// SPDX-License-Identifier: MIT// SPDX-FileCopyrightText: 2024 Michael Jeanson <mjeanson@efficios.com> #ifndef _GNU_SOURCE#define _GNU_SOURCE#endif #include <assert.h>#include <stdint.h>#include <syscall.h>#include <string.h>#include <unistd.h> #include "rseq.h" static int sys_rseq(void *rseq_abi, uint32_t rseq_len,		    int flags, uint32_t sig){	return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);} /* * Check the value of errno on some expected failures of the rseq syscall. */ int main(void){	struct rseq_abi *global_rseq = rseq_get_abi();	int ret;	int errno_copy; 	if (!rseq_available()) {		fprintf(stderr, "rseq syscall unavailable");		goto error;	} 	/* The current thread is NOT registered. */ 	/* EINVAL */	errno = 0;	ret = sys_rseq(global_rseq, 32, -1, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Registration with invalid flag fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EINVAL)		goto error; 	errno = 0;	ret = sys_rseq((char *) global_rseq + 1, 32, 0, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Registration with unaligned rseq_abi fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EINVAL)		goto error; 	errno = 0;	ret = sys_rseq(global_rseq, 31, 0, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Registration with invalid size fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EINVAL)		goto error;  #if defined(__LP64__) && (!defined(__s390__) && !defined(__s390x__))	/*	 * We haven't found a reliable way to find an invalid address when	 * running a 32bit userspace on a 64bit kernel, so only run this test	 * on 64bit builds for the moment.	 *	 * Also exclude architectures that select	 * CONFIG_ALTERNATE_USER_ADDRESS_SPACE where the kernel and userspace	 * have their own address space and this failure can't happen.	 */ 	/* EFAULT */	errno = 0;	ret = sys_rseq((void *) -4096UL, 32, 0, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Registration with invalid address fails with errno set to EFAULT (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EFAULT)		goto error;#endif 	errno = 0;	ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Registration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret != 0 && errno != 0)		goto error; 	/* The current thread is registered. */ 	/* EBUSY */	errno = 0;	ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Double registration fails with errno set to EBUSY (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EBUSY)		goto error; 	/* EPERM */	errno = 0;	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG + 1);	errno_copy = errno;	fprintf(stderr, "Unregistration with wrong RSEQ_SIG fails with errno to EPERM (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EPERM)		goto error; 	errno = 0;	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Unregistration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret != 0)		goto error; 	errno = 0;	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);	errno_copy = errno;	fprintf(stderr, "Double unregistration fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));	if (ret == 0 || errno_copy != EINVAL)		goto error; 	return 0;error:	return -1;}