build with _GNU_SOURCE.

Reported-by: Muhammad Usama Anjum <[e-mail]>
Acked-by: Claudio Imbrenda <[e-mail]>
Acked-by: Oliver Upton <[e-mail]>
Acked-by: Anup Patel <[e-mail]>
Reviewed-by: Muhammad Usama Anjum <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sean Christopherson <[e-mail]>

tools/testing/selftests/kvm/Makefile

···
 endif
 CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -O2 -g -std=gnu99 \
 	-Wno-gnu-variable-sized-type-not-at-end -MD -MP -DCONFIG_64BIT \
-	-fno-builtin-memcmp -fno-builtin-memcpy -fno-builtin-memset \
-	-fno-builtin-strnlen \
+	-D_GNU_SOURCE -fno-builtin-memcmp -fno-builtin-memcpy \
+	-fno-builtin-memset -fno-builtin-strnlen \
 	-fno-stack-protector -fno-PIE -I$(LINUX_TOOL_INCLUDE) \
 	-I$(LINUX_TOOL_ARCH_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude \
 	-I$(<D) -Iinclude/$(ARCH_DIR) -I ../rseq -I.. $(EXTRA_CFLAGS) \

tools/testing/selftests/kvm/aarch64/arch_timer.c

···
  *
  * Copyright (c) 2021, Google LLC.
  */
-#define _GNU_SOURCE
-
 #include "arch_timer.h"
 #include "delay.h"
 #include "gic.h"

tools/testing/selftests/kvm/aarch64/page_fault_test.c

···
  * 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>

tools/testing/selftests/kvm/aarch64/psci_test.c

···
  *  - 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"

tools/testing/selftests/kvm/aarch64/vgic_init.c

···
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
-#define _GNU_SOURCE
 #include <linux/kernel.h>
 #include <sys/syscall.h>
 #include <asm/kvm.h>

tools/testing/selftests/kvm/arch_timer.c

···
  *
  * Copyright (c) 2021, Google LLC.
  */
-
-#define _GNU_SOURCE
-
 #include <stdlib.h>
 #include <pthread.h>
 #include <linux/sizes.h>

tools/testing/selftests/kvm/demand_paging_test.c

···
  * 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>

tools/testing/selftests/kvm/dirty_log_test.c

···
  *
  * Copyright (C) 2018, Red Hat, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>

tools/testing/selftests/kvm/guest_memfd_test.c

···
  *
  * Author: Chao Peng <[e-mail]>
  */
-
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>

tools/testing/selftests/kvm/hardware_disable_test.c

···
  * 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>

tools/testing/selftests/kvm/include/kvm_util_base.h

···
 
 /*
  * Provide a version of static_assert() that is guaranteed to have an optional
- * message param.  If _ISOC11_SOURCE is defined, glibc (/usr/include/assert.h)
- * #undefs and #defines static_assert() as a direct alias to _Static_assert(),
- * i.e. effectively makes the message mandatory.  Many KVM selftests #define
- * _GNU_SOURCE for various reasons, and _GNU_SOURCE implies _ISOC11_SOURCE.  As
- * a result, static_assert() behavior is non-deterministic and may or may not
- * require a message depending on #include order.
+ * message param.  _GNU_SOURCE is defined for all KVM selftests, _GNU_SOURCE
+ * implies _ISOC11_SOURCE, and if _ISOC11_SOURCE is defined, glibc #undefs and
+ * #defines static_assert() as a direct alias to _Static_assert() (see
+ * usr/include/assert.h).  Define a custom macro instead of redefining
+ * static_assert() to avoid creating non-deterministic behavior that is
+ * dependent on include order.
  */
 #define __kvm_static_assert(expr, msg, ...) _Static_assert(expr, msg)
 #define kvm_static_assert(expr, ...) __kvm_static_assert(expr, ##__VA_ARGS__, #expr)

tools/testing/selftests/kvm/include/userfaultfd_util.h

···
  * 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>

tools/testing/selftests/kvm/kvm_binary_stats_test.c

···
  *
  * 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>

tools/testing/selftests/kvm/kvm_create_max_vcpus.c

···
  *
  * 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>

tools/testing/selftests/kvm/kvm_page_table_test.c

···
  * 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>

tools/testing/selftests/kvm/lib/assert.c

···
  *
  * Copyright (C) 2018, Google LLC.
  */
-
-#define _GNU_SOURCE /* for getline(3) and strchrnul(3)*/
-
 #include "test_util.h"
 
 #include <execinfo.h>

tools/testing/selftests/kvm/lib/kvm_util.c

···
  *
  * Copyright (C) 2018, Google LLC.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"

tools/testing/selftests/kvm/lib/memstress.c

···
 /*
  * Copyright (C) 2020, Google LLC.
  */
-#define _GNU_SOURCE
-
 #include <inttypes.h>
 #include <linux/bitmap.h>
 

tools/testing/selftests/kvm/lib/test_util.c

···
  *
  * Copyright (C) 2020, Google LLC.
  */
-
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdarg.h>
 #include <assert.h>

tools/testing/selftests/kvm/lib/userfaultfd_util.c

···
  * 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>

tools/testing/selftests/kvm/lib/x86_64/sev.c

···
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <stdint.h>
 #include <stdbool.h>
 

tools/testing/selftests/kvm/max_guest_memory_test.c

···
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>

tools/testing/selftests/kvm/memslot_modification_stress_test.c

···
  * 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>

tools/testing/selftests/kvm/riscv/arch_timer.c

···
  *
  * Copyright (c) 2024, Intel Corporation.
  */
-
-#define _GNU_SOURCE
-
 #include "arch_timer.h"
 #include "kvm_util.h"
 #include "processor.h"

tools/testing/selftests/kvm/rseq_test.c

···
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
+
+/*
+ * Include rseq.c without _GNU_SOURCE defined, before including any headers, so
+ * that rseq.c is compiled with its configuration, not KVM selftests' config.
+ */
+#undef _GNU_SOURCE
+#include "../rseq/rseq.c"
+#define _GNU_SOURCE
+
 #include <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
···
 #include "kvm_util.h"
 #include "processor.h"
 #include "test_util.h"
-
-#include "../rseq/rseq.c"
 
 /*
  * Any bug related to task migration is likely to be timing-dependent; perform

tools/testing/selftests/kvm/s390x/cmma_test.c

···
  * Authors:
  *  Nico Boehr <[e-mail]>
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>

tools/testing/selftests/kvm/s390x/sync_regs_test.c

···
  *
  * 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>

tools/testing/selftests/kvm/set_memory_region_test.c

···
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <pthread.h>
 #include <sched.h>

tools/testing/selftests/kvm/steal_time.c

···
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <time.h>
 #include <sched.h>

tools/testing/selftests/kvm/x86_64/amx_test.c

···
  *
  * 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>

tools/testing/selftests/kvm/x86_64/exit_on_emulation_failure_test.c

···
  *
  * Test for KVM_CAP_EXIT_ON_EMULATION_FAILURE.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
-
 #include "flds_emulation.h"
 
 #include "test_util.h"

tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c

···
 /*
  * Copyright (C) 2023, Google LLC.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <sys/ioctl.h>
 
 #include "test_util.h"

tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c

···
  * 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>

tools/testing/selftests/kvm/x86_64/hyperv_evmcs.c

···
  *
  * 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>

tools/testing/selftests/kvm/x86_64/hyperv_ipi.c

···
  * Copyright (C) 2022, Red Hat, Inc.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <pthread.h>
 #include <inttypes.h>
 

tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c

···
  *
  * Tests for Hyper-V extensions to SVM.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>

tools/testing/selftests/kvm/x86_64/hyperv_tlb_flush.c

···
  * Copyright (C) 2022, Red Hat, Inc.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <asm/barrier.h>
 #include <pthread.h>
 #include <inttypes.h>

tools/testing/selftests/kvm/x86_64/nested_exceptions_test.c

···
 // 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"

tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c

···
  *
  * Copyright (C) 2022, Google LLC.
  */
-
-#define _GNU_SOURCE
-
 #include <fcntl.h>
 #include <stdint.h>
 #include <time.h>

tools/testing/selftests/kvm/x86_64/platform_info_test.c

···
  * 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>

tools/testing/selftests/kvm/x86_64/pmu_counters_test.c

···
 /*
  * Copyright (C) 2023, Tencent, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <x86intrin.h>
 
 #include "pmu.h"

tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c

···
  * 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"

tools/testing/selftests/kvm/x86_64/private_mem_conversions_test.c

···
 /*
  * Copyright (C) 2022, Google LLC.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <limits.h>
 #include <pthread.h>

tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c

···
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
-#define _GNU_SOURCE /* for program_invocation_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>

tools/testing/selftests/kvm/x86_64/set_sregs_test.c

···
  * 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>

tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c

···
  * 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"

tools/testing/selftests/kvm/x86_64/smm_test.c

···
  *
  * Tests for SMM.
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>

tools/testing/selftests/kvm/x86_64/state_test.c

···
  *
  * 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>

tools/testing/selftests/kvm/x86_64/sync_regs_test.c

···
  * 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>

tools/testing/selftests/kvm/x86_64/ucna_injection_test.c

···
  * delivered into the guest or not.
  *
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <pthread.h>
 #include <inttypes.h>
 #include <string.h>

tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c

···
  *
  * 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"

tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c

···
  *
  * Copyright (C) 2018, Red Hat, Inc.
  */
-
-#define _GNU_SOURCE /* for program_invocation_name */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <linux/bitmap.h>

tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c

···
  * 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>

tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c

···
  * value instead of partially decayed timer value
  *
  */
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>

tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c

···
  * 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>

tools/testing/selftests/kvm/x86_64/xapic_state_test.c

···
 // SPDX-License-Identifier: GPL-2.0-only
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>

tools/testing/selftests/kvm/x86_64/xss_msr_test.c

···
  *
  * Tests for the IA32_XSS MSR.
  */
-
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <sys/ioctl.h>
 
 #include "test_util.h"