[PATCHv5 00/37] kernel: Introduce Time Namespace

[PATCHv5 00/37] kernel: Introduce Time Namespace

[Dmitry Safonov]

Discussions around time namespace are there for a long time. The first
attempt to implement it was in 2006 by Jeff Dike. From that time, the
topic appears on and off in various discussions.

There are two main use cases for time namespaces:
1. change date and time inside a container;
2. adjust clocks for a container restored from a checkpoint.

“It seems like this might be one of the last major obstacles keeping
migration from being used in production systems, given that not all
containers and connections can be migrated as long as a time dependency
is capable of messing it up.” (by github.com/dav-ell)

The kernel provides access to several clocks: CLOCK_REALTIME,
CLOCK_MONOTONIC, CLOCK_BOOTTIME. Last two clocks are monotonous, but the
start points for them are not defined and are different for each
system. When a container is migrated from one node to another, all
clocks have to be restored into consistent states; in other words, they
have to continue running from the same points where they have been
dumped.

The main idea of this patch set is adding per-namespace offsets for
system clocks. When a process in a non-root time namespace requests
time of a clock, a namespace offset is added to the current value of
this clock and the sum is returned.

All offsets are placed on a separate page, this allows us to map it as
part of VVAR into user processes and use offsets from VDSO calls.

Now offsets are implemented for CLOCK_MONOTONIC and CLOCK_BOOTTIME
clocks.

v4..v5 Changes:
* Rebased over generic vdso (already in master)
* Addressing review comments by Thomas Gleixner
  (thanks much for your time and patience):
  - Dropping `timens` prefix from subjects (it's not a subsystem)
  - Keeping commit messages in a neutral technical form
  - Splitting unreasonably large patches
  - Document code with missing comments
  - Dropped dead code that's not compiled with !CONFIG_TIME_NS
* Updated performance results [here, at the bottom]
* Split vdso jump tables patch
* Allow unshare() with many threads: it's safe until fork()/clone(),
  where we check for CLONE_THREADS
* Add missed check in setns() for CLONE_VM | CLONE_THREADS
* Fixed compilation with !CONFIG_UTS_NS
* Add a plan in selftests (prevents new warning "Planned tests != run tests")
* Set jump table section address & size to (-1UL) just in case if there
  is no such section while running vdso2c (and WARN() on boot in such
  case)

[v1..v4 Changelog is at the very bottom here]

Our performance measurements show that the price of VDSO's clock_gettime()
in a child time namespace is about 8% with a hot CPU cache and about 90%
with a cold CPU cache. There is no performance regression for host
processes outside time namespace on those tests.

We wrote two small benchmarks. The first one gettime_perf.c calls
clock_gettime() in a loop for 3 seconds. It shows us performance with
a hot CPU cache (more clock_gettime() cycles - the better):

        | before    | CONFIG_TIME_NS=n | host      | inside timens
--------------------------------------------------------------
        | 161822960 | 161147792        | 160187142 | 150584782
        | 161891728 | 161489804        | 159914989 | 150417019
        | 161891770 | 161098734        | 160123179 | 150601277
        | 161687686 | 161114738        | 159874249 | 150243276
        | 161247151 | 161411636        | 159096392 | 149637536
--------------------------------------------------------------
avg     | 161708259 | 161252540        | 159839190 | 150296778
diff %  | 100       | 99.7             | 98.8      | 92.9
-------------------------------------------------------------
stdev % | 0.2       | 0.1              | 0.1       | 0.2

The gettime_perf_cold test does 10K iterations. In each iteration, it
drops cpu caches for vdso pages, clflush is used for this, then it runs
rdtsc(); clock_gettime; rdtsc(); and prints the number of tsc cycles.

(lesser tsc per cycle - the better):

           | before    | CONFIG_TIME_NS=n | host      | inside timens
--------------------------------------------------------------
tsc        | 434       | 433              | 437       | 477
stdev(tsc) | 5         | 5                | 5         | 3
diff (%)   | 1         | 1                | 100.1     | 109

vdsotest results: https://gist.github.com/avagin/f290afb8b721ae0522a561d585f34de0

The numbers gathered on Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz.

Cc: Adrian Reber <adrian@lisas.de>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: containers@lists.linux-foundation.org
Cc: criu@openvz.org
Cc: linux-api@vger.kernel.org
Cc: x86@kernel.org

v5 on github (if someone prefers `git pull` or `git log`):
https://github.com/0x7f454c46/linux/tree/timens-v5

v4: https://lkml.kernel.org/r/20190612192628.23797-1-dima@arista.com
v3: https://lkml.kernel.org/r/20190425161416.26600-1-dima@arista.com
v2: https://lore.kernel.org/lkml/20190206001107.16488-1-dima@arista.com/
RFC: https://lkml.kernel.org/r/20180919205037.9574-1-dima@arista.com/

v3..v4 Changes:

* CLOCKE_NEWTIME is unshare()-only flag now (CLON_PIDFD took previous value)
* Addressing Jann Horn's feedback - we don't allow CLONE_THREAD or
  CLONE_VM together with CLONE_NEWTIME (thanks for spotting!)
* Addressing issues found by Thomas - removed unmaintainable CLOCK_TIMENS
  and introduced another call back into k_clock to get ktime instead
  of getting timespec and converting it (Patch 03)
* Renaming timens_offsets members to omit _offset postfix
  (thanks Cyrill for the suggestion)
* Suggestions, renaming and making code more maintainable from Thomas's
  feedback (thanks much!)
* Fixing out-of-bounds and other issues in procfs file (kudos Jann Horn)
* vdso_fault() can be called on a remote task by /proc/$pid/mem or
  process_vm_readv() - addressed by adding a slow-path with searching
  for owner's namespace (thanks for spotting this unobvious issue, Jann)
* Other nits by Jann Horn

v2..v3: Major changes:

* Simplify two VDSO images by using static_branch() in vclock_gettime()
  Removes unwanted conflicts with generic VDSO movement patches and
  simplifies things by dropping too invasive linker magic.
  As an alternative to static_branch() we tested an attempt to introduce
  home-made dynamic patching called retcalls:
  https://github.com/0x7f454c46/linux/commit/4cc0180f6d65
  Considering some theoretical problems with toolchains, we decided to go
  with long well-tested nop-patching in static_branch(). Though, it was
  needed to provide backend for relative code.

* address Thomas' comments.
* add sanity checks for offsets:
  - the current clock time in a namespace has to be in [0, KTIME_MAX / 2).
    KTIME_MAX is divided by two here to be sure that the KTIME_MAX limit
    is still unreachable.
Link: https://lkml.org/lkml/2018/9/19/950
Link: https://lkml.org/lkml/2019/2/5/867

v1..v2: There are two major changes:

* Two versions of the VDSO library to avoid a performance penalty for
  host tasks outside time namespace (as suggested by Andy and Thomas).

  As it has been discussed on timens RFC, adding a new conditional branch
  `if (inside_time_ns)` on VDSO for all processes is undesirable.
  It will add a penalty for everybody as branch predictor may mispredict
  the jump. Also there are instruction cache lines wasted on cmp/jmp.

  Those effects of introducing time namespace are very much unwanted
  having in mind how much work have been spent on micro-optimisation
  VDSO code.

  Addressing those problems, there are two versions of VDSO's .so:
  for host tasks (without any penalty) and for processes inside of time
  namespace with clk_to_ns() that subtracts offsets from host's time.


* Allow to set clock offsets for a namespace only before any processes
  appear in it.

  Now a time namespace looks similar to a pid namespace in a way how it is
  created: unshare(CLONE_NEWTIME) system call creates a new time namespace,
  but doesn't set it to the current process. Then all children of
  the process will be born in the new time namespace, or a process can
  use the setns() system call to join a namespace.

  This scheme allows to create a new time namespaces, set clock offsets
  and then populate the namespace with processes.


Andrei Vagin (25):
  ns: Introduce Time Namespace
  timens: Add timens_offsets
  posix-clocks: Rename the clock_get() into clock_get_timespec()
  posix-clocks: Rename *_clock_get() functions into
    *_clock_get_timespec()
  alarmtimer: Rename gettime() callback to get_ktime()
  alarmtimer: Provide get_timespec() callback
  posix-clocks: Introduce clock_get_ktime() callback
  posix-timers: Use clock_get_ktime() in common_timer_get()
  posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets
  posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset
  kernel: Add do_timens_ktime_to_host() helper
  timerfd: Make timerfd_settime() time namespace aware
  posix-timers: Make timer_settime() time namespace aware
  alarmtimer: Make nanosleep time namespace aware
  hrtimers: Prepare hrtimer_nanosleep() for time namespaces
  posix-timers: Make clock_nanosleep() time namespace aware
  x86/vdso: Add offsets page in vvar
  vdso: Introduce vdso_static_branch_unlikely()
  x86/vdso: Enable static branches for the timens vdso
  fs/proc: Introduce /proc/pid/timens_offsets
  selftest/timens: Add a test for timerfd
  selftest/timens: Add a test for clock_nanosleep()
  selftest/timens: Add timer offsets test
  selftests/timens: Add a simple perf test for clock_gettime()
  selftest/timens: Check that a right vdso is mapped after fork and exec

Dmitry Safonov (12):
  fd/proc: Respect boottime inside time namespace for /proc/uptime
  x86/vdso2c: Correct err messages on file opening
  x86/vdso2c: Convert iterator to unsigned
  x86/vdso/Makefile: Add vobjs32
  x86/vdso: Restrict splitting VVAR VMA
  x86/vdso: Rename vdso_image {.data=>.text}
  x86/vdso: Allocate timens vdso
  x86/vdso: Switch image on setns()/clone()
  x86/vdso2c: Process jump tables
  posix-clocks: Add align for timens_offsets
  selftest/timens: Add Time Namespace test for supported clocks
  selftest/timens: Add procfs selftest

 MAINTAINERS                                   |   3 +
 arch/Kconfig                                  |   5 +
 arch/x86/Kconfig                              |   1 +
 arch/x86/entry/vdso/Makefile                  |  15 +-
 arch/x86/entry/vdso/vdso-layout.lds.S         |  10 +-
 arch/x86/entry/vdso/vdso2c.c                  |   7 +-
 arch/x86/entry/vdso/vdso2c.h                  |  22 +-
 arch/x86/entry/vdso/vma.c                     | 177 +++++++-
 arch/x86/include/asm/jump_label.h             |  14 +
 arch/x86/include/asm/vdso.h                   |  14 +-
 arch/x86/kernel/jump_label.c                  |  14 +
 fs/proc/base.c                                |  95 +++++
 fs/proc/namespaces.c                          |   4 +
 fs/proc/uptime.c                              |   3 +
 fs/timerfd.c                                  |   3 +
 include/linux/hrtimer.h                       |   2 +-
 include/linux/jump_label.h                    |   8 +
 include/linux/nsproxy.h                       |   2 +
 include/linux/posix-timers.h                  |   3 +
 include/linux/proc_ns.h                       |   3 +
 include/linux/time_namespace.h                | 114 ++++++
 include/linux/timens_offsets.h                |  18 +
 include/linux/user_namespace.h                |   1 +
 include/uapi/linux/sched.h                    |   6 +
 init/Kconfig                                  |   9 +
 kernel/Makefile                               |   1 +
 kernel/fork.c                                 |  16 +-
 kernel/nsproxy.c                              |  41 +-
 kernel/time/alarmtimer.c                      |  68 +++-
 kernel/time/hrtimer.c                         |   8 +-
 kernel/time/posix-clock.c                     |   8 +-
 kernel/time/posix-cpu-timers.c                |  32 +-
 kernel/time/posix-stubs.c                     |  15 +-
 kernel/time/posix-timers.c                    |  89 ++--
 kernel/time/posix-timers.h                    |   7 +-
 kernel/time_namespace.c                       | 385 ++++++++++++++++++
 lib/vdso/gettimeofday.c                       |  53 +++
 tools/testing/selftests/Makefile              |   1 +
 tools/testing/selftests/timens/.gitignore     |   8 +
 tools/testing/selftests/timens/Makefile       |  12 +
 .../selftests/timens/clock_nanosleep.c        | 102 +++++
 tools/testing/selftests/timens/config         |   1 +
 tools/testing/selftests/timens/exec.c         |  93 +++++
 tools/testing/selftests/timens/gettime_perf.c | 101 +++++
 .../selftests/timens/gettime_perf_cold.c      | 160 ++++++++
 tools/testing/selftests/timens/log.h          |  26 ++
 tools/testing/selftests/timens/procfs.c       | 144 +++++++
 tools/testing/selftests/timens/timens.c       | 185 +++++++++
 tools/testing/selftests/timens/timens.h       |  63 +++
 tools/testing/selftests/timens/timer.c        | 118 ++++++
 tools/testing/selftests/timens/timerfd.c      | 129 ++++++
 51 files changed, 2304 insertions(+), 115 deletions(-)
 create mode 100644 include/linux/time_namespace.h
 create mode 100644 include/linux/timens_offsets.h
 create mode 100644 kernel/time_namespace.c
 create mode 100644 tools/testing/selftests/timens/.gitignore
 create mode 100644 tools/testing/selftests/timens/Makefile
 create mode 100644 tools/testing/selftests/timens/clock_nanosleep.c
 create mode 100644 tools/testing/selftests/timens/config
 create mode 100644 tools/testing/selftests/timens/exec.c
 create mode 100644 tools/testing/selftests/timens/gettime_perf.c
 create mode 100644 tools/testing/selftests/timens/gettime_perf_cold.c
 create mode 100644 tools/testing/selftests/timens/log.h
 create mode 100644 tools/testing/selftests/timens/procfs.c
 create mode 100644 tools/testing/selftests/timens/timens.c
 create mode 100644 tools/testing/selftests/timens/timens.h
 create mode 100644 tools/testing/selftests/timens/timer.c
 create mode 100644 tools/testing/selftests/timens/timerfd.c

-- 
2.22.0

[PATCHv5 01/37] ns: Introduce Time Namespace

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Time Namespace isolates clock values.

The kernel provides access to several clocks CLOCK_REALTIME,
CLOCK_MONOTONIC, CLOCK_BOOTTIME, etc.

CLOCK_REALTIME
      System-wide clock that measures real (i.e., wall-clock) time.

CLOCK_MONOTONIC
      Clock that cannot be set and represents monotonic time since
      some unspecified starting point.

CLOCK_BOOTTIME
      Identical to CLOCK_MONOTONIC, except it also includes any time
      that the system is suspended.

For many users, the time namespace means the ability to changes date and
time in a container (CLOCK_REALTIME).

But in a context of the checkpoint/restore functionality, monotonic and
bootime clocks become interesting. Both clocks are monotonic with
unspecified staring points. These clocks are widely used to measure time
slices and set timers. After restoring or migrating processes, we have to
guarantee that they never go backward. In an ideal case, the behavior of
these clocks should be the same as for a case when a whole system is
suspended. All this means that we need to be able to set CLOCK_MONOTONIC
and CLOCK_BOOTTIME clocks, what can be done by adding per-namespace
offsets for clocks.

A time namespace is similar to a pid namespace in a way how it is
created: unshare(CLONE_NEWTIME) system call creates a new time namespace,
but doesn't set it to the current process. Then all children of
the process will be born in the new time namespace, or a process can
use the setns() system call to join a namespace.

This scheme allows setting clock offsets for a namespace, before any
processes appear in it.

All available clone flags have been used, so CLONE_NEWTIME uses the
highest bit of CSIGNAL. It means that we can use it with the unshare
system call only. Rith now, this works for us, because time namespace
offsets can be set only when a new time namespace is not populated. In a
future, we will have the clone3 system call [1] which will allow to use
the CSIGNAL mask for clone flags.

[1]: httmps://lkml.kernel.org/r/20190604160944.4058-1-christian@brauner.io

Link: https://criu.org/Time_namespace
Link: https://lists.openvz.org/pipermail/criu/2018-June/041504.html
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 MAINTAINERS                    |   2 +
 fs/proc/namespaces.c           |   4 +
 include/linux/nsproxy.h        |   2 +
 include/linux/proc_ns.h        |   3 +
 include/linux/time_namespace.h |  69 +++++++++++
 include/linux/user_namespace.h |   1 +
 include/uapi/linux/sched.h     |   6 +
 init/Kconfig                   |   7 ++
 kernel/Makefile                |   1 +
 kernel/fork.c                  |  16 ++-
 kernel/nsproxy.c               |  41 +++++--
 kernel/time_namespace.c        | 217 +++++++++++++++++++++++++++++++++
 12 files changed, 359 insertions(+), 10 deletions(-)
 create mode 100644 include/linux/time_namespace.h
 create mode 100644 kernel/time_namespace.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 6426db5198f0..ce6ff88f7efd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12836,6 +12836,8 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
 S:	Maintained
 F:	fs/timerfd.c
 F:	include/linux/timer*
+F:	include/linux/time_namespace.h
+F:	kernel/time_namespace.c
 F:	kernel/time/*timer*
 
 POWER MANAGEMENT CORE
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index dd2b35f78b09..8b5c720fe5d7 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -33,6 +33,10 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_CGROUPS
 	&cgroupns_operations,
 #endif
+#ifdef CONFIG_TIME_NS
+	&timens_operations,
+	&timens_for_children_operations,
+#endif
 };
 
 static const char *proc_ns_get_link(struct dentry *dentry,
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 2ae1b1a4d84d..074f395b9ad2 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -35,6 +35,8 @@ struct nsproxy {
 	struct mnt_namespace *mnt_ns;
 	struct pid_namespace *pid_ns_for_children;
 	struct net 	     *net_ns;
+	struct time_namespace *time_ns;
+	struct time_namespace *time_ns_for_children;
 	struct cgroup_namespace *cgroup_ns;
 };
 extern struct nsproxy init_nsproxy;
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index d31cb6215905..d312e6281e69 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -32,6 +32,8 @@ extern const struct proc_ns_operations pidns_for_children_operations;
 extern const struct proc_ns_operations userns_operations;
 extern const struct proc_ns_operations mntns_operations;
 extern const struct proc_ns_operations cgroupns_operations;
+extern const struct proc_ns_operations timens_operations;
+extern const struct proc_ns_operations timens_for_children_operations;
 
 /*
  * We always define these enumerators
@@ -43,6 +45,7 @@ enum {
 	PROC_USER_INIT_INO	= 0xEFFFFFFDU,
 	PROC_PID_INIT_INO	= 0xEFFFFFFCU,
 	PROC_CGROUP_INIT_INO	= 0xEFFFFFFBU,
+	PROC_TIME_INIT_INO	= 0xEFFFFFFAU,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
new file mode 100644
index 000000000000..9507ed7072fe
--- /dev/null
+++ b/include/linux/time_namespace.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TIMENS_H
+#define _LINUX_TIMENS_H
+
+
+#include <linux/sched.h>
+#include <linux/kref.h>
+#include <linux/nsproxy.h>
+#include <linux/ns_common.h>
+#include <linux/err.h>
+
+struct user_namespace;
+extern struct user_namespace init_user_ns;
+
+struct time_namespace {
+	struct kref kref;
+	struct user_namespace *user_ns;
+	struct ucounts *ucounts;
+	struct ns_common ns;
+	struct timens_offsets *offsets;
+	bool   initialized;
+} __randomize_layout;
+extern struct time_namespace init_time_ns;
+
+#ifdef CONFIG_TIME_NS
+static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
+{
+	kref_get(&ns->kref);
+	return ns;
+}
+
+extern struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns);
+extern void free_time_ns(struct kref *kref);
+extern int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
+
+static inline void put_time_ns(struct time_namespace *ns)
+{
+	kref_put(&ns->kref, free_time_ns);
+}
+
+
+#else
+static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
+{
+	return NULL;
+}
+
+static inline void put_time_ns(struct time_namespace *ns)
+{
+}
+
+static inline struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns)
+{
+	if (flags & CLONE_NEWTIME)
+		return ERR_PTR(-EINVAL);
+
+	return old_ns;
+}
+
+static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+{
+	return 0;
+}
+
+#endif
+
+#endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index fb9f4f799554..6ef1c7109fc4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -45,6 +45,7 @@ enum ucount_type {
 	UCOUNT_NET_NAMESPACES,
 	UCOUNT_MNT_NAMESPACES,
 	UCOUNT_CGROUP_NAMESPACES,
+	UCOUNT_TIME_NAMESPACES,
 #ifdef CONFIG_INOTIFY_USER
 	UCOUNT_INOTIFY_INSTANCES,
 	UCOUNT_INOTIFY_WATCHES,
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index b3105ac1381a..551739227e96 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -33,6 +33,12 @@
 #define CLONE_NEWNET		0x40000000	/* New network namespace */
 #define CLONE_IO		0x80000000	/* Clone io context */
 
+/*
+ * cloning flags intersect with CSIGNAL so can be used with unshare and clone3
+ * syscalls only:
+ */
+#define CLONE_NEWTIME	0x00000080	/* New time namespace */
+
 /*
  * Arguments for the clone3 syscall
  */
diff --git a/init/Kconfig b/init/Kconfig
index bd7d650d4a99..a7cbc9b470c7 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1069,6 +1069,13 @@ config UTS_NS
 	  In this namespace tasks see different info provided with the
 	  uname() system call
 
+config TIME_NS
+	bool "TIME namespace"
+	default y
+	help
+	  In this namespace boottime and monotonic clocks can be set.
+	  The time will keep going with the same pace.
+
 config IPC_NS
 	bool "IPC namespace"
 	depends on (SYSVIPC || POSIX_MQUEUE)
diff --git a/kernel/Makefile b/kernel/Makefile
index a8d923b5481b..a8654c9aa2f5 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup/
 obj-$(CONFIG_UTS_NS) += utsname.o
+obj-$(CONFIG_TIME_NS) += time_namespace.o
 obj-$(CONFIG_USER_NS) += user_namespace.o
 obj-$(CONFIG_PID_NS) += pid_namespace.o
 obj-$(CONFIG_IKCONFIG) += configs.o
diff --git a/kernel/fork.c b/kernel/fork.c
index 2852d0e76ea3..3dbb2d33dc52 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1777,6 +1777,7 @@ static __latent_entropy struct task_struct *copy_process(
 	struct multiprocess_signals delayed;
 	struct file *pidfile = NULL;
 	u64 clone_flags = args->flags;
+	struct nsproxy *nsp = current->nsproxy;
 
 	/*
 	 * Don't allow sharing the root directory with processes in a different
@@ -1819,8 +1820,16 @@ static __latent_entropy struct task_struct *copy_process(
 	 */
 	if (clone_flags & CLONE_THREAD) {
 		if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
-		    (task_active_pid_ns(current) !=
-				current->nsproxy->pid_ns_for_children))
+		    (task_active_pid_ns(current) != nsp->pid_ns_for_children))
+			return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * If the new process will be in a different time namespace
+	 * do not allow it to share VM or a thread group with the forking task.
+	 */
+	if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
+		if (nsp->time_ns != nsp->time_ns_for_children)
 			return ERR_PTR(-EINVAL);
 	}
 
@@ -2707,7 +2716,8 @@ static int check_unshare_flags(unsigned long unshare_flags)
 	if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
 				CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
 				CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
-				CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP))
+				CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
+				CLONE_NEWTIME))
 		return -EINVAL;
 	/*
 	 * Not implemented, but pretend it works if there is nothing
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index c815f58e6bc0..ed9882108cd2 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -18,6 +18,7 @@
 #include <linux/pid_namespace.h>
 #include <net/net_namespace.h>
 #include <linux/ipc_namespace.h>
+#include <linux/time_namespace.h>
 #include <linux/proc_ns.h>
 #include <linux/file.h>
 #include <linux/syscalls.h>
@@ -40,6 +41,10 @@ struct nsproxy init_nsproxy = {
 #ifdef CONFIG_CGROUPS
 	.cgroup_ns		= &init_cgroup_ns,
 #endif
+#ifdef CONFIG_TIME_NS
+	.time_ns		= &init_time_ns,
+	.time_ns_for_children	= &init_time_ns,
+#endif
 };
 
 static inline struct nsproxy *create_nsproxy(void)
@@ -106,8 +111,18 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
 		goto out_net;
 	}
 
+	new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
+					tsk->nsproxy->time_ns_for_children);
+	if (IS_ERR(new_nsp->time_ns_for_children)) {
+		err = PTR_ERR(new_nsp->time_ns_for_children);
+		goto out_time;
+	}
+	new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
+
 	return new_nsp;
 
+out_time:
+	put_net(new_nsp->net_ns);
 out_net:
 	put_cgroup_ns(new_nsp->cgroup_ns);
 out_cgroup:
@@ -136,15 +151,16 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 	struct nsproxy *old_ns = tsk->nsproxy;
 	struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
 	struct nsproxy *new_ns;
+	int ret;
 
 	if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 			      CLONE_NEWPID | CLONE_NEWNET |
-			      CLONE_NEWCGROUP)))) {
-		get_nsproxy(old_ns);
-		return 0;
-	}
-
-	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+			      CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
+		if (likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
+			get_nsproxy(old_ns);
+			return 0;
+		}
+	} else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	/*
@@ -162,6 +178,12 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 	if (IS_ERR(new_ns))
 		return  PTR_ERR(new_ns);
 
+	ret = timens_on_fork(new_ns, tsk);
+	if (ret) {
+		free_nsproxy(new_ns);
+		return ret;
+	}
+
 	tsk->nsproxy = new_ns;
 	return 0;
 }
@@ -176,6 +198,10 @@ void free_nsproxy(struct nsproxy *ns)
 		put_ipc_ns(ns->ipc_ns);
 	if (ns->pid_ns_for_children)
 		put_pid_ns(ns->pid_ns_for_children);
+	if (ns->time_ns)
+		put_time_ns(ns->time_ns);
+	if (ns->time_ns_for_children)
+		put_time_ns(ns->time_ns_for_children);
 	put_cgroup_ns(ns->cgroup_ns);
 	put_net(ns->net_ns);
 	kmem_cache_free(nsproxy_cachep, ns);
@@ -192,7 +218,8 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 	int err = 0;
 
 	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
-			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
+			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
+			       CLONE_NEWTIME)))
 		return 0;
 
 	user_ns = new_cred ? new_cred->user_ns : current_user_ns();
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
new file mode 100644
index 000000000000..7ee6be0647bc
--- /dev/null
+++ b/kernel/time_namespace.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Andrei Vagin <avagin@openvz.org>
+ * Author: Dmitry Safonov <dima@arista.com>
+ */
+
+#include <linux/time_namespace.h>
+#include <linux/user_namespace.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/proc_ns.h>
+#include <linux/export.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+
+static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
+{
+	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
+}
+
+static void dec_time_namespaces(struct ucounts *ucounts)
+{
+	dec_ucount(ucounts, UCOUNT_TIME_NAMESPACES);
+}
+
+static struct time_namespace *create_time_ns(void)
+{
+	struct time_namespace *time_ns;
+
+	time_ns = kmalloc(sizeof(struct time_namespace), GFP_KERNEL);
+	if (time_ns) {
+		kref_init(&time_ns->kref);
+		time_ns->initialized = false;
+	}
+	return time_ns;
+}
+
+/*
+ * Clone a new ns copying @old_ns, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return the new ns or ERR_PTR.
+ */
+static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
+					  struct time_namespace *old_ns)
+{
+	struct time_namespace *ns;
+	struct ucounts *ucounts;
+	int err;
+
+	err = -ENOSPC;
+	ucounts = inc_time_namespaces(user_ns);
+	if (!ucounts)
+		goto fail;
+
+	err = -ENOMEM;
+	ns = create_time_ns();
+	if (!ns)
+		goto fail_dec;
+
+	err = ns_alloc_inum(&ns->ns);
+	if (err)
+		goto fail_free;
+
+	ns->ucounts = ucounts;
+	ns->ns.ops = &timens_operations;
+	ns->user_ns = get_user_ns(user_ns);
+	return ns;
+
+fail_free:
+	kfree(ns);
+fail_dec:
+	dec_time_namespaces(ucounts);
+fail:
+	return ERR_PTR(err);
+}
+
+/*
+ * Add a reference to old_ns, or clone it if @flags specify CLONE_NEWTIME.
+ * In latter case, changes to the time of this process won't be seen by parent,
+ * and vice versa.
+ */
+struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns)
+{
+	if (!(flags & CLONE_NEWTIME))
+		return get_time_ns(old_ns);
+
+	return clone_time_ns(user_ns, old_ns);
+}
+
+void free_time_ns(struct kref *kref)
+{
+	struct time_namespace *ns;
+
+	ns = container_of(kref, struct time_namespace, kref);
+	dec_time_namespaces(ns->ucounts);
+	put_user_ns(ns->user_ns);
+	ns_free_inum(&ns->ns);
+	kfree(ns);
+}
+
+static struct time_namespace *to_time_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct time_namespace, ns);
+}
+
+static struct ns_common *timens_get(struct task_struct *task)
+{
+	struct time_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->time_ns;
+		get_time_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static struct ns_common *timens_for_children_get(struct task_struct *task)
+{
+	struct time_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->time_ns_for_children;
+		get_time_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void timens_put(struct ns_common *ns)
+{
+	put_time_ns(to_time_ns(ns));
+}
+
+static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+	struct time_namespace *ns = to_time_ns(new);
+
+	if (!thread_group_empty(current))
+		return -EINVAL;
+
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+		return -EPERM;
+
+	get_time_ns(ns);
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns);
+	put_time_ns(nsproxy->time_ns_for_children);
+	nsproxy->time_ns = ns;
+	nsproxy->time_ns_for_children = ns;
+	ns->initialized = true;
+	return 0;
+}
+
+int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+{
+	struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
+	struct time_namespace *ns = to_time_ns(nsc);
+
+	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
+		return 0;
+
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns);
+	nsproxy->time_ns = ns;
+	ns->initialized = true;
+
+	return 0;
+}
+
+static struct user_namespace *timens_owner(struct ns_common *ns)
+{
+	return to_time_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations timens_operations = {
+	.name		= "time",
+	.type		= CLONE_NEWTIME,
+	.get		= timens_get,
+	.put		= timens_put,
+	.install	= timens_install,
+	.owner		= timens_owner,
+};
+
+const struct proc_ns_operations timens_for_children_operations = {
+	.name		= "time_for_children",
+	.type		= CLONE_NEWTIME,
+	.get		= timens_for_children_get,
+	.put		= timens_put,
+	.install	= timens_install,
+	.owner		= timens_owner,
+};
+
+struct time_namespace init_time_ns = {
+	.kref = KREF_INIT(3),
+	.user_ns = &init_user_ns,
+	.ns.inum = PROC_TIME_INIT_INO,
+	.ns.ops = &timens_operations,
+};
+
+static int __init time_ns_init(void)
+{
+	return 0;
+}
+subsys_initcall(time_ns_init);
-- 
2.22.0

[PATCHv5 02/37] timens: Add timens_offsets

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Introduce offsets for time namespace. They will contain an adjustment
needed to convert clocks to/from host's.

Allocate one page for each time namespace that will be premapped into
userspace among vvar pages.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 MAINTAINERS                    |  1 +
 include/linux/time_namespace.h |  1 +
 include/linux/timens_offsets.h |  8 ++++++++
 kernel/time_namespace.c        | 14 ++++++++++++--
 4 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/timens_offsets.h

diff --git a/MAINTAINERS b/MAINTAINERS
index ce6ff88f7efd..b58c49d331eb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12837,6 +12837,7 @@ S:	Maintained
 F:	fs/timerfd.c
 F:	include/linux/timer*
 F:	include/linux/time_namespace.h
+F:	include/linux/timens_offsets.h
 F:	kernel/time_namespace.c
 F:	kernel/time/*timer*
 
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 9507ed7072fe..b6985aa87479 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -8,6 +8,7 @@
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/err.h>
+#include <linux/timens_offsets.h>
 
 struct user_namespace;
 extern struct user_namespace init_user_ns;
diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
new file mode 100644
index 000000000000..7d7cb68ea778
--- /dev/null
+++ b/include/linux/timens_offsets.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TIME_OFFSETS_H
+#define _LINUX_TIME_OFFSETS_H
+
+struct timens_offsets {
+};
+
+#endif
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index 7ee6be0647bc..f849c59f1108 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/cred.h>
 #include <linux/err.h>
+#include <linux/mm.h>
 
 static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
 {
@@ -47,6 +48,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 {
 	struct time_namespace *ns;
 	struct ucounts *ucounts;
+	struct page *page;
 	int err;
 
 	err = -ENOSPC;
@@ -59,15 +61,22 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 	if (!ns)
 		goto fail_dec;
 
+	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	if (!page)
+		goto fail_free;
+	ns->offsets = page_address(page);
+	BUILD_BUG_ON(sizeof(*ns->offsets) > PAGE_SIZE);
+
 	err = ns_alloc_inum(&ns->ns);
 	if (err)
-		goto fail_free;
+		goto fail_page;
 
 	ns->ucounts = ucounts;
 	ns->ns.ops = &timens_operations;
 	ns->user_ns = get_user_ns(user_ns);
 	return ns;
-
+fail_page:
+	free_page((unsigned long)ns->offsets);
 fail_free:
 	kfree(ns);
 fail_dec:
@@ -95,6 +104,7 @@ void free_time_ns(struct kref *kref)
 	struct time_namespace *ns;
 
 	ns = container_of(kref, struct time_namespace, kref);
+	free_page((unsigned long)ns->offsets);
 	dec_time_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
 	ns_free_inum(&ns->ns);
-- 
2.22.0

[PATCHv5 03/37] posix-clocks: Rename the clock_get() into clock_get_timespec()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
 - The time in a task's time namespace for sys_clock_gettime()
 - The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format, rather than in (struct timespec).

Rename clock_get() callback into clock_get_timespec() as a preparation
for introducing clock_get_ktime().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c       |  4 ++--
 kernel/time/posix-clock.c      |  8 ++++----
 kernel/time/posix-cpu-timers.c | 32 ++++++++++++++++----------------
 kernel/time/posix-timers.c     | 22 +++++++++++-----------
 kernel/time/posix-timers.h     |  4 ++--
 5 files changed, 35 insertions(+), 35 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 57518efc3810..cada96fdc615 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -644,7 +644,7 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
 }
 
 /**
- * alarm_clock_get - posix clock_get interface
+ * alarm_clock_get - posix clock_get_timespec interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
@@ -824,7 +824,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
-	.clock_get		= alarm_clock_get,
+	.clock_get_timespec	= alarm_clock_get,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_del		= common_timer_del,
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index ec960bb939fd..c8f9c9b1cd82 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -315,8 +315,8 @@ static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
 }
 
 const struct k_clock clock_posix_dynamic = {
-	.clock_getres	= pc_clock_getres,
-	.clock_set	= pc_clock_settime,
-	.clock_get	= pc_clock_gettime,
-	.clock_adj	= pc_clock_adjtime,
+	.clock_getres		= pc_clock_getres,
+	.clock_set		= pc_clock_settime,
+	.clock_get_timespec	= pc_clock_gettime,
+	.clock_adj		= pc_clock_adjtime,
 };
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 0a426f4e3125..dccf7dfcd36a 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1417,26 +1417,26 @@ static int thread_cpu_timer_create(struct k_itimer *timer)
 }
 
 const struct k_clock clock_posix_cpu = {
-	.clock_getres	= posix_cpu_clock_getres,
-	.clock_set	= posix_cpu_clock_set,
-	.clock_get	= posix_cpu_clock_get,
-	.timer_create	= posix_cpu_timer_create,
-	.nsleep		= posix_cpu_nsleep,
-	.timer_set	= posix_cpu_timer_set,
-	.timer_del	= posix_cpu_timer_del,
-	.timer_get	= posix_cpu_timer_get,
-	.timer_rearm	= posix_cpu_timer_rearm,
+	.clock_getres		= posix_cpu_clock_getres,
+	.clock_set		= posix_cpu_clock_set,
+	.clock_get_timespec	= posix_cpu_clock_get,
+	.timer_create		= posix_cpu_timer_create,
+	.nsleep			= posix_cpu_nsleep,
+	.timer_set		= posix_cpu_timer_set,
+	.timer_del		= posix_cpu_timer_del,
+	.timer_get		= posix_cpu_timer_get,
+	.timer_rearm		= posix_cpu_timer_rearm,
 };
 
 const struct k_clock clock_process = {
-	.clock_getres	= process_cpu_clock_getres,
-	.clock_get	= process_cpu_clock_get,
-	.timer_create	= process_cpu_timer_create,
-	.nsleep		= process_cpu_nsleep,
+	.clock_getres		= process_cpu_clock_getres,
+	.clock_get_timespec	= process_cpu_clock_get,
+	.timer_create		= process_cpu_timer_create,
+	.nsleep			= process_cpu_nsleep,
 };
 
 const struct k_clock clock_thread = {
-	.clock_getres	= thread_cpu_clock_getres,
-	.clock_get	= thread_cpu_clock_get,
-	.timer_create	= thread_cpu_timer_create,
+	.clock_getres		= thread_cpu_clock_getres,
+	.clock_get_timespec	= thread_cpu_clock_get,
+	.timer_create		= thread_cpu_timer_create,
 };
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index d7f2d91acdac..6c9c0f2d2f1e 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -667,7 +667,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 	 * The timespec64 based conversion is suboptimal, but it's not
 	 * worth to implement yet another callback.
 	 */
-	kc->clock_get(timr->it_clock, &ts64);
+	kc->clock_get_timespec(timr->it_clock, &ts64);
 	now = timespec64_to_ktime(ts64);
 
 	/*
@@ -781,7 +781,7 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
 	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
 	 * clock modifications, so they become CLOCK_MONOTONIC based under the
 	 * hood. See hrtimer_init(). Update timr->kclock, so the generic
-	 * functions which use timr->kclock->clock_get() work.
+	 * functions which use timr->kclock->clock_get_timespec() work.
 	 *
 	 * Note: it_clock stays unmodified, because the next timer_set() might
 	 * use ABSTIME, so it needs to switch back.
@@ -1032,7 +1032,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 	if (!kc)
 		return -EINVAL;
 
-	error = kc->clock_get(which_clock, &kernel_tp);
+	error = kc->clock_get_timespec(which_clock, &kernel_tp);
 
 	if (!error && put_timespec64(&kernel_tp, tp))
 		error = -EFAULT;
@@ -1114,7 +1114,7 @@ SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
 	if (!kc)
 		return -EINVAL;
 
-	err = kc->clock_get(which_clock, &ts);
+	err = kc->clock_get_timespec(which_clock, &ts);
 
 	if (!err && put_old_timespec32(&ts, tp))
 		err = -EFAULT;
@@ -1226,7 +1226,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_clock_realtime_get,
+	.clock_get_timespec	= posix_clock_realtime_get,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1243,7 +1243,7 @@ static const struct k_clock clock_realtime = {
 
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_ktime_get_ts,
+	.clock_get_timespec	= posix_ktime_get_ts,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1258,22 +1258,22 @@ static const struct k_clock clock_monotonic = {
 
 static const struct k_clock clock_monotonic_raw = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_monotonic_raw,
+	.clock_get_timespec	= posix_get_monotonic_raw,
 };
 
 static const struct k_clock clock_realtime_coarse = {
 	.clock_getres		= posix_get_coarse_res,
-	.clock_get		= posix_get_realtime_coarse,
+	.clock_get_timespec	= posix_get_realtime_coarse,
 };
 
 static const struct k_clock clock_monotonic_coarse = {
 	.clock_getres		= posix_get_coarse_res,
-	.clock_get		= posix_get_monotonic_coarse,
+	.clock_get_timespec	= posix_get_monotonic_coarse,
 };
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_tai,
+	.clock_get_timespec	= posix_get_tai,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1288,7 +1288,7 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_boottime,
+	.clock_get_timespec	= posix_get_boottime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index de5daa6d975a..b3cc9ee36a6b 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -6,8 +6,8 @@ struct k_clock {
 				struct timespec64 *tp);
 	int	(*clock_set)(const clockid_t which_clock,
 			     const struct timespec64 *tp);
-	int	(*clock_get)(const clockid_t which_clock,
-			     struct timespec64 *tp);
+	int	(*clock_get_timespec)(const clockid_t which_clock,
+				      struct timespec64 *tp);
 	int	(*clock_adj)(const clockid_t which_clock, struct __kernel_timex *tx);
 	int	(*timer_create)(struct k_itimer *timer);
 	int	(*nsleep)(const clockid_t which_clock, int flags,
-- 
2.22.0

[PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a task's time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format in (struct k_clock).

As a preparation ground for introducing clock_get_ktime(), the original
callback clock_get() was renamed into clock_get_timespec().
Reflect the renaming into callbacks realizations.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c   |  6 +++---
 kernel/time/posix-timers.c | 17 +++++++++--------
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index cada96fdc615..c191254f178b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -644,13 +644,13 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
 }
 
 /**
- * alarm_clock_get - posix clock_get_timespec interface
+ * alarm_clock_get_timespec - posix clock_get_timespec interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
  * Provides the underlying alarm base time.
  */
-static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
+static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 
@@ -824,7 +824,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
-	.clock_get_timespec	= alarm_clock_get,
+	.clock_get_timespec	= alarm_clock_get_timespec,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_del		= common_timer_del,
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 6c9c0f2d2f1e..a71e43178a7d 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -165,7 +165,8 @@ static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 }
 
 /* Get clock_realtime */
-static int posix_clock_realtime_get(clockid_t which_clock, struct timespec64 *tp)
+static int
+posix_clock_realtime_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_real_ts64(tp);
 	return 0;
@@ -187,7 +188,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 /*
  * Get monotonic time for posix timers
  */
-static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
+static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
@@ -222,13 +223,13 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
-static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
+static int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
 	return 0;
 }
 
-static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
+static int posix_get_tai_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_clocktai_ts64(tp);
 	return 0;
@@ -1226,7 +1227,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_clock_realtime_get,
+	.clock_get_timespec	= posix_clock_realtime_get_timespec,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1243,7 +1244,7 @@ static const struct k_clock clock_realtime = {
 
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_ktime_get_ts,
+	.clock_get_timespec	= posix_get_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1273,7 +1274,7 @@ static const struct k_clock clock_monotonic_coarse = {
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_get_tai,
+	.clock_get_timespec	= posix_get_tai_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1288,7 +1289,7 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_get_boottime,
+	.clock_get_timespec	= posix_get_boottime_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
-- 
2.22.0

[PATCHv5 05/37] alarmtimer: Rename gettime() callback to get_ktime()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a tasks time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

struct alarm_base needs to follow the same name convention, so rename
.gettime() callback into get_ktime() as a preparation for introducing
get_timespec().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index c191254f178b..37254eb64459 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -36,13 +36,13 @@
  * struct alarm_base - Alarm timer bases
  * @lock:		Lock for syncrhonized access to the base
  * @timerqueue:		Timerqueue head managing the list of events
- * @gettime:		Function to read the time correlating to the base
+ * @get_ktime:		Function to read the time correlating to the base
  * @base_clockid:	clockid for the base
  */
 static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
-	ktime_t			(*gettime)(void);
+	ktime_t			(*get_ktime)(void);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
@@ -207,7 +207,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 	spin_unlock_irqrestore(&base->lock, flags);
 
 	if (alarm->function)
-		restart = alarm->function(alarm, base->gettime());
+		restart = alarm->function(alarm, base->get_ktime());
 
 	spin_lock_irqsave(&base->lock, flags);
 	if (restart != ALARMTIMER_NORESTART) {
@@ -217,7 +217,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 	}
 	spin_unlock_irqrestore(&base->lock, flags);
 
-	trace_alarmtimer_fired(alarm, base->gettime());
+	trace_alarmtimer_fired(alarm, base->get_ktime());
 	return ret;
 
 }
@@ -225,7 +225,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
-	return ktime_sub(alarm->node.expires, base->gettime());
+	return ktime_sub(alarm->node.expires, base->get_ktime());
 }
 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 
@@ -270,7 +270,7 @@ static int alarmtimer_suspend(struct device *dev)
 		spin_unlock_irqrestore(&base->lock, flags);
 		if (!next)
 			continue;
-		delta = ktime_sub(next->expires, base->gettime());
+		delta = ktime_sub(next->expires, base->get_ktime());
 		if (!min || (delta < min)) {
 			expires = next->expires;
 			min = delta;
@@ -364,7 +364,7 @@ void alarm_start(struct alarm *alarm, ktime_t start)
 	hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 	spin_unlock_irqrestore(&base->lock, flags);
 
-	trace_alarmtimer_start(alarm, base->gettime());
+	trace_alarmtimer_start(alarm, base->get_ktime());
 }
 EXPORT_SYMBOL_GPL(alarm_start);
 
@@ -377,7 +377,7 @@ void alarm_start_relative(struct alarm *alarm, ktime_t start)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 
-	start = ktime_add_safe(start, base->gettime());
+	start = ktime_add_safe(start, base->get_ktime());
 	alarm_start(alarm, start);
 }
 EXPORT_SYMBOL_GPL(alarm_start_relative);
@@ -414,7 +414,7 @@ int alarm_try_to_cancel(struct alarm *alarm)
 		alarmtimer_dequeue(base, alarm);
 	spin_unlock_irqrestore(&base->lock, flags);
 
-	trace_alarmtimer_cancel(alarm, base->gettime());
+	trace_alarmtimer_cancel(alarm, base->get_ktime());
 	return ret;
 }
 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
@@ -474,7 +474,7 @@ u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 
-	return alarm_forward(alarm, base->gettime(), interval);
+	return alarm_forward(alarm, base->get_ktime(), interval);
 }
 EXPORT_SYMBOL_GPL(alarm_forward_now);
 
@@ -500,7 +500,7 @@ static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 		return;
 	}
 
-	delta = ktime_sub(absexp, base->gettime());
+	delta = ktime_sub(absexp, base->get_ktime());
 
 	spin_lock_irqsave(&freezer_delta_lock, flags);
 	if (!freezer_delta || (delta < freezer_delta)) {
@@ -619,7 +619,7 @@ static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 	struct alarm_base *base = &alarm_bases[alarm->type];
 
 	if (!absolute)
-		expires = ktime_add_safe(expires, base->gettime());
+		expires = ktime_add_safe(expires, base->get_ktime());
 	if (sigev_none)
 		alarm->node.expires = expires;
 	else
@@ -657,7 +657,7 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;
 
-	*tp = ktime_to_timespec64(base->gettime());
+	*tp = ktime_to_timespec64(base->get_ktime());
 	return 0;
 }
 
@@ -734,7 +734,7 @@ static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 		struct timespec64 rmt;
 		ktime_t rem;
 
-		rem = ktime_sub(absexp, alarm_bases[type].gettime());
+		rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 
 		if (rem <= 0)
 			return 0;
@@ -803,7 +803,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 	exp = timespec64_to_ktime(*tsreq);
 	/* Convert (if necessary) to absolute time */
 	if (flags != TIMER_ABSTIME) {
-		ktime_t now = alarm_bases[type].gettime();
+		ktime_t now = alarm_bases[type].get_ktime();
 
 		exp = ktime_add_safe(now, exp);
 	}
@@ -868,9 +868,9 @@ static int __init alarmtimer_init(void)
 
 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
-	alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
+	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
-	alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
+	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
-- 
2.22.0

[PATCHv5 06/37] alarmtimer: Provide get_timespec() callback

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a task's time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

Wire up alarm bases with get_timespec().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/posix-timers.h | 3 +++
 kernel/time/alarmtimer.c     | 8 ++++++--
 kernel/time/posix-timers.c   | 4 ++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index b20798fc5191..fe13ab265213 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -127,4 +127,7 @@ void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
 
 void posixtimer_rearm(struct kernel_siginfo *info);
+
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp);
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp);
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 37254eb64459..d9e6baa9976a 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -37,12 +37,15 @@
  * @lock:		Lock for syncrhonized access to the base
  * @timerqueue:		Timerqueue head managing the list of events
  * @get_ktime:		Function to read the time correlating to the base
+ * @get_timespec:	Function to read the namespace time correlating to the base
  * @base_clockid:	clockid for the base
  */
 static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
 	ktime_t			(*get_ktime)(void);
+	int			(*get_timespec)(const clockid_t which_clock,
+						struct timespec64 *tp);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
@@ -657,8 +660,7 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;
 
-	*tp = ktime_to_timespec64(base->get_ktime());
-	return 0;
+	return base->get_timespec(base->base_clockid, tp);
 }
 
 /**
@@ -869,8 +871,10 @@ static int __init alarmtimer_init(void)
 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
+	alarm_bases[ALARM_REALTIME].get_timespec = posix_get_timespec,
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
+	alarm_bases[ALARM_BOOTTIME].get_timespec = posix_get_boottime_timespec;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index a71e43178a7d..a600b8b3e9bf 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -188,7 +188,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 /*
  * Get monotonic time for posix timers
  */
-static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
@@ -223,7 +223,7 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
-static int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
 	return 0;
-- 
2.22.0

[PATCHv5 07/37] posix-clocks: Introduce clock_get_ktime() callback

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The callsite in common_timer_get() has already a comment:
    /*
     * The timespec64 based conversion is suboptimal, but it's not
     * worth to implement yet another callback.
     */
    kc->clock_get(timr->it_clock, &ts64);
    now = timespec64_to_ktime(ts64);

The upcoming support for time namespaces requires to have access to:
- The time in a task's time namespace for sys_clock_gettime()
- The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c   | 19 ++++++++++++++++++-
 kernel/time/posix-timers.c | 26 +++++++++++++++++++++++++-
 kernel/time/posix-timers.h |  3 +++
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index d9e6baa9976a..55cb6e78d082 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -651,7 +651,7 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
- * Provides the underlying alarm base time.
+ * Provides the underlying alarm base time in a tasks time namespace.
  */
 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
@@ -663,6 +663,22 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	return base->get_timespec(base->base_clockid, tp);
 }
 
+/**
+ * alarm_clock_get_ktime - posix clock_get_ktime interface
+ * @which_clock: clockid
+ *
+ * Provides the underlying alarm base time in the root namespace.
+ */
+static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
+{
+	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
+
+	if (!alarmtimer_get_rtcdev())
+		return -EINVAL;
+
+	return base->get_ktime();
+}
+
 /**
  * alarm_timer_create - posix timer_create interface
  * @new_timer: k_itimer pointer to manage
@@ -826,6 +842,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
+	.clock_get_ktime	= alarm_clock_get_ktime,
 	.clock_get_timespec	= alarm_clock_get_timespec,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index a600b8b3e9bf..fb1848c84241 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -172,6 +172,11 @@ posix_clock_realtime_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
+static ktime_t posix_clock_realtime_get_ktime(clockid_t which_clock)
+{
+	return ktime_get_real();
+}
+
 /* Set clock_realtime */
 static int posix_clock_realtime_set(const clockid_t which_clock,
 				    const struct timespec64 *tp)
@@ -194,6 +199,11 @@ int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
+static ktime_t posix_get_ktime(clockid_t which_clock)
+{
+	return ktime_get();
+}
+
 /*
  * Get monotonic-raw time for posix timers
  */
@@ -229,12 +239,22 @@ int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
+static ktime_t posix_get_boottime_ktime(const clockid_t which_clock)
+{
+	return ktime_get_boottime();
+}
+
 static int posix_get_tai_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_clocktai_ts64(tp);
 	return 0;
 }
 
+static ktime_t posix_get_tai_ktime(clockid_t which_clock)
+{
+	return ktime_get_clocktai();
+}
+
 static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
 {
 	tp->tv_sec = 0;
@@ -782,7 +802,7 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
 	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
 	 * clock modifications, so they become CLOCK_MONOTONIC based under the
 	 * hood. See hrtimer_init(). Update timr->kclock, so the generic
-	 * functions which use timr->kclock->clock_get_timespec() work.
+	 * functions which use timr->kclock->clock_get_*() work.
 	 *
 	 * Note: it_clock stays unmodified, because the next timer_set() might
 	 * use ABSTIME, so it needs to switch back.
@@ -1228,6 +1248,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_timespec	= posix_clock_realtime_get_timespec,
+	.clock_get_ktime	= posix_clock_realtime_get_ktime,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1245,6 +1266,7 @@ static const struct k_clock clock_realtime = {
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_timespec	= posix_get_timespec,
+	.clock_get_ktime	= posix_get_ktime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1274,6 +1296,7 @@ static const struct k_clock clock_monotonic_coarse = {
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get_ktime	= posix_get_tai_ktime,
 	.clock_get_timespec	= posix_get_tai_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
@@ -1289,6 +1312,7 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get_ktime	= posix_get_boottime_ktime,
 	.clock_get_timespec	= posix_get_boottime_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index b3cc9ee36a6b..183994f7e466 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -6,8 +6,11 @@ struct k_clock {
 				struct timespec64 *tp);
 	int	(*clock_set)(const clockid_t which_clock,
 			     const struct timespec64 *tp);
+	/* Returns the clock value in the current time namespace. */
 	int	(*clock_get_timespec)(const clockid_t which_clock,
 				      struct timespec64 *tp);
+	/* Returns the clock value in the root time namespace. */
+	ktime_t	(*clock_get_ktime)(const clockid_t which_clock);
 	int	(*clock_adj)(const clockid_t which_clock, struct __kernel_timex *tx);
 	int	(*timer_create)(struct k_itimer *timer);
 	int	(*nsleep)(const clockid_t which_clock, int flags,
-- 
2.22.0

[PATCHv5 08/37] posix-timers: Use clock_get_ktime() in common_timer_get()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Now, when the clock_get_ktime() callback exists, the suboptimal
timespec64-based conversion can be removed from common_timer_get().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/posix-timers.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index fb1848c84241..aae7ab53790d 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -666,7 +666,6 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 {
 	const struct k_clock *kc = timr->kclock;
 	ktime_t now, remaining, iv;
-	struct timespec64 ts64;
 	bool sig_none;
 
 	sig_none = timr->it_sigev_notify == SIGEV_NONE;
@@ -684,12 +683,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 			return;
 	}
 
-	/*
-	 * The timespec64 based conversion is suboptimal, but it's not
-	 * worth to implement yet another callback.
-	 */
-	kc->clock_get_timespec(timr->it_clock, &ts64);
-	now = timespec64_to_ktime(ts64);
+	now = kc->clock_get_ktime(timr->it_clock);
 
 	/*
 	 * When a requeue is pending or this is a SIGEV_NONE timer move the
-- 
2.22.0

[PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Add monotonic time virtualisation for time namespace.
Introduce timespec for monotionic clock into timens offsets and wire
clock_gettime() syscall.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h | 8 ++++++++
 include/linux/timens_offsets.h | 1 +
 kernel/time/posix-stubs.c      | 2 ++
 kernel/time/posix-timers.c     | 4 ++++
 4 files changed, 15 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index b6985aa87479..186c134fe222 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -40,6 +40,13 @@ static inline void put_time_ns(struct time_namespace *ns)
 	kref_put(&ns->kref, free_time_ns);
 }
 
+static inline void timens_add_monotonic(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
+
+	if (ns_offsets)
+		*ts = timespec64_add(*ts, ns_offsets->monotonic);
+}
 
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
@@ -65,6 +72,7 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 	return 0;
 }
 
+static inline void timens_add_monotonic(struct timespec64 *ts) {}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index 7d7cb68ea778..eaac2c82be5c 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -3,6 +3,7 @@
 #define _LINUX_TIME_OFFSETS_H
 
 struct timens_offsets {
+	struct timespec64 monotonic;
 };
 
 #endif
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 67df65f887ac..17c67e0aecd8 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -14,6 +14,7 @@
 #include <linux/ktime.h>
 #include <linux/timekeeping.h>
 #include <linux/posix-timers.h>
+#include <linux/time_namespace.h>
 #include <linux/compat.h>
 
 #ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
@@ -77,6 +78,7 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 		break;
 	case CLOCK_MONOTONIC:
 		ktime_get_ts64(tp);
+		timens_add_monotonic(tp);
 		break;
 	case CLOCK_BOOTTIME:
 		ktime_get_boottime_ts64(tp);
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index aae7ab53790d..cfeb0477d1f9 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -30,6 +30,7 @@
 #include <linux/hashtable.h>
 #include <linux/compat.h>
 #include <linux/nospec.h>
+#include <linux/time_namespace.h>
 
 #include "timekeeping.h"
 #include "posix-timers.h"
@@ -196,6 +197,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
@@ -210,6 +212,7 @@ static ktime_t posix_get_ktime(clockid_t which_clock)
 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_raw_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
@@ -224,6 +227,7 @@ static int posix_get_monotonic_coarse(clockid_t which_clock,
 						struct timespec64 *tp)
 {
 	ktime_get_coarse_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
-- 
2.22.0

[PATCHv5 10/37] posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Adds boottime virtualisation for time namespace.
Introduce timespec for boottime clock into timens offsets and wire
clock_gettime() syscall.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h | 9 +++++++++
 include/linux/timens_offsets.h | 1 +
 kernel/time/alarmtimer.c       | 1 +
 kernel/time/posix-stubs.c      | 1 +
 kernel/time/posix-timers.c     | 1 +
 5 files changed, 13 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 186c134fe222..334c1a1c6607 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -48,6 +48,14 @@ static inline void timens_add_monotonic(struct timespec64 *ts)
 		*ts = timespec64_add(*ts, ns_offsets->monotonic);
 }
 
+static inline void timens_add_boottime(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
+
+	if (ns_offsets)
+		*ts = timespec64_add(*ts, ns_offsets->boottime);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -73,6 +81,7 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 }
 
 static inline void timens_add_monotonic(struct timespec64 *ts) {}
+static inline void timens_add_boottime(struct timespec64 *ts) {}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index eaac2c82be5c..e93aabaa5e45 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -4,6 +4,7 @@
 
 struct timens_offsets {
 	struct timespec64 monotonic;
+	struct timespec64 boottime;
 };
 
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 55cb6e78d082..b1e82bb6cc6b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -26,6 +26,7 @@
 #include <linux/freezer.h>
 #include <linux/compat.h>
 #include <linux/module.h>
+#include <linux/time_namespace.h>
 
 #include "posix-timers.h"
 
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 17c67e0aecd8..edaf075d1ee4 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -82,6 +82,7 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 		break;
 	case CLOCK_BOOTTIME:
 		ktime_get_boottime_ts64(tp);
+		timens_add_boottime(tp);
 		break;
 	default:
 		return -EINVAL;
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index cfeb0477d1f9..265fbc816520 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -240,6 +240,7 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
+	timens_add_boottime(tp);
 	return 0;
 }
 
-- 
2.22.0

[PATCHv5 11/37] kernel: Add do_timens_ktime_to_host() helper

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The helper subtracts namespace's clock offset from the given time
and checks that the result is in [0, KTIME_MAX].

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h | 17 ++++++++++++++
 kernel/time_namespace.c        | 43 ++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 334c1a1c6607..9ba9664ff0ab 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -56,6 +56,18 @@ static inline void timens_add_boottime(struct timespec64 *ts)
 		*ts = timespec64_add(*ts, ns_offsets->boottime);
 }
 
+ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
+				struct timens_offsets *offsets);
+static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
+{
+	struct timens_offsets *offsets = current->nsproxy->time_ns->offsets;
+
+	if (!offsets)
+		return tim;
+
+	return do_timens_ktime_to_host(clockid, tim, offsets);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -82,6 +94,11 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 
 static inline void timens_add_monotonic(struct timespec64 *ts) {}
 static inline void timens_add_boottime(struct timespec64 *ts) {}
+
+static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
+{
+	return tim;
+}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index f849c59f1108..9807c5c90cb2 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -16,6 +16,49 @@
 #include <linux/err.h>
 #include <linux/mm.h>
 
+ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
+				struct timens_offsets *ns_offsets)
+{
+	ktime_t offset;
+
+	switch (clockid) {
+	case CLOCK_MONOTONIC:
+		offset = timespec64_to_ktime(ns_offsets->monotonic);
+		break;
+	case CLOCK_BOOTTIME:
+	case CLOCK_BOOTTIME_ALARM:
+		offset = timespec64_to_ktime(ns_offsets->boottime);
+		break;
+	default:
+		return tim;
+	}
+
+	/*
+	 * Check that @tim value is in [offset, KTIME_MAX + offset]
+	 * and subtract offset.
+	 */
+	if (tim < offset) {
+		/*
+		 * User can specify @tim *absolute* value - if it's lesser than
+		 * the time namespace's offset - it's already expired.
+		 */
+		tim = 0;
+	} else if (KTIME_MAX - tim < -offset) {
+		/*
+		 * User-supplied @tim may be close or even equal KTIME_MAX
+		 * and time namespace offset can be negative.
+		 * Let's check (tim - offset) for an overflow.
+		 * Return KTIME_MAX in such case, as the time value is
+		 * thousands *years* in future anyway.
+		 */
+		tim = KTIME_MAX;
+	} else {
+		tim = ktime_sub(tim, offset);
+	}
+
+	return tim;
+}
+
 static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
 {
 	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
-- 
2.22.0

[PATCHv5 12/37] timerfd: Make timerfd_settime() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

timerfd_settime() accepts an absolute value of the experation time if
TFD_TIMER_ABSTIME is specified. This value is in task's time namespace
and has to be converted to the host's time namespace.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 fs/timerfd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/timerfd.c b/fs/timerfd.c
index 6a6fc8aa1de7..9b0c2f65e7e8 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -26,6 +26,7 @@
 #include <linux/syscalls.h>
 #include <linux/compat.h>
 #include <linux/rcupdate.h>
+#include <linux/time_namespace.h>
 
 struct timerfd_ctx {
 	union {
@@ -196,6 +197,8 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
 	}
 
 	if (texp != 0) {
+		if (flags & TFD_TIMER_ABSTIME)
+			texp = timens_ktime_to_host(clockid, texp);
 		if (isalarm(ctx)) {
 			if (flags & TFD_TIMER_ABSTIME)
 				alarm_start(&ctx->t.alarm, texp);
-- 
2.22.0

[PATCHv5 13/37] posix-timers: Make timer_settime() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Wire timer_settime() syscall into time namespace virtualization.

sys_timer_settime() calls the ktime->timer_set() callback. Right now,
common_timer_set() is the only implementation for the callback.

There user-supplied timer's value is converted from timespec64 to ktime
and then timens_ktime_to_host() can be used to convert namespace's time
to the host time.

Inside a time namespace kernel's time differ on a fixed offset from
a user-supplied, but only absolute values (TIMER_ABSTIME) must
be converted.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/posix-timers.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 265fbc816520..c979e720a5a1 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -857,6 +857,8 @@ int common_timer_set(struct k_itimer *timr, int flags,
 
 	timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
 	expires = timespec64_to_ktime(new_setting->it_value);
+	if (flags & TIMER_ABSTIME)
+		expires = timens_ktime_to_host(timr->it_clock, expires);
 	sigev_none = timr->it_sigev_notify == SIGEV_NONE;
 
 	kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
-- 
2.22.0

[PATCHv5 14/37] alarmtimer: Make nanosleep time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

clock_nanosleep() accepts absolute values of expiration time when
TIMER_ABSTIME flag is set. This absolute value is inside the task's
time namespace, and has to be converted to the host's time.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index b1e82bb6cc6b..f21c743f6ede 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -825,6 +825,8 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 		ktime_t now = alarm_bases[type].get_ktime();
 
 		exp = ktime_add_safe(now, exp);
+	} else {
+		exp = timens_ktime_to_host(which_clock, exp);
 	}
 
 	ret = alarmtimer_do_nsleep(&alarm, exp, type);
-- 
2.22.0

[PATCHv5 15/37] hrtimers: Prepare hrtimer_nanosleep() for time namespaces

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

clock_nanosleep() accepts absolute values of expiration time when
TIMER_ABSTIME flag is set. This absolute value is inside the task's
time namespace, and has to be converted to the host's time.

There is timens_ktime_to_host() helper for converting time, but
it accepts ktime argument.

As a preparation, make hrtimer_nanosleep() accept a clock value in ktime
instead of timespec64.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/hrtimer.h   | 2 +-
 kernel/time/hrtimer.c     | 8 ++++----
 kernel/time/posix-stubs.c | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 4971100a8cab..3285d75b5a0f 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -459,7 +459,7 @@ static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 /* Precise sleep: */
 
 extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
-extern long hrtimer_nanosleep(const struct timespec64 *rqtp,
+extern long hrtimer_nanosleep(ktime_t rqtp,
 			      const enum hrtimer_mode mode,
 			      const clockid_t clockid);
 
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 5ee77f1a8a92..b67927c65410 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1716,7 +1716,7 @@ static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
 	return ret;
 }
 
-long hrtimer_nanosleep(const struct timespec64 *rqtp,
+long hrtimer_nanosleep(ktime_t rqtp,
 		       const enum hrtimer_mode mode, const clockid_t clockid)
 {
 	struct restart_block *restart;
@@ -1729,7 +1729,7 @@ long hrtimer_nanosleep(const struct timespec64 *rqtp,
 		slack = 0;
 
 	hrtimer_init_on_stack(&t.timer, clockid, mode);
-	hrtimer_set_expires_range_ns(&t.timer, timespec64_to_ktime(*rqtp), slack);
+	hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
 	ret = do_nanosleep(&t, mode);
 	if (ret != -ERESTART_RESTARTBLOCK)
 		goto out;
@@ -1764,7 +1764,7 @@ SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
 
 	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
 	current->restart_block.nanosleep.rmtp = rmtp;
-	return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 }
 
 #endif
@@ -1784,7 +1784,7 @@ SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
 
 	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
 	current->restart_block.nanosleep.compat_rmtp = rmtp;
-	return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 }
 #endif
 
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index edaf075d1ee4..2ccefc9ce184 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -147,7 +147,7 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 		rmtp = NULL;
 	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
 	current->restart_block.nanosleep.rmtp = rmtp;
-	return hrtimer_nanosleep(&t, flags & TIMER_ABSTIME ?
+	return hrtimer_nanosleep(timespec64_to_ktime(t), flags & TIMER_ABSTIME ?
 				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 				 which_clock);
 }
@@ -233,7 +233,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 		rmtp = NULL;
 	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
 	current->restart_block.nanosleep.compat_rmtp = rmtp;
-	return hrtimer_nanosleep(&t, flags & TIMER_ABSTIME ?
+	return hrtimer_nanosleep(timespec64_to_ktime(t), flags & TIMER_ABSTIME ?
 				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 				 which_clock);
 }
-- 
2.22.0

[PATCHv5 16/37] posix-timers: Make clock_nanosleep() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

clock_nanosleep() accepts absolute values of expiration time, if the
TIMER_ABSTIME flag is set. This value is in the task time namespace,
which has to be converted to the host time namespace.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/posix-stubs.c  | 12 ++++++++++--
 kernel/time/posix-timers.c | 21 ++++++++++++++++++---
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 2ccefc9ce184..47ee2684d250 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -129,6 +129,7 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 		struct __kernel_timespec __user *, rmtp)
 {
 	struct timespec64 t;
+	ktime_t texp;
 
 	switch (which_clock) {
 	case CLOCK_REALTIME:
@@ -147,7 +148,10 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 		rmtp = NULL;
 	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
 	current->restart_block.nanosleep.rmtp = rmtp;
-	return hrtimer_nanosleep(timespec64_to_ktime(t), flags & TIMER_ABSTIME ?
+	texp = timespec64_to_ktime(t);
+	if (flags & TIMER_ABSTIME)
+		texp = timens_ktime_to_host(clockid, texp);
+	return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
 				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 				 which_clock);
 }
@@ -215,6 +219,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 		struct old_timespec32 __user *, rmtp)
 {
 	struct timespec64 t;
+	ktime texp;
 
 	switch (which_clock) {
 	case CLOCK_REALTIME:
@@ -233,7 +238,10 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 		rmtp = NULL;
 	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
 	current->restart_block.nanosleep.compat_rmtp = rmtp;
-	return hrtimer_nanosleep(timespec64_to_ktime(t), flags & TIMER_ABSTIME ?
+	texp = timespec64_to_ktime(t);
+	if (flags & TIMER_ABSTIME)
+		texp = timens_ktime_to_host(clockid, texp);
+	return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
 				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 				 which_clock);
 }
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index c979e720a5a1..4dc46d697144 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1187,7 +1187,22 @@ SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
 static int common_nsleep(const clockid_t which_clock, int flags,
 			 const struct timespec64 *rqtp)
 {
-	return hrtimer_nanosleep(rqtp, flags & TIMER_ABSTIME ?
+	ktime_t texp = timespec64_to_ktime(*rqtp);
+
+	return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
+				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
+				 which_clock);
+}
+
+static int common_nsleep_timens(const clockid_t which_clock, int flags,
+			 const struct timespec64 *rqtp)
+{
+	ktime_t texp = timespec64_to_ktime(*rqtp);
+
+	if (flags & TIMER_ABSTIME)
+		texp = timens_ktime_to_host(which_clock, texp);
+
+	return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
 				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 				 which_clock);
 }
@@ -1268,7 +1283,7 @@ static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_timespec	= posix_get_timespec,
 	.clock_get_ktime	= posix_get_ktime,
-	.nsleep			= common_nsleep,
+	.nsleep			= common_nsleep_timens,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_get		= common_timer_get,
@@ -1315,7 +1330,7 @@ static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_ktime	= posix_get_boottime_ktime,
 	.clock_get_timespec	= posix_get_boottime_timespec,
-	.nsleep			= common_nsleep,
+	.nsleep			= common_nsleep_timens,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_get		= common_timer_get,
-- 
2.22.0

[PATCHv5 17/37] fd/proc: Respect boottime inside time namespace for /proc/uptime

[Dmitry Safonov]

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 fs/proc/uptime.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index a4c2791ab70b..5a1b228964fb 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -5,6 +5,7 @@
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/time.h>
+#include <linux/time_namespace.h>
 #include <linux/kernel_stat.h>
 
 static int uptime_proc_show(struct seq_file *m, void *v)
@@ -20,6 +21,8 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 		nsec += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
 
 	ktime_get_boottime_ts64(&uptime);
+	timens_add_boottime(&uptime);
+
 	idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
 	idle.tv_nsec = rem;
 	seq_printf(m, "%lu.%02lu %lu.%02lu\n",
-- 
2.22.0

[PATCHv5 18/37] x86/vdso2c: Correct err messages on file opening

[Dmitry Safonov]

err() message in main() is misleading: it should print `outfilename`,
which is argv[3], not argv[2].

Correct error messages to be more precise about what failed and for
which file.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vdso2c.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c
index 3a4d8d4d39f8..ce67370d14e5 100644
--- a/arch/x86/entry/vdso/vdso2c.c
+++ b/arch/x86/entry/vdso/vdso2c.c
@@ -184,7 +184,7 @@ static void map_input(const char *name, void **addr, size_t *len, int prot)
 
 	int fd = open(name, O_RDONLY);
 	if (fd == -1)
-		err(1, "%s", name);
+		err(1, "open(%s)", name);
 
 	tmp_len = lseek(fd, 0, SEEK_END);
 	if (tmp_len == (off_t)-1)
@@ -237,7 +237,7 @@ int main(int argc, char **argv)
 	outfilename = argv[3];
 	outfile = fopen(outfilename, "w");
 	if (!outfile)
-		err(1, "%s", argv[2]);
+		err(1, "fopen(%s)", outfilename);
 
 	go(raw_addr, raw_len, stripped_addr, stripped_len, outfile, name);
 
-- 
2.22.0

[PATCHv5 19/37] x86/vdso2c: Convert iterator to unsigned

[Dmitry Safonov]

i and j are used everywhere with unsigned types.
Cleanup and prettify the code a bit.

Introduce syms_nr for readability and as a preparation for allocating an
array of vDSO entries that will be needed for creating two vdso .so's:
one for host tasks and another for processes inside time namespace.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vdso2c.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index a20b134de2a8..80be339ee93e 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -13,7 +13,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 	unsigned long load_size = -1;  /* Work around bogus warning */
 	unsigned long mapping_size;
 	ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
-	int i;
+	unsigned int i, syms_nr;
 	unsigned long j;
 	ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
 		*alt_sec = NULL;
@@ -86,11 +86,10 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 	strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
 		GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);
 
+	syms_nr = GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
 	/* Walk the symbol table */
-	for (i = 0;
-	     i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
-	     i++) {
-		int k;
+	for (i = 0; i < syms_nr; i++) {
+		unsigned int k;
 		ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) +
 			GET_LE(&symtab_hdr->sh_entsize) * i;
 		const char *sym_name = raw_addr +
-- 
2.22.0

[PATCHv5 20/37] x86/vdso/Makefile: Add vobjs32

[Dmitry Safonov]

Treat ia32/i386 objects in array the same As for 64-bit vdso objects.
This is a preparation ground to avoid code duplication on introduction
timens vdso.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/Makefile | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 8df549138193..d4bffc4cabd1 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -24,6 +24,8 @@ VDSO32-$(CONFIG_IA32_EMULATION)	:= y
 
 # files to link into the vdso
 vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
+vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
+vobjs32-y += vdso32/vclock_gettime.o
 
 # files to link into kernel
 obj-y				+= vma.o
@@ -37,10 +39,12 @@ vdso_img-$(VDSO32-y)		+= 32
 obj-$(VDSO32-y)			+= vdso32-setup.o
 
 vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
+vobjs32 := $(foreach F,$(vobjs32-y),$(obj)/$F)
 
 $(obj)/vdso.o: $(obj)/vdso.so
 
 targets += vdso.lds $(vobjs-y)
+targets += vdso32/vdso32.lds $(vobjs32-y)
 
 # Build the vDSO image C files and link them in.
 vdso_img_objs := $(vdso_img-y:%=vdso-image-%.o)
@@ -131,10 +135,6 @@ $(obj)/vdsox32.so.dbg: $(obj)/vdsox32.lds $(vobjx32s) FORCE
 CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds)
 VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -soname linux-gate.so.1
 
-targets += vdso32/vdso32.lds
-targets += vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
-targets += vdso32/vclock_gettime.o
-
 KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) -DBUILD_VDSO
 $(obj)/vdso32.so.dbg: KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
 $(obj)/vdso32.so.dbg: asflags-$(CONFIG_X86_64) += -m32
@@ -159,12 +159,7 @@ endif
 
 $(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
 
-$(obj)/vdso32.so.dbg: FORCE \
-		      $(obj)/vdso32/vdso32.lds \
-		      $(obj)/vdso32/vclock_gettime.o \
-		      $(obj)/vdso32/note.o \
-		      $(obj)/vdso32/system_call.o \
-		      $(obj)/vdso32/sigreturn.o
+$(obj)/vdso32.so.dbg: $(obj)/vdso32/vdso32.lds $(vobjs32) FORCE
 	$(call if_changed,vdso_and_check)
 
 #
-- 
2.22.0

[PATCHv5 21/37] x86/vdso: Restrict splitting VVAR VMA

[Dmitry Safonov]

Although, time namespace can work with VVAR VMA split, it seems worth
to forbid splitting VVAR resulting in stricter ABI and reducing amount
of corner-cases to consider while working further on VDSO.

I don't think there is any use-case for partial mremap() of vvar,
but if there is any - this patch can be easily reverted.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vma.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 349a61d8bf34..3f05418642a8 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -84,6 +84,18 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
+static int vvar_mremap(const struct vm_special_mapping *sm,
+		struct vm_area_struct *new_vma)
+{
+	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+	const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;
+
+	if (new_size != -image->sym_vvar_start)
+		return -EINVAL;
+
+	return 0;
+}
+
 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
@@ -136,6 +148,7 @@ static const struct vm_special_mapping vdso_mapping = {
 static const struct vm_special_mapping vvar_mapping = {
 	.name = "[vvar]",
 	.fault = vvar_fault,
+	.mremap = vvar_mremap,
 };
 
 /*
-- 
2.22.0

[PATCHv5 22/37] x86/vdso: Rename vdso_image {.data=>.text}

[Dmitry Safonov]

To avoid any confusion with VVAR.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vdso2c.h | 2 +-
 arch/x86/entry/vdso/vma.c    | 6 +++---
 arch/x86/include/asm/vdso.h  | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 80be339ee93e..7556bb70ed8b 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -158,7 +158,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 	fprintf(outfile, "\n};\n\n");
 
 	fprintf(outfile, "const struct vdso_image %s = {\n", image_name);
-	fprintf(outfile, "\t.data = raw_data,\n");
+	fprintf(outfile, "\t.text = raw_data,\n");
 	fprintf(outfile, "\t.size = %lu,\n", mapping_size);
 	if (alt_sec) {
 		fprintf(outfile, "\t.alt = %lu,\n",
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 3f05418642a8..2dc4f0b5481c 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -32,8 +32,8 @@ void __init init_vdso_image(const struct vdso_image *image)
 {
 	BUG_ON(image->size % PAGE_SIZE != 0);
 
-	apply_alternatives((struct alt_instr *)(image->data + image->alt),
-			   (struct alt_instr *)(image->data + image->alt +
+	apply_alternatives((struct alt_instr *)(image->text + image->alt),
+			   (struct alt_instr *)(image->text + image->alt +
 						image->alt_len));
 }
 
@@ -47,7 +47,7 @@ static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
 	if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
 		return VM_FAULT_SIGBUS;
 
-	vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
+	vmf->page = virt_to_page(image->text + (vmf->pgoff << PAGE_SHIFT));
 	get_page(vmf->page);
 	return 0;
 }
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 230474e2ddb5..dffdc12cc7d6 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -11,7 +11,7 @@
 #include <linux/mm_types.h>
 
 struct vdso_image {
-	void *data;
+	void *text;
 	unsigned long size;   /* Always a multiple of PAGE_SIZE */
 
 	unsigned long alt, alt_len;
-- 
2.22.0

[PATCHv5 23/37] x86/vdso: Add offsets page in vvar

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

As modern applications fetch time from VDSO without entering the kernel,
it's needed to provide offsets for userspace code inside time namespace.

A page for timens offsets is allocated on time namespace construction.
Put that page into VVAR for tasks inside timens and zero page for
host processes.

As VDSO code is already optimized as much as possible in terms of speed,
any new if-condition in VDSO code is undesirable; the goal is to provide
two .so(s), as was originally suggested by Andy and Thomas:
- for host tasks with optimized-out clk_to_ns() without any penalty
- for processes inside timens with clk_to_ns()
For this purpose, define clk_to_ns() under CONFIG_TIME_NS.

To eliminate any performance regression, clk_to_ns() will be called
under static_branch with follow-up patches, that adds support for
patching vdso.

VDSO mappings are platform-specific, add Kconfig dependency for arch.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/Kconfig                          |  5 +++
 arch/x86/Kconfig                      |  1 +
 arch/x86/entry/vdso/vdso-layout.lds.S |  9 ++++-
 arch/x86/entry/vdso/vdso2c.c          |  3 ++
 arch/x86/entry/vdso/vma.c             | 12 +++++++
 arch/x86/include/asm/vdso.h           |  1 +
 init/Kconfig                          |  1 +
 lib/vdso/gettimeofday.c               | 47 +++++++++++++++++++++++++++
 8 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index a7b57dd42c26..e43d27f510ec 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -729,6 +729,11 @@ config HAVE_ARCH_NVRAM_OPS
 config ISA_BUS_API
 	def_bool ISA
 
+config ARCH_HAS_VDSO_TIME_NS
+	bool
+	help
+	 VDSO can add time-ns offsets without entering kernel.
+
 #
 # ABI hall of shame
 #
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 222855cc0158..91615938b470 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -81,6 +81,7 @@ config X86
 	select ARCH_HAS_STRICT_MODULE_RWX
 	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_VDSO_TIME_NS
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
 	select ARCH_MIGHT_HAVE_PC_PARPORT
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index 93c6dc7812d0..ba216527e59f 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -7,6 +7,12 @@
  * This script controls its layout.
  */
 
+#ifdef CONFIG_TIME_NS
+# define TIMENS_SZ	PAGE_SIZE
+#else
+# define TIMENS_SZ	0
+#endif
+
 SECTIONS
 {
 	/*
@@ -16,7 +22,7 @@ SECTIONS
 	 * segment.
 	 */
 
-	vvar_start = . - 3 * PAGE_SIZE;
+	vvar_start = . - (3 * PAGE_SIZE + TIMENS_SZ);
 	vvar_page = vvar_start;
 
 	/* Place all vvars at the offsets in asm/vvar.h. */
@@ -28,6 +34,7 @@ SECTIONS
 
 	pvclock_page = vvar_start + PAGE_SIZE;
 	hvclock_page = vvar_start + 2 * PAGE_SIZE;
+	timens_page = vvar_start + 3 * PAGE_SIZE;
 
 	. = SIZEOF_HEADERS;
 
diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c
index ce67370d14e5..7380908045c7 100644
--- a/arch/x86/entry/vdso/vdso2c.c
+++ b/arch/x86/entry/vdso/vdso2c.c
@@ -75,12 +75,14 @@ enum {
 	sym_vvar_page,
 	sym_pvclock_page,
 	sym_hvclock_page,
+	sym_timens_page,
 };
 
 const int special_pages[] = {
 	sym_vvar_page,
 	sym_pvclock_page,
 	sym_hvclock_page,
+	sym_timens_page,
 };
 
 struct vdso_sym {
@@ -93,6 +95,7 @@ struct vdso_sym required_syms[] = {
 	[sym_vvar_page] = {"vvar_page", true},
 	[sym_pvclock_page] = {"pvclock_page", true},
 	[sym_hvclock_page] = {"hvclock_page", true},
+	[sym_timens_page] = {"timens_page", true},
 	{"VDSO32_NOTE_MASK", true},
 	{"__kernel_vsyscall", true},
 	{"__kernel_sigreturn", true},
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 2dc4f0b5481c..9bd66f84db5e 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -14,6 +14,7 @@
 #include <linux/elf.h>
 #include <linux/cpu.h>
 #include <linux/ptrace.h>
+#include <linux/time_namespace.h>
 #include <asm/pvclock.h>
 #include <asm/vgtod.h>
 #include <asm/proto.h>
@@ -23,6 +24,7 @@
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
 #include <clocksource/hyperv_timer.h>
+#include <asm/page.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
@@ -135,6 +137,16 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
 			return vmf_insert_pfn(vma, vmf->address,
 					vmalloc_to_pfn(tsc_pg));
+	} else if (sym_offset == image->sym_timens_page) {
+		struct time_namespace *ns = current->nsproxy->time_ns;
+		unsigned long pfn;
+
+		if (!ns->offsets)
+			pfn = page_to_pfn(ZERO_PAGE(0));
+		else
+			pfn = page_to_pfn(virt_to_page(ns->offsets));
+
+		return vmf_insert_pfn(vma, vmf->address, pfn);
 	}
 
 	return VM_FAULT_SIGBUS;
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index dffdc12cc7d6..9d420c545607 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -21,6 +21,7 @@ struct vdso_image {
 	long sym_vvar_page;
 	long sym_pvclock_page;
 	long sym_hvclock_page;
+	long sym_timens_page;
 	long sym_VDSO32_NOTE_MASK;
 	long sym___kernel_sigreturn;
 	long sym___kernel_rt_sigreturn;
diff --git a/init/Kconfig b/init/Kconfig
index a7cbc9b470c7..9e40c07da4e1 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1071,6 +1071,7 @@ config UTS_NS
 
 config TIME_NS
 	bool "TIME namespace"
+	depends on ARCH_HAS_VDSO_TIME_NS
 	default y
 	help
 	  In this namespace boottime and monotonic clocks can be set.
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 2d1c1f241fd9..7525433f8ba4 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -7,6 +7,7 @@
 #include <linux/time.h>
 #include <linux/kernel.h>
 #include <linux/hrtimer_defs.h>
+#include <linux/timens_offsets.h>
 #include <vdso/datapage.h>
 #include <vdso/helpers.h>
 
@@ -38,6 +39,48 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 }
 #endif
 
+#ifdef CONFIG_TIME_NS
+extern u8 timens_page
+	__attribute__((visibility("hidden")));
+
+notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_timespec *ts)
+{
+	struct timens_offsets *timens = (struct timens_offsets *) &timens_page;
+	struct timespec64 *offset64;
+
+	switch (clk) {
+	case CLOCK_MONOTONIC:
+	case CLOCK_MONOTONIC_COARSE:
+	case CLOCK_MONOTONIC_RAW:
+		offset64 = &timens->monotonic;
+		break;
+	case CLOCK_BOOTTIME:
+		offset64 = &timens->boottime;
+		break;
+	default:
+		return;
+	}
+
+	/*
+	 * The kernel allows to set a negative offset only if the current clock
+	 * value in a namespace is positive, so the result tv_sec can't be
+	 * negative here.
+	 */
+	ts->tv_nsec += offset64->tv_nsec;
+	ts->tv_sec += offset64->tv_sec;
+	if (ts->tv_nsec >= NSEC_PER_SEC) {
+		ts->tv_nsec -= NSEC_PER_SEC;
+		ts->tv_sec++;
+	}
+	if (ts->tv_nsec < 0) {
+		ts->tv_nsec += NSEC_PER_SEC;
+		ts->tv_sec--;
+	}
+}
+#else
+notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_timespec *ts) {}
+#endif
+
 static int do_hres(const struct vdso_data *vd, clockid_t clk,
 		   struct __kernel_timespec *ts)
 {
@@ -65,6 +108,8 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
 	ts->tv_nsec = ns;
 
+	clk_to_ns(clk, ts);
+
 	return 0;
 }
 
@@ -79,6 +124,8 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 		ts->tv_sec = vdso_ts->sec;
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));
+
+	clk_to_ns(clk, ts);
 }
 
 static __maybe_unused int
-- 
2.22.0

[PATCHv5 24/37] x86/vdso: Allocate timens vdso

[Dmitry Safonov]

As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.
It will add a penalty for everybody as branch predictor may mispredict
the jump. Also there are instruction cache lines wasted on cmp/jmp.

Those effects of introducing time namespace are very much unwanted
having in mind how much work have been spent on micro-optimisation
vdso code.

The propose is to allocate a second vdso code with dynamically
patched out (disabled by static_branch) timens code on boot time.

Allocate another vdso and copy original code.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vdso2c.h |   2 +-
 arch/x86/entry/vdso/vma.c    | 113 +++++++++++++++++++++++++++++++++--
 arch/x86/include/asm/vdso.h  |   9 +--
 3 files changed, 114 insertions(+), 10 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 7556bb70ed8b..885b988aea19 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -157,7 +157,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 	}
 	fprintf(outfile, "\n};\n\n");
 
-	fprintf(outfile, "const struct vdso_image %s = {\n", image_name);
+	fprintf(outfile, "struct vdso_image %s __ro_after_init = {\n", image_name);
 	fprintf(outfile, "\t.text = raw_data,\n");
 	fprintf(outfile, "\t.size = %lu,\n", mapping_size);
 	if (alt_sec) {
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 9bd66f84db5e..8a8211fd4cfc 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -30,26 +30,128 @@
 unsigned int __read_mostly vdso64_enabled = 1;
 #endif
 
-void __init init_vdso_image(const struct vdso_image *image)
+void __init init_vdso_image(struct vdso_image *image)
 {
 	BUG_ON(image->size % PAGE_SIZE != 0);
 
 	apply_alternatives((struct alt_instr *)(image->text + image->alt),
 			   (struct alt_instr *)(image->text + image->alt +
 						image->alt_len));
+#ifdef CONFIG_TIME_NS
+	image->text_timens = vmalloc_32(image->size);
+	if (WARN_ON(image->text_timens == NULL))
+		return;
+
+	memcpy(image->text_timens, image->text, image->size);
+#endif
 }
 
 struct linux_binprm;
 
+#ifdef CONFIG_TIME_NS
+static inline struct timens_offsets *current_timens_offsets(void)
+{
+	return current->nsproxy->time_ns->offsets;
+}
+
+static int vdso_check_timens(struct vm_area_struct *vma, bool *in_timens)
+{
+	struct task_struct *tsk;
+
+	if (likely(vma->vm_mm == current->mm)) {
+		*in_timens = !!current_timens_offsets();
+		return 0;
+	}
+
+	/*
+	 * .fault() handler can be called over remote process through
+	 * interfaces like /proc/$pid/mem or process_vm_{readv,writev}()
+	 * Considering such access to vdso as a slow-path.
+	 */
+
+#ifdef CONFIG_MEMCG
+	rcu_read_lock();
+
+	tsk = rcu_dereference(vma->vm_mm->owner);
+	if (tsk) {
+		task_lock(tsk);
+		/*
+		 * Shouldn't happen: nsproxy is unset in exit_mm().
+		 * Before that exit_mm() holds mmap_sem to set (mm = NULL).
+		 * It's impossible to have a fault in task without mm
+		 * and mmap_sem is taken during the fault.
+		 */
+		if (WARN_ON_ONCE(tsk->nsproxy == NULL)) {
+			task_unlock(tsk);
+			rcu_read_unlock();
+			return -EIO;
+		}
+		*in_timens = !!tsk->nsproxy->time_ns->offsets;
+		task_unlock(tsk);
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+#endif
+
+	read_lock(&tasklist_lock);
+	for_each_process(tsk) {
+		struct task_struct *c;
+
+		if (tsk->flags & PF_KTHREAD)
+			continue;
+		for_each_thread(tsk, c) {
+			if (c->mm == vma->vm_mm)
+				goto found;
+			if (c->mm)
+				break;
+		}
+	}
+	read_unlock(&tasklist_lock);
+	return -ESRCH;
+
+found:
+	task_lock(tsk);
+	read_unlock(&tasklist_lock);
+	*in_timens = !!tsk->nsproxy->time_ns->offsets;
+	task_unlock(tsk);
+
+	return 0;
+}
+#else /* CONFIG_TIME_NS */
+static inline int vdso_check_timens(struct vm_area_struct *vma, bool *in_timens)
+{
+	*in_timens = false;
+	return 0;
+}
+static inline struct timens_offsets *current_timens_offsets(void)
+{
+	return NULL;
+}
+#endif /* CONFIG_TIME_NS */
+
 static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+	unsigned long offset = vmf->pgoff << PAGE_SHIFT;
+	bool in_timens;
+	int err;
 
 	if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
 		return VM_FAULT_SIGBUS;
 
-	vmf->page = virt_to_page(image->text + (vmf->pgoff << PAGE_SHIFT));
+	err = vdso_check_timens(vma, &in_timens);
+	if (err)
+		return VM_FAULT_SIGBUS;
+
+	WARN_ON_ONCE(in_timens && !image->text_timens);
+
+	if (in_timens && image->text_timens)
+		vmf->page = vmalloc_to_page(image->text_timens + offset);
+	else
+		vmf->page = virt_to_page(image->text + offset);
+
 	get_page(vmf->page);
 	return 0;
 }
@@ -138,13 +240,14 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 			return vmf_insert_pfn(vma, vmf->address,
 					vmalloc_to_pfn(tsc_pg));
 	} else if (sym_offset == image->sym_timens_page) {
-		struct time_namespace *ns = current->nsproxy->time_ns;
+		/* We can fault only in current context for VM_PFNMAP mapping */
+		struct timens_offsets *offsets = current_timens_offsets();
 		unsigned long pfn;
 
-		if (!ns->offsets)
+		if (!offsets)
 			pfn = page_to_pfn(ZERO_PAGE(0));
 		else
-			pfn = page_to_pfn(virt_to_page(ns->offsets));
+			pfn = page_to_pfn(virt_to_page(offsets));
 
 		return vmf_insert_pfn(vma, vmf->address, pfn);
 	}
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 9d420c545607..03f468c63a24 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -12,6 +12,7 @@
 
 struct vdso_image {
 	void *text;
+	void *text_timens;
 	unsigned long size;   /* Always a multiple of PAGE_SIZE */
 
 	unsigned long alt, alt_len;
@@ -30,18 +31,18 @@ struct vdso_image {
 };
 
 #ifdef CONFIG_X86_64
-extern const struct vdso_image vdso_image_64;
+extern struct vdso_image vdso_image_64;
 #endif
 
 #ifdef CONFIG_X86_X32
-extern const struct vdso_image vdso_image_x32;
+extern struct vdso_image vdso_image_x32;
 #endif
 
 #if defined CONFIG_X86_32 || defined CONFIG_COMPAT
-extern const struct vdso_image vdso_image_32;
+extern struct vdso_image vdso_image_32;
 #endif
 
-extern void __init init_vdso_image(const struct vdso_image *image);
+extern void __init init_vdso_image(struct vdso_image *image);
 
 extern int map_vdso_once(const struct vdso_image *image, unsigned long addr);
 
-- 
2.22.0

[PATCHv5 25/37] x86/vdso: Switch image on setns()/clone()

[Dmitry Safonov]

As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.
It will add a penalty for everybody as branch predictor may mispredict
the jump. Also there are instruction cache lines wasted on cmp/jmp.

Those effects of introducing time namespace are very much unwanted
having in mind how much work have been spent on micro-optimisation
vdso code.

Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside of time
namespace with clk_to_ns() that subtracts offsets from host's time.

Whenever a user does setns() or unshare(CLONE_TIMENS) followed
by clone(), change VDSO image in mm and zap VVAR/VDSO page tables.
They will be re-faulted with corresponding image and VVAR offsets.

Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vma.c   | 23 +++++++++++++++++++++++
 arch/x86/include/asm/vdso.h |  1 +
 kernel/time_namespace.c     | 11 +++++++++++
 3 files changed, 35 insertions(+)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8a8211fd4cfc..91cf5a5c8c9e 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -25,6 +25,7 @@
 #include <asm/cpufeature.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/page.h>
+#include <asm/tlb.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
@@ -266,6 +267,28 @@ static const struct vm_special_mapping vvar_mapping = {
 	.mremap = vvar_mremap,
 };
 
+#ifdef CONFIG_TIME_NS
+int vdso_join_timens(struct task_struct *task)
+{
+	struct mm_struct *mm = task->mm;
+	struct vm_area_struct *vma;
+
+	if (down_write_killable(&mm->mmap_sem))
+		return -EINTR;
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		unsigned long size = vma->vm_end - vma->vm_start;
+
+		if (vma_is_special_mapping(vma, &vvar_mapping) ||
+		    vma_is_special_mapping(vma, &vdso_mapping))
+			zap_page_range(vma, vma->vm_start, size);
+	}
+
+	up_write(&mm->mmap_sem);
+	return 0;
+}
+#endif
+
 /*
  * Add vdso and vvar mappings to current process.
  * @image          - blob to map
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 03f468c63a24..ccf89dedd04f 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -45,6 +45,7 @@ extern struct vdso_image vdso_image_32;
 extern void __init init_vdso_image(struct vdso_image *image);
 
 extern int map_vdso_once(const struct vdso_image *image, unsigned long addr);
+extern int vdso_join_timens(struct task_struct *task);
 
 #endif /* __ASSEMBLER__ */
 
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index 9807c5c90cb2..4b2eb92ad595 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -15,6 +15,7 @@
 #include <linux/cred.h>
 #include <linux/err.h>
 #include <linux/mm.h>
+#include <asm/vdso.h>
 
 ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
 				struct timens_offsets *ns_offsets)
@@ -199,6 +200,7 @@ static void timens_put(struct ns_common *ns)
 static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 {
 	struct time_namespace *ns = to_time_ns(new);
+	int ret;
 
 	if (!thread_group_empty(current))
 		return -EINVAL;
@@ -207,6 +209,10 @@ static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
+	ret = vdso_join_timens(current);
+	if (ret)
+		return ret;
+
 	get_time_ns(ns);
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
@@ -221,10 +227,15 @@ int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
 {
 	struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
 	struct time_namespace *ns = to_time_ns(nsc);
+	int ret;
 
 	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
 		return 0;
 
+	ret = vdso_join_timens(tsk);
+	if (ret)
+		return ret;
+
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
 	nsproxy->time_ns = ns;
-- 
2.22.0

[PATCHv5 26/37] vdso: Introduce vdso_static_branch_unlikely()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.

Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside of time
namespace with clk_to_ns() that subtracts offsets from host's time.

Introduce vdso_static_branch_unlikely(), which is similar to
static_branch_unlikely(); alias it with timens_static_branch_unlikely()
under CONFIG_TIME_NS.

The timens code in vdso will look like this:

   if (timens_static_branch_unlikely()) {
	   clk_to_ns(clk, ts);
   }

The version of vdso which is compiled from sources will never execute
clk_to_ns(). And then we can patch the 'no-op' in the straight-line
codepath with a 'jump' instruction to the out-of-line true branch and
get the timens version of the vdso library.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/include/asm/jump_label.h | 14 ++++++++++++++
 lib/vdso/gettimeofday.c           | 10 ++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 06c3cc22a058..376efb53183b 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -53,6 +53,20 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 	return true;
 }
 
+static __always_inline bool vdso_static_branch_unlikely(void)
+{
+	asm_volatile_goto("1:\n\t"
+		".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
+		 ".pushsection __jump_table,  \"aw\"\n\t"
+		 "2: .word 1b - 2b, %l[l_yes] - 2b\n\t"
+		 ".popsection\n\t"
+		 : :  :  : l_yes);
+
+	return false;
+l_yes:
+	return true;
+}
+
 #else	/* __ASSEMBLY__ */
 
 .macro STATIC_JUMP_IF_TRUE target, key, def
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 7525433f8ba4..605bdb92055d 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -8,6 +8,7 @@
 #include <linux/kernel.h>
 #include <linux/hrtimer_defs.h>
 #include <linux/timens_offsets.h>
+#include <linux/jump_label.h>
 #include <vdso/datapage.h>
 #include <vdso/helpers.h>
 
@@ -43,6 +44,8 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 extern u8 timens_page
 	__attribute__((visibility("hidden")));
 
+#define timens_static_branch_unlikely vdso_static_branch_unlikely
+
 notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_timespec *ts)
 {
 	struct timens_offsets *timens = (struct timens_offsets *) &timens_page;
@@ -79,6 +82,7 @@ notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_tim
 }
 #else
 notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_timespec *ts) {}
+notrace static __always_inline bool timens_static_branch_unlikely(void) { return false; }
 #endif
 
 static int do_hres(const struct vdso_data *vd, clockid_t clk,
@@ -108,7 +112,8 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
 	ts->tv_nsec = ns;
 
-	clk_to_ns(clk, ts);
+	if (timens_static_branch_unlikely())
+		clk_to_ns(clk, ts);
 
 	return 0;
 }
@@ -125,7 +130,8 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));
 
-	clk_to_ns(clk, ts);
+	if (timens_static_branch_unlikely())
+		clk_to_ns(clk, ts);
 }
 
 static __maybe_unused int
-- 
2.22.0

[PATCHv5 27/37] x86/vdso2c: Process jump tables

[Dmitry Safonov]

As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.

Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside time
namespace with clk_to_ns() that subtracts offsets from host's time.

The timens code in vdso looks like this:

      if (timens_static_branch()) {
              clk_to_ns(clk, ts);
      }

Static branch mechanism adds a __jump_table section into vdso.
Vdso's linker script drops all unwanted sections in compile time.

Preserve __jump_table section and add it into (struct vdso_image),
as it's needed for enabling (patching) static branches that are
present on vdso.

Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vdso-layout.lds.S | 1 +
 arch/x86/entry/vdso/vdso2c.h          | 9 ++++++++-
 arch/x86/include/asm/vdso.h           | 1 +
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index ba216527e59f..69dbe4821aa5 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -45,6 +45,7 @@ SECTIONS
 	.gnu.version	: { *(.gnu.version) }
 	.gnu.version_d	: { *(.gnu.version_d) }
 	.gnu.version_r	: { *(.gnu.version_r) }
+	__jump_table	: { *(__jump_table) }	:text
 
 	.dynamic	: { *(.dynamic) }		:text	:dynamic
 
diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 885b988aea19..318b278ca396 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -14,7 +14,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 	unsigned long mapping_size;
 	ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
 	unsigned int i, syms_nr;
-	unsigned long j;
+	unsigned long j, jump_table_addr = -1UL, jump_table_size = -1UL;
 	ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
 		*alt_sec = NULL;
 	ELF(Dyn) *dyn = 0, *dyn_end = 0;
@@ -78,6 +78,10 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 		if (!strcmp(secstrings + GET_LE(&sh->sh_name),
 			    ".altinstructions"))
 			alt_sec = sh;
+		if (!strcmp(secstrings + GET_LE(&sh->sh_name), "__jump_table")) {
+			jump_table_addr = GET_LE(&sh->sh_offset);
+			jump_table_size = GET_LE(&sh->sh_size);
+		}
 	}
 
 	if (!symtab_hdr)
@@ -166,6 +170,9 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 		fprintf(outfile, "\t.alt_len = %lu,\n",
 			(unsigned long)GET_LE(&alt_sec->sh_size));
 	}
+	fprintf(outfile, "\t.jump_table = %luUL,\n", jump_table_addr);
+	fprintf(outfile, "\t.jump_table_len = %luUL,\n", jump_table_size);
+
 	for (i = 0; i < NSYMS; i++) {
 		if (required_syms[i].export && syms[i])
 			fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index ccf89dedd04f..5e83bd3cda22 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -16,6 +16,7 @@ struct vdso_image {
 	unsigned long size;   /* Always a multiple of PAGE_SIZE */
 
 	unsigned long alt, alt_len;
+	unsigned long jump_table, jump_table_len;
 
 	long sym_vvar_start;  /* Negative offset to the vvar area */
 
-- 
2.22.0

[PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.

Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside of time
namespace with clk_to_ns() that subtracts offsets from host's time.

The timens code in vdso looks like this:

if (timens_static_branch_unlikely()) {
       clk_to_ns(clk, ts);
}

This static branch is disabled by default. And the code generated consist
of a single atomic 'no-op' instruction, in the straight-line code path.

Enable static branches in the timens vdso: the 'no-op' instruction
gets replaced with a 'jump' instruction to the out-of-line true branch.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vma.c    | 30 ++++++++++++++++++++++++------
 arch/x86/kernel/jump_label.c | 14 ++++++++++++++
 include/linux/jump_label.h   |  8 ++++++++
 init/Kconfig                 |  1 +
 4 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 91cf5a5c8c9e..1a3eb4656eb6 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -15,6 +15,7 @@
 #include <linux/cpu.h>
 #include <linux/ptrace.h>
 #include <linux/time_namespace.h>
+#include <linux/jump_label.h>
 #include <asm/pvclock.h>
 #include <asm/vgtod.h>
 #include <asm/proto.h>
@@ -31,20 +32,37 @@
 unsigned int __read_mostly vdso64_enabled = 1;
 #endif
 
-void __init init_vdso_image(struct vdso_image *image)
+#ifdef CONFIG_TIME_NS
+static __init void init_timens(struct vdso_image *image)
 {
-	BUG_ON(image->size % PAGE_SIZE != 0);
+	struct vdso_jump_entry *entries;
+	unsigned long entries_nr;
+
+	if (WARN_ON(image->jump_table == -1UL))
+		return;
 
-	apply_alternatives((struct alt_instr *)(image->text + image->alt),
-			   (struct alt_instr *)(image->text + image->alt +
-						image->alt_len));
-#ifdef CONFIG_TIME_NS
 	image->text_timens = vmalloc_32(image->size);
 	if (WARN_ON(image->text_timens == NULL))
 		return;
 
 	memcpy(image->text_timens, image->text, image->size);
+
+	entries = image->text_timens + image->jump_table;
+	entries_nr = image->jump_table_len / sizeof(struct vdso_jump_entry);
+	apply_vdso_jump_labels(entries, entries_nr);
+}
+#else
+static inline void init_timens(struct vdso_image *image) {}
 #endif
+
+void __init init_vdso_image(struct vdso_image *image)
+{
+	BUG_ON(image->size % PAGE_SIZE != 0);
+
+	apply_alternatives((struct alt_instr *)(image->text + image->alt),
+			   (struct alt_instr *)(image->text + image->alt +
+						image->alt_len));
+	init_timens(image);
 }
 
 struct linux_binprm;
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 044053235302..7820ac61b688 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -24,6 +24,20 @@ union jump_code_union {
 	} __attribute__((packed));
 };
 
+__init void apply_vdso_jump_labels(struct vdso_jump_entry *ent, unsigned long nr)
+{
+	while (nr--) {
+		void *code_addr	= (void *)ent + ent->code;
+		union jump_code_union jmp;
+
+		jmp.jump	= 0xe9; /* JMP rel32 */
+		jmp.offset	= ent->target - ent->code - JUMP_LABEL_NOP_SIZE;
+		memcpy(code_addr, &jmp, JUMP_LABEL_NOP_SIZE);
+
+		ent++;
+	}
+}
+
 static void bug_at(unsigned char *ip, int line)
 {
 	/*
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 3526c0aee954..bb9d828ee49a 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -125,6 +125,11 @@ struct jump_entry {
 	long key;	// key may be far away from the core kernel under KASLR
 };
 
+struct vdso_jump_entry {
+	u16 code;
+	u16 target;
+};
+
 static inline unsigned long jump_entry_code(const struct jump_entry *entry)
 {
 	return (unsigned long)&entry->code + entry->code;
@@ -229,6 +234,9 @@ extern void static_key_enable(struct static_key *key);
 extern void static_key_disable(struct static_key *key);
 extern void static_key_enable_cpuslocked(struct static_key *key);
 extern void static_key_disable_cpuslocked(struct static_key *key);
+extern void apply_vdso_jump_labels(struct vdso_jump_entry *ent,
+				   unsigned long nr);
+
 
 /*
  * We should be using ATOMIC_INIT() for initializing .enabled, but
diff --git a/init/Kconfig b/init/Kconfig
index 9e40c07da4e1..be8bd41774f6 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1072,6 +1072,7 @@ config UTS_NS
 config TIME_NS
 	bool "TIME namespace"
 	depends on ARCH_HAS_VDSO_TIME_NS
+	depends on JUMP_LABEL
 	default y
 	help
 	  In this namespace boottime and monotonic clocks can be set.
-- 
2.22.0

[PATCHv5 29/37] posix-clocks: Add align for timens_offsets

[Dmitry Safonov]

Align offsets so that time namespace will work for ia32 applications on
x86_64 host.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/timens_offsets.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index e93aabaa5e45..05da1b0563ce 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -2,9 +2,17 @@
 #ifndef _LINUX_TIME_OFFSETS_H
 #define _LINUX_TIME_OFFSETS_H
 
+/*
+ * Time offsets need align as they're placed on VVAR page,
+ * which is used by x86_64 and ia32 VDSO code.
+ * On ia32 offset::tv_sec (u64) has align(4), so re-align offsets
+ * to the same positions as 64-bit offsets.
+ * On 64-bit big-endian systems VDSO should convert to timespec64
+ * to timespec because of a padding occurring between the fields.
+ */
 struct timens_offsets {
-	struct timespec64 monotonic;
-	struct timespec64 boottime;
+	struct timespec64 monotonic __aligned(8);
+	struct timespec64 boottime __aligned(8);
 };
 
 #endif
-- 
2.22.0

[PATCHv5 30/37] fs/proc: Introduce /proc/pid/timens_offsets

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

API to set time namespace offsets for children processes, i.e.:
echo "clockid off_ses off_nsec" > /proc/self/timens_offsets

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 fs/proc/base.c                 |  95 ++++++++++++++++++++++++++++++
 include/linux/time_namespace.h |  10 ++++
 kernel/time_namespace.c        | 104 +++++++++++++++++++++++++++++++++
 3 files changed, 209 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index ebea9501afb8..1d2007365e87 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -94,6 +94,7 @@
 #include <linux/sched/debug.h>
 #include <linux/sched/stat.h>
 #include <linux/posix-timers.h>
+#include <linux/time_namespace.h>
 #include <trace/events/oom.h>
 #include "internal.h"
 #include "fd.h"
@@ -1533,6 +1534,97 @@ static const struct file_operations proc_pid_sched_autogroup_operations = {
 
 #endif /* CONFIG_SCHED_AUTOGROUP */
 
+#ifdef CONFIG_TIME_NS
+static int timens_offsets_show(struct seq_file *m, void *v)
+{
+	struct task_struct *p;
+
+	p = get_proc_task(file_inode(m->file));
+	if (!p)
+		return -ESRCH;
+	proc_timens_show_offsets(p, m);
+
+	put_task_struct(p);
+
+	return 0;
+}
+
+static ssize_t
+timens_offsets_write(struct file *file, const char __user *buf,
+	    size_t count, loff_t *ppos)
+{
+	struct inode *inode = file_inode(file);
+	struct proc_timens_offset offsets[2];
+	char *kbuf = NULL, *pos, *next_line;
+	struct task_struct *p;
+	int ret, noffsets;
+
+	/* Only allow < page size writes at the beginning of the file */
+	if ((*ppos != 0) || (count >= PAGE_SIZE))
+		return -EINVAL;
+
+	/* Slurp in the user data */
+	kbuf = memdup_user_nul(buf, count);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	/* Parse the user data */
+	ret = -EINVAL;
+	noffsets = 0;
+	for (pos = kbuf; pos; pos = next_line) {
+		struct proc_timens_offset *off = &offsets[noffsets];
+		int err;
+
+		/* Find the end of line and ensure we don't look past it */
+		next_line = strchr(pos, '\n');
+		if (next_line) {
+			*next_line = '\0';
+			next_line++;
+			if (*next_line == '\0')
+				next_line = NULL;
+		}
+
+		err = sscanf(pos, "%u %lld %lu", &off->clockid,
+				&off->val.tv_sec, &off->val.tv_nsec);
+		if (err != 3 || off->val.tv_nsec >= NSEC_PER_SEC)
+			goto out;
+		noffsets++;
+		if (noffsets == ARRAY_SIZE(offsets)) {
+			if (next_line)
+				count = next_line - kbuf;
+			break;
+		}
+	}
+
+	ret = -ESRCH;
+	p = get_proc_task(inode);
+	if (!p)
+		goto out;
+	ret = proc_timens_set_offset(file, p, offsets, noffsets);
+	put_task_struct(p);
+	if (ret)
+		goto out;
+
+	ret = count;
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static int timens_offsets_open(struct inode *inode, struct file *filp)
+{
+	return single_open(filp, timens_offsets_show, inode);
+}
+
+static const struct file_operations proc_timens_offsets_operations = {
+	.open		= timens_offsets_open,
+	.read		= seq_read,
+	.write		= timens_offsets_write,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+#endif /* CONFIG_TIME_NS */
+
 static ssize_t comm_write(struct file *file, const char __user *buf,
 				size_t count, loff_t *offset)
 {
@@ -3015,6 +3107,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #endif
 #ifdef CONFIG_SCHED_AUTOGROUP
 	REG("autogroup",  S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
+#endif
+#ifdef CONFIG_TIME_NS
+	REG("timens_offsets",  S_IRUGO|S_IWUSR, proc_timens_offsets_operations),
 #endif
 	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 9ba9664ff0ab..3f4d457ff0dc 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -40,6 +40,16 @@ static inline void put_time_ns(struct time_namespace *ns)
 	kref_put(&ns->kref, free_time_ns);
 }
 
+extern void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m);
+
+struct proc_timens_offset {
+	int clockid;
+	struct timespec64 val;
+};
+
+extern int proc_timens_set_offset(struct file *file, struct task_struct *p,
+				struct proc_timens_offset *offsets, int n);
+
 static inline void timens_add_monotonic(struct timespec64 *ts)
 {
 	struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index 4b2eb92ad595..e17b8569bead 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -8,6 +8,7 @@
 #include <linux/user_namespace.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/task.h>
+#include <linux/seq_file.h>
 #include <linux/proc_ns.h>
 #include <linux/export.h>
 #include <linux/time.h>
@@ -249,6 +250,109 @@ static struct user_namespace *timens_owner(struct ns_common *ns)
 	return to_time_ns(ns)->user_ns;
 }
 
+static void show_offset(struct seq_file *m, int clockid, struct timespec64 *ts)
+{
+	seq_printf(m, "%d %lld %ld\n", clockid, ts->tv_sec, ts->tv_nsec);
+}
+
+void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m)
+{
+	struct ns_common *ns;
+	struct time_namespace *time_ns;
+	struct timens_offsets *ns_offsets;
+
+	ns = timens_for_children_get(p);
+	if (!ns)
+		return;
+	time_ns = to_time_ns(ns);
+
+	if (!time_ns->offsets) {
+		put_time_ns(time_ns);
+		return;
+	}
+	ns_offsets = time_ns->offsets;
+
+	show_offset(m, CLOCK_MONOTONIC, &ns_offsets->monotonic);
+	show_offset(m, CLOCK_BOOTTIME, &ns_offsets->boottime);
+	put_time_ns(time_ns);
+}
+
+int proc_timens_set_offset(struct file *file, struct task_struct *p,
+			   struct proc_timens_offset *offsets, int noffsets)
+{
+	struct ns_common *ns;
+	struct time_namespace *time_ns;
+	struct timens_offsets *ns_offsets;
+	struct timespec64 *offset;
+	struct timespec64 tp;
+	int i, err;
+
+	ns = timens_for_children_get(p);
+	if (!ns)
+		return -ESRCH;
+	time_ns = to_time_ns(ns);
+
+	if (!time_ns->offsets || time_ns->initialized ||
+	    !file_ns_capable(file, time_ns->user_ns, CAP_SYS_TIME)) {
+		put_time_ns(time_ns);
+		return -EPERM;
+	}
+	ns_offsets = time_ns->offsets;
+
+	for (i = 0; i < noffsets; i++) {
+		struct proc_timens_offset *off = &offsets[i];
+
+		switch (off->clockid) {
+		case CLOCK_MONOTONIC:
+			ktime_get_ts64(&tp);
+			break;
+		case CLOCK_BOOTTIME:
+			ktime_get_boottime_ts64(&tp);
+			break;
+		default:
+			err = -EINVAL;
+			goto out;
+		}
+
+		err = -ERANGE;
+
+		if (off->val.tv_sec > KTIME_SEC_MAX || off->val.tv_sec < -KTIME_SEC_MAX)
+			goto out;
+
+		tp = timespec64_add(tp, off->val);
+		/*
+		 * KTIME_SEC_MAX is divided by 2 to be sure that KTIME_MAX is
+		 * still unreachable.
+		 */
+		if (tp.tv_sec < 0 || tp.tv_sec > KTIME_SEC_MAX / 2)
+			goto out;
+	}
+
+	err = 0;
+	/* don't report errors after this line */
+	for (i = 0; i < noffsets; i++) {
+		struct proc_timens_offset *off = &offsets[i];
+
+		switch (off->clockid) {
+		case CLOCK_MONOTONIC:
+			offset = &ns_offsets->monotonic;
+			break;
+		case CLOCK_BOOTTIME:
+			offset = &ns_offsets->boottime;
+			break;
+		default:
+			goto out;
+		}
+
+		*offset = off->val;
+	}
+
+out:
+	put_time_ns(time_ns);
+
+	return err;
+}
+
 const struct proc_ns_operations timens_operations = {
 	.name		= "time",
 	.type		= CLONE_NEWTIME,
-- 
2.22.0

[PATCHv5 31/37] selftest/timens: Add Time Namespace test for supported clocks

[Dmitry Safonov]

A test to check that all supported clocks work on host and inside
a new time namespace. Use both ways to get time: through VDSO and
by entering the kernel with implicit syscall.

Introduce a new timens directory in selftests framework for
the next timens tests.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/Makefile          |   1 +
 tools/testing/selftests/timens/.gitignore |   1 +
 tools/testing/selftests/timens/Makefile   |   5 +
 tools/testing/selftests/timens/config     |   1 +
 tools/testing/selftests/timens/log.h      |  26 +++
 tools/testing/selftests/timens/timens.c   | 185 ++++++++++++++++++++++
 tools/testing/selftests/timens/timens.h   |  63 ++++++++
 7 files changed, 282 insertions(+)
 create mode 100644 tools/testing/selftests/timens/.gitignore
 create mode 100644 tools/testing/selftests/timens/Makefile
 create mode 100644 tools/testing/selftests/timens/config
 create mode 100644 tools/testing/selftests/timens/log.h
 create mode 100644 tools/testing/selftests/timens/timens.c
 create mode 100644 tools/testing/selftests/timens/timens.h

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 25b43a8c2b15..6fc63b84a857 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -47,6 +47,7 @@ TARGETS += splice
 TARGETS += static_keys
 TARGETS += sync
 TARGETS += sysctl
+TARGETS += timens
 ifneq (1, $(quicktest))
 TARGETS += timers
 endif
diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
new file mode 100644
index 000000000000..27a693229ce1
--- /dev/null
+++ b/tools/testing/selftests/timens/.gitignore
@@ -0,0 +1 @@
+timens
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
new file mode 100644
index 000000000000..b877efb78974
--- /dev/null
+++ b/tools/testing/selftests/timens/Makefile
@@ -0,0 +1,5 @@
+TEST_GEN_PROGS := timens
+
+CFLAGS := -Wall -Werror
+
+include ../lib.mk
diff --git a/tools/testing/selftests/timens/config b/tools/testing/selftests/timens/config
new file mode 100644
index 000000000000..4480620f6f49
--- /dev/null
+++ b/tools/testing/selftests/timens/config
@@ -0,0 +1 @@
+CONFIG_TIME_NS=y
diff --git a/tools/testing/selftests/timens/log.h b/tools/testing/selftests/timens/log.h
new file mode 100644
index 000000000000..db64df2a8483
--- /dev/null
+++ b/tools/testing/selftests/timens/log.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __SELFTEST_TIMENS_LOG_H__
+#define __SELFTEST_TIMENS_LOG_H__
+
+#define pr_msg(fmt, lvl, ...)						\
+	ksft_print_msg("[%s] (%s:%d)\t" fmt "\n",			\
+			lvl, __FILE__, __LINE__, ##__VA_ARGS__)
+
+#define pr_p(func, fmt, ...)	func(fmt ": %m", ##__VA_ARGS__)
+
+#define pr_err(fmt, ...)						\
+	({								\
+		ksft_test_result_error(fmt "\n", ##__VA_ARGS__);		\
+		-1;							\
+	})
+
+#define pr_fail(fmt, ...)					\
+	({							\
+		ksft_test_result_fail(fmt, ##__VA_ARGS__);	\
+		-1;						\
+	})
+
+#define pr_perror(fmt, ...)	pr_p(pr_err, fmt, ##__VA_ARGS__)
+
+#endif
diff --git a/tools/testing/selftests/timens/timens.c b/tools/testing/selftests/timens/timens.c
new file mode 100644
index 000000000000..55d38f02eb64
--- /dev/null
+++ b/tools/testing/selftests/timens/timens.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+#include <time.h>
+#include <string.h>
+
+#include "log.h"
+#include "timens.h"
+
+/*
+ * Test shouldn't be run for a day, so add 10 days to child
+ * time and check parent's time to be in the same day.
+ */
+#define DAY_IN_SEC			(60*60*24)
+#define TEN_DAYS_IN_SEC			(10*DAY_IN_SEC)
+
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
+struct test_clock {
+	clockid_t id;
+	char *name;
+	/*
+	 * off_id is -1 if a clock has own offset, or it contains an index
+	 * which contains a right offset of this clock.
+	 */
+	int off_id;
+	time_t offset;
+};
+
+#define ct(clock, off_id)	{ clock, #clock, off_id }
+static struct test_clock clocks[] = {
+	ct(CLOCK_BOOTTIME, -1),
+	ct(CLOCK_BOOTTIME_ALARM, 1),
+	ct(CLOCK_MONOTONIC, -1),
+	ct(CLOCK_MONOTONIC_COARSE, 1),
+	ct(CLOCK_MONOTONIC_RAW, 1),
+};
+#undef ct
+
+static int child_ns, parent_ns = -1;
+
+static int switch_ns(int fd)
+{
+	if (setns(fd, CLONE_NEWTIME)) {
+		pr_perror("setns()");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int init_namespaces(void)
+{
+	char path[] = "/proc/self/ns/time_for_children";
+	struct stat st1, st2;
+
+	if (parent_ns == -1) {
+		parent_ns = open(path, O_RDONLY);
+		if (parent_ns <= 0)
+			return pr_perror("Unable to open %s", path);
+	}
+
+	if (fstat(parent_ns, &st1))
+		return pr_perror("Unable to stat the parent timens");
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	child_ns = open(path, O_RDONLY);
+	if (child_ns <= 0)
+		return pr_perror("Unable to open %s", path);
+
+	if (fstat(child_ns, &st2))
+		return pr_perror("Unable to stat the timens");
+
+	if (st1.st_ino == st2.st_ino)
+		return pr_perror("The same child_ns after CLONE_NEWTIME");
+
+	return 0;
+}
+
+static int test_gettime(clockid_t clock_index, bool raw_syscall, time_t offset)
+{
+	struct timespec child_ts_new, parent_ts_old, cur_ts;
+	char *entry = raw_syscall ? "syscall" : "vdso";
+	double precision = 0.0;
+
+	switch (clocks[clock_index].id) {
+	case CLOCK_MONOTONIC_COARSE:
+	case CLOCK_MONOTONIC_RAW:
+		precision = -2.0;
+		break;
+	}
+
+	if (switch_ns(parent_ns))
+		return pr_err("switch_ns(%d)", child_ns);
+
+	if (_gettime(clocks[clock_index].id, &parent_ts_old, raw_syscall))
+		return -1;
+
+	child_ts_new.tv_nsec = parent_ts_old.tv_nsec;
+	child_ts_new.tv_sec = parent_ts_old.tv_sec + offset;
+
+	if (switch_ns(child_ns))
+		return pr_err("switch_ns(%d)", child_ns);
+
+	if (_gettime(clocks[clock_index].id, &cur_ts, raw_syscall))
+		return -1;
+
+	if (difftime(cur_ts.tv_sec, child_ts_new.tv_sec) < precision) {
+		ksft_test_result_fail(
+			"Child's %s (%s) time has not changed: %lu -> %lu [%lu]\n",
+			clocks[clock_index].name, entry, parent_ts_old.tv_sec,
+			child_ts_new.tv_sec, cur_ts.tv_sec);
+		return -1;
+	}
+
+	if (switch_ns(parent_ns))
+		return pr_err("switch_ns(%d)", parent_ns);
+
+	if (_gettime(clocks[clock_index].id, &cur_ts, raw_syscall))
+		return -1;
+
+	if (difftime(cur_ts.tv_sec, parent_ts_old.tv_sec) > DAY_IN_SEC) {
+		ksft_test_result_fail(
+			"Parent's %s (%s) time has changed: %lu -> %lu [%lu]\n",
+			clocks[clock_index].name, entry, parent_ts_old.tv_sec,
+			child_ts_new.tv_sec, cur_ts.tv_sec);
+		/* Let's play nice and put it closer to original */
+		clock_settime(clocks[clock_index].id, &cur_ts);
+		return -1;
+	}
+
+	ksft_test_result_pass("Passed for %s (%s)\n",
+				clocks[clock_index].name, entry);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	time_t offset;
+	int ret = 0;
+
+	nscheck();
+
+	ksft_set_plan(ARRAY_SIZE(clocks) * 2);
+
+	if (init_namespaces())
+		return 1;
+
+	/* Offsets have to be set before tasks enter the namespace. */
+	for (i = 0; i < ARRAY_SIZE(clocks); i++) {
+		if (clocks[i].off_id != -1)
+			continue;
+		offset = TEN_DAYS_IN_SEC + i * 1000;
+		clocks[i].offset = offset;
+		if (_settime(clocks[i].id, offset))
+			return 1;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(clocks); i++) {
+		if (clocks[i].off_id != -1)
+			offset = clocks[clocks[i].off_id].offset;
+		else
+			offset = clocks[i].offset;
+		ret |= test_gettime(i, true, offset);
+		ret |= test_gettime(i, false, offset);
+	}
+
+	if (ret)
+		ksft_exit_fail();
+
+	ksft_exit_pass();
+	return !!ret;
+}
diff --git a/tools/testing/selftests/timens/timens.h b/tools/testing/selftests/timens/timens.h
new file mode 100644
index 000000000000..77c127384810
--- /dev/null
+++ b/tools/testing/selftests/timens/timens.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __TIMENS_H__
+#define __TIMENS_H__
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "../kselftest.h"
+
+#ifndef CLONE_NEWTIME
+# define CLONE_NEWTIME	0x00000080
+#endif
+
+static inline int _settime(clockid_t clk_id, time_t offset)
+{
+	int fd, len;
+	char buf[4096];
+
+	if (clk_id == CLOCK_MONOTONIC_COARSE || clk_id == CLOCK_MONOTONIC_RAW)
+		clk_id = CLOCK_MONOTONIC;
+
+	len = snprintf(buf, sizeof(buf), "%d %ld 0", clk_id, offset);
+
+	fd = open("/proc/self/timens_offsets", O_WRONLY);
+	if (fd < 0)
+		return pr_perror("/proc/self/timens_offsets");
+
+	if (write(fd, buf, len) != len)
+		return pr_perror("/proc/self/timens_offsets");
+
+	close(fd);
+
+	return 0;
+}
+
+static inline int _gettime(clockid_t clk_id, struct timespec *res, bool raw_syscall)
+{
+	int err;
+
+	if (!raw_syscall) {
+		if (clock_gettime(clk_id, res)) {
+			pr_perror("clock_gettime(%d)", (int)clk_id);
+			return -1;
+		}
+		return 0;
+	}
+
+	err = syscall(SYS_clock_gettime, clk_id, res);
+	if (err)
+		pr_perror("syscall(SYS_clock_gettime(%d))", (int)clk_id);
+
+	return err;
+}
+
+static inline void nscheck(void)
+{
+	if (access("/proc/self/ns/time", F_OK) < 0)
+		ksft_exit_skip("Time namespaces are not supported\n");
+}
+
+#endif
-- 
2.22.0

[PATCHv5 32/37] selftest/timens: Add a test for timerfd

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Check that timerfd_create() takes into account clock offsets.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore |   1 +
 tools/testing/selftests/timens/Makefile   |   2 +-
 tools/testing/selftests/timens/timerfd.c  | 129 ++++++++++++++++++++++
 3 files changed, 131 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/timerfd.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 27a693229ce1..b609f6ee9fb9 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1 +1,2 @@
 timens
+timerfd
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index b877efb78974..66b90cd28e5c 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens
+TEST_GEN_PROGS := timens timerfd
 
 CFLAGS := -Wall -Werror
 
diff --git a/tools/testing/selftests/timens/timerfd.c b/tools/testing/selftests/timens/timerfd.c
new file mode 100644
index 000000000000..b87076aae040
--- /dev/null
+++ b/tools/testing/selftests/timens/timerfd.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <sys/timerfd.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+
+#include "log.h"
+#include "timens.h"
+
+static int tclock_gettime(clock_t clockid, struct timespec *now)
+{
+	if (clockid == CLOCK_BOOTTIME_ALARM)
+		clockid = CLOCK_BOOTTIME;
+	return clock_gettime(clockid, now);
+}
+
+int run_test(int clockid, struct timespec now)
+{
+	struct itimerspec new_value;
+	long long elapsed;
+	int fd, i;
+
+	if (tclock_gettime(clockid, &now))
+		return pr_perror("clock_gettime(%d)", clockid);
+
+	for (i = 0; i < 2; i++) {
+		int flags = 0;
+
+		new_value.it_value.tv_sec = 3600;
+		new_value.it_value.tv_nsec = 0;
+		new_value.it_interval.tv_sec = 1;
+		new_value.it_interval.tv_nsec = 0;
+
+		if (i == 1) {
+			new_value.it_value.tv_sec += now.tv_sec;
+			new_value.it_value.tv_nsec += now.tv_nsec;
+		}
+
+		fd = timerfd_create(clockid, 0);
+		if (fd == -1)
+			return pr_perror("timerfd_create(%d)", clockid);
+
+		if (i == 1)
+			flags |= TFD_TIMER_ABSTIME;
+
+		if (timerfd_settime(fd, flags, &new_value, NULL))
+			return pr_perror("timerfd_settime(%d)", clockid);
+
+		if (timerfd_gettime(fd, &new_value))
+			return pr_perror("timerfd_gettime(%d)", clockid);
+
+		elapsed = new_value.it_value.tv_sec;
+		if (abs(elapsed - 3600) > 60) {
+			ksft_test_result_fail("clockid: %d elapsed: %lld\n",
+					      clockid, elapsed);
+			return 1;
+		}
+
+		close(fd);
+	}
+
+	ksft_test_result_pass("clockid=%d\n", clockid);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, status, len, fd;
+	char buf[4096];
+	pid_t pid;
+	struct timespec btime_now, mtime_now;
+
+	nscheck();
+
+	ksft_set_plan(3);
+
+	clock_gettime(CLOCK_MONOTONIC, &mtime_now);
+	clock_gettime(CLOCK_BOOTTIME, &btime_now);
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("unshare");
+
+	len = snprintf(buf, sizeof(buf), "%d %d 0\n%d %d 0",
+			CLOCK_MONOTONIC, 70 * 24 * 3600,
+			CLOCK_BOOTTIME, 9 * 24 * 3600);
+	fd = open("/proc/self/timens_offsets", O_WRONLY);
+	if (fd < 0)
+		return pr_perror("/proc/self/timens_offsets");
+
+	if (write(fd, buf, len) != len)
+		return pr_perror("/proc/self/timens_offsets");
+
+	close(fd);
+	mtime_now.tv_sec += 70 * 24 * 3600;
+	btime_now.tv_sec += 9 * 24 * 3600;
+
+	pid = fork();
+	if (pid < 0)
+		return pr_perror("Unable to fork");
+	if (pid == 0) {
+		ret = 0;
+		ret |= run_test(CLOCK_BOOTTIME, btime_now);
+		ret |= run_test(CLOCK_MONOTONIC, mtime_now);
+		ret |= run_test(CLOCK_BOOTTIME_ALARM, btime_now);
+
+		if (ret)
+			ksft_exit_fail();
+		ksft_exit_pass();
+		return ret;
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Unable to wait the child process");
+
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+
+	return 1;
+}
+
-- 
2.22.0

[PATCHv5 33/37] selftest/timens: Add a test for clock_nanosleep()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Check that clock_nanosleep() takes into account clock offsets.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore     |   1 +
 tools/testing/selftests/timens/Makefile       |   2 +-
 .../selftests/timens/clock_nanosleep.c        | 102 ++++++++++++++++++
 3 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/clock_nanosleep.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index b609f6ee9fb9..9b6c8ddac2c8 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1,2 +1,3 @@
+clock_nanosleep
 timens
 timerfd
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index 66b90cd28e5c..76a1dc891184 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd
+TEST_GEN_PROGS := timens timerfd clock_nanosleep
 
 CFLAGS := -Wall -Werror
 
diff --git a/tools/testing/selftests/timens/clock_nanosleep.c b/tools/testing/selftests/timens/clock_nanosleep.c
new file mode 100644
index 000000000000..7956e65d3032
--- /dev/null
+++ b/tools/testing/selftests/timens/clock_nanosleep.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <sys/timerfd.h>
+#include <sys/syscall.h>
+#include <time.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+
+#include "log.h"
+#include "timens.h"
+
+static long long get_elapsed_time(int clockid, struct timespec *start)
+{
+	struct timespec curr;
+	long long secs, nsecs;
+
+	if (clock_gettime(clockid, &curr) == -1)
+		return pr_perror("clock_gettime");
+
+	secs = curr.tv_sec - start->tv_sec;
+	nsecs = curr.tv_nsec - start->tv_nsec;
+	if (nsecs < 0) {
+		secs--;
+		nsecs += 1000000000;
+	}
+	if (nsecs > 1000000000) {
+		secs++;
+		nsecs -= 1000000000;
+	}
+	return secs * 1000 + nsecs / 1000000;
+}
+
+int run_test(int clockid)
+{
+	long long elapsed;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		struct timespec now = {};
+		struct timespec start;
+
+		if (clock_gettime(clockid, &start) == -1)
+			return pr_perror("clock_gettime");
+
+
+		if (i == 1) {
+			now.tv_sec = start.tv_sec;
+			now.tv_nsec = start.tv_nsec;
+		}
+
+		now.tv_sec += 2;
+		clock_nanosleep(clockid, i ? TIMER_ABSTIME : 0, &now, NULL);
+
+		elapsed = get_elapsed_time(clockid, &start);
+		if (elapsed < 1900 || elapsed > 2100) {
+			pr_fail("clockid: %d abs: %d elapsed: %lld\n",
+				clockid, i, elapsed);
+			return 1;
+		}
+		ksft_test_result_pass("clockid: %d abs:%d\n", clockid, i);
+	}
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, nsfd;
+
+	nscheck();
+
+	ksft_set_plan(4);
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("unshare");
+
+	if (_settime(CLOCK_MONOTONIC, 7 * 24 * 3600))
+		return 1;
+	if (_settime(CLOCK_BOOTTIME, 9 * 24 * 3600))
+		return 1;
+
+	nsfd = open("/proc/self/ns/time_for_children", O_RDONLY);
+	if (nsfd < 0)
+		return pr_perror("Unable to open timens_for_children");
+
+	if (setns(nsfd, CLONE_NEWTIME))
+		return pr_perror("Unable to set timens");
+
+	ret = 0;
+	ret |= run_test(CLOCK_MONOTONIC);
+	ret |= run_test(CLOCK_BOOTTIME_ALARM);
+
+	if (ret)
+		ksft_exit_fail();
+	ksft_exit_pass();
+	return ret;
+}
+
-- 
2.22.0

[PATCHv5 34/37] selftest/timens: Add procfs selftest

[Dmitry Safonov]

Check that /proc/uptime is correct inside a new time namespace.

Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore |   1 +
 tools/testing/selftests/timens/Makefile   |   2 +-
 tools/testing/selftests/timens/procfs.c   | 144 ++++++++++++++++++++++
 3 files changed, 146 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/procfs.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 9b6c8ddac2c8..94ffdd9cead7 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1,3 +1,4 @@
 clock_nanosleep
+procfs
 timens
 timerfd
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index 76a1dc891184..f96f50d1fef8 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd clock_nanosleep
+TEST_GEN_PROGS := timens timerfd clock_nanosleep procfs
 
 CFLAGS := -Wall -Werror
 
diff --git a/tools/testing/selftests/timens/procfs.c b/tools/testing/selftests/timens/procfs.c
new file mode 100644
index 000000000000..3c3c6e634d50
--- /dev/null
+++ b/tools/testing/selftests/timens/procfs.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <math.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+#include <time.h>
+
+#include "log.h"
+#include "timens.h"
+
+/*
+ * Test shouldn't be run for a day, so add 10 days to child
+ * time and check parent's time to be in the same day.
+ */
+#define MAX_TEST_TIME_SEC		(60*5)
+#define DAY_IN_SEC			(60*60*24)
+#define TEN_DAYS_IN_SEC			(10*DAY_IN_SEC)
+
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
+static int child_ns, parent_ns;
+
+static int switch_ns(int fd)
+{
+	if (setns(fd, CLONE_NEWTIME))
+		return pr_perror("setns()");
+
+	return 0;
+}
+
+static int init_namespaces(void)
+{
+	char path[] = "/proc/self/ns/time_for_children";
+	struct stat st1, st2;
+
+	parent_ns = open(path, O_RDONLY);
+	if (parent_ns <= 0)
+		return pr_perror("Unable to open %s", path);
+
+	if (fstat(parent_ns, &st1))
+		return pr_perror("Unable to stat the parent timens");
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	child_ns = open(path, O_RDONLY);
+	if (child_ns <= 0)
+		return pr_perror("Unable to open %s", path);
+
+	if (fstat(child_ns, &st2))
+		return pr_perror("Unable to stat the timens");
+
+	if (st1.st_ino == st2.st_ino)
+		return pr_err("The same child_ns after CLONE_NEWTIME");
+
+	if (_settime(CLOCK_BOOTTIME, TEN_DAYS_IN_SEC))
+		return -1;
+
+	return 0;
+}
+
+static int read_proc_uptime(struct timespec *uptime)
+{
+	unsigned long up_sec, up_nsec;
+	FILE *proc;
+
+	proc = fopen("/proc/uptime", "r");
+	if (proc == NULL) {
+		pr_perror("Unable to open /proc/uptime");
+		return -1;
+	}
+
+	if (fscanf(proc, "%lu.%02lu", &up_sec, &up_nsec) != 2) {
+		if (errno) {
+			pr_perror("fscanf");
+			return -errno;
+		}
+		pr_err("failed to parse /proc/uptime");
+		return -1;
+	}
+	fclose(proc);
+
+	uptime->tv_sec = up_sec;
+	uptime->tv_nsec = up_nsec;
+	return 0;
+}
+
+static int check_uptime(void)
+{
+	struct timespec uptime_new, uptime_old;
+	time_t uptime_expected;
+	double prec = MAX_TEST_TIME_SEC;
+
+	if (switch_ns(parent_ns))
+		return pr_err("switch_ns(%d)", parent_ns);
+
+	if (read_proc_uptime(&uptime_old))
+		return 1;
+
+	if (switch_ns(child_ns))
+		return pr_err("switch_ns(%d)", child_ns);
+
+	if (read_proc_uptime(&uptime_new))
+		return 1;
+
+	uptime_expected = uptime_old.tv_sec + TEN_DAYS_IN_SEC;
+	if (fabs(difftime(uptime_new.tv_sec, uptime_expected)) > prec) {
+		pr_fail("uptime in /proc/uptime: old %ld, new %ld [%ld]",
+			uptime_old.tv_sec, uptime_new.tv_sec,
+			uptime_old.tv_sec + TEN_DAYS_IN_SEC);
+		return 1;
+	}
+
+	ksft_test_result_pass("Passed for /proc/uptime\n");
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret = 0;
+
+	nscheck();
+
+	ksft_set_plan(1);
+
+	if (init_namespaces())
+		return 1;
+
+	ret |= check_uptime();
+
+	if (ret)
+		ksft_exit_fail();
+	ksft_exit_pass();
+	return ret;
+}
-- 
2.22.0

[PATCHv5 35/37] selftest/timens: Add timer offsets test

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Check that timer_create() takes into account clock offsets.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore |   1 +
 tools/testing/selftests/timens/Makefile   |   3 +-
 tools/testing/selftests/timens/timer.c    | 118 ++++++++++++++++++++++
 3 files changed, 121 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/timer.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 94ffdd9cead7..3b7eda8f35ce 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1,4 +1,5 @@
 clock_nanosleep
 procfs
 timens
+timer
 timerfd
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index f96f50d1fef8..ae1ffd24cc43 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,5 +1,6 @@
-TEST_GEN_PROGS := timens timerfd clock_nanosleep procfs
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs
 
 CFLAGS := -Wall -Werror
+LDFLAGS := -lrt
 
 include ../lib.mk
diff --git a/tools/testing/selftests/timens/timer.c b/tools/testing/selftests/timens/timer.c
new file mode 100644
index 000000000000..45a9dd3cbb12
--- /dev/null
+++ b/tools/testing/selftests/timens/timer.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <signal.h>
+#include <time.h>
+
+#include "log.h"
+#include "timens.h"
+
+int run_test(int clockid, struct timespec now)
+{
+	struct itimerspec new_value;
+	long long elapsed;
+	timer_t fd;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		struct sigevent sevp = {.sigev_notify = SIGEV_NONE};
+		int flags = 0;
+
+		new_value.it_value.tv_sec = 3600;
+		new_value.it_value.tv_nsec = 0;
+		new_value.it_interval.tv_sec = 1;
+		new_value.it_interval.tv_nsec = 0;
+
+		if (i == 1) {
+			new_value.it_value.tv_sec += now.tv_sec;
+			new_value.it_value.tv_nsec += now.tv_nsec;
+		}
+
+		if (timer_create(clockid, &sevp, &fd) == -1)
+			return pr_perror("timerfd_create");
+
+		if (i == 1)
+			flags |= TIMER_ABSTIME;
+		if (timer_settime(fd, flags, &new_value, NULL) == -1)
+			return pr_perror("timerfd_settime");
+
+		if (timer_gettime(fd, &new_value) == -1)
+			return pr_perror("timerfd_gettime");
+
+		elapsed = new_value.it_value.tv_sec;
+		if (abs(elapsed - 3600) > 60) {
+			ksft_test_result_fail("clockid: %d elapsed: %lld\n",
+					      clockid, elapsed);
+			return 1;
+		}
+	}
+
+	ksft_test_result_pass("clockid=%d\n", clockid);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, status, len, fd;
+	char buf[4096];
+	pid_t pid;
+	struct timespec btime_now, mtime_now;
+
+	nscheck();
+
+	ksft_set_plan(3);
+
+	clock_gettime(CLOCK_MONOTONIC, &mtime_now);
+	clock_gettime(CLOCK_BOOTTIME, &btime_now);
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("unshare");
+
+	len = snprintf(buf, sizeof(buf), "%d %d 0\n%d %d 0",
+			CLOCK_MONOTONIC, 70 * 24 * 3600,
+			CLOCK_BOOTTIME, 9 * 24 * 3600);
+	fd = open("/proc/self/timens_offsets", O_WRONLY);
+	if (fd < 0)
+		return pr_perror("/proc/self/timens_offsets");
+
+	if (write(fd, buf, len) != len)
+		return pr_perror("/proc/self/timens_offsets");
+
+	close(fd);
+	mtime_now.tv_sec += 70 * 24 * 3600;
+	btime_now.tv_sec += 9 * 24 * 3600;
+
+	pid = fork();
+	if (pid < 0)
+		return pr_perror("Unable to fork");
+	if (pid == 0) {
+		ret = 0;
+		ret |= run_test(CLOCK_BOOTTIME, btime_now);
+		ret |= run_test(CLOCK_MONOTONIC, mtime_now);
+		ret |= run_test(CLOCK_BOOTTIME_ALARM, btime_now);
+
+		if (ret)
+			ksft_exit_fail();
+		ksft_exit_pass();
+		return ret;
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Unable to wait the child process");
+
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+
+	return 1;
+}
+
-- 
2.22.0

[PATCHv5 36/37] selftests/timens: Add a simple perf test for clock_gettime()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore     |   2 +
 tools/testing/selftests/timens/Makefile       |  10 +-
 tools/testing/selftests/timens/gettime_perf.c | 101 +++++++++++
 .../selftests/timens/gettime_perf_cold.c      | 160 ++++++++++++++++++
 4 files changed, 271 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/timens/gettime_perf.c
 create mode 100644 tools/testing/selftests/timens/gettime_perf_cold.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 3b7eda8f35ce..16292e4d08a5 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1,4 +1,6 @@
 clock_nanosleep
+gettime_perf
+gettime_perf_cold
 procfs
 timens
 timer
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index ae1ffd24cc43..97e0460eaf48 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,6 +1,12 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs gettime_perf
+
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)
+ifeq ($(ARCH),x86_64)
+TEST_GEN_PROGS += gettime_perf_cold
+endif
 
 CFLAGS := -Wall -Werror
-LDFLAGS := -lrt
+LDFLAGS := -lrt -ldl
 
 include ../lib.mk
diff --git a/tools/testing/selftests/timens/gettime_perf.c b/tools/testing/selftests/timens/gettime_perf.c
new file mode 100644
index 000000000000..f7d7832c0293
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <time.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <dlfcn.h>
+
+#include "log.h"
+#include "timens.h"
+
+//#define TEST_SYSCALL
+
+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+
+vgettime_t vdso_clock_gettime;
+
+static void fill_function_pointers(void)
+{
+	void *vdso = dlopen("linux-vdso.so.1",
+			    RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso)
+		vdso = dlopen("linux-gate.so.1",
+			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso) {
+		pr_err("[WARN]\tfailed to find vDSO\n");
+		return;
+	}
+
+	vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+	if (!vdso_clock_gettime)
+		pr_err("Warning: failed to find clock_gettime in vDSO\n");
+
+}
+
+static void test(clock_t clockid, char *clockstr, bool in_ns)
+{
+	struct timespec tp, start;
+	long i = 0;
+	const int timeout = 3;
+
+#ifndef TEST_SYSCALL
+	vdso_clock_gettime(clockid, &start);
+#else
+	syscall(__NR_clock_gettime, clockid, &start);
+#endif
+	tp = start;
+	for (tp = start; start.tv_sec + timeout > tp.tv_sec ||
+			 (start.tv_sec + timeout == tp.tv_sec &&
+			  start.tv_nsec > tp.tv_nsec); i++) {
+#ifndef TEST_SYSCALL
+		vdso_clock_gettime(clockid, &tp);
+#else
+		syscall(__NR_clock_gettime, clockid, &tp);
+#endif
+	}
+
+	ksft_test_result_pass("%s:\tclock: %10s\tcycles:\t%10ld\n",
+			      in_ns ? "ns" : "host", clockstr, i);
+}
+
+int main(int argc, char *argv[])
+{
+	time_t offset = 10;
+	int nsfd;
+
+	ksft_set_plan(4);
+
+	fill_function_pointers();
+
+	test(CLOCK_MONOTONIC, "monotonic", false);
+	test(CLOCK_BOOTTIME, "boottime", false);
+
+	nscheck();
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	nsfd = open("/proc/self/ns/time_for_children", O_RDONLY);
+	if (nsfd < 0)
+		return pr_perror("Can't open a time namespace");
+
+	if (_settime(CLOCK_MONOTONIC, offset))
+		return 1;
+	if (_settime(CLOCK_BOOTTIME, offset))
+		return 1;
+
+	if (setns(nsfd, CLONE_NEWTIME))
+		return pr_perror("setns");
+
+	test(CLOCK_MONOTONIC, "monotonic", true);
+	test(CLOCK_BOOTTIME, "boottime", true);
+
+	ksft_exit_pass();
+	return 0;
+}
diff --git a/tools/testing/selftests/timens/gettime_perf_cold.c b/tools/testing/selftests/timens/gettime_perf_cold.c
new file mode 100644
index 000000000000..2ab0869744a6
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf_cold.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <time.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <string.h>
+#include <dlfcn.h>
+#include <signal.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define PAGE_SIZE 4096
+#define CACHE_LINE_SIZE 64
+
+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+
+vgettime_t vdso_clock_gettime;
+
+static void fill_function_pointers(void)
+{
+	void *vdso = dlopen("linux-vdso.so.1",
+			    RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso)
+		vdso = dlopen("linux-gate.so.1",
+			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso) {
+		pr_err("[WARN]\tfailed to find vDSO\n");
+		return;
+	}
+
+	vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+	if (!vdso_clock_gettime)
+		pr_err("Warning: failed to find clock_gettime in vDSO\n");
+
+}
+
+static inline __attribute__((always_inline)) unsigned long long rdtsc(void)
+{
+	unsigned int hi, lo;
+
+	__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
+	return ((unsigned long long) lo) | (((unsigned long long)hi) << 32);
+}
+
+static inline __attribute__((always_inline)) void test(clock_t clockid, char *clockstr)
+{
+	struct timespec tp;
+	long long s, e;
+
+	s = rdtsc();
+	vdso_clock_gettime(clockid, &tp);
+	e = rdtsc();
+	printf("%lld\n", e - s);
+}
+
+static inline void clflush(volatile void *__p)
+{
+	asm volatile("clflush %0" : "+m"(*(volatile char *)__p));
+}
+
+void *pg_addr;
+void sigh(int sig)
+{
+	void *addr;
+
+	addr = mmap(pg_addr, PAGE_SIZE, PROT_READ,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+	if (addr != pg_addr) {
+		pr_perror("Unable to map %lx", (long) pg_addr);
+		exit(1);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	time_t offset = 10;
+	void *vdso_start = 0, *vdso_end = 0;
+	void *vvar_start = 0, *vvar_end = 0;
+	char buf[PAGE_SIZE];
+	int nsfd, i;
+	FILE *maps;
+
+	fill_function_pointers();
+	if (argc == 1)
+		goto out;
+	nscheck();
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	nsfd = open("/proc/self/ns/time_for_children", O_RDONLY);
+	if (nsfd < 0)
+		return pr_perror("Can't open a time namespace");
+
+	if (_settime(CLOCK_MONOTONIC, offset))
+		return 1;
+
+	if (setns(nsfd, CLONE_NEWTIME))
+		return pr_perror("setns");
+
+out:
+	maps = fopen("/proc/self/maps", "r");
+	if (!maps) {
+		pr_perror("Unable to open /proc/self/maps");
+		return 1;
+	}
+
+	while (fgets(buf, sizeof(buf), maps)) {
+		unsigned long start, end;
+		char tail[PAGE_SIZE];
+		int r;
+
+		r = sscanf(buf, "%lx-%lx %*s %*s %*s %*s %s\n", &start, &end, tail);
+
+		if (r < 3)
+			continue;
+
+		if (strcmp(tail, "[vdso]") == 0) {
+			vdso_start = (void *)start;
+			vdso_end = (void *)end;
+		}
+		if (strcmp(tail, "[vvar]") == 0) {
+			vvar_start = (void *)start;
+			vvar_end = (void *)end;
+		}
+	}
+	if (!vvar_start || !vdso_start) {
+		pr_err("Unable to find vdso\n");
+		return 1;
+	}
+
+	/* Map zero pages instead of unreadable vdso pages. */
+	signal(SIGSEGV, sigh);
+	signal(SIGBUS, sigh);
+	for (pg_addr = vdso_start; pg_addr < vdso_end; pg_addr += PAGE_SIZE)
+		buf[0] += *(char *)pg_addr;
+	for (pg_addr = vvar_start; pg_addr < vvar_end; pg_addr += PAGE_SIZE)
+		buf[0] += *(char *)pg_addr;
+	signal(SIGSEGV, SIG_DFL);
+	signal(SIGBUS, SIG_DFL);
+
+	for (i = 0; i < 10240; i++) {
+		void *p;
+
+		for (p = vdso_start; p < vdso_end; p += CACHE_LINE_SIZE)
+			clflush(p);
+		for (p = vvar_start; p < vvar_end; p += CACHE_LINE_SIZE)
+			clflush(p);
+		test(CLOCK_MONOTONIC, "monotonic");
+	}
+	return 0;
+}
-- 
2.22.0

[PATCHv5 37/37] selftest/timens: Check that a right vdso is mapped after fork and exec

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore |  1 +
 tools/testing/selftests/timens/Makefile   |  2 +-
 tools/testing/selftests/timens/exec.c     | 93 +++++++++++++++++++++++
 3 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/exec.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 16292e4d08a5..789f21e81028 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1,4 +1,5 @@
 clock_nanosleep
+exec
 gettime_perf
 gettime_perf_cold
 procfs
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index 97e0460eaf48..b77fe22fa24d 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs gettime_perf
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs gettime_perf exec
 
 uname_M := $(shell uname -m 2>/dev/null || echo not)
 ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)
diff --git a/tools/testing/selftests/timens/exec.c b/tools/testing/selftests/timens/exec.c
new file mode 100644
index 000000000000..de7798832429
--- /dev/null
+++ b/tools/testing/selftests/timens/exec.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+#include <time.h>
+#include <string.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define OFFSET (36000)
+
+int main(int argc, char *argv[])
+{
+	struct timespec now, tst;
+	int status, i;
+	pid_t pid;
+
+	if (argc > 1) {
+		if (sscanf(argv[1], "%ld", &now.tv_sec) != 1)
+			return pr_perror("sscanf");
+
+		for (i = 0; i < 2; i++) {
+			_gettime(CLOCK_MONOTONIC, &tst, i);
+			if (abs(tst.tv_sec - now.tv_sec) > 5)
+				return pr_fail("%ld %ld\n", now.tv_sec, tst.tv_sec);
+		}
+	}
+
+	nscheck();
+
+	ksft_set_plan(1);
+
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	if (_settime(CLOCK_MONOTONIC, OFFSET))
+		return 1;
+
+	for (i = 0; i < 2; i++) {
+		_gettime(CLOCK_MONOTONIC, &tst, i);
+		if (abs(tst.tv_sec - now.tv_sec) > 5)
+			return pr_fail("%ld %ld\n",
+					now.tv_sec, tst.tv_sec);
+	}
+
+	if (argc > 1)
+		return 0;
+
+	pid = fork();
+	if (pid < 0)
+		return pr_perror("fork");
+
+	if (pid == 0) {
+		char now_str[64];
+		char *cargv[] = {"exec", now_str, NULL};
+		char *cenv[] = {NULL};
+
+		/* Check that a child process is in the new timens. */
+		for (i = 0; i < 2; i++) {
+			_gettime(CLOCK_MONOTONIC, &tst, i);
+			if (abs(tst.tv_sec - now.tv_sec - OFFSET) > 5)
+				return pr_fail("%ld %ld\n",
+						now.tv_sec + OFFSET, tst.tv_sec);
+		}
+
+		/* Check that a proper vdso will be mapped after execve. */
+		snprintf(now_str, sizeof(now_str), "%ld", now.tv_sec + OFFSET);
+		execve("/proc/self/exe", cargv, cenv);
+		return pr_perror("execve");
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("waitpid");
+
+	if (status)
+		ksft_exit_fail();
+
+	ksft_test_result_pass("exec\n");
+	ksft_exit_pass();
+	return 0;
+}
-- 
2.22.0

[PATCHv5 00/37] kernel: Introduce Time Namespace

[Dmitry Safonov]

Discussions around time namespace are there for a long time. The first
attempt to implement it was in 2006 by Jeff Dike. From that time, the
topic appears on and off in various discussions.

There are two main use cases for time namespaces:
1. change date and time inside a container;
2. adjust clocks for a container restored from a checkpoint.

“It seems like this might be one of the last major obstacles keeping
migration from being used in production systems, given that not all
containers and connections can be migrated as long as a time dependency
is capable of messing it up.” (by github.com/dav-ell)

The kernel provides access to several clocks: CLOCK_REALTIME,
CLOCK_MONOTONIC, CLOCK_BOOTTIME. Last two clocks are monotonous, but the
start points for them are not defined and are different for each
system. When a container is migrated from one node to another, all
clocks have to be restored into consistent states; in other words, they
have to continue running from the same points where they have been
dumped.

The main idea of this patch set is adding per-namespace offsets for
system clocks. When a process in a non-root time namespace requests
time of a clock, a namespace offset is added to the current value of
this clock and the sum is returned.

All offsets are placed on a separate page, this allows us to map it as
part of VVAR into user processes and use offsets from VDSO calls.

Now offsets are implemented for CLOCK_MONOTONIC and CLOCK_BOOTTIME
clocks.

v4..v5 Changes:
* Rebased over generic vdso (already in master)
* Addressing review comments by Thomas Gleixner
  (thanks much for your time and patience):
  - Dropping `timens` prefix from subjects (it's not a subsystem)
  - Keeping commit messages in a neutral technical form
  - Splitting unreasonably large patches
  - Document code with missing comments
  - Dropped dead code that's not compiled with !CONFIG_TIME_NS
* Updated performance results [here, at the bottom]
* Split vdso jump tables patch
* Allow unshare() with many threads: it's safe until fork()/clone(),
  where we check for CLONE_THREADS
* Add missed check in setns() for CLONE_VM | CLONE_THREADS
* Fixed compilation with !CONFIG_UTS_NS
* Add a plan in selftests (prevents new warning "Planned tests != run tests")
* Set jump table section address & size to (-1UL) just in case if there
  is no such section while running vdso2c (and WARN() on boot in such
  case)

[v1..v4 Changelog is at the very bottom here]

Our performance measurements show that the price of VDSO's clock_gettime()
in a child time namespace is about 8% with a hot CPU cache and about 90%
with a cold CPU cache. There is no performance regression for host
processes outside time namespace on those tests.

We wrote two small benchmarks. The first one gettime_perf.c calls
clock_gettime() in a loop for 3 seconds. It shows us performance with
a hot CPU cache (more clock_gettime() cycles - the better):

        | before    | CONFIG_TIME_NS=n | host      | inside timens
--------------------------------------------------------------
        | 161822960 | 161147792        | 160187142 | 150584782
        | 161891728 | 161489804        | 159914989 | 150417019
        | 161891770 | 161098734        | 160123179 | 150601277
        | 161687686 | 161114738        | 159874249 | 150243276
        | 161247151 | 161411636        | 159096392 | 149637536
--------------------------------------------------------------
avg     | 161708259 | 161252540        | 159839190 | 150296778
diff %  | 100       | 99.7             | 98.8      | 92.9
-------------------------------------------------------------
stdev % | 0.2       | 0.1              | 0.1       | 0.2

The gettime_perf_cold test does 10K iterations. In each iteration, it
drops cpu caches for vdso pages, clflush is used for this, then it runs
rdtsc(); clock_gettime; rdtsc(); and prints the number of tsc cycles.

(lesser tsc per cycle - the better):

           | before    | CONFIG_TIME_NS=n | host      | inside timens
--------------------------------------------------------------
tsc        | 434       | 433              | 437       | 477
stdev(tsc) | 5         | 5                | 5         | 3
diff (%)   | 1         | 1                | 100.1     | 109

vdsotest results: https://gist.github.com/avagin/f290afb8b721ae0522a561d585f34de0

The numbers gathered on Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz.

Cc: Adrian Reber <adrian@lisas.de>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: containers@lists.linux-foundation.org
Cc: criu@openvz.org
Cc: linux-api@vger.kernel.org
Cc: x86@kernel.org

v5 on github (if someone prefers `git pull` or `git log`):
https://github.com/0x7f454c46/linux/tree/timens-v5

v4: https://lkml.kernel.org/r/20190612192628.23797-1-dima@arista.com
v3: https://lkml.kernel.org/r/20190425161416.26600-1-dima@arista.com
v2: https://lore.kernel.org/lkml/20190206001107.16488-1-dima@arista.com/
RFC: https://lkml.kernel.org/r/20180919205037.9574-1-dima@arista.com/

v3..v4 Changes:

* CLOCKE_NEWTIME is unshare()-only flag now (CLON_PIDFD took previous value)
* Addressing Jann Horn's feedback - we don't allow CLONE_THREAD or
  CLONE_VM together with CLONE_NEWTIME (thanks for spotting!)
* Addressing issues found by Thomas - removed unmaintainable CLOCK_TIMENS
  and introduced another call back into k_clock to get ktime instead
  of getting timespec and converting it (Patch 03)
* Renaming timens_offsets members to omit _offset postfix
  (thanks Cyrill for the suggestion)
* Suggestions, renaming and making code more maintainable from Thomas's
  feedback (thanks much!)
* Fixing out-of-bounds and other issues in procfs file (kudos Jann Horn)
* vdso_fault() can be called on a remote task by /proc/$pid/mem or
  process_vm_readv() - addressed by adding a slow-path with searching
  for owner's namespace (thanks for spotting this unobvious issue, Jann)
* Other nits by Jann Horn

v2..v3: Major changes:

* Simplify two VDSO images by using static_branch() in vclock_gettime()
  Removes unwanted conflicts with generic VDSO movement patches and
  simplifies things by dropping too invasive linker magic.
  As an alternative to static_branch() we tested an attempt to introduce
  home-made dynamic patching called retcalls:
  https://github.com/0x7f454c46/linux/commit/4cc0180f6d65
  Considering some theoretical problems with toolchains, we decided to go
  with long well-tested nop-patching in static_branch(). Though, it was
  needed to provide backend for relative code.

* address Thomas' comments.
* add sanity checks for offsets:
  - the current clock time in a namespace has to be in [0, KTIME_MAX / 2).
    KTIME_MAX is divided by two here to be sure that the KTIME_MAX limit
    is still unreachable.
Link: https://lkml.org/lkml/2018/9/19/950
Link: https://lkml.org/lkml/2019/2/5/867

v1..v2: There are two major changes:

* Two versions of the VDSO library to avoid a performance penalty for
  host tasks outside time namespace (as suggested by Andy and Thomas).

  As it has been discussed on timens RFC, adding a new conditional branch
  `if (inside_time_ns)` on VDSO for all processes is undesirable.
  It will add a penalty for everybody as branch predictor may mispredict
  the jump. Also there are instruction cache lines wasted on cmp/jmp.

  Those effects of introducing time namespace are very much unwanted
  having in mind how much work have been spent on micro-optimisation
  VDSO code.

  Addressing those problems, there are two versions of VDSO's .so:
  for host tasks (without any penalty) and for processes inside of time
  namespace with clk_to_ns() that subtracts offsets from host's time.


* Allow to set clock offsets for a namespace only before any processes
  appear in it.

  Now a time namespace looks similar to a pid namespace in a way how it is
  created: unshare(CLONE_NEWTIME) system call creates a new time namespace,
  but doesn't set it to the current process. Then all children of
  the process will be born in the new time namespace, or a process can
  use the setns() system call to join a namespace.

  This scheme allows to create a new time namespaces, set clock offsets
  and then populate the namespace with processes.


Andrei Vagin (25):
  ns: Introduce Time Namespace
  timens: Add timens_offsets
  posix-clocks: Rename the clock_get() into clock_get_timespec()
  posix-clocks: Rename *_clock_get() functions into
    *_clock_get_timespec()
  alarmtimer: Rename gettime() callback to get_ktime()
  alarmtimer: Provide get_timespec() callback
  posix-clocks: Introduce clock_get_ktime() callback
  posix-timers: Use clock_get_ktime() in common_timer_get()
  posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets
  posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset
  kernel: Add do_timens_ktime_to_host() helper
  timerfd: Make timerfd_settime() time namespace aware
  posix-timers: Make timer_settime() time namespace aware
  alarmtimer: Make nanosleep time namespace aware
  hrtimers: Prepare hrtimer_nanosleep() for time namespaces
  posix-timers: Make clock_nanosleep() time namespace aware
  x86/vdso: Add offsets page in vvar
  vdso: Introduce vdso_static_branch_unlikely()
  x86/vdso: Enable static branches for the timens vdso
  fs/proc: Introduce /proc/pid/timens_offsets
  selftest/timens: Add a test for timerfd
  selftest/timens: Add a test for clock_nanosleep()
  selftest/timens: Add timer offsets test
  selftests/timens: Add a simple perf test for clock_gettime()
  selftest/timens: Check that a right vdso is mapped after fork and exec

Dmitry Safonov (12):
  fd/proc: Respect boottime inside time namespace for /proc/uptime
  x86/vdso2c: Correct err messages on file opening
  x86/vdso2c: Convert iterator to unsigned
  x86/vdso/Makefile: Add vobjs32
  x86/vdso: Restrict splitting VVAR VMA
  x86/vdso: Rename vdso_image {.data=>.text}
  x86/vdso: Allocate timens vdso
  x86/vdso: Switch image on setns()/clone()
  x86/vdso2c: Process jump tables
  posix-clocks: Add align for timens_offsets
  selftest/timens: Add Time Namespace test for supported clocks
  selftest/timens: Add procfs selftest

 MAINTAINERS                                   |   3 +
 arch/Kconfig                                  |   5 +
 arch/x86/Kconfig                              |   1 +
 arch/x86/entry/vdso/Makefile                  |  15 +-
 arch/x86/entry/vdso/vdso-layout.lds.S         |  10 +-
 arch/x86/entry/vdso/vdso2c.c                  |   7 +-
 arch/x86/entry/vdso/vdso2c.h                  |  22 +-
 arch/x86/entry/vdso/vma.c                     | 177 +++++++-
 arch/x86/include/asm/jump_label.h             |  14 +
 arch/x86/include/asm/vdso.h                   |  14 +-
 arch/x86/kernel/jump_label.c                  |  14 +
 fs/proc/base.c                                |  95 +++++
 fs/proc/namespaces.c                          |   4 +
 fs/proc/uptime.c                              |   3 +
 fs/timerfd.c                                  |   3 +
 include/linux/hrtimer.h                       |   2 +-
 include/linux/jump_label.h                    |   8 +
 include/linux/nsproxy.h                       |   2 +
 include/linux/posix-timers.h                  |   3 +
 include/linux/proc_ns.h                       |   3 +
 include/linux/time_namespace.h                | 114 ++++++
 include/linux/timens_offsets.h                |  18 +
 include/linux/user_namespace.h                |   1 +
 include/uapi/linux/sched.h                    |   6 +
 init/Kconfig                                  |   9 +
 kernel/Makefile                               |   1 +
 kernel/fork.c                                 |  16 +-
 kernel/nsproxy.c                              |  41 +-
 kernel/time/alarmtimer.c                      |  68 +++-
 kernel/time/hrtimer.c                         |   8 +-
 kernel/time/posix-clock.c                     |   8 +-
 kernel/time/posix-cpu-timers.c                |  32 +-
 kernel/time/posix-stubs.c                     |  15 +-
 kernel/time/posix-timers.c                    |  89 ++--
 kernel/time/posix-timers.h                    |   7 +-
 kernel/time_namespace.c                       | 385 ++++++++++++++++++
 lib/vdso/gettimeofday.c                       |  53 +++
 tools/testing/selftests/Makefile              |   1 +
 tools/testing/selftests/timens/.gitignore     |   8 +
 tools/testing/selftests/timens/Makefile       |  12 +
 .../selftests/timens/clock_nanosleep.c        | 102 +++++
 tools/testing/selftests/timens/config         |   1 +
 tools/testing/selftests/timens/exec.c         |  93 +++++
 tools/testing/selftests/timens/gettime_perf.c | 101 +++++
 .../selftests/timens/gettime_perf_cold.c      | 160 ++++++++
 tools/testing/selftests/timens/log.h          |  26 ++
 tools/testing/selftests/timens/procfs.c       | 144 +++++++
 tools/testing/selftests/timens/timens.c       | 185 +++++++++
 tools/testing/selftests/timens/timens.h       |  63 +++
 tools/testing/selftests/timens/timer.c        | 118 ++++++
 tools/testing/selftests/timens/timerfd.c      | 129 ++++++
 51 files changed, 2304 insertions(+), 115 deletions(-)
 create mode 100644 include/linux/time_namespace.h
 create mode 100644 include/linux/timens_offsets.h
 create mode 100644 kernel/time_namespace.c
 create mode 100644 tools/testing/selftests/timens/.gitignore
 create mode 100644 tools/testing/selftests/timens/Makefile
 create mode 100644 tools/testing/selftests/timens/clock_nanosleep.c
 create mode 100644 tools/testing/selftests/timens/config
 create mode 100644 tools/testing/selftests/timens/exec.c
 create mode 100644 tools/testing/selftests/timens/gettime_perf.c
 create mode 100644 tools/testing/selftests/timens/gettime_perf_cold.c
 create mode 100644 tools/testing/selftests/timens/log.h
 create mode 100644 tools/testing/selftests/timens/procfs.c
 create mode 100644 tools/testing/selftests/timens/timens.c
 create mode 100644 tools/testing/selftests/timens/timens.h
 create mode 100644 tools/testing/selftests/timens/timer.c
 create mode 100644 tools/testing/selftests/timens/timerfd.c

-- 
2.22.0

[PATCHv5 01/37] ns: Introduce Time Namespace

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Time Namespace isolates clock values.

The kernel provides access to several clocks CLOCK_REALTIME,
CLOCK_MONOTONIC, CLOCK_BOOTTIME, etc.

CLOCK_REALTIME
      System-wide clock that measures real (i.e., wall-clock) time.

CLOCK_MONOTONIC
      Clock that cannot be set and represents monotonic time since
      some unspecified starting point.

CLOCK_BOOTTIME
      Identical to CLOCK_MONOTONIC, except it also includes any time
      that the system is suspended.

For many users, the time namespace means the ability to changes date and
time in a container (CLOCK_REALTIME).

But in a context of the checkpoint/restore functionality, monotonic and
bootime clocks become interesting. Both clocks are monotonic with
unspecified staring points. These clocks are widely used to measure time
slices and set timers. After restoring or migrating processes, we have to
guarantee that they never go backward. In an ideal case, the behavior of
these clocks should be the same as for a case when a whole system is
suspended. All this means that we need to be able to set CLOCK_MONOTONIC
and CLOCK_BOOTTIME clocks, what can be done by adding per-namespace
offsets for clocks.

A time namespace is similar to a pid namespace in a way how it is
created: unshare(CLONE_NEWTIME) system call creates a new time namespace,
but doesn't set it to the current process. Then all children of
the process will be born in the new time namespace, or a process can
use the setns() system call to join a namespace.

This scheme allows setting clock offsets for a namespace, before any
processes appear in it.

All available clone flags have been used, so CLONE_NEWTIME uses the
highest bit of CSIGNAL. It means that we can use it with the unshare
system call only. Rith now, this works for us, because time namespace
offsets can be set only when a new time namespace is not populated. In a
future, we will have the clone3 system call [1] which will allow to use
the CSIGNAL mask for clone flags.

[1]: httmps://lkml.kernel.org/r/20190604160944.4058-1-christian@brauner.io

Link: https://criu.org/Time_namespace
Link: https://lists.openvz.org/pipermail/criu/2018-June/041504.html
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 MAINTAINERS                    |   2 +
 fs/proc/namespaces.c           |   4 +
 include/linux/nsproxy.h        |   2 +
 include/linux/proc_ns.h        |   3 +
 include/linux/time_namespace.h |  69 +++++++++++
 include/linux/user_namespace.h |   1 +
 include/uapi/linux/sched.h     |   6 +
 init/Kconfig                   |   7 ++
 kernel/Makefile                |   1 +
 kernel/fork.c                  |  16 ++-
 kernel/nsproxy.c               |  41 +++++--
 kernel/time_namespace.c        | 217 +++++++++++++++++++++++++++++++++
 12 files changed, 359 insertions(+), 10 deletions(-)
 create mode 100644 include/linux/time_namespace.h
 create mode 100644 kernel/time_namespace.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 6426db5198f0..ce6ff88f7efd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12836,6 +12836,8 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
 S:	Maintained
 F:	fs/timerfd.c
 F:	include/linux/timer*
+F:	include/linux/time_namespace.h
+F:	kernel/time_namespace.c
 F:	kernel/time/*timer*
 
 POWER MANAGEMENT CORE
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index dd2b35f78b09..8b5c720fe5d7 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -33,6 +33,10 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_CGROUPS
 	&cgroupns_operations,
 #endif
+#ifdef CONFIG_TIME_NS
+	&timens_operations,
+	&timens_for_children_operations,
+#endif
 };
 
 static const char *proc_ns_get_link(struct dentry *dentry,
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 2ae1b1a4d84d..074f395b9ad2 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -35,6 +35,8 @@ struct nsproxy {
 	struct mnt_namespace *mnt_ns;
 	struct pid_namespace *pid_ns_for_children;
 	struct net 	     *net_ns;
+	struct time_namespace *time_ns;
+	struct time_namespace *time_ns_for_children;
 	struct cgroup_namespace *cgroup_ns;
 };
 extern struct nsproxy init_nsproxy;
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index d31cb6215905..d312e6281e69 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -32,6 +32,8 @@ extern const struct proc_ns_operations pidns_for_children_operations;
 extern const struct proc_ns_operations userns_operations;
 extern const struct proc_ns_operations mntns_operations;
 extern const struct proc_ns_operations cgroupns_operations;
+extern const struct proc_ns_operations timens_operations;
+extern const struct proc_ns_operations timens_for_children_operations;
 
 /*
  * We always define these enumerators
@@ -43,6 +45,7 @@ enum {
 	PROC_USER_INIT_INO	= 0xEFFFFFFDU,
 	PROC_PID_INIT_INO	= 0xEFFFFFFCU,
 	PROC_CGROUP_INIT_INO	= 0xEFFFFFFBU,
+	PROC_TIME_INIT_INO	= 0xEFFFFFFAU,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
new file mode 100644
index 000000000000..9507ed7072fe
--- /dev/null
+++ b/include/linux/time_namespace.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TIMENS_H
+#define _LINUX_TIMENS_H
+
+
+#include <linux/sched.h>
+#include <linux/kref.h>
+#include <linux/nsproxy.h>
+#include <linux/ns_common.h>
+#include <linux/err.h>
+
+struct user_namespace;
+extern struct user_namespace init_user_ns;
+
+struct time_namespace {
+	struct kref kref;
+	struct user_namespace *user_ns;
+	struct ucounts *ucounts;
+	struct ns_common ns;
+	struct timens_offsets *offsets;
+	bool   initialized;
+} __randomize_layout;
+extern struct time_namespace init_time_ns;
+
+#ifdef CONFIG_TIME_NS
+static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
+{
+	kref_get(&ns->kref);
+	return ns;
+}
+
+extern struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns);
+extern void free_time_ns(struct kref *kref);
+extern int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
+
+static inline void put_time_ns(struct time_namespace *ns)
+{
+	kref_put(&ns->kref, free_time_ns);
+}
+
+
+#else
+static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
+{
+	return NULL;
+}
+
+static inline void put_time_ns(struct time_namespace *ns)
+{
+}
+
+static inline struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns)
+{
+	if (flags & CLONE_NEWTIME)
+		return ERR_PTR(-EINVAL);
+
+	return old_ns;
+}
+
+static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+{
+	return 0;
+}
+
+#endif
+
+#endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index fb9f4f799554..6ef1c7109fc4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -45,6 +45,7 @@ enum ucount_type {
 	UCOUNT_NET_NAMESPACES,
 	UCOUNT_MNT_NAMESPACES,
 	UCOUNT_CGROUP_NAMESPACES,
+	UCOUNT_TIME_NAMESPACES,
 #ifdef CONFIG_INOTIFY_USER
 	UCOUNT_INOTIFY_INSTANCES,
 	UCOUNT_INOTIFY_WATCHES,
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index b3105ac1381a..551739227e96 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -33,6 +33,12 @@
 #define CLONE_NEWNET		0x40000000	/* New network namespace */
 #define CLONE_IO		0x80000000	/* Clone io context */
 
+/*
+ * cloning flags intersect with CSIGNAL so can be used with unshare and clone3
+ * syscalls only:
+ */
+#define CLONE_NEWTIME	0x00000080	/* New time namespace */
+
 /*
  * Arguments for the clone3 syscall
  */
diff --git a/init/Kconfig b/init/Kconfig
index bd7d650d4a99..a7cbc9b470c7 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1069,6 +1069,13 @@ config UTS_NS
 	  In this namespace tasks see different info provided with the
 	  uname() system call
 
+config TIME_NS
+	bool "TIME namespace"
+	default y
+	help
+	  In this namespace boottime and monotonic clocks can be set.
+	  The time will keep going with the same pace.
+
 config IPC_NS
 	bool "IPC namespace"
 	depends on (SYSVIPC || POSIX_MQUEUE)
diff --git a/kernel/Makefile b/kernel/Makefile
index a8d923b5481b..a8654c9aa2f5 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup/
 obj-$(CONFIG_UTS_NS) += utsname.o
+obj-$(CONFIG_TIME_NS) += time_namespace.o
 obj-$(CONFIG_USER_NS) += user_namespace.o
 obj-$(CONFIG_PID_NS) += pid_namespace.o
 obj-$(CONFIG_IKCONFIG) += configs.o
diff --git a/kernel/fork.c b/kernel/fork.c
index 2852d0e76ea3..3dbb2d33dc52 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1777,6 +1777,7 @@ static __latent_entropy struct task_struct *copy_process(
 	struct multiprocess_signals delayed;
 	struct file *pidfile = NULL;
 	u64 clone_flags = args->flags;
+	struct nsproxy *nsp = current->nsproxy;
 
 	/*
 	 * Don't allow sharing the root directory with processes in a different
@@ -1819,8 +1820,16 @@ static __latent_entropy struct task_struct *copy_process(
 	 */
 	if (clone_flags & CLONE_THREAD) {
 		if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
-		    (task_active_pid_ns(current) !=
-				current->nsproxy->pid_ns_for_children))
+		    (task_active_pid_ns(current) != nsp->pid_ns_for_children))
+			return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * If the new process will be in a different time namespace
+	 * do not allow it to share VM or a thread group with the forking task.
+	 */
+	if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
+		if (nsp->time_ns != nsp->time_ns_for_children)
 			return ERR_PTR(-EINVAL);
 	}
 
@@ -2707,7 +2716,8 @@ static int check_unshare_flags(unsigned long unshare_flags)
 	if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
 				CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
 				CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
-				CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP))
+				CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
+				CLONE_NEWTIME))
 		return -EINVAL;
 	/*
 	 * Not implemented, but pretend it works if there is nothing
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index c815f58e6bc0..ed9882108cd2 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -18,6 +18,7 @@
 #include <linux/pid_namespace.h>
 #include <net/net_namespace.h>
 #include <linux/ipc_namespace.h>
+#include <linux/time_namespace.h>
 #include <linux/proc_ns.h>
 #include <linux/file.h>
 #include <linux/syscalls.h>
@@ -40,6 +41,10 @@ struct nsproxy init_nsproxy = {
 #ifdef CONFIG_CGROUPS
 	.cgroup_ns		= &init_cgroup_ns,
 #endif
+#ifdef CONFIG_TIME_NS
+	.time_ns		= &init_time_ns,
+	.time_ns_for_children	= &init_time_ns,
+#endif
 };
 
 static inline struct nsproxy *create_nsproxy(void)
@@ -106,8 +111,18 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
 		goto out_net;
 	}
 
+	new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
+					tsk->nsproxy->time_ns_for_children);
+	if (IS_ERR(new_nsp->time_ns_for_children)) {
+		err = PTR_ERR(new_nsp->time_ns_for_children);
+		goto out_time;
+	}
+	new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
+
 	return new_nsp;
 
+out_time:
+	put_net(new_nsp->net_ns);
 out_net:
 	put_cgroup_ns(new_nsp->cgroup_ns);
 out_cgroup:
@@ -136,15 +151,16 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 	struct nsproxy *old_ns = tsk->nsproxy;
 	struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
 	struct nsproxy *new_ns;
+	int ret;
 
 	if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 			      CLONE_NEWPID | CLONE_NEWNET |
-			      CLONE_NEWCGROUP)))) {
-		get_nsproxy(old_ns);
-		return 0;
-	}
-
-	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+			      CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
+		if (likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
+			get_nsproxy(old_ns);
+			return 0;
+		}
+	} else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	/*
@@ -162,6 +178,12 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 	if (IS_ERR(new_ns))
 		return  PTR_ERR(new_ns);
 
+	ret = timens_on_fork(new_ns, tsk);
+	if (ret) {
+		free_nsproxy(new_ns);
+		return ret;
+	}
+
 	tsk->nsproxy = new_ns;
 	return 0;
 }
@@ -176,6 +198,10 @@ void free_nsproxy(struct nsproxy *ns)
 		put_ipc_ns(ns->ipc_ns);
 	if (ns->pid_ns_for_children)
 		put_pid_ns(ns->pid_ns_for_children);
+	if (ns->time_ns)
+		put_time_ns(ns->time_ns);
+	if (ns->time_ns_for_children)
+		put_time_ns(ns->time_ns_for_children);
 	put_cgroup_ns(ns->cgroup_ns);
 	put_net(ns->net_ns);
 	kmem_cache_free(nsproxy_cachep, ns);
@@ -192,7 +218,8 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 	int err = 0;
 
 	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
-			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
+			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
+			       CLONE_NEWTIME)))
 		return 0;
 
 	user_ns = new_cred ? new_cred->user_ns : current_user_ns();
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
new file mode 100644
index 000000000000..7ee6be0647bc
--- /dev/null
+++ b/kernel/time_namespace.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Andrei Vagin <avagin@openvz.org>
+ * Author: Dmitry Safonov <dima@arista.com>
+ */
+
+#include <linux/time_namespace.h>
+#include <linux/user_namespace.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/proc_ns.h>
+#include <linux/export.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+
+static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
+{
+	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
+}
+
+static void dec_time_namespaces(struct ucounts *ucounts)
+{
+	dec_ucount(ucounts, UCOUNT_TIME_NAMESPACES);
+}
+
+static struct time_namespace *create_time_ns(void)
+{
+	struct time_namespace *time_ns;
+
+	time_ns = kmalloc(sizeof(struct time_namespace), GFP_KERNEL);
+	if (time_ns) {
+		kref_init(&time_ns->kref);
+		time_ns->initialized = false;
+	}
+	return time_ns;
+}
+
+/*
+ * Clone a new ns copying @old_ns, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return the new ns or ERR_PTR.
+ */
+static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
+					  struct time_namespace *old_ns)
+{
+	struct time_namespace *ns;
+	struct ucounts *ucounts;
+	int err;
+
+	err = -ENOSPC;
+	ucounts = inc_time_namespaces(user_ns);
+	if (!ucounts)
+		goto fail;
+
+	err = -ENOMEM;
+	ns = create_time_ns();
+	if (!ns)
+		goto fail_dec;
+
+	err = ns_alloc_inum(&ns->ns);
+	if (err)
+		goto fail_free;
+
+	ns->ucounts = ucounts;
+	ns->ns.ops = &timens_operations;
+	ns->user_ns = get_user_ns(user_ns);
+	return ns;
+
+fail_free:
+	kfree(ns);
+fail_dec:
+	dec_time_namespaces(ucounts);
+fail:
+	return ERR_PTR(err);
+}
+
+/*
+ * Add a reference to old_ns, or clone it if @flags specify CLONE_NEWTIME.
+ * In latter case, changes to the time of this process won't be seen by parent,
+ * and vice versa.
+ */
+struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns)
+{
+	if (!(flags & CLONE_NEWTIME))
+		return get_time_ns(old_ns);
+
+	return clone_time_ns(user_ns, old_ns);
+}
+
+void free_time_ns(struct kref *kref)
+{
+	struct time_namespace *ns;
+
+	ns = container_of(kref, struct time_namespace, kref);
+	dec_time_namespaces(ns->ucounts);
+	put_user_ns(ns->user_ns);
+	ns_free_inum(&ns->ns);
+	kfree(ns);
+}
+
+static struct time_namespace *to_time_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct time_namespace, ns);
+}
+
+static struct ns_common *timens_get(struct task_struct *task)
+{
+	struct time_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->time_ns;
+		get_time_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static struct ns_common *timens_for_children_get(struct task_struct *task)
+{
+	struct time_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->time_ns_for_children;
+		get_time_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void timens_put(struct ns_common *ns)
+{
+	put_time_ns(to_time_ns(ns));
+}
+
+static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+	struct time_namespace *ns = to_time_ns(new);
+
+	if (!thread_group_empty(current))
+		return -EINVAL;
+
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+		return -EPERM;
+
+	get_time_ns(ns);
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns);
+	put_time_ns(nsproxy->time_ns_for_children);
+	nsproxy->time_ns = ns;
+	nsproxy->time_ns_for_children = ns;
+	ns->initialized = true;
+	return 0;
+}
+
+int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+{
+	struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
+	struct time_namespace *ns = to_time_ns(nsc);
+
+	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
+		return 0;
+
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns);
+	nsproxy->time_ns = ns;
+	ns->initialized = true;
+
+	return 0;
+}
+
+static struct user_namespace *timens_owner(struct ns_common *ns)
+{
+	return to_time_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations timens_operations = {
+	.name		= "time",
+	.type		= CLONE_NEWTIME,
+	.get		= timens_get,
+	.put		= timens_put,
+	.install	= timens_install,
+	.owner		= timens_owner,
+};
+
+const struct proc_ns_operations timens_for_children_operations = {
+	.name		= "time_for_children",
+	.type		= CLONE_NEWTIME,
+	.get		= timens_for_children_get,
+	.put		= timens_put,
+	.install	= timens_install,
+	.owner		= timens_owner,
+};
+
+struct time_namespace init_time_ns = {
+	.kref = KREF_INIT(3),
+	.user_ns = &init_user_ns,
+	.ns.inum = PROC_TIME_INIT_INO,
+	.ns.ops = &timens_operations,
+};
+
+static int __init time_ns_init(void)
+{
+	return 0;
+}
+subsys_initcall(time_ns_init);
-- 
2.22.0

[PATCHv5 02/37] timens: Add timens_offsets

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Introduce offsets for time namespace. They will contain an adjustment
needed to convert clocks to/from host's.

Allocate one page for each time namespace that will be premapped into
userspace among vvar pages.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 MAINTAINERS                    |  1 +
 include/linux/time_namespace.h |  1 +
 include/linux/timens_offsets.h |  8 ++++++++
 kernel/time_namespace.c        | 14 ++++++++++++--
 4 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/timens_offsets.h

diff --git a/MAINTAINERS b/MAINTAINERS
index ce6ff88f7efd..b58c49d331eb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12837,6 +12837,7 @@ S:	Maintained
 F:	fs/timerfd.c
 F:	include/linux/timer*
 F:	include/linux/time_namespace.h
+F:	include/linux/timens_offsets.h
 F:	kernel/time_namespace.c
 F:	kernel/time/*timer*
 
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 9507ed7072fe..b6985aa87479 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -8,6 +8,7 @@
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/err.h>
+#include <linux/timens_offsets.h>
 
 struct user_namespace;
 extern struct user_namespace init_user_ns;
diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
new file mode 100644
index 000000000000..7d7cb68ea778
--- /dev/null
+++ b/include/linux/timens_offsets.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TIME_OFFSETS_H
+#define _LINUX_TIME_OFFSETS_H
+
+struct timens_offsets {
+};
+
+#endif
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index 7ee6be0647bc..f849c59f1108 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/cred.h>
 #include <linux/err.h>
+#include <linux/mm.h>
 
 static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
 {
@@ -47,6 +48,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 {
 	struct time_namespace *ns;
 	struct ucounts *ucounts;
+	struct page *page;
 	int err;
 
 	err = -ENOSPC;
@@ -59,15 +61,22 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 	if (!ns)
 		goto fail_dec;
 
+	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	if (!page)
+		goto fail_free;
+	ns->offsets = page_address(page);
+	BUILD_BUG_ON(sizeof(*ns->offsets) > PAGE_SIZE);
+
 	err = ns_alloc_inum(&ns->ns);
 	if (err)
-		goto fail_free;
+		goto fail_page;
 
 	ns->ucounts = ucounts;
 	ns->ns.ops = &timens_operations;
 	ns->user_ns = get_user_ns(user_ns);
 	return ns;
-
+fail_page:
+	free_page((unsigned long)ns->offsets);
 fail_free:
 	kfree(ns);
 fail_dec:
@@ -95,6 +104,7 @@ void free_time_ns(struct kref *kref)
 	struct time_namespace *ns;
 
 	ns = container_of(kref, struct time_namespace, kref);
+	free_page((unsigned long)ns->offsets);
 	dec_time_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
 	ns_free_inum(&ns->ns);
-- 
2.22.0

[PATCHv5 03/37] posix-clocks: Rename the clock_get() into clock_get_timespec()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
 - The time in a task's time namespace for sys_clock_gettime()
 - The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format, rather than in (struct timespec).

Rename clock_get() callback into clock_get_timespec() as a preparation
for introducing clock_get_ktime().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c       |  4 ++--
 kernel/time/posix-clock.c      |  8 ++++----
 kernel/time/posix-cpu-timers.c | 32 ++++++++++++++++----------------
 kernel/time/posix-timers.c     | 22 +++++++++++-----------
 kernel/time/posix-timers.h     |  4 ++--
 5 files changed, 35 insertions(+), 35 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 57518efc3810..cada96fdc615 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -644,7 +644,7 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
 }
 
 /**
- * alarm_clock_get - posix clock_get interface
+ * alarm_clock_get - posix clock_get_timespec interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
@@ -824,7 +824,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
-	.clock_get		= alarm_clock_get,
+	.clock_get_timespec	= alarm_clock_get,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_del		= common_timer_del,
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index ec960bb939fd..c8f9c9b1cd82 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -315,8 +315,8 @@ static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
 }
 
 const struct k_clock clock_posix_dynamic = {
-	.clock_getres	= pc_clock_getres,
-	.clock_set	= pc_clock_settime,
-	.clock_get	= pc_clock_gettime,
-	.clock_adj	= pc_clock_adjtime,
+	.clock_getres		= pc_clock_getres,
+	.clock_set		= pc_clock_settime,
+	.clock_get_timespec	= pc_clock_gettime,
+	.clock_adj		= pc_clock_adjtime,
 };
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 0a426f4e3125..dccf7dfcd36a 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1417,26 +1417,26 @@ static int thread_cpu_timer_create(struct k_itimer *timer)
 }
 
 const struct k_clock clock_posix_cpu = {
-	.clock_getres	= posix_cpu_clock_getres,
-	.clock_set	= posix_cpu_clock_set,
-	.clock_get	= posix_cpu_clock_get,
-	.timer_create	= posix_cpu_timer_create,
-	.nsleep		= posix_cpu_nsleep,
-	.timer_set	= posix_cpu_timer_set,
-	.timer_del	= posix_cpu_timer_del,
-	.timer_get	= posix_cpu_timer_get,
-	.timer_rearm	= posix_cpu_timer_rearm,
+	.clock_getres		= posix_cpu_clock_getres,
+	.clock_set		= posix_cpu_clock_set,
+	.clock_get_timespec	= posix_cpu_clock_get,
+	.timer_create		= posix_cpu_timer_create,
+	.nsleep			= posix_cpu_nsleep,
+	.timer_set		= posix_cpu_timer_set,
+	.timer_del		= posix_cpu_timer_del,
+	.timer_get		= posix_cpu_timer_get,
+	.timer_rearm		= posix_cpu_timer_rearm,
 };
 
 const struct k_clock clock_process = {
-	.clock_getres	= process_cpu_clock_getres,
-	.clock_get	= process_cpu_clock_get,
-	.timer_create	= process_cpu_timer_create,
-	.nsleep		= process_cpu_nsleep,
+	.clock_getres		= process_cpu_clock_getres,
+	.clock_get_timespec	= process_cpu_clock_get,
+	.timer_create		= process_cpu_timer_create,
+	.nsleep			= process_cpu_nsleep,
 };
 
 const struct k_clock clock_thread = {
-	.clock_getres	= thread_cpu_clock_getres,
-	.clock_get	= thread_cpu_clock_get,
-	.timer_create	= thread_cpu_timer_create,
+	.clock_getres		= thread_cpu_clock_getres,
+	.clock_get_timespec	= thread_cpu_clock_get,
+	.timer_create		= thread_cpu_timer_create,
 };
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index d7f2d91acdac..6c9c0f2d2f1e 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -667,7 +667,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 	 * The timespec64 based conversion is suboptimal, but it's not
 	 * worth to implement yet another callback.
 	 */
-	kc->clock_get(timr->it_clock, &ts64);
+	kc->clock_get_timespec(timr->it_clock, &ts64);
 	now = timespec64_to_ktime(ts64);
 
 	/*
@@ -781,7 +781,7 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
 	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
 	 * clock modifications, so they become CLOCK_MONOTONIC based under the
 	 * hood. See hrtimer_init(). Update timr->kclock, so the generic
-	 * functions which use timr->kclock->clock_get() work.
+	 * functions which use timr->kclock->clock_get_timespec() work.
 	 *
 	 * Note: it_clock stays unmodified, because the next timer_set() might
 	 * use ABSTIME, so it needs to switch back.
@@ -1032,7 +1032,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 	if (!kc)
 		return -EINVAL;
 
-	error = kc->clock_get(which_clock, &kernel_tp);
+	error = kc->clock_get_timespec(which_clock, &kernel_tp);
 
 	if (!error && put_timespec64(&kernel_tp, tp))
 		error = -EFAULT;
@@ -1114,7 +1114,7 @@ SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
 	if (!kc)
 		return -EINVAL;
 
-	err = kc->clock_get(which_clock, &ts);
+	err = kc->clock_get_timespec(which_clock, &ts);
 
 	if (!err && put_old_timespec32(&ts, tp))
 		err = -EFAULT;
@@ -1226,7 +1226,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_clock_realtime_get,
+	.clock_get_timespec	= posix_clock_realtime_get,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1243,7 +1243,7 @@ static const struct k_clock clock_realtime = {
 
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_ktime_get_ts,
+	.clock_get_timespec	= posix_ktime_get_ts,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1258,22 +1258,22 @@ static const struct k_clock clock_monotonic = {
 
 static const struct k_clock clock_monotonic_raw = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_monotonic_raw,
+	.clock_get_timespec	= posix_get_monotonic_raw,
 };
 
 static const struct k_clock clock_realtime_coarse = {
 	.clock_getres		= posix_get_coarse_res,
-	.clock_get		= posix_get_realtime_coarse,
+	.clock_get_timespec	= posix_get_realtime_coarse,
 };
 
 static const struct k_clock clock_monotonic_coarse = {
 	.clock_getres		= posix_get_coarse_res,
-	.clock_get		= posix_get_monotonic_coarse,
+	.clock_get_timespec	= posix_get_monotonic_coarse,
 };
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_tai,
+	.clock_get_timespec	= posix_get_tai,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1288,7 +1288,7 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get		= posix_get_boottime,
+	.clock_get_timespec	= posix_get_boottime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index de5daa6d975a..b3cc9ee36a6b 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -6,8 +6,8 @@ struct k_clock {
 				struct timespec64 *tp);
 	int	(*clock_set)(const clockid_t which_clock,
 			     const struct timespec64 *tp);
-	int	(*clock_get)(const clockid_t which_clock,
-			     struct timespec64 *tp);
+	int	(*clock_get_timespec)(const clockid_t which_clock,
+				      struct timespec64 *tp);
 	int	(*clock_adj)(const clockid_t which_clock, struct __kernel_timex *tx);
 	int	(*timer_create)(struct k_itimer *timer);
 	int	(*nsleep)(const clockid_t which_clock, int flags,
-- 
2.22.0

[PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a task's time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format in (struct k_clock).

As a preparation ground for introducing clock_get_ktime(), the original
callback clock_get() was renamed into clock_get_timespec().
Reflect the renaming into callbacks realizations.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c   |  6 +++---
 kernel/time/posix-timers.c | 17 +++++++++--------
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index cada96fdc615..c191254f178b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -644,13 +644,13 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
 }
 
 /**
- * alarm_clock_get - posix clock_get_timespec interface
+ * alarm_clock_get_timespec - posix clock_get_timespec interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
  * Provides the underlying alarm base time.
  */
-static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
+static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 
@@ -824,7 +824,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
-	.clock_get_timespec	= alarm_clock_get,
+	.clock_get_timespec	= alarm_clock_get_timespec,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_del		= common_timer_del,
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 6c9c0f2d2f1e..a71e43178a7d 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -165,7 +165,8 @@ static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 }
 
 /* Get clock_realtime */
-static int posix_clock_realtime_get(clockid_t which_clock, struct timespec64 *tp)
+static int
+posix_clock_realtime_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_real_ts64(tp);
 	return 0;
@@ -187,7 +188,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 /*
  * Get monotonic time for posix timers
  */
-static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
+static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
@@ -222,13 +223,13 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
-static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
+static int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
 	return 0;
 }
 
-static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
+static int posix_get_tai_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_clocktai_ts64(tp);
 	return 0;
@@ -1226,7 +1227,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_clock_realtime_get,
+	.clock_get_timespec	= posix_clock_realtime_get_timespec,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1243,7 +1244,7 @@ static const struct k_clock clock_realtime = {
 
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_ktime_get_ts,
+	.clock_get_timespec	= posix_get_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1273,7 +1274,7 @@ static const struct k_clock clock_monotonic_coarse = {
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_get_tai,
+	.clock_get_timespec	= posix_get_tai_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1288,7 +1289,7 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
-	.clock_get_timespec	= posix_get_boottime,
+	.clock_get_timespec	= posix_get_boottime_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
-- 
2.22.0

[PATCHv5 05/37] alarmtimer: Rename gettime() callback to get_ktime()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a tasks time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

struct alarm_base needs to follow the same name convention, so rename
.gettime() callback into get_ktime() as a preparation for introducing
get_timespec().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index c191254f178b..37254eb64459 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -36,13 +36,13 @@
  * struct alarm_base - Alarm timer bases
  * @lock:		Lock for syncrhonized access to the base
  * @timerqueue:		Timerqueue head managing the list of events
- * @gettime:		Function to read the time correlating to the base
+ * @get_ktime:		Function to read the time correlating to the base
  * @base_clockid:	clockid for the base
  */
 static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
-	ktime_t			(*gettime)(void);
+	ktime_t			(*get_ktime)(void);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
@@ -207,7 +207,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 	spin_unlock_irqrestore(&base->lock, flags);
 
 	if (alarm->function)
-		restart = alarm->function(alarm, base->gettime());
+		restart = alarm->function(alarm, base->get_ktime());
 
 	spin_lock_irqsave(&base->lock, flags);
 	if (restart != ALARMTIMER_NORESTART) {
@@ -217,7 +217,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 	}
 	spin_unlock_irqrestore(&base->lock, flags);
 
-	trace_alarmtimer_fired(alarm, base->gettime());
+	trace_alarmtimer_fired(alarm, base->get_ktime());
 	return ret;
 
 }
@@ -225,7 +225,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
-	return ktime_sub(alarm->node.expires, base->gettime());
+	return ktime_sub(alarm->node.expires, base->get_ktime());
 }
 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 
@@ -270,7 +270,7 @@ static int alarmtimer_suspend(struct device *dev)
 		spin_unlock_irqrestore(&base->lock, flags);
 		if (!next)
 			continue;
-		delta = ktime_sub(next->expires, base->gettime());
+		delta = ktime_sub(next->expires, base->get_ktime());
 		if (!min || (delta < min)) {
 			expires = next->expires;
 			min = delta;
@@ -364,7 +364,7 @@ void alarm_start(struct alarm *alarm, ktime_t start)
 	hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 	spin_unlock_irqrestore(&base->lock, flags);
 
-	trace_alarmtimer_start(alarm, base->gettime());
+	trace_alarmtimer_start(alarm, base->get_ktime());
 }
 EXPORT_SYMBOL_GPL(alarm_start);
 
@@ -377,7 +377,7 @@ void alarm_start_relative(struct alarm *alarm, ktime_t start)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 
-	start = ktime_add_safe(start, base->gettime());
+	start = ktime_add_safe(start, base->get_ktime());
 	alarm_start(alarm, start);
 }
 EXPORT_SYMBOL_GPL(alarm_start_relative);
@@ -414,7 +414,7 @@ int alarm_try_to_cancel(struct alarm *alarm)
 		alarmtimer_dequeue(base, alarm);
 	spin_unlock_irqrestore(&base->lock, flags);
 
-	trace_alarmtimer_cancel(alarm, base->gettime());
+	trace_alarmtimer_cancel(alarm, base->get_ktime());
 	return ret;
 }
 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
@@ -474,7 +474,7 @@ u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 
-	return alarm_forward(alarm, base->gettime(), interval);
+	return alarm_forward(alarm, base->get_ktime(), interval);
 }
 EXPORT_SYMBOL_GPL(alarm_forward_now);
 
@@ -500,7 +500,7 @@ static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 		return;
 	}
 
-	delta = ktime_sub(absexp, base->gettime());
+	delta = ktime_sub(absexp, base->get_ktime());
 
 	spin_lock_irqsave(&freezer_delta_lock, flags);
 	if (!freezer_delta || (delta < freezer_delta)) {
@@ -619,7 +619,7 @@ static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 	struct alarm_base *base = &alarm_bases[alarm->type];
 
 	if (!absolute)
-		expires = ktime_add_safe(expires, base->gettime());
+		expires = ktime_add_safe(expires, base->get_ktime());
 	if (sigev_none)
 		alarm->node.expires = expires;
 	else
@@ -657,7 +657,7 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;
 
-	*tp = ktime_to_timespec64(base->gettime());
+	*tp = ktime_to_timespec64(base->get_ktime());
 	return 0;
 }
 
@@ -734,7 +734,7 @@ static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 		struct timespec64 rmt;
 		ktime_t rem;
 
-		rem = ktime_sub(absexp, alarm_bases[type].gettime());
+		rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 
 		if (rem <= 0)
 			return 0;
@@ -803,7 +803,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 	exp = timespec64_to_ktime(*tsreq);
 	/* Convert (if necessary) to absolute time */
 	if (flags != TIMER_ABSTIME) {
-		ktime_t now = alarm_bases[type].gettime();
+		ktime_t now = alarm_bases[type].get_ktime();
 
 		exp = ktime_add_safe(now, exp);
 	}
@@ -868,9 +868,9 @@ static int __init alarmtimer_init(void)
 
 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
-	alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
+	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
-	alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
+	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
-- 
2.22.0

[PATCHv5 06/37] alarmtimer: Provide get_timespec() callback

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a task's time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

Wire up alarm bases with get_timespec().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/posix-timers.h | 3 +++
 kernel/time/alarmtimer.c     | 8 ++++++--
 kernel/time/posix-timers.c   | 4 ++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index b20798fc5191..fe13ab265213 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -127,4 +127,7 @@ void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
 
 void posixtimer_rearm(struct kernel_siginfo *info);
+
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp);
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp);
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 37254eb64459..d9e6baa9976a 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -37,12 +37,15 @@
  * @lock:		Lock for syncrhonized access to the base
  * @timerqueue:		Timerqueue head managing the list of events
  * @get_ktime:		Function to read the time correlating to the base
+ * @get_timespec:	Function to read the namespace time correlating to the base
  * @base_clockid:	clockid for the base
  */
 static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
 	ktime_t			(*get_ktime)(void);
+	int			(*get_timespec)(const clockid_t which_clock,
+						struct timespec64 *tp);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
@@ -657,8 +660,7 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;
 
-	*tp = ktime_to_timespec64(base->get_ktime());
-	return 0;
+	return base->get_timespec(base->base_clockid, tp);
 }
 
 /**
@@ -869,8 +871,10 @@ static int __init alarmtimer_init(void)
 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
+	alarm_bases[ALARM_REALTIME].get_timespec = posix_get_timespec,
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
+	alarm_bases[ALARM_BOOTTIME].get_timespec = posix_get_boottime_timespec;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index a71e43178a7d..a600b8b3e9bf 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -188,7 +188,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 /*
  * Get monotonic time for posix timers
  */
-static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
@@ -223,7 +223,7 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
-static int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
 	return 0;
-- 
2.22.0

[PATCHv5 07/37] posix-clocks: Introduce clock_get_ktime() callback

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The callsite in common_timer_get() has already a comment:
    /*
     * The timespec64 based conversion is suboptimal, but it's not
     * worth to implement yet another callback.
     */
    kc->clock_get(timr->it_clock, &ts64);
    now = timespec64_to_ktime(ts64);

The upcoming support for time namespaces requires to have access to:
- The time in a task's time namespace for sys_clock_gettime()
- The time in the root name space for common_timer_get()

That adds a valid reason to finally implement a separate callback which
returns the time in ktime_t format.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/alarmtimer.c   | 19 ++++++++++++++++++-
 kernel/time/posix-timers.c | 26 +++++++++++++++++++++++++-
 kernel/time/posix-timers.h |  3 +++
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index d9e6baa9976a..55cb6e78d082 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -651,7 +651,7 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
- * Provides the underlying alarm base time.
+ * Provides the underlying alarm base time in a tasks time namespace.
  */
 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
@@ -663,6 +663,22 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	return base->get_timespec(base->base_clockid, tp);
 }
 
+/**
+ * alarm_clock_get_ktime - posix clock_get_ktime interface
+ * @which_clock: clockid
+ *
+ * Provides the underlying alarm base time in the root namespace.
+ */
+static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
+{
+	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
+
+	if (!alarmtimer_get_rtcdev())
+		return -EINVAL;
+
+	return base->get_ktime();
+}
+
 /**
  * alarm_timer_create - posix timer_create interface
  * @new_timer: k_itimer pointer to manage
@@ -826,6 +842,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
 const struct k_clock alarm_clock = {
 	.clock_getres		= alarm_clock_getres,
+	.clock_get_ktime	= alarm_clock_get_ktime,
 	.clock_get_timespec	= alarm_clock_get_timespec,
 	.timer_create		= alarm_timer_create,
 	.timer_set		= common_timer_set,
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index a600b8b3e9bf..fb1848c84241 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -172,6 +172,11 @@ posix_clock_realtime_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
+static ktime_t posix_clock_realtime_get_ktime(clockid_t which_clock)
+{
+	return ktime_get_real();
+}
+
 /* Set clock_realtime */
 static int posix_clock_realtime_set(const clockid_t which_clock,
 				    const struct timespec64 *tp)
@@ -194,6 +199,11 @@ int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
+static ktime_t posix_get_ktime(clockid_t which_clock)
+{
+	return ktime_get();
+}
+
 /*
  * Get monotonic-raw time for posix timers
  */
@@ -229,12 +239,22 @@ int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
+static ktime_t posix_get_boottime_ktime(const clockid_t which_clock)
+{
+	return ktime_get_boottime();
+}
+
 static int posix_get_tai_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_clocktai_ts64(tp);
 	return 0;
 }
 
+static ktime_t posix_get_tai_ktime(clockid_t which_clock)
+{
+	return ktime_get_clocktai();
+}
+
 static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
 {
 	tp->tv_sec = 0;
@@ -782,7 +802,7 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
 	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
 	 * clock modifications, so they become CLOCK_MONOTONIC based under the
 	 * hood. See hrtimer_init(). Update timr->kclock, so the generic
-	 * functions which use timr->kclock->clock_get_timespec() work.
+	 * functions which use timr->kclock->clock_get_*() work.
 	 *
 	 * Note: it_clock stays unmodified, because the next timer_set() might
 	 * use ABSTIME, so it needs to switch back.
@@ -1228,6 +1248,7 @@ SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
 static const struct k_clock clock_realtime = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_timespec	= posix_clock_realtime_get_timespec,
+	.clock_get_ktime	= posix_clock_realtime_get_ktime,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1245,6 +1266,7 @@ static const struct k_clock clock_realtime = {
 static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_timespec	= posix_get_timespec,
+	.clock_get_ktime	= posix_get_ktime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1274,6 +1296,7 @@ static const struct k_clock clock_monotonic_coarse = {
 
 static const struct k_clock clock_tai = {
 	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get_ktime	= posix_get_tai_ktime,
 	.clock_get_timespec	= posix_get_tai_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
@@ -1289,6 +1312,7 @@ static const struct k_clock clock_tai = {
 
 static const struct k_clock clock_boottime = {
 	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get_ktime	= posix_get_boottime_ktime,
 	.clock_get_timespec	= posix_get_boottime_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index b3cc9ee36a6b..183994f7e466 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -6,8 +6,11 @@ struct k_clock {
 				struct timespec64 *tp);
 	int	(*clock_set)(const clockid_t which_clock,
 			     const struct timespec64 *tp);
+	/* Returns the clock value in the current time namespace. */
 	int	(*clock_get_timespec)(const clockid_t which_clock,
 				      struct timespec64 *tp);
+	/* Returns the clock value in the root time namespace. */
+	ktime_t	(*clock_get_ktime)(const clockid_t which_clock);
 	int	(*clock_adj)(const clockid_t which_clock, struct __kernel_timex *tx);
 	int	(*timer_create)(struct k_itimer *timer);
 	int	(*nsleep)(const clockid_t which_clock, int flags,
-- 
2.22.0

[PATCHv5 08/37] posix-timers: Use clock_get_ktime() in common_timer_get()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Now, when the clock_get_ktime() callback exists, the suboptimal
timespec64-based conversion can be removed from common_timer_get().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/posix-timers.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index fb1848c84241..aae7ab53790d 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -666,7 +666,6 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 {
 	const struct k_clock *kc = timr->kclock;
 	ktime_t now, remaining, iv;
-	struct timespec64 ts64;
 	bool sig_none;
 
 	sig_none = timr->it_sigev_notify == SIGEV_NONE;
@@ -684,12 +683,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
 			return;
 	}
 
-	/*
-	 * The timespec64 based conversion is suboptimal, but it's not
-	 * worth to implement yet another callback.
-	 */
-	kc->clock_get_timespec(timr->it_clock, &ts64);
-	now = timespec64_to_ktime(ts64);
+	now = kc->clock_get_ktime(timr->it_clock);
 
 	/*
 	 * When a requeue is pending or this is a SIGEV_NONE timer move the
-- 
2.22.0

[PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Add monotonic time virtualisation for time namespace.
Introduce timespec for monotionic clock into timens offsets and wire
clock_gettime() syscall.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h | 8 ++++++++
 include/linux/timens_offsets.h | 1 +
 kernel/time/posix-stubs.c      | 2 ++
 kernel/time/posix-timers.c     | 4 ++++
 4 files changed, 15 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index b6985aa87479..186c134fe222 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -40,6 +40,13 @@ static inline void put_time_ns(struct time_namespace *ns)
 	kref_put(&ns->kref, free_time_ns);
 }
 
+static inline void timens_add_monotonic(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
+
+	if (ns_offsets)
+		*ts = timespec64_add(*ts, ns_offsets->monotonic);
+}
 
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
@@ -65,6 +72,7 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 	return 0;
 }
 
+static inline void timens_add_monotonic(struct timespec64 *ts) {}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index 7d7cb68ea778..eaac2c82be5c 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -3,6 +3,7 @@
 #define _LINUX_TIME_OFFSETS_H
 
 struct timens_offsets {
+	struct timespec64 monotonic;
 };
 
 #endif
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 67df65f887ac..17c67e0aecd8 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -14,6 +14,7 @@
 #include <linux/ktime.h>
 #include <linux/timekeeping.h>
 #include <linux/posix-timers.h>
+#include <linux/time_namespace.h>
 #include <linux/compat.h>
 
 #ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
@@ -77,6 +78,7 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 		break;
 	case CLOCK_MONOTONIC:
 		ktime_get_ts64(tp);
+		timens_add_monotonic(tp);
 		break;
 	case CLOCK_BOOTTIME:
 		ktime_get_boottime_ts64(tp);
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index aae7ab53790d..cfeb0477d1f9 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -30,6 +30,7 @@
 #include <linux/hashtable.h>
 #include <linux/compat.h>
 #include <linux/nospec.h>
+#include <linux/time_namespace.h>
 
 #include "timekeeping.h"
 #include "posix-timers.h"
@@ -196,6 +197,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
@@ -210,6 +212,7 @@ static ktime_t posix_get_ktime(clockid_t which_clock)
 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_raw_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
@@ -224,6 +227,7 @@ static int posix_get_monotonic_coarse(clockid_t which_clock,
 						struct timespec64 *tp)
 {
 	ktime_get_coarse_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
-- 
2.22.0

[PATCHv5 10/37] posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Adds boottime virtualisation for time namespace.
Introduce timespec for boottime clock into timens offsets and wire
clock_gettime() syscall.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h | 9 +++++++++
 include/linux/timens_offsets.h | 1 +
 kernel/time/alarmtimer.c       | 1 +
 kernel/time/posix-stubs.c      | 1 +
 kernel/time/posix-timers.c     | 1 +
 5 files changed, 13 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 186c134fe222..334c1a1c6607 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -48,6 +48,14 @@ static inline void timens_add_monotonic(struct timespec64 *ts)
 		*ts = timespec64_add(*ts, ns_offsets->monotonic);
 }
 
+static inline void timens_add_boottime(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
+
+	if (ns_offsets)
+		*ts = timespec64_add(*ts, ns_offsets->boottime);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -73,6 +81,7 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 }
 
 static inline void timens_add_monotonic(struct timespec64 *ts) {}
+static inline void timens_add_boottime(struct timespec64 *ts) {}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index eaac2c82be5c..e93aabaa5e45 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -4,6 +4,7 @@
 
 struct timens_offsets {
 	struct timespec64 monotonic;
+	struct timespec64 boottime;
 };
 
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 55cb6e78d082..b1e82bb6cc6b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -26,6 +26,7 @@
 #include <linux/freezer.h>
 #include <linux/compat.h>
 #include <linux/module.h>
+#include <linux/time_namespace.h>
 
 #include "posix-timers.h"
 
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 17c67e0aecd8..edaf075d1ee4 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -82,6 +82,7 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 		break;
 	case CLOCK_BOOTTIME:
 		ktime_get_boottime_ts64(tp);
+		timens_add_boottime(tp);
 		break;
 	default:
 		return -EINVAL;
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index cfeb0477d1f9..265fbc816520 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -240,6 +240,7 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
+	timens_add_boottime(tp);
 	return 0;
 }
 
-- 
2.22.0

[PATCHv5 11/37] kernel: Add do_timens_ktime_to_host() helper

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

The helper subtracts namespace's clock offset from the given time
and checks that the result is in [0, KTIME_MAX].

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h | 17 ++++++++++++++
 kernel/time_namespace.c        | 43 ++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 334c1a1c6607..9ba9664ff0ab 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -56,6 +56,18 @@ static inline void timens_add_boottime(struct timespec64 *ts)
 		*ts = timespec64_add(*ts, ns_offsets->boottime);
 }
 
+ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
+				struct timens_offsets *offsets);
+static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
+{
+	struct timens_offsets *offsets = current->nsproxy->time_ns->offsets;
+
+	if (!offsets)
+		return tim;
+
+	return do_timens_ktime_to_host(clockid, tim, offsets);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -82,6 +94,11 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 
 static inline void timens_add_monotonic(struct timespec64 *ts) {}
 static inline void timens_add_boottime(struct timespec64 *ts) {}
+
+static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
+{
+	return tim;
+}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index f849c59f1108..9807c5c90cb2 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -16,6 +16,49 @@
 #include <linux/err.h>
 #include <linux/mm.h>
 
+ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
+				struct timens_offsets *ns_offsets)
+{
+	ktime_t offset;
+
+	switch (clockid) {
+	case CLOCK_MONOTONIC:
+		offset = timespec64_to_ktime(ns_offsets->monotonic);
+		break;
+	case CLOCK_BOOTTIME:
+	case CLOCK_BOOTTIME_ALARM:
+		offset = timespec64_to_ktime(ns_offsets->boottime);
+		break;
+	default:
+		return tim;
+	}
+
+	/*
+	 * Check that @tim value is in [offset, KTIME_MAX + offset]
+	 * and subtract offset.
+	 */
+	if (tim < offset) {
+		/*
+		 * User can specify @tim *absolute* value - if it's lesser than
+		 * the time namespace's offset - it's already expired.
+		 */
+		tim = 0;
+	} else if (KTIME_MAX - tim < -offset) {
+		/*
+		 * User-supplied @tim may be close or even equal KTIME_MAX
+		 * and time namespace offset can be negative.
+		 * Let's check (tim - offset) for an overflow.
+		 * Return KTIME_MAX in such case, as the time value is
+		 * thousands *years* in future anyway.
+		 */
+		tim = KTIME_MAX;
+	} else {
+		tim = ktime_sub(tim, offset);
+	}
+
+	return tim;
+}
+
 static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
 {
 	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
-- 
2.22.0

[PATCHv5 12/37] timerfd: Make timerfd_settime() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

timerfd_settime() accepts an absolute value of the experation time if
TFD_TIMER_ABSTIME is specified. This value is in task's time namespace
and has to be converted to the host's time namespace.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 fs/timerfd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/timerfd.c b/fs/timerfd.c
index 6a6fc8aa1de7..9b0c2f65e7e8 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -26,6 +26,7 @@
 #include <linux/syscalls.h>
 #include <linux/compat.h>
 #include <linux/rcupdate.h>
+#include <linux/time_namespace.h>
 
 struct timerfd_ctx {
 	union {
@@ -196,6 +197,8 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
 	}
 
 	if (texp != 0) {
+		if (flags & TFD_TIMER_ABSTIME)
+			texp = timens_ktime_to_host(clockid, texp);
 		if (isalarm(ctx)) {
 			if (flags & TFD_TIMER_ABSTIME)
 				alarm_start(&ctx->t.alarm, texp);
-- 
2.22.0

[PATCHv5 13/37] posix-timers: Make timer_settime() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Wire timer_settime() syscall into time namespace virtualization.

sys_timer_settime() calls the ktime->timer_set() callback. Right now,
common_timer_set() is the only implementation for the callback.

There user-supplied timer's value is converted from timespec64 to ktime
and then timens_ktime_to_host() can be used to convert namespace's time
to the host time.

Inside a time namespace kernel's time differ on a fixed offset from
a user-supplied, but only absolute values (TIMER_ABSTIME) must
be converted.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 kernel/time/posix-timers.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 265fbc816520..c979e720a5a1 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -857,6 +857,8 @@ int common_timer_set(struct k_itimer *timr, int flags,
 
 	timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
 	expires = timespec64_to_ktime(new_setting->it_value);
+	if (flags & TIMER_ABSTIME)
+		expires = timens_ktime_to_host(timr->it_clock, expires);
 	sigev_none = timr->it_sigev_notify == SIGEV_NONE;
 
 	kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
-- 
2.22.0

Re: [PATCHv5 00/37] kernel: Introduce Time Namespace

[Dmitry Safonov]

Sorry for spamming this twice.

I did `git send-email --to linux-kernel@vger.kernel.org /tmp/timens/
--cc 'Dmitry Safonov <0x7f454c46@gmail.com>' /tmp/timens/`

And didn't notice that I've put the same folder ^^ twice :(

Pardon again.

On 7/29/19 10:57 PM, Dmitry Safonov wrote:
> Discussions around time namespace are there for a long time. The first
> attempt to implement it was in 2006 by Jeff Dike. From that time, the
> topic appears on and off in various discussions.
> 
[..]

Thanks,
          Dmitry

Re: [PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso

[Andy Lutomirski]

On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>
> From: Andrei Vagin <avagin@gmail.com>
>
> As it has been discussed on timens RFC, adding a new conditional branch
> `if (inside_time_ns)` on VDSO for all processes is undesirable.
>
> Addressing those problems, there are two versions of VDSO's .so:
> for host tasks (without any penalty) and for processes inside of time
> namespace with clk_to_ns() that subtracts offsets from host's time.
>
> The timens code in vdso looks like this:
>
> if (timens_static_branch_unlikely()) {
>        clk_to_ns(clk, ts);
> }

I'm confused.  Now we effectively have *three* versions: the vDSO
without timens, and vDSO with timens but with it switched off, and the
vDSO with timens on.  This seems like too much.

What you need is, IMO, a static-branch-ish thing that is per mm.  This
has a fundamental problem that the vDSO can be modified using
FOLL_FORCE.  Perhaps any CoW of the vDSO should implicitly switch the
static branch on, which at least gives some degree of correctness even
if it's a bit surprising.

--Andy

Re: [PATCHv5 23/37] x86/vdso: Add offsets page in vvar

[Andy Lutomirski]

On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>
> From: Andrei Vagin <avagin@openvz.org>
>
> As modern applications fetch time from VDSO without entering the kernel,
> it's needed to provide offsets for userspace code inside time namespace.
>
> A page for timens offsets is allocated on time namespace construction.
> Put that page into VVAR for tasks inside timens and zero page for
> host processes.
>
> As VDSO code is already optimized as much as possible in terms of speed,
> any new if-condition in VDSO code is undesirable; the goal is to provide
> two .so(s), as was originally suggested by Andy and Thomas:
> - for host tasks with optimized-out clk_to_ns() without any penalty
> - for processes inside timens with clk_to_ns()
> For this purpose, define clk_to_ns() under CONFIG_TIME_NS.
>
> To eliminate any performance regression, clk_to_ns() will be called
> under static_branch with follow-up patches, that adds support for
> patching vdso.
>
> VDSO mappings are platform-specific, add Kconfig dependency for arch.
>
> Signed-off-by: Andrei Vagin <avagin@gmail.com>
> Co-developed-by: Dmitry Safonov <dima@arista.com>
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> ---
>  arch/Kconfig                          |  5 +++
>  arch/x86/Kconfig                      |  1 +
>  arch/x86/entry/vdso/vdso-layout.lds.S |  9 ++++-
>  arch/x86/entry/vdso/vdso2c.c          |  3 ++
>  arch/x86/entry/vdso/vma.c             | 12 +++++++
>  arch/x86/include/asm/vdso.h           |  1 +
>  init/Kconfig                          |  1 +
>  lib/vdso/gettimeofday.c               | 47 +++++++++++++++++++++++++++
>  8 files changed, 78 insertions(+), 1 deletion(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index a7b57dd42c26..e43d27f510ec 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -729,6 +729,11 @@ config HAVE_ARCH_NVRAM_OPS
>  config ISA_BUS_API
>         def_bool ISA
>
> +config ARCH_HAS_VDSO_TIME_NS
> +       bool
> +       help
> +        VDSO can add time-ns offsets without entering kernel.
> +
>  #
>  # ABI hall of shame
>  #
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 222855cc0158..91615938b470 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -81,6 +81,7 @@ config X86
>         select ARCH_HAS_STRICT_MODULE_RWX
>         select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
>         select ARCH_HAS_UBSAN_SANITIZE_ALL
> +       select ARCH_HAS_VDSO_TIME_NS
>         select ARCH_HAVE_NMI_SAFE_CMPXCHG
>         select ARCH_MIGHT_HAVE_ACPI_PDC         if ACPI
>         select ARCH_MIGHT_HAVE_PC_PARPORT
> diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
> index 93c6dc7812d0..ba216527e59f 100644
> --- a/arch/x86/entry/vdso/vdso-layout.lds.S
> +++ b/arch/x86/entry/vdso/vdso-layout.lds.S
> @@ -7,6 +7,12 @@
>   * This script controls its layout.
>   */
>
> +#ifdef CONFIG_TIME_NS
> +# define TIMENS_SZ     PAGE_SIZE
> +#else
> +# define TIMENS_SZ     0
> +#endif
> +
>  SECTIONS
>  {
>         /*
> @@ -16,7 +22,7 @@ SECTIONS
>          * segment.
>          */
>
> -       vvar_start = . - 3 * PAGE_SIZE;
> +       vvar_start = . - (3 * PAGE_SIZE + TIMENS_SZ);
>         vvar_page = vvar_start;
>
>         /* Place all vvars at the offsets in asm/vvar.h. */
> @@ -28,6 +34,7 @@ SECTIONS
>
>         pvclock_page = vvar_start + PAGE_SIZE;
>         hvclock_page = vvar_start + 2 * PAGE_SIZE;
> +       timens_page = vvar_start + 3 * PAGE_SIZE;
>
>         . = SIZEOF_HEADERS;
>
> diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c
> index ce67370d14e5..7380908045c7 100644
> --- a/arch/x86/entry/vdso/vdso2c.c
> +++ b/arch/x86/entry/vdso/vdso2c.c
> @@ -75,12 +75,14 @@ enum {
>         sym_vvar_page,
>         sym_pvclock_page,
>         sym_hvclock_page,
> +       sym_timens_page,
>  };
>
>  const int special_pages[] = {
>         sym_vvar_page,
>         sym_pvclock_page,
>         sym_hvclock_page,
> +       sym_timens_page,
>  };
>
>  struct vdso_sym {
> @@ -93,6 +95,7 @@ struct vdso_sym required_syms[] = {
>         [sym_vvar_page] = {"vvar_page", true},
>         [sym_pvclock_page] = {"pvclock_page", true},
>         [sym_hvclock_page] = {"hvclock_page", true},
> +       [sym_timens_page] = {"timens_page", true},
>         {"VDSO32_NOTE_MASK", true},
>         {"__kernel_vsyscall", true},
>         {"__kernel_sigreturn", true},
> diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
> index 2dc4f0b5481c..9bd66f84db5e 100644
> --- a/arch/x86/entry/vdso/vma.c
> +++ b/arch/x86/entry/vdso/vma.c
> @@ -14,6 +14,7 @@
>  #include <linux/elf.h>
>  #include <linux/cpu.h>
>  #include <linux/ptrace.h>
> +#include <linux/time_namespace.h>
>  #include <asm/pvclock.h>
>  #include <asm/vgtod.h>
>  #include <asm/proto.h>
> @@ -23,6 +24,7 @@
>  #include <asm/desc.h>
>  #include <asm/cpufeature.h>
>  #include <clocksource/hyperv_timer.h>
> +#include <asm/page.h>
>
>  #if defined(CONFIG_X86_64)
>  unsigned int __read_mostly vdso64_enabled = 1;
> @@ -135,6 +137,16 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
>                 if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
>                         return vmf_insert_pfn(vma, vmf->address,
>                                         vmalloc_to_pfn(tsc_pg));
> +       } else if (sym_offset == image->sym_timens_page) {
> +               struct time_namespace *ns = current->nsproxy->time_ns;

What, if anything, guarantees that all tasks in the mm share the same timens?

--Andy

Re: [PATCHv5 21/37] x86/vdso: Restrict splitting VVAR VMA

[Andy Lutomirski]

On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>
> Although, time namespace can work with VVAR VMA split, it seems worth
> to forbid splitting VVAR resulting in stricter ABI and reducing amount
> of corner-cases to consider while working further on VDSO.
>
> I don't think there is any use-case for partial mremap() of vvar,
> but if there is any - this patch can be easily reverted.

Seems reasonable to me.

Re: [PATCHv5 01/37] ns: Introduce Time Namespace

[Andy Lutomirski]

On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>
> From: Andrei Vagin <avagin@openvz.org>
>
> Time Namespace isolates clock values.

> +static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
> +{
> +       struct time_namespace *ns = to_time_ns(new);
> +
> +       if (!thread_group_empty(current))
> +               return -EINVAL;

You also need to check for other users of the mm.

> +
> +       if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
> +           !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
> +               return -EPERM;
> +
> +       get_time_ns(ns);
> +       get_time_ns(ns);
> +       put_time_ns(nsproxy->time_ns);
> +       put_time_ns(nsproxy->time_ns_for_children);
> +       nsproxy->time_ns = ns;
> +       nsproxy->time_ns_for_children = ns;
> +       ns->initialized = true;

I really really wish that setns() took an explicit flag for "change
now" or "change for children", since the semantics are different.  Oh
well.

Re: [PATCHv5 25/37] x86/vdso: Switch image on setns()/clone()

[Andy Lutomirski]

On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>
> As it has been discussed on timens RFC, adding a new conditional branch
> `if (inside_time_ns)` on VDSO for all processes is undesirable.
> It will add a penalty for everybody as branch predictor may mispredict
> the jump. Also there are instruction cache lines wasted on cmp/jmp.


>
> +#ifdef CONFIG_TIME_NS
> +int vdso_join_timens(struct task_struct *task)
> +{
> +       struct mm_struct *mm = task->mm;
> +       struct vm_area_struct *vma;
> +
> +       if (down_write_killable(&mm->mmap_sem))
> +               return -EINTR;
> +
> +       for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +               unsigned long size = vma->vm_end - vma->vm_start;
> +
> +               if (vma_is_special_mapping(vma, &vvar_mapping) ||
> +                   vma_is_special_mapping(vma, &vdso_mapping))
> +                       zap_page_range(vma, vma->vm_start, size);
> +       }

This is, unfortunately, fundamentally buggy.  If any thread is in the
vDSO or has the vDSO on the stack (due to a signal, for example), this
will crash it.  I can think of three solutions:

1. Say that you can't setns() if you have other mms and ignore the
signal issue.  Anything with green threads will disapprove.  It's also
rather gross.

2. Make it so that you can flip the static branch safely.  As in my
other email, you'll need to deal with CoW somehow,

3. Make it so that you can't change timens, or at least that you can't
turn timens on or off, without execve() or fork().

BTW, that static branch probably needs to be aligned to a cache line
or something similar to avoid all the nastiness with trying to poke
text that might be concurrently executing.  This will be a mess.

Re: [PATCHv5 25/37] x86/vdso: Switch image on setns()/clone()

[hpa]

On July 31, 2019 10:34:26 PM PDT, Andy Lutomirski <luto@kernel.org> wrote:
>On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>>
>> As it has been discussed on timens RFC, adding a new conditional
>branch
>> `if (inside_time_ns)` on VDSO for all processes is undesirable.
>> It will add a penalty for everybody as branch predictor may
>mispredict
>> the jump. Also there are instruction cache lines wasted on cmp/jmp.
>
>
>>
>> +#ifdef CONFIG_TIME_NS
>> +int vdso_join_timens(struct task_struct *task)
>> +{
>> +       struct mm_struct *mm = task->mm;
>> +       struct vm_area_struct *vma;
>> +
>> +       if (down_write_killable(&mm->mmap_sem))
>> +               return -EINTR;
>> +
>> +       for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> +               unsigned long size = vma->vm_end - vma->vm_start;
>> +
>> +               if (vma_is_special_mapping(vma, &vvar_mapping) ||
>> +                   vma_is_special_mapping(vma, &vdso_mapping))
>> +                       zap_page_range(vma, vma->vm_start, size);
>> +       }
>
>This is, unfortunately, fundamentally buggy.  If any thread is in the
>vDSO or has the vDSO on the stack (due to a signal, for example), this
>will crash it.  I can think of three solutions:
>
>1. Say that you can't setns() if you have other mms and ignore the
>signal issue.  Anything with green threads will disapprove.  It's also
>rather gross.
>
>2. Make it so that you can flip the static branch safely.  As in my
>other email, you'll need to deal with CoW somehow,
>
>3. Make it so that you can't change timens, or at least that you can't
>turn timens on or off, without execve() or fork().
>
>BTW, that static branch probably needs to be aligned to a cache line
>or something similar to avoid all the nastiness with trying to poke
>text that might be concurrently executing.  This will be a mess.

Since we are talking about different physical addresses I believe we should be okay as long as they don't cross page boundaries, and even if they do it can be managed with proper page invalidation sequencing – it's not like the problems of having to deal with XMC on live pages like in the kernel.

Still, you really need each instruction sequence to be present, with the only difference being specific patch sites.

Any fundamental reason this can't be strictly data driven? Seems odd to me if it couldn't, but I might be missing something obvious.
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Re: [PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso

[Thomas Gleixner]

On Wed, 31 Jul 2019, Andy Lutomirski wrote:
> On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
> > As it has been discussed on timens RFC, adding a new conditional branch
> > `if (inside_time_ns)` on VDSO for all processes is undesirable.
> >
> > Addressing those problems, there are two versions of VDSO's .so:
> > for host tasks (without any penalty) and for processes inside of time
> > namespace with clk_to_ns() that subtracts offsets from host's time.
> >
> > The timens code in vdso looks like this:
> >
> > if (timens_static_branch_unlikely()) {
> >        clk_to_ns(clk, ts);
> > }
> 
> I'm confused.  Now we effectively have *three* versions: the vDSO
> without timens, and vDSO with timens but with it switched off, and the
> vDSO with timens on.  This seems like too much.

The problem is that if you have a single VDSO, then omce one process joins
a time namespace _ALL_ other processes get an extra conditional with at
least one extra  cache line as a bonus.

This has been discussed at Plumbers last year and the agreement was to
create VDSO plain (no namespace support) and VDSO extra (namespace
support).

The performance hit of the conditional + one etra cache line for tasks
which do not use a time name space is measurable.

That also avoids the whole mess of dealing with the static branch being
flipped. The time name space property is determined on fork/exec _before_
anything can touch the VDSO and depending on it the approriate version of
the VDSO is loaded.

Thanks,

	tglx

Re: [PATCHv5 25/37] x86/vdso: Switch image on setns()/clone()

[Andy Lutomirski]

On Wed, Jul 31, 2019 at 11:09 PM <hpa@zytor.com> wrote:
>
> On July 31, 2019 10:34:26 PM PDT, Andy Lutomirski <luto@kernel.org> wrote:
> >On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
> >>
> >> As it has been discussed on timens RFC, adding a new conditional
> >branch
> >> `if (inside_time_ns)` on VDSO for all processes is undesirable.
> >> It will add a penalty for everybody as branch predictor may
> >mispredict
> >> the jump. Also there are instruction cache lines wasted on cmp/jmp.
> >
> >
> >>
> >> +#ifdef CONFIG_TIME_NS
> >> +int vdso_join_timens(struct task_struct *task)
> >> +{
> >> +       struct mm_struct *mm = task->mm;
> >> +       struct vm_area_struct *vma;
> >> +
> >> +       if (down_write_killable(&mm->mmap_sem))
> >> +               return -EINTR;
> >> +
> >> +       for (vma = mm->mmap; vma; vma = vma->vm_next) {
> >> +               unsigned long size = vma->vm_end - vma->vm_start;
> >> +
> >> +               if (vma_is_special_mapping(vma, &vvar_mapping) ||
> >> +                   vma_is_special_mapping(vma, &vdso_mapping))
> >> +                       zap_page_range(vma, vma->vm_start, size);
> >> +       }
> >
> >This is, unfortunately, fundamentally buggy.  If any thread is in the
> >vDSO or has the vDSO on the stack (due to a signal, for example), this
> >will crash it.  I can think of three solutions:
> >
> >1. Say that you can't setns() if you have other mms and ignore the
> >signal issue.  Anything with green threads will disapprove.  It's also
> >rather gross.
> >
> >2. Make it so that you can flip the static branch safely.  As in my
> >other email, you'll need to deal with CoW somehow,
> >
> >3. Make it so that you can't change timens, or at least that you can't
> >turn timens on or off, without execve() or fork().
> >
> >BTW, that static branch probably needs to be aligned to a cache line
> >or something similar to avoid all the nastiness with trying to poke
> >text that might be concurrently executing.  This will be a mess.
>
> Since we are talking about different physical addresses I believe we should be okay as long as they don't cross page boundaries, and even if they do it can be managed with proper page invalidation sequencing – it's not like the problems of having to deal with XMC on live pages like in the kernel.
>
> Still, you really need each instruction sequence to be present, with the only difference being specific patch sites.
>
> Any fundamental reason this can't be strictly data driven? Seems odd to me if it couldn't, but I might be missing something obvious.

I think it can be.  There are at least two places where vDSO slow
paths could hook without affecting fast paths: vclock_mode and the low
bit of the sequence number.

Re: [PATCHv5 01/37] ns: Introduce Time Namespace

[Dmitry Safonov]

Hi Andy,

Thank you for the review,

On 8/1/19 6:29 AM, Andy Lutomirski wrote:
> On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov <dima@arista.com> wrote:
>>
>> From: Andrei Vagin <avagin@openvz.org>
>>
>> Time Namespace isolates clock values.
> 
>> +static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
>> +{
>> +       struct time_namespace *ns = to_time_ns(new);
>> +
>> +       if (!thread_group_empty(current))
>> +               return -EINVAL;
> 
> You also need to check for other users of the mm.

Oops. It seems like, if the check was

if (!current_is_single_threaded())
    return -EUSERS;

instead of thread_group_empty(current), it would address the concerns
from 23/37 and 25/37 patches, too?

> 
>> +
>> +       if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
>> +           !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
>> +               return -EPERM;
>> +
>> +       get_time_ns(ns);
>> +       get_time_ns(ns);
>> +       put_time_ns(nsproxy->time_ns);
>> +       put_time_ns(nsproxy->time_ns_for_children);
>> +       nsproxy->time_ns = ns;
>> +       nsproxy->time_ns_for_children = ns;
>> +       ns->initialized = true;
> 
> I really really wish that setns() took an explicit flag for "change
> now" or "change for children", since the semantics are different.  Oh
> well.
> 

Thanks,
          Dmitry

[PATCHv6 01/37] ns: Introduce Time Namespace

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Time Namespace isolates clock values.

The kernel provides access to several clocks CLOCK_REALTIME,
CLOCK_MONOTONIC, CLOCK_BOOTTIME, etc.

CLOCK_REALTIME
      System-wide clock that measures real (i.e., wall-clock) time.

CLOCK_MONOTONIC
      Clock that cannot be set and represents monotonic time since
      some unspecified starting point.

CLOCK_BOOTTIME
      Identical to CLOCK_MONOTONIC, except it also includes any time
      that the system is suspended.

For many users, the time namespace means the ability to changes date and
time in a container (CLOCK_REALTIME).

But in a context of the checkpoint/restore functionality, monotonic and
bootime clocks become interesting. Both clocks are monotonic with
unspecified staring points. These clocks are widely used to measure time
slices and set timers. After restoring or migrating processes, we have to
guarantee that they never go backward. In an ideal case, the behavior of
these clocks should be the same as for a case when a whole system is
suspended. All this means that we need to be able to set CLOCK_MONOTONIC
and CLOCK_BOOTTIME clocks, what can be done by adding per-namespace
offsets for clocks.

A time namespace is similar to a pid namespace in a way how it is
created: unshare(CLONE_NEWTIME) system call creates a new time namespace,
but doesn't set it to the current process. Then all children of
the process will be born in the new time namespace, or a process can
use the setns() system call to join a namespace.

This scheme allows setting clock offsets for a namespace, before any
processes appear in it.

All available clone flags have been used, so CLONE_NEWTIME uses the
highest bit of CSIGNAL. It means that we can use it with the unshare
system call only. Rith now, this works for us, because time namespace
offsets can be set only when a new time namespace is not populated. In a
future, we will have the clone3 system call [1] which will allow to use
the CSIGNAL mask for clone flags.

[1]: httmps://lkml.kernel.org/r/20190604160944.4058-1-christian@brauner.io

Link: https://criu.org/Time_namespace
Link: https://lists.openvz.org/pipermail/criu/2018-June/041504.html
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
v5..v6 Change:
  Used current_is_single_threaded() instead of thread_group_empty().
  Changed errno code to something more grepabble (EUSERS).

 MAINTAINERS                    |   2 +
 fs/proc/namespaces.c           |   4 +
 include/linux/nsproxy.h        |   2 +
 include/linux/proc_ns.h        |   3 +
 include/linux/time_namespace.h |  69 +++++++++++
 include/linux/user_namespace.h |   1 +
 include/uapi/linux/sched.h     |   6 +
 init/Kconfig                   |   7 ++
 kernel/Makefile                |   1 +
 kernel/fork.c                  |  16 ++-
 kernel/nsproxy.c               |  41 +++++--
 kernel/time_namespace.c        | 217 +++++++++++++++++++++++++++++++++
 12 files changed, 359 insertions(+), 10 deletions(-)
 create mode 100644 include/linux/time_namespace.h
 create mode 100644 kernel/time_namespace.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a2c343ee3b2c..8a44c833f264 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12841,6 +12841,8 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
 S:	Maintained
 F:	fs/timerfd.c
 F:	include/linux/timer*
+F:	include/linux/time_namespace.h
+F:	kernel/time_namespace.c
 F:	kernel/time/*timer*
 
 POWER MANAGEMENT CORE
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index dd2b35f78b09..8b5c720fe5d7 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -33,6 +33,10 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_CGROUPS
 	&cgroupns_operations,
 #endif
+#ifdef CONFIG_TIME_NS
+	&timens_operations,
+	&timens_for_children_operations,
+#endif
 };
 
 static const char *proc_ns_get_link(struct dentry *dentry,
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 2ae1b1a4d84d..074f395b9ad2 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -35,6 +35,8 @@ struct nsproxy {
 	struct mnt_namespace *mnt_ns;
 	struct pid_namespace *pid_ns_for_children;
 	struct net 	     *net_ns;
+	struct time_namespace *time_ns;
+	struct time_namespace *time_ns_for_children;
 	struct cgroup_namespace *cgroup_ns;
 };
 extern struct nsproxy init_nsproxy;
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index d31cb6215905..d312e6281e69 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -32,6 +32,8 @@ extern const struct proc_ns_operations pidns_for_children_operations;
 extern const struct proc_ns_operations userns_operations;
 extern const struct proc_ns_operations mntns_operations;
 extern const struct proc_ns_operations cgroupns_operations;
+extern const struct proc_ns_operations timens_operations;
+extern const struct proc_ns_operations timens_for_children_operations;
 
 /*
  * We always define these enumerators
@@ -43,6 +45,7 @@ enum {
 	PROC_USER_INIT_INO	= 0xEFFFFFFDU,
 	PROC_PID_INIT_INO	= 0xEFFFFFFCU,
 	PROC_CGROUP_INIT_INO	= 0xEFFFFFFBU,
+	PROC_TIME_INIT_INO	= 0xEFFFFFFAU,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
new file mode 100644
index 000000000000..9507ed7072fe
--- /dev/null
+++ b/include/linux/time_namespace.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TIMENS_H
+#define _LINUX_TIMENS_H
+
+
+#include <linux/sched.h>
+#include <linux/kref.h>
+#include <linux/nsproxy.h>
+#include <linux/ns_common.h>
+#include <linux/err.h>
+
+struct user_namespace;
+extern struct user_namespace init_user_ns;
+
+struct time_namespace {
+	struct kref kref;
+	struct user_namespace *user_ns;
+	struct ucounts *ucounts;
+	struct ns_common ns;
+	struct timens_offsets *offsets;
+	bool   initialized;
+} __randomize_layout;
+extern struct time_namespace init_time_ns;
+
+#ifdef CONFIG_TIME_NS
+static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
+{
+	kref_get(&ns->kref);
+	return ns;
+}
+
+extern struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns);
+extern void free_time_ns(struct kref *kref);
+extern int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
+
+static inline void put_time_ns(struct time_namespace *ns)
+{
+	kref_put(&ns->kref, free_time_ns);
+}
+
+
+#else
+static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
+{
+	return NULL;
+}
+
+static inline void put_time_ns(struct time_namespace *ns)
+{
+}
+
+static inline struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns)
+{
+	if (flags & CLONE_NEWTIME)
+		return ERR_PTR(-EINVAL);
+
+	return old_ns;
+}
+
+static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+{
+	return 0;
+}
+
+#endif
+
+#endif /* _LINUX_TIMENS_H */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index fb9f4f799554..6ef1c7109fc4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -45,6 +45,7 @@ enum ucount_type {
 	UCOUNT_NET_NAMESPACES,
 	UCOUNT_MNT_NAMESPACES,
 	UCOUNT_CGROUP_NAMESPACES,
+	UCOUNT_TIME_NAMESPACES,
 #ifdef CONFIG_INOTIFY_USER
 	UCOUNT_INOTIFY_INSTANCES,
 	UCOUNT_INOTIFY_WATCHES,
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index b3105ac1381a..551739227e96 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -33,6 +33,12 @@
 #define CLONE_NEWNET		0x40000000	/* New network namespace */
 #define CLONE_IO		0x80000000	/* Clone io context */
 
+/*
+ * cloning flags intersect with CSIGNAL so can be used with unshare and clone3
+ * syscalls only:
+ */
+#define CLONE_NEWTIME	0x00000080	/* New time namespace */
+
 /*
  * Arguments for the clone3 syscall
  */
diff --git a/init/Kconfig b/init/Kconfig
index bd7d650d4a99..a7cbc9b470c7 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1069,6 +1069,13 @@ config UTS_NS
 	  In this namespace tasks see different info provided with the
 	  uname() system call
 
+config TIME_NS
+	bool "TIME namespace"
+	default y
+	help
+	  In this namespace boottime and monotonic clocks can be set.
+	  The time will keep going with the same pace.
+
 config IPC_NS
 	bool "IPC namespace"
 	depends on (SYSVIPC || POSIX_MQUEUE)
diff --git a/kernel/Makefile b/kernel/Makefile
index ef0d95a190b4..0f2d5affc377 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup/
 obj-$(CONFIG_UTS_NS) += utsname.o
+obj-$(CONFIG_TIME_NS) += time_namespace.o
 obj-$(CONFIG_USER_NS) += user_namespace.o
 obj-$(CONFIG_PID_NS) += pid_namespace.o
 obj-$(CONFIG_IKCONFIG) += configs.o
diff --git a/kernel/fork.c b/kernel/fork.c
index 2852d0e76ea3..3dbb2d33dc52 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1777,6 +1777,7 @@ static __latent_entropy struct task_struct *copy_process(
 	struct multiprocess_signals delayed;
 	struct file *pidfile = NULL;
 	u64 clone_flags = args->flags;
+	struct nsproxy *nsp = current->nsproxy;
 
 	/*
 	 * Don't allow sharing the root directory with processes in a different
@@ -1819,8 +1820,16 @@ static __latent_entropy struct task_struct *copy_process(
 	 */
 	if (clone_flags & CLONE_THREAD) {
 		if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
-		    (task_active_pid_ns(current) !=
-				current->nsproxy->pid_ns_for_children))
+		    (task_active_pid_ns(current) != nsp->pid_ns_for_children))
+			return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * If the new process will be in a different time namespace
+	 * do not allow it to share VM or a thread group with the forking task.
+	 */
+	if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
+		if (nsp->time_ns != nsp->time_ns_for_children)
 			return ERR_PTR(-EINVAL);
 	}
 
@@ -2707,7 +2716,8 @@ static int check_unshare_flags(unsigned long unshare_flags)
 	if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
 				CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
 				CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
-				CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP))
+				CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
+				CLONE_NEWTIME))
 		return -EINVAL;
 	/*
 	 * Not implemented, but pretend it works if there is nothing
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index c815f58e6bc0..ed9882108cd2 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -18,6 +18,7 @@
 #include <linux/pid_namespace.h>
 #include <net/net_namespace.h>
 #include <linux/ipc_namespace.h>
+#include <linux/time_namespace.h>
 #include <linux/proc_ns.h>
 #include <linux/file.h>
 #include <linux/syscalls.h>
@@ -40,6 +41,10 @@ struct nsproxy init_nsproxy = {
 #ifdef CONFIG_CGROUPS
 	.cgroup_ns		= &init_cgroup_ns,
 #endif
+#ifdef CONFIG_TIME_NS
+	.time_ns		= &init_time_ns,
+	.time_ns_for_children	= &init_time_ns,
+#endif
 };
 
 static inline struct nsproxy *create_nsproxy(void)
@@ -106,8 +111,18 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
 		goto out_net;
 	}
 
+	new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
+					tsk->nsproxy->time_ns_for_children);
+	if (IS_ERR(new_nsp->time_ns_for_children)) {
+		err = PTR_ERR(new_nsp->time_ns_for_children);
+		goto out_time;
+	}
+	new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
+
 	return new_nsp;
 
+out_time:
+	put_net(new_nsp->net_ns);
 out_net:
 	put_cgroup_ns(new_nsp->cgroup_ns);
 out_cgroup:
@@ -136,15 +151,16 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 	struct nsproxy *old_ns = tsk->nsproxy;
 	struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
 	struct nsproxy *new_ns;
+	int ret;
 
 	if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 			      CLONE_NEWPID | CLONE_NEWNET |
-			      CLONE_NEWCGROUP)))) {
-		get_nsproxy(old_ns);
-		return 0;
-	}
-
-	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+			      CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
+		if (likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
+			get_nsproxy(old_ns);
+			return 0;
+		}
+	} else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	/*
@@ -162,6 +178,12 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 	if (IS_ERR(new_ns))
 		return  PTR_ERR(new_ns);
 
+	ret = timens_on_fork(new_ns, tsk);
+	if (ret) {
+		free_nsproxy(new_ns);
+		return ret;
+	}
+
 	tsk->nsproxy = new_ns;
 	return 0;
 }
@@ -176,6 +198,10 @@ void free_nsproxy(struct nsproxy *ns)
 		put_ipc_ns(ns->ipc_ns);
 	if (ns->pid_ns_for_children)
 		put_pid_ns(ns->pid_ns_for_children);
+	if (ns->time_ns)
+		put_time_ns(ns->time_ns);
+	if (ns->time_ns_for_children)
+		put_time_ns(ns->time_ns_for_children);
 	put_cgroup_ns(ns->cgroup_ns);
 	put_net(ns->net_ns);
 	kmem_cache_free(nsproxy_cachep, ns);
@@ -192,7 +218,8 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 	int err = 0;
 
 	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
-			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
+			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
+			       CLONE_NEWTIME)))
 		return 0;
 
 	user_ns = new_cred ? new_cred->user_ns : current_user_ns();
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
new file mode 100644
index 000000000000..8fd8384b7261
--- /dev/null
+++ b/kernel/time_namespace.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Andrei Vagin <avagin@openvz.org>
+ * Author: Dmitry Safonov <dima@arista.com>
+ */
+
+#include <linux/time_namespace.h>
+#include <linux/user_namespace.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/proc_ns.h>
+#include <linux/export.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+
+static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
+{
+	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
+}
+
+static void dec_time_namespaces(struct ucounts *ucounts)
+{
+	dec_ucount(ucounts, UCOUNT_TIME_NAMESPACES);
+}
+
+static struct time_namespace *create_time_ns(void)
+{
+	struct time_namespace *time_ns;
+
+	time_ns = kmalloc(sizeof(struct time_namespace), GFP_KERNEL);
+	if (time_ns) {
+		kref_init(&time_ns->kref);
+		time_ns->initialized = false;
+	}
+	return time_ns;
+}
+
+/*
+ * Clone a new ns copying @old_ns, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return the new ns or ERR_PTR.
+ */
+static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
+					  struct time_namespace *old_ns)
+{
+	struct time_namespace *ns;
+	struct ucounts *ucounts;
+	int err;
+
+	err = -ENOSPC;
+	ucounts = inc_time_namespaces(user_ns);
+	if (!ucounts)
+		goto fail;
+
+	err = -ENOMEM;
+	ns = create_time_ns();
+	if (!ns)
+		goto fail_dec;
+
+	err = ns_alloc_inum(&ns->ns);
+	if (err)
+		goto fail_free;
+
+	ns->ucounts = ucounts;
+	ns->ns.ops = &timens_operations;
+	ns->user_ns = get_user_ns(user_ns);
+	return ns;
+
+fail_free:
+	kfree(ns);
+fail_dec:
+	dec_time_namespaces(ucounts);
+fail:
+	return ERR_PTR(err);
+}
+
+/*
+ * Add a reference to old_ns, or clone it if @flags specify CLONE_NEWTIME.
+ * In latter case, changes to the time of this process won't be seen by parent,
+ * and vice versa.
+ */
+struct time_namespace *copy_time_ns(unsigned long flags,
+	struct user_namespace *user_ns, struct time_namespace *old_ns)
+{
+	if (!(flags & CLONE_NEWTIME))
+		return get_time_ns(old_ns);
+
+	return clone_time_ns(user_ns, old_ns);
+}
+
+void free_time_ns(struct kref *kref)
+{
+	struct time_namespace *ns;
+
+	ns = container_of(kref, struct time_namespace, kref);
+	dec_time_namespaces(ns->ucounts);
+	put_user_ns(ns->user_ns);
+	ns_free_inum(&ns->ns);
+	kfree(ns);
+}
+
+static struct time_namespace *to_time_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct time_namespace, ns);
+}
+
+static struct ns_common *timens_get(struct task_struct *task)
+{
+	struct time_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->time_ns;
+		get_time_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static struct ns_common *timens_for_children_get(struct task_struct *task)
+{
+	struct time_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->time_ns_for_children;
+		get_time_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void timens_put(struct ns_common *ns)
+{
+	put_time_ns(to_time_ns(ns));
+}
+
+static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+	struct time_namespace *ns = to_time_ns(new);
+
+	if (!current_is_single_threaded())
+		return -EUSERS;
+
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+		return -EPERM;
+
+	get_time_ns(ns);
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns);
+	put_time_ns(nsproxy->time_ns_for_children);
+	nsproxy->time_ns = ns;
+	nsproxy->time_ns_for_children = ns;
+	ns->initialized = true;
+	return 0;
+}
+
+int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+{
+	struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
+	struct time_namespace *ns = to_time_ns(nsc);
+
+	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
+		return 0;
+
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns);
+	nsproxy->time_ns = ns;
+	ns->initialized = true;
+
+	return 0;
+}
+
+static struct user_namespace *timens_owner(struct ns_common *ns)
+{
+	return to_time_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations timens_operations = {
+	.name		= "time",
+	.type		= CLONE_NEWTIME,
+	.get		= timens_get,
+	.put		= timens_put,
+	.install	= timens_install,
+	.owner		= timens_owner,
+};
+
+const struct proc_ns_operations timens_for_children_operations = {
+	.name		= "time_for_children",
+	.type		= CLONE_NEWTIME,
+	.get		= timens_for_children_get,
+	.put		= timens_put,
+	.install	= timens_install,
+	.owner		= timens_owner,
+};
+
+struct time_namespace init_time_ns = {
+	.kref = KREF_INIT(3),
+	.user_ns = &init_user_ns,
+	.ns.inum = PROC_TIME_INIT_INO,
+	.ns.ops = &timens_operations,
+};
+
+static int __init time_ns_init(void)
+{
+	return 0;
+}
+subsys_initcall(time_ns_init);
-- 
2.22.0

[PATCHv6 25/37] x86/vdso: Switch image on setns()/clone()

[Dmitry Safonov]

As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.
It will add a penalty for everybody as branch predictor may mispredict
the jump. Also there are instruction cache lines wasted on cmp/jmp.

Those effects of introducing time namespace are very much unwanted
having in mind how much work have been spent on micro-optimisation
vdso code.

Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside of time
namespace with clk_to_ns() that subtracts offsets from host's time.

Whenever a user does setns() or unshare(CLONE_TIMENS) followed
by clone(), change VDSO image in mm and zap VVAR/VDSO page tables.
They will be re-faulted with corresponding image and VVAR offsets.

Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
v5..v6 Change:
  Rebased over current_is_single_threaded() change in the first patch.

 arch/x86/entry/vdso/vma.c   | 23 +++++++++++++++++++++++
 arch/x86/include/asm/vdso.h |  1 +
 kernel/time_namespace.c     | 11 +++++++++++
 3 files changed, 35 insertions(+)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8a8211fd4cfc..91cf5a5c8c9e 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -25,6 +25,7 @@
 #include <asm/cpufeature.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/page.h>
+#include <asm/tlb.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
@@ -266,6 +267,28 @@ static const struct vm_special_mapping vvar_mapping = {
 	.mremap = vvar_mremap,
 };
 
+#ifdef CONFIG_TIME_NS
+int vdso_join_timens(struct task_struct *task)
+{
+	struct mm_struct *mm = task->mm;
+	struct vm_area_struct *vma;
+
+	if (down_write_killable(&mm->mmap_sem))
+		return -EINTR;
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		unsigned long size = vma->vm_end - vma->vm_start;
+
+		if (vma_is_special_mapping(vma, &vvar_mapping) ||
+		    vma_is_special_mapping(vma, &vdso_mapping))
+			zap_page_range(vma, vma->vm_start, size);
+	}
+
+	up_write(&mm->mmap_sem);
+	return 0;
+}
+#endif
+
 /*
  * Add vdso and vvar mappings to current process.
  * @image          - blob to map
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 03f468c63a24..ccf89dedd04f 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -45,6 +45,7 @@ extern struct vdso_image vdso_image_32;
 extern void __init init_vdso_image(struct vdso_image *image);
 
 extern int map_vdso_once(const struct vdso_image *image, unsigned long addr);
+extern int vdso_join_timens(struct task_struct *task);
 
 #endif /* __ASSEMBLER__ */
 
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index cdfa1b75bd0d..2e7e0af44f04 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -15,6 +15,7 @@
 #include <linux/cred.h>
 #include <linux/err.h>
 #include <linux/mm.h>
+#include <asm/vdso.h>
 
 ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
 				struct timens_offsets *ns_offsets)
@@ -199,6 +200,7 @@ static void timens_put(struct ns_common *ns)
 static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 {
 	struct time_namespace *ns = to_time_ns(new);
+	int ret;
 
 	if (!current_is_single_threaded())
 		return -EUSERS;
@@ -207,6 +209,10 @@ static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
+	ret = vdso_join_timens(current);
+	if (ret)
+		return ret;
+
 	get_time_ns(ns);
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
@@ -221,10 +227,15 @@ int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
 {
 	struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
 	struct time_namespace *ns = to_time_ns(nsc);
+	int ret;
 
 	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
 		return 0;
 
+	ret = vdso_join_timens(tsk);
+	if (ret)
+		return ret;
+
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
 	nsproxy->time_ns = ns;
-- 
2.22.0

Re: [PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec()

[Thomas Gleixner]

On Mon, 29 Jul 2019, Dmitry Safonov wrote:
>  static const struct k_clock clock_monotonic = {
>  	.clock_getres		= posix_get_hrtimer_res,
> -	.clock_get_timespec	= posix_ktime_get_ts,
> +	.clock_get_timespec	= posix_get_timespec,

 posix_get_monotonic_timespec

Please.

Re: [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback

[Thomas Gleixner]

On Mon, 29 Jul 2019, Dmitry Safonov wrote:
>  /**
> @@ -869,8 +871,10 @@ static int __init alarmtimer_init(void)
>  	/* Initialize alarm bases */
>  	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
>  	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
> +	alarm_bases[ALARM_REALTIME].get_timespec = posix_get_timespec,

That's just wrong:

>  /*
>   * Get monotonic time for posix timers
>   */
> -static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
> +int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
>  {
>  	ktime_get_ts64(tp);
>  	return 0;

Using a proper function name would have avoided this.

Re: [PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets

[Thomas Gleixner]

On Mon, 29 Jul 2019, Dmitry Safonov wrote:
>  
> +static inline void timens_add_monotonic(struct timespec64 *ts)
> +{
> +	struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
> +
> +	if (ns_offsets)
> +		*ts = timespec64_add(*ts, ns_offsets->monotonic);
> +}

This helper is not posix timer specific and should be introduced either in
the name space patches or in a separate patch,

Thanks

	tglx

Re: [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback

[Andrei Vagin]

On Wed, Aug 07, 2019 at 08:04:10AM +0200, Thomas Gleixner wrote:
> On Mon, 29 Jul 2019, Dmitry Safonov wrote:
> >  /**
> > @@ -869,8 +871,10 @@ static int __init alarmtimer_init(void)
> >  	/* Initialize alarm bases */
> >  	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
> >  	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
> > +	alarm_bases[ALARM_REALTIME].get_timespec = posix_get_timespec,
> 
> That's just wrong:
> 
> >  /*
> >   * Get monotonic time for posix timers
> >   */
> > -static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
> > +int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
> >  {
> >  	ktime_get_ts64(tp);
> >  	return 0;
> 
> Using a proper function name would have avoided this.

You are right. Will fix. Thanks!
>