linux(4): Add a simple rseq syscall implementation.

To avoid annoyng messages from glibc-2.35 test suite add the simple
implementation of rseq syscall which is do nothing for now.

I plan to implement it if and when the API stabilizes.

MFC after:	2 weeks

4 files changed, 89 insertions, 3 deletions

diff --git a/sys/compat/linux/linux_dummy.c b/sys/compat/linux/linux_dummy.c
index e254bf94c026..57360c0d1a00 100644
--- a/sys/compat/linux/linux_dummy.c
+++ b/sys/compat/linux/linux_dummy.c
@@ -144,7 +144,6 @@ DUMMY(epoll_pwait2);
 DUMMY(mount_setattr);
 /* Linux 4.18: */
 DUMMY(io_pgetevents);
-DUMMY(rseq);
 /* Linux 5.0: */
 DUMMY(pidfd_send_signal);
 DUMMY(io_uring_setup);
diff --git a/sys/compat/linux/linux_rseq.c b/sys/compat/linux/linux_rseq.c
new file mode 100644
index 000000000000..89bf526a4271
--- /dev/null
+++ b/sys/compat/linux/linux_rseq.c
@@ -0,0 +1,87 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Dmitry Chagin <dchagin@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+
+#ifdef COMPAT_LINUX32
+#include <machine/../linux32/linux.h>
+#include <machine/../linux32/linux32_proto.h>
+#else
+#include <machine/../linux/linux.h>
+#include <machine/../linux/linux_proto.h>
+#endif
+
+
+enum linux_rseq_cpu_id_state {
+	LINUX_RSEQ_CPU_ID_UNINITIALIZED			= -1,
+	LINUX_RSEQ_CPU_ID_REGISTRATION_FAILED		= -2,
+};
+
+enum linux_rseq_flags {
+	LINUX_RSEQ_FLAG_UNREGISTER			= (1 << 0),
+};
+
+enum linux_rseq_cs_flags_bit {
+	LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT	= 0,
+	LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT	= 1,
+	LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT	= 2,
+};
+
+enum linux_rseq_cs_flags {
+	LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT	=
+		(1U << LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
+	LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL	=
+		(1U << LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
+	LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE	=
+		(1U << LINUX_RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
+};
+
+struct linux_rseq_cs {
+	uint32_t version;
+	uint32_t flags;
+	uint64_t start_ip;
+	uint64_t post_commit_offset;
+	uint64_t abort_ip;
+} __attribute__((aligned(4 * sizeof(uint64_t))));
+
+struct linux_rseq {
+	uint32_t cpu_id_start;
+	uint32_t cpu_id;
+	uint64_t rseq_cs;
+	uint32_t flags;
+} __attribute__((aligned(4 * sizeof(uint64_t))));
+
+int
+linux_rseq(struct thread *td, struct linux_rseq_args *args)
+{
+
+	return (ENOSYS);
+}
diff --git a/sys/modules/linux/Makefile b/sys/modules/linux/Makefile
index 089187ca7cff..9b4453045c09 100644
--- a/sys/modules/linux/Makefile
+++ b/sys/modules/linux/Makefile
@@ -16,7 +16,7 @@ SRCS=	linux_fork.c linux${SFX}_dummy_machdep.c linux_file.c linux_event.c \
 	linux${SFX}_machdep.c linux_misc.c linux_signal.c \
 	linux_socket.c linux_stats.c linux_sysctl.c linux${SFX}_sysent.c \
 	linux${SFX}_sysvec.c linux_uid16.c linux_time.c \
-	linux_timer.c linux_vdso.c \
+	linux_timer.c linux_vdso.c linux_rseq.c \
 	opt_inet6.h opt_compat.h opt_posix.h opt_usb.h vnode_if.h \
 	device_if.h bus_if.h
 .if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64"
diff --git a/sys/modules/linux64/Makefile b/sys/modules/linux64/Makefile
index e2a408f49bad..4a4a84d38c73 100644
--- a/sys/modules/linux64/Makefile
+++ b/sys/modules/linux64/Makefile
@@ -10,7 +10,7 @@ SRCS=	linux_elf64.c linux_fork.c linux_dummy_machdep.c linux_file.c \
 	linux_event.c linux_futex.c linux_getcwd.c linux_ioctl.c linux_ipc.c \
 	linux_machdep.c linux_misc.c linux_ptrace.c linux_signal.c \
 	linux_socket.c linux_stats.c linux_sysctl.c linux_sysent.c \
-	linux_sysvec.c linux_time.c linux_vdso.c linux_timer.c \
+	linux_sysvec.c linux_time.c linux_vdso.c linux_timer.c linux_rseq.c \
 	opt_compat.h opt_inet6.h opt_posix.h opt_usb.h \
 	vnode_if.h device_if.h bus_if.h \
 	linux_support.s