[PATCHv7 00/33] kernel: Introduce Time Namespace

[PATCHv7 00/33] 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.

v6..v7 Changes:
* Based on Andy & Thomas suggestions and the patches that Thomas kindely
  sent, reworked from two VDSO code images into trick with odd seq
  number for timens page that goes on the place of vvar page inside ns.
* Moved kernel/time_namespace.c => kernel/time/namespace.c
* Fixed bpf 5sec example
* Added selftests outputs
* By Thomas's suggestion simplified overflow check as ktime_sub(tim, offset)
* Other Thomas's review notes: stylistic, simplifications and
  clearifications (Thanks!)
* Split VDSO patches on generic/x86 parts
* Fixed kernel-doc warnings
* Added checks in selftests for capabilities
* Fixed bisectability issues

v5..v6 Changes:
* Used current_is_single_threaded() instead of thread_group_empty()
  (Thanks for the review, Andy).
* Changed errno code when there are threads on timens joining to
  something more grepabble (EUSERS).
* posix_get_timespec() should have been posix_get_monotonic_timespec()
  (Thanks, Thomas)
* timens_add_monotonic() & timens_add_boottime() were relocated to
  the patch that introduces (struct timens_offsets) (Thomas)
* Avoid breaking alarmtimer for ALARM_REALTIME (Thanks, Thomas)
* Nested namespace inherits father's offsets now
  (Andrei while working on CRIU side for time namespace)
* A minor conflict with commit dbc1625fc9de ("hrtimer: Consolidate
  hrtimer_init() + hrtimer_init_sleeper() calls") in linux-next
  [Sending against next-20190814]

[v1..v5 Changelogs 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
--------------------------------------------------------------
        | 153242367 | 153567617        | 150933203 | 139310914
        | 153324800 | 153115132        | 150919828 | 139299761
        | 153125401 | 153686868        | 150930471 | 139273917
        | 153399355 | 153694866        | 151083410 | 139286081
        | 153489417 | 153739716        | 150997262 | 139146403
        | 153494270 | 153724332        | 150035651 | 138835612
-----------------------------------------------------------
avg     | 153345935 | 153588088        | 150816637 | 139192114
diff %  | 100       | 100.1            | 98.3      | 90.7
-------------------------------------------------------------
stdev % | 0.09      | 0.15              |0.25      | 0.13


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.

Cold CPU cache (lesser tsc per cycle - the better):

           | before    | CONFIG_TIME_NS=n | host      | inside timens
--------------------------------------------------------------
tsc        | 476       | 480              | 487       | 531
stdev(tsc) | 0.6       | 1.3              | 4.3       | 5.7
diff (%)   | 100       | 100.9            | 102       | 112

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

v7 on github (if someone prefers `git pull` to `git am`):
https://github.com/0x7f454c46/linux/tree/timens-v7

v6: https://lkml.kernel.org/r/20190815163836.2927-1-dima@arista.com
v5: https://lkml.kernel.org/r/20190729215758.28405-1-dima@arista.com
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/

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)

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 (22):
  ns: Introduce Time Namespace
  time: Add timens_offsets to be used for tasks in timens
  posix-clocks: Rename the clock_get() callback to clock_get_timespec()
  posix-clocks: Rename .clock_get_timespec() callbacks accordingly
  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: Wire up clock_gettime() with timens offsets
  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
  lib/vdso: Add unlikely() hint into vdso_read_begin()
  fs/proc: Introduce /proc/pid/timens_offsets
  selftests/timens: Add a test for timerfd
  selftests/timens: Add a test for clock_nanosleep()
  selftests/timens: Add timer offsets test
  selftests/timens: Add a simple perf test for clock_gettime()
  selftests/timens: Check for right timens offsets after fork and exec

Dmitry Safonov (10):
  fs/proc: Respect boottime inside time namespace for /proc/uptime
  x86/vdso: Restrict splitting VVAR VMA
  x86/vdso: Provide vdso_data offset on vvar_page
  x86/vdso: Add timens page
  time: Allocate per-timens vvar page
  x86/vdso: Handle faults on timens page
  x86/vdso: On timens page fault prefault also VVAR page
  x86/vdso: Zap vvar pages on switch a time namspace
  selftests/timens: Add Time Namespace test for supported clocks
  selftests/timens: Add procfs selftest

Thomas Gleixner (1):
  lib/vdso: Prepare for time namespace support

 MAINTAINERS                                   |   2 +
 arch/x86/Kconfig                              |   1 +
 arch/x86/entry/vdso/vdso-layout.lds.S         |  13 +-
 arch/x86/entry/vdso/vdso2c.c                  |   3 +
 arch/x86/entry/vdso/vma.c                     | 119 ++++-
 arch/x86/include/asm/vdso.h                   |   1 +
 arch/x86/include/asm/vdso/gettimeofday.h      |   9 +
 arch/x86/include/asm/vvar.h                   |  13 +-
 arch/x86/kernel/vmlinux.lds.S                 |   4 +-
 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/nsproxy.h                       |   2 +
 include/linux/posix-timers.h                  |   3 +
 include/linux/proc_ns.h                       |   3 +
 include/linux/time.h                          |   6 +
 include/linux/time_namespace.h                | 119 +++++
 include/linux/user_namespace.h                |   1 +
 include/uapi/linux/sched.h                    |   6 +
 include/vdso/datapage.h                       |  19 +-
 include/vdso/helpers.h                        |   2 +-
 init/Kconfig                                  |   7 +
 kernel/fork.c                                 |  16 +-
 kernel/nsproxy.c                              |  41 +-
 kernel/time/Makefile                          |   1 +
 kernel/time/alarmtimer.c                      |  68 ++-
 kernel/time/hrtimer.c                         |   8 +-
 kernel/time/namespace.c                       | 466 ++++++++++++++++++
 kernel/time/posix-clock.c                     |   8 +-
 kernel/time/posix-cpu-timers.c                |  32 +-
 kernel/time/posix-stubs.c                     |  15 +-
 kernel/time/posix-timers.c                    |  88 +++-
 kernel/time/posix-timers.h                    |   7 +-
 lib/vdso/Kconfig                              |   6 +
 lib/vdso/gettimeofday.c                       | 128 ++++-
 mm/mmap.c                                     |   2 +
 tools/perf/examples/bpf/5sec.c                |   6 +-
 tools/testing/selftests/Makefile              |   1 +
 tools/testing/selftests/timens/.gitignore     |   8 +
 tools/testing/selftests/timens/Makefile       |   7 +
 .../selftests/timens/clock_nanosleep.c        | 143 ++++++
 tools/testing/selftests/timens/config         |   1 +
 tools/testing/selftests/timens/exec.c         |  94 ++++
 tools/testing/selftests/timens/gettime_perf.c |  91 ++++
 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       |  73 +++
 tools/testing/selftests/timens/timer.c        | 118 +++++
 tools/testing/selftests/timens/timerfd.c      | 129 +++++
 52 files changed, 2246 insertions(+), 106 deletions(-)
 create mode 100644 include/linux/time_namespace.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/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

-- 
2.23.0

[PATCHv7 01/33] 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@gmail.com>
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 |  66 ++++++++++
 include/linux/user_namespace.h |   1 +
 include/uapi/linux/sched.h     |   6 +
 init/Kconfig                   |   7 ++
 kernel/fork.c                  |  16 ++-
 kernel/nsproxy.c               |  41 +++++--
 kernel/time/Makefile           |   1 +
 kernel/time/namespace.c        | 217 +++++++++++++++++++++++++++++++++
 12 files changed, 356 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 d44d6732510d..cabe7bddbf69 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13009,6 +13009,8 @@ 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..873b908c9ba8
--- /dev/null
+++ b/include/linux/time_namespace.h
@@ -0,0 +1,66 @@
+/* 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;
+} __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 99335e1f4a27..5b7511ac2005 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 */
+
 #ifndef __ASSEMBLY__
 /**
  * struct clone_args - arguments for the clone3 syscall
diff --git a/init/Kconfig b/init/Kconfig
index b4daad2bac23..bc2ee93408ad 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1096,6 +1096,13 @@ 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/fork.c b/kernel/fork.c
index bcdf53125210..aa65333dbc45 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1772,6 +1772,7 @@ 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
@@ -1814,8 +1815,16 @@ 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);
 	}
 
@@ -2703,7 +2712,8 @@ 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/Makefile b/kernel/time/Makefile
index 1867044800bb..c8f00168afe8 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -19,3 +19,4 @@ obj-$(CONFIG_TICK_ONESHOT)			+= tick-oneshot.o tick-sched.o
 obj-$(CONFIG_HAVE_GENERIC_VDSO)			+= vsyscall.o
 obj-$(CONFIG_DEBUG_FS)				+= timekeeping_debug.o
 obj-$(CONFIG_TEST_UDELAY)			+= test_udelay.o
+obj-$(CONFIG_TIME_NS)				+= namespace.o
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
new file mode 100644
index 000000000000..2662a69e0382
--- /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);
+}
+
+/**
+ * clone_time_ns - Clone a time namespace
+ * @user_ns:	User namespace which owns a new namespace.
+ * @old_ns:	Namespace to clone
+ *
+ * Clone @old_ns and set the clone refcount to 1
+ *
+ * Return: The new namespace 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 = kmalloc(sizeof(*ns), GFP_KERNEL);
+	if (!ns)
+		goto fail_dec;
+
+	kref_init(&ns->kref);
+
+	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);
+}
+
+/**
+ * copy_time_ns - Create timens_for_children from @old_ns
+ * @flags:	Cloning flags
+ * @user_ns:	User namespace which owns a new namespace.
+ * @old_ns:	Namespace to clone
+ *
+ * If CLONE_NEWTIME specified in @flags, creates a new timens_for_children;
+ * adds a refcounter to @old_ns otherwise.
+ *
+ * Return: timens_for_children namespace or ERR_PTR.
+ */
+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);
+	put_time_ns(nsproxy->time_ns);
+	nsproxy->time_ns = ns;
+
+	get_time_ns(ns);
+	put_time_ns(nsproxy->time_ns_for_children);
+	nsproxy->time_ns_for_children = ns;
+	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);
+
+	/* create_new_namespaces() already incremented the ref counter */
+	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;
+
+	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);
-- 
2.23.0

[PATCHv7 02/33] time: Add timens_offsets to be used for tasks in timens

[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.

A new namespace is created with the same offsets as the time namespace
of the current process.

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 | 22 ++++++++++++++++++++++
 kernel/time/namespace.c        |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 873b908c9ba8..3d429c7ecca5 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -12,11 +12,17 @@
 struct user_namespace;
 extern struct user_namespace init_user_ns;
 
+struct timens_offsets {
+	struct timespec64 monotonic;
+	struct timespec64 boottime;
+};
+
 struct time_namespace {
 	struct kref kref;
 	struct user_namespace *user_ns;
 	struct ucounts *ucounts;
 	struct ns_common ns;
+	struct timens_offsets offsets;
 } __randomize_layout;
 extern struct time_namespace init_time_ns;
 
@@ -37,6 +43,20 @@ 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;
+
+	*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;
+
+	*ts = timespec64_add(*ts, ns_offsets->boottime);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -61,6 +81,8 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 	return 0;
 }
 
+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/kernel/time/namespace.c b/kernel/time/namespace.c
index 2662a69e0382..c2a58e45fc4b 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)
 {
@@ -60,6 +61,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 	ns->ucounts = ucounts;
 	ns->ns.ops = &timens_operations;
 	ns->user_ns = get_user_ns(user_ns);
+	ns->offsets = old_ns->offsets;
 	return ns;
 
 fail_free:
-- 
2.23.0

[PATCHv7 03/33] posix-clocks: Rename the clock_get() callback to 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 the clock_get() callback to 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 451f9d05ccfe..8523df726fee 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -657,7 +657,7 @@ 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.
  *
@@ -837,7 +837,7 @@ 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 92a431981b1c..c84ee50e2eab 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1391,26 +1391,26 @@ 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 0ec5b7a1d769..44d4f9cb782d 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.
@@ -1067,7 +1067,7 @@ 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;
@@ -1149,7 +1149,7 @@ 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;
@@ -1261,7 +1261,7 @@ 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,
@@ -1279,7 +1279,7 @@ 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,
@@ -1295,22 +1295,22 @@ 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,
@@ -1326,7 +1326,7 @@ 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 897c29e162b9..070611b2c253 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,
-- 
2.23.0

[PATCHv7 04/33] posix-clocks: Rename .clock_get_timespec() callbacks accordingly

[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 | 16 ++++++++--------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 8523df726fee..62b06cfa710d 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -657,13 +657,13 @@ 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)];
 
@@ -837,7 +837,7 @@ 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 44d4f9cb782d..68d4690cc225 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -165,7 +165,7 @@ 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_get_realtime_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_real_ts64(tp);
 	return 0;
@@ -187,7 +187,7 @@ 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_monotonic_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
@@ -222,13 +222,13 @@ 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;
@@ -1261,7 +1261,7 @@ 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_get_realtime_timespec,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1279,7 +1279,7 @@ 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_monotonic_timespec,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1310,7 +1310,7 @@ 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,
@@ -1326,7 +1326,7 @@ 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,
-- 
2.23.0

[PATCHv7 05/33] 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 62b06cfa710d..22b6f9b133b2 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)) {
@@ -632,7 +632,7 @@ 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
@@ -670,7 +670,7 @@ 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;
 }
 
@@ -747,7 +747,7 @@ 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;
@@ -816,7 +816,7 @@ 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);
 	}
@@ -882,9 +882,9 @@ 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);
-- 
2.23.0

[PATCHv7 06/33] 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 3d10c84a97a9..d535d52eb3ca 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -230,4 +230,7 @@ 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_realtime_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 22b6f9b133b2..73a5458194c7 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];
 
@@ -670,8 +673,7 @@ 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);
 }
 
 /**
@@ -883,8 +885,10 @@ 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_realtime_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 68d4690cc225..e65241a46038 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -165,7 +165,7 @@ static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 }
 
 /* Get clock_realtime */
-static int posix_get_realtime_timespec(clockid_t which_clock, struct timespec64 *tp)
+int posix_get_realtime_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_real_ts64(tp);
 	return 0;
@@ -222,7 +222,7 @@ 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;
-- 
2.23.0

[PATCHv7 07/33] 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 73a5458194c7..9415c83f8cca 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -664,7 +664,7 @@ 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)
 {
@@ -676,6 +676,22 @@ 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
@@ -839,6 +855,7 @@ 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 e65241a46038..1d7329e8425f 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -171,6 +171,11 @@ int posix_get_realtime_timespec(clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
+static ktime_t posix_get_realtime_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)
@@ -193,6 +198,11 @@ static int posix_get_monotonic_timespec(clockid_t which_clock, struct timespec64
 	return 0;
 }
 
+static ktime_t posix_get_monotonic_ktime(clockid_t which_clock)
+{
+	return ktime_get();
+}
+
 /*
  * Get monotonic-raw time for posix timers
  */
@@ -228,12 +238,22 @@ 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;
@@ -781,7 +801,7 @@ 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.
@@ -1262,6 +1282,7 @@ 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_get_realtime_timespec,
+	.clock_get_ktime	= posix_get_realtime_ktime,
 	.clock_set		= posix_clock_realtime_set,
 	.clock_adj		= posix_clock_realtime_adj,
 	.nsleep			= common_nsleep,
@@ -1280,6 +1301,7 @@ 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_monotonic_timespec,
+	.clock_get_ktime	= posix_get_monotonic_ktime,
 	.nsleep			= common_nsleep,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
@@ -1310,6 +1332,7 @@ 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,
@@ -1326,6 +1349,7 @@ 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 070611b2c253..f32a2ebba9b8 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,
-- 
2.23.0

[PATCHv7 08/33] 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 1d7329e8425f..47a8d43fe1c6 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -665,7 +665,6 @@ 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;
@@ -683,12 +682,7 @@ 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
-- 
2.23.0

[PATCHv7 09/33] posix-clocks: Wire up clock_gettime() with timens offsets

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Adjust monotonic and boottime clocks with per-timens offsets.
As the result a process inside time namespace will see timers and clocks
corrected to offsets that were set on creating namespace.

Note that applications usually go through vDSO to get time, which is not
yet adjusted. Further changes complete time namespace virtualisation
with vDSO support.

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   | 1 +
 kernel/time/posix-stubs.c  | 3 +++
 kernel/time/posix-timers.c | 5 +++++
 3 files changed, 9 insertions(+)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 9415c83f8cca..c326427bb4cb 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 67df65f887ac..edaf075d1ee4 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
@@ -77,9 +78,11 @@ 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);
+		timens_add_boottime(tp);
 		break;
 	default:
 		return -EINVAL;
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 47a8d43fe1c6..d8b5bd4cbae1 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"
@@ -195,6 +196,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 static int posix_get_monotonic_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
@@ -209,6 +211,7 @@ static ktime_t posix_get_monotonic_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;
 }
 
@@ -223,6 +226,7 @@ static int posix_get_monotonic_coarse(clockid_t which_clock,
 						struct timespec64 *tp)
 {
 	ktime_get_coarse_ts64(tp);
+	timens_add_monotonic(tp);
 	return 0;
 }
 
@@ -235,6 +239,7 @@ 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;
 }
 
-- 
2.23.0

[PATCHv7 10/33] 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 | 14 +++++++++++++
 kernel/time/namespace.c        | 36 ++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 3d429c7ecca5..9a77d3854830 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -57,6 +57,15 @@ 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;
+
+	return do_timens_ktime_to_host(clockid, tim, offsets);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -83,6 +92,11 @@ 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 c2a58e45fc4b..1a0fbaa5d2d4 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -16,6 +16,42 @@
 #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 {
+		tim = ktime_sub(tim, offset);
+		if (unlikely(tim > KTIME_MAX))
+			tim = KTIME_MAX;
+	}
+
+	return tim;
+}
+
 static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
 {
 	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
-- 
2.23.0

[PATCHv7 11/33] timerfd: Make timerfd_settime() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

timerfd_settime() accepts an absolute value of the expiration 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 48305ba41e3c..f9da5752a79e 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);
-- 
2.23.0

[PATCHv7 12/33] 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 d8b5bd4cbae1..6e350cc8f600 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -885,6 +885,8 @@ 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);
-- 
2.23.0

[PATCHv7 13/33] 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 c326427bb4cb..353e46f9acc2 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -838,6 +838,8 @@ 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);
-- 
2.23.0

[PATCHv7 14/33] 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 ++--
 kernel/time/posix-timers.c     | 4 +++-
 tools/perf/examples/bpf/5sec.c | 6 ++++--
 5 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 1b9a51a1bccb..cdcb2e9cd54a 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -502,7 +502,7 @@ 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 0d4dc241c0fb..19cc504bd7cc 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1907,7 +1907,7 @@ 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;
@@ -1920,7 +1920,7 @@ long hrtimer_nanosleep(const struct timespec64 *rqtp,
 		slack = 0;
 
 	hrtimer_init_sleeper_on_stack(&t, 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;
@@ -1955,7 +1955,7 @@ 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
@@ -1975,7 +1975,7 @@ 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);
 }
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 6e350cc8f600..c0ae1f6d2add 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1221,7 +1221,9 @@ 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);
 }
diff --git a/tools/perf/examples/bpf/5sec.c b/tools/perf/examples/bpf/5sec.c
index b9c203219691..e6b6181c6dc6 100644
--- a/tools/perf/examples/bpf/5sec.c
+++ b/tools/perf/examples/bpf/5sec.c
@@ -41,9 +41,11 @@
 
 #include <bpf.h>
 
-int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec)
+#define NSEC_PER_SEC	1000000000L
+
+int probe(hrtimer_nanosleep, rqtp)(void *ctx, int err, long long sec)
 {
-	return sec == 5;
+	return sec / NSEC_PER_SEC == 5ULL;
 }
 
 license(GPL);
-- 
2.23.0

[PATCHv7 15/33] posix-timers: Make clock_nanosleep() time namespace aware

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

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 | 17 +++++++++++++++--
 2 files changed, 25 insertions(+), 4 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 c0ae1f6d2add..ccae99a645e1 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1228,6 +1228,19 @@ static int common_nsleep(const clockid_t which_clock, int flags,
 				 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);
+}
+
 SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 		const struct __kernel_timespec __user *, rqtp,
 		struct __kernel_timespec __user *, rmtp)
@@ -1305,7 +1318,7 @@ static const struct k_clock clock_monotonic = {
 	.clock_getres		= posix_get_hrtimer_res,
 	.clock_get_timespec	= posix_get_monotonic_timespec,
 	.clock_get_ktime	= posix_get_monotonic_ktime,
-	.nsleep			= common_nsleep,
+	.nsleep			= common_nsleep_timens,
 	.timer_create		= common_timer_create,
 	.timer_set		= common_timer_set,
 	.timer_get		= common_timer_get,
@@ -1354,7 +1367,7 @@ 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,
-- 
2.23.0

[PATCHv7 16/33] fs/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",
-- 
2.23.0

[PATCHv7 17/33] x86/vdso: Restrict splitting VVAR VMA

[Dmitry Safonov]

Forbid splitting VVAR resulting in stricter ABI and reducing amount
of corner-cases to consider while working further on VDSO.

As offset from timens to VVAR page is computed compile-time,
the pages in VVAR should stay together and not being partically
mremap()'ed.

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 f5937742b290..000db8282cc8 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,
 };
 
 /*
-- 
2.23.0

[PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Place the branch with no concurrent write before contended case.

Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
(more clock_gettime() cycles - the better):
        | before    | after
-----------------------------------
        | 150252214 | 153242367
        | 150301112 | 153324800
        | 150392773 | 153125401
        | 150373957 | 153399355
        | 150303157 | 153489417
        | 150365237 | 153494270
-----------------------------------
avg     | 150331408 | 153345935
diff %  | 2	    | 0
-----------------------------------
stdev % | 0.3	    | 0.1

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/vdso/helpers.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
index 01641dbb68ef..9a2af9fca45e 100644
--- a/include/vdso/helpers.h
+++ b/include/vdso/helpers.h
@@ -10,7 +10,7 @@ static __always_inline u32 vdso_read_begin(const struct vdso_data *vd)
 {
 	u32 seq;
 
-	while ((seq = READ_ONCE(vd->seq)) & 1)
+	while (unlikely((seq = READ_ONCE(vd->seq)) & 1))
 		cpu_relax();
 
 	smp_rmb();
-- 
2.23.0

[PATCHv7 19/33] lib/vdso: Prepare for time namespace support

[Dmitry Safonov]

From: Thomas Gleixner <tglx@linutronix.de>

To support time namespaces in the vdso with a minimal impact on regular non
time namespace affected tasks, the namespace handling needs to be hidden in
a slow path.

The most obvious place is vdso_seq_begin(). If a task belongs to a time
namespace then the VVAR page which contains the system wide vdso data is
replaced with a namespace specific page which has the same layout as the
VVAR page. That page has vdso_data->seq set to 1 to enforce the slow path
and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time
namespace handling path.

The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the vdso data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.

If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.

If VDSO time namespace support is disabled the whole magic is compiled out.

Initial testing shows that the disabled case is almost identical to the
host case which does not take the slow timens path. With the special timens
page installed the performance hit is constant time and in the range of
5-7%.

For the vdso functions which are not using the sequence count an
unconditional check for vdso_data->clock_mode is added which switches to
the real vdso when the clock_mode is VCLOCK_TIMENS.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time.h    |   6 ++
 include/vdso/datapage.h |  19 +++++-
 lib/vdso/Kconfig        |   6 ++
 lib/vdso/gettimeofday.c | 128 +++++++++++++++++++++++++++++++++++++++-
 4 files changed, 155 insertions(+), 4 deletions(-)

diff --git a/include/linux/time.h b/include/linux/time.h
index 27d83fd2ae61..b1a592638d7d 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -96,4 +96,10 @@ static inline bool itimerspec64_valid(const struct itimerspec64 *its)
  */
 #define time_after32(a, b)	((s32)((u32)(b) - (u32)(a)) < 0)
 #define time_before32(b, a)	time_after32(a, b)
+
+struct timens_offset {
+	s64	sec;
+	u64	nsec;
+};
+
 #endif
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 2e302c0f41f7..65a38acce27e 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -21,6 +21,8 @@
 #define CS_RAW		1
 #define CS_BASES	(CS_RAW + 1)
 
+#define VCLOCK_TIMENS	UINT_MAX
+
 /**
  * struct vdso_timestamp - basetime per clock_id
  * @sec:	seconds
@@ -48,6 +50,7 @@ struct vdso_timestamp {
  * @mult:		clocksource multiplier
  * @shift:		clocksource shift
  * @basetime[clock_id]:	basetime per clock_id
+ * @offset[clock_id]:	time namespace offset per clock_id
  * @tz_minuteswest:	minutes west of Greenwich
  * @tz_dsttime:		type of DST correction
  * @hrtimer_res:	hrtimer resolution
@@ -55,6 +58,17 @@ struct vdso_timestamp {
  *
  * vdso_data will be accessed by 64 bit and compat code at the same time
  * so we should be careful before modifying this structure.
+ *
+ * @basetime is used to store the base time for the system wide time getter
+ * VVAR page.
+ *
+ * @offset is used by the special time namespace VVAR pages which are
+ * installed instead of the real VVAR page. These namespace pages must set
+ * @seq to 1 and @clock_mode to VLOCK_TIMENS to force the code into the
+ * time namespace slow path. The namespace aware functions retrieve the
+ * real system wide VVAR page, read host time and add the per clock offset.
+ * For clocks which are not affected by time namespace adjustement the
+ * offset must be zero.
  */
 struct vdso_data {
 	u32			seq;
@@ -65,7 +79,10 @@ struct vdso_data {
 	u32			mult;
 	u32			shift;
 
-	struct vdso_timestamp	basetime[VDSO_BASES];
+	union {
+		struct vdso_timestamp	basetime[VDSO_BASES];
+		struct timens_offset	offset[VDSO_BASES];
+	};
 
 	s32			tz_minuteswest;
 	s32			tz_dsttime;
diff --git a/lib/vdso/Kconfig b/lib/vdso/Kconfig
index 9fe698ff62ec..85276de70dba 100644
--- a/lib/vdso/Kconfig
+++ b/lib/vdso/Kconfig
@@ -24,4 +24,10 @@ config GENERIC_COMPAT_VDSO
 	help
 	  This config option enables the compat VDSO layer.
 
+config VDSO_TIMENS
+	bool
+	help
+	  Selected by architectures which support time namespaces in the
+	  VDSO
+
 endif
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index e630e7ff57f1..25244b677823 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -38,6 +38,51 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 }
 #endif
 
+#ifndef CONFIG_VDSO_TIMENS
+static __always_inline
+const struct vdso_data *__arch_get_timens_vdso_data(void)
+{
+	return NULL;
+}
+#endif
+
+static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
+		      struct __kernel_timespec *ts)
+{
+	const struct vdso_data *vd = __arch_get_timens_vdso_data();
+	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
+	const struct timens_offset *offs = &vdns->offset[clk];
+	u64 cycles, last, ns;
+	s64 sec;
+	u32 seq;
+
+	do {
+		seq = vdso_read_begin(vd);
+		cycles = __arch_get_hw_counter(vd->clock_mode);
+		ns = vdso_ts->nsec;
+		last = vd->cycle_last;
+		if (unlikely((s64)cycles < 0))
+			return -1;
+
+		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
+		ns >>= vd->shift;
+		sec = vdso_ts->sec;
+	} while (unlikely(vdso_read_retry(vd, seq)));
+
+	/* Add the namespace offset */
+	sec += offs->sec;
+	ns += offs->nsec;
+
+	/*
+	 * Do this outside the loop: a race inside the loop could result
+	 * in __iter_div_u64_rem() being extremely slow.
+	 */
+	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+	ts->tv_nsec = ns;
+
+	return 0;
+}
+
 static int do_hres(const struct vdso_data *vd, clockid_t clk,
 		   struct __kernel_timespec *ts)
 {
@@ -46,7 +91,28 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	u32 seq;
 
 	do {
-		seq = vdso_read_begin(vd);
+		/*
+		 * Open coded to handle VCLOCK_TIMENS. Time namespace
+		 * enabled tasks have a special VVAR page installed which
+		 * has vd->seq set to 1 and vd->clock_mode set to
+		 * VCLOCK_TIMENS. For non time namespace affected tasks
+		 * this does not affect performance because if vd->seq is
+		 * odd, i.e. a concurrent update is in progress the extra
+		 * check for vd->clock_mode is just a few extra
+		 * instructions while spin waiting for vd->seq to become
+		 * even again.
+		 */
+		while (1) {
+			seq = READ_ONCE(vd->seq);
+			if (likely(!(seq & 1)))
+				break;
+			if (IS_ENABLED(CONFIG_VDSO_TIMENS) &&
+			    vd->clock_mode == VCLOCK_TIMENS)
+				return do_hres_timens(vd, clk, ts);
+			cpu_relax();
+		}
+		smp_rmb();
+
 		cycles = __arch_get_hw_counter(vd->clock_mode);
 		ns = vdso_ts->nsec;
 		last = vd->cycle_last;
@@ -68,6 +134,34 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	return 0;
 }
 
+static void do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
+			 struct __kernel_timespec *ts)
+{
+	const struct vdso_data *vd = __arch_get_timens_vdso_data();
+	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
+	const struct timens_offset *offs = &vdns->offset[clk];
+	u64 nsec;
+	s64 sec;
+	s32 seq;
+
+	do {
+		seq = vdso_read_begin(vd);
+		sec = vdso_ts->sec;
+		nsec = vdso_ts->nsec;
+	} while (unlikely(vdso_read_retry(vd, seq)));
+
+	/* Add the namespace offset */
+	sec += offs->sec;
+	nsec += offs->nsec;
+
+	/*
+	 * Do this outside the loop: a race inside the loop could result
+	 * in __iter_div_u64_rem() being extremely slow.
+	 */
+	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
+	ts->tv_nsec = nsec;
+}
+
 static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 		      struct __kernel_timespec *ts)
 {
@@ -75,7 +169,23 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 	u32 seq;
 
 	do {
-		seq = vdso_read_begin(vd);
+		/*
+		 * Open coded to handle VCLOCK_TIMENS. See comment in
+		 * do_hres().
+		 */
+		while (1) {
+			seq = READ_ONCE(vd->seq);
+			if (likely(!(seq & 1)))
+				break;
+			if (IS_ENABLED(CONFIG_VDSO_TIMENS) &&
+			    vd->clock_mode == VCLOCK_TIMENS) {
+				do_coarse_timens(vd, clk, ts);
+				return;
+			}
+			cpu_relax();
+		}
+		smp_rmb();
+
 		ts->tv_sec = vdso_ts->sec;
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));
@@ -156,6 +266,10 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 	}
 
 	if (unlikely(tz != NULL)) {
+		if (IS_ENABLED(CONFIG_VDSO_TIMENS) &&
+		    vd->clock_mode == VCLOCK_TIMENS)
+			vd = __arch_get_timens_vdso_data();
+
 		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
 		tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
 	}
@@ -167,7 +281,12 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 static __maybe_unused time_t __cvdso_time(time_t *time)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
-	time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
+	time_t t;
+
+	if (IS_ENABLED(CONFIG_VDSO_TIMENS) && vd->clock_mode == VCLOCK_TIMENS)
+		vd = __arch_get_timens_vdso_data();
+
+	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
 
 	if (time)
 		*time = t;
@@ -189,6 +308,9 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 	if (unlikely((u32) clock >= MAX_CLOCKS))
 		return -1;
 
+	if (IS_ENABLED(CONFIG_VDSO_TIMENS) && vd->clock_mode == VCLOCK_TIMENS)
+		vd = __arch_get_timens_vdso_data();
+
 	hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
 	/*
 	 * Convert the clockid to a bitmask and use it to check which
-- 
2.23.0

[PATCHv7 20/33] x86/vdso: Provide vdso_data offset on vvar_page

[Dmitry Safonov]

VDSO support for Time namespace needs to set up a page with the same
layout as VVAR. That timens page will be placed on position of VVAR page
inside namespace. That page has vdso_data->seq set to 1 to enforce
the slow path and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce
the time namespace handling path.

To prepare timens page kernel needs to know the vdso_data offset.
Provide arch_get_vdso_data() helper for locating vdso_data on VVAR page.

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/vdso-layout.lds.S |  2 --
 arch/x86/entry/vdso/vma.c             | 11 +++++++++++
 arch/x86/include/asm/vvar.h           |  8 ++++----
 arch/x86/kernel/vmlinux.lds.S         |  4 +---
 include/linux/time_namespace.h        |  1 +
 5 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index 93c6dc7812d0..2330daad67c3 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -21,9 +21,7 @@ SECTIONS
 
 	/* Place all vvars at the offsets in asm/vvar.h. */
 #define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
-#define __VVAR_KERNEL_LDS
 #include <asm/vvar.h>
-#undef __VVAR_KERNEL_LDS
 #undef EMIT_VVAR
 
 	pvclock_page = vvar_start + PAGE_SIZE;
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 000db8282cc8..5dab706aca2e 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -24,6 +24,17 @@
 #include <asm/cpufeature.h>
 #include <clocksource/hyperv_timer.h>
 
+#undef _ASM_X86_VVAR_H
+#define EMIT_VVAR(name, offset)	\
+	const size_t name ## _offset = offset;
+#include <asm/vvar.h>
+
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+	return (struct vdso_data *)(vvar_page + _vdso_data_offset);
+}
+#undef EMIT_VVAR
+
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
 #endif
diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h
index 32f5d9a0b90e..ff2de3025388 100644
--- a/arch/x86/include/asm/vvar.h
+++ b/arch/x86/include/asm/vvar.h
@@ -19,10 +19,10 @@
 #ifndef _ASM_X86_VVAR_H
 #define _ASM_X86_VVAR_H
 
-#if defined(__VVAR_KERNEL_LDS)
-
-/* The kernel linker script defines its own magic to put vvars in the
- * right place.
+#ifdef EMIT_VVAR
+/*
+ * EMIT_VVAR() is used by the kernel linker script to put vvars in the
+ * right place. Also, it's used by kernel code to import offsets values.
  */
 #define DECLARE_VVAR(offset, type, name) \
 	EMIT_VVAR(name, offset)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index e2feacf921a0..ca02d0d301cd 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -195,12 +195,10 @@ SECTIONS
 		__vvar_beginning_hack = .;
 
 		/* Place all vvars at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) 			\
+#define EMIT_VVAR(name, offset)				\
 		. = __vvar_beginning_hack + offset;	\
 		*(.vvar_ ## name)
-#define __VVAR_KERNEL_LDS
 #include <asm/vvar.h>
-#undef __VVAR_KERNEL_LDS
 #undef EMIT_VVAR
 
 		/*
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 9a77d3854830..772911945944 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -37,6 +37,7 @@ 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);
+extern struct vdso_data *arch_get_vdso_data(void *vvar_page);
 
 static inline void put_time_ns(struct time_namespace *ns)
 {
-- 
2.23.0

[PATCHv7 21/33] x86/vdso: Add timens page

[Dmitry Safonov]

To support time namespaces in the VDSO with a minimal impact on regular non
time namespace affected tasks, the namespace handling needs to be hidden in
a slow path.

The most obvious place is vdso_seq_begin(). If a task belongs to a time
namespace then the VVAR page which contains the system wide VDSO data is
replaced with a namespace specific page which has the same layout as the
VVAR page. That page has vdso_data->seq set to 1 to enforce the slow path
and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time
namespace handling path.

The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the VDSO data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.

If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.

Allocate Timens page among VVAR pages and place vdso_data on it.
Provide __arch_get_timens_vdso_data() helper for VDSO code to get the
code-relative position of VVARs on that special page.

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/Kconfig                         |  1 +
 arch/x86/entry/vdso/vdso-layout.lds.S    | 11 +++++++++--
 arch/x86/entry/vdso/vdso2c.c             |  3 +++
 arch/x86/include/asm/vdso.h              |  1 +
 arch/x86/include/asm/vdso/gettimeofday.h |  9 +++++++++
 arch/x86/include/asm/vvar.h              |  5 ++++-
 6 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d6e1faa28c58..15f076eb2b1c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -226,6 +226,7 @@ config X86
 	select VIRT_TO_BUS
 	select X86_FEATURE_NAMES		if PROC_FS
 	select PROC_PID_ARCH_STATUS		if PROC_FS
+	select VDSO_TIMENS			if TIME_NS
 
 config INSTRUCTION_DECODER
 	def_bool y
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index 2330daad67c3..ea7e0155c604 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -16,8 +16,8 @@ SECTIONS
 	 * segment.
 	 */
 
-	vvar_start = . - 3 * PAGE_SIZE;
-	vvar_page = vvar_start;
+	vvar_start = . - 4 * PAGE_SIZE;
+	vvar_page  = vvar_start;
 
 	/* Place all vvars at the offsets in asm/vvar.h. */
 #define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
@@ -26,6 +26,13 @@ SECTIONS
 
 	pvclock_page = vvar_start + PAGE_SIZE;
 	hvclock_page = vvar_start + 2 * PAGE_SIZE;
+	timens_page  = vvar_start + 3 * PAGE_SIZE;
+
+#undef _ASM_X86_VVAR_H
+	/* Place all vvars in timens too at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) timens_ ## name = timens_page + offset;
+#include <asm/vvar.h>
+#undef EMIT_VVAR
 
 	. = SIZEOF_HEADERS;
 
diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c
index 3a4d8d4d39f8..3842873b3ae3 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/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 230474e2ddb5..bbcdc7b8f963 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/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index e9ee139cf29e..39a551df4fea 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -21,6 +21,7 @@
 #include <clocksource/hyperv_timer.h>
 
 #define __vdso_data (VVAR(_vdso_data))
+#define __timens_vdso_data (TIMENS(_vdso_data))
 
 #define VDSO_HAS_TIME 1
 
@@ -56,6 +57,14 @@ extern struct ms_hyperv_tsc_page hvclock_page
 	__attribute__((visibility("hidden")));
 #endif
 
+#ifdef CONFIG_VDSO_TIMENS
+static __always_inline
+const struct vdso_data *__arch_get_timens_vdso_data(void)
+{
+	return __timens_vdso_data;
+}
+#endif
+
 #ifndef BUILD_VDSO32
 
 static __always_inline
diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h
index ff2de3025388..183e98e49ab9 100644
--- a/arch/x86/include/asm/vvar.h
+++ b/arch/x86/include/asm/vvar.h
@@ -33,9 +33,12 @@ extern char __vvar_page;
 
 #define DECLARE_VVAR(offset, type, name)				\
 	extern type vvar_ ## name[CS_BASES]				\
-	__attribute__((visibility("hidden")));
+	__attribute__((visibility("hidden")));				\
+	extern type timens_ ## name[CS_BASES]				\
+	__attribute__((visibility("hidden")));				\
 
 #define VVAR(name) (vvar_ ## name)
+#define TIMENS(name) (timens_ ## name)
 
 #define DEFINE_VVAR(type, name)						\
 	type name[CS_BASES]						\
-- 
2.23.0

[PATCHv7 22/33] time: Allocate per-timens vvar page

[Dmitry Safonov]

VDSO support for Time namespace needs to set up a page with the same
layout as VVAR. That timens page will be placed on position of VVAR page
inside namespace. That page contains time namespace clock offsets and it
has vdso_data->seq set to 1 to enforce the slow path and
vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time namespace
handling path.

Allocate the timens page during namespace creation. Setup the offsets
when the first task enters the ns and freeze them to guarantee the pace
of monotonic/boottime clocks and to avoid breakage of applications.

The design decision is to have a global offset_lock which is used
during namespace offsets set up and to freeze offsets when first task
joins the new ns. That is better in terms of memory usage comparing
to having per-ns mutex that's used only during the set up period.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Based-on-work-by: Thomas Gleixner <tglx@linutronix.de>
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/time_namespace.h |   3 +
 kernel/time/namespace.c        | 103 ++++++++++++++++++++++++++++++++-
 2 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 772911945944..c479cfda2c3e 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -23,6 +23,9 @@ struct time_namespace {
 	struct ucounts *ucounts;
 	struct ns_common ns;
 	struct timens_offsets offsets;
+	struct page *vvar_page;
+	/* Disallow changing offsets after any task joined namespace. */
+	bool frozen_offsets;
 } __randomize_layout;
 extern struct time_namespace init_time_ns;
 
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 1a0fbaa5d2d4..e14cd1ca387d 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 <vdso/datapage.h>
 
 ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
 				struct timens_offsets *ns_offsets)
@@ -90,16 +91,23 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 
 	kref_init(&ns->kref);
 
+	ns->vvar_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	if (!ns->vvar_page)
+		goto fail_free;
+
 	err = ns_alloc_inum(&ns->ns);
 	if (err)
-		goto fail_free;
+		goto fail_free_page;
 
 	ns->ucounts = ucounts;
 	ns->ns.ops = &timens_operations;
 	ns->user_ns = get_user_ns(user_ns);
 	ns->offsets = old_ns->offsets;
+	ns->frozen_offsets = false;
 	return ns;
 
+fail_free_page:
+	__free_page(ns->vvar_page);
 fail_free:
 	kfree(ns);
 fail_dec:
@@ -128,6 +136,93 @@ struct time_namespace *copy_time_ns(unsigned long flags,
 	return clone_time_ns(user_ns, old_ns);
 }
 
+static struct timens_offset offset_from_ts(struct timespec64 off)
+{
+	struct timens_offset ret;
+
+	ret.sec = off.tv_sec;
+	ret.nsec = off.tv_nsec;
+
+	return ret;
+}
+
+/*
+ * A time namespace VVAR page has the same layout as the VVAR page which
+ * contains the system wide VDSO data.
+ *
+ * For a normal task the VVAR pages are installed in the normal ordering:
+ *     VVAR
+ *     PVCLOCK
+ *     HVCLOCK
+ *     TIMENS   <- Not really required
+ *
+ * Now for a timens task the pages are installed in the following order:
+ *     TIMENS
+ *     PVCLOCK
+ *     HVCLOCK
+ *     VVAR
+ *
+ * The check for vdso_data->clock_mode is in the unlikely path of
+ * the seq begin magic. So for the non-timens case most of the time
+ * 'seq' is even, so the branch is not taken.
+ *
+ * If 'seq' is odd, i.e. a concurrent update is in progress, the extra check
+ * for vdso_data->clock_mode is a non-issue. The task is spin waiting for the
+ * update to finish and for 'seq' to become even anyway.
+ *
+ * Timens page has vdso_data->clock_mode set to VCLOCK_TIMENS which enforces
+ * the time namespace handling path.
+ */
+static void timens_setup_vdso_data(struct vdso_data *vdata,
+				   struct time_namespace *ns)
+{
+	struct timens_offset *offset = vdata->offset;
+	struct timens_offset monotonic = offset_from_ts(ns->offsets.monotonic);
+	struct timens_offset boottime = offset_from_ts(ns->offsets.boottime);
+
+	vdata->seq			= 1;
+	vdata->clock_mode		= VCLOCK_TIMENS;
+	offset[CLOCK_MONOTONIC]		= monotonic;
+	offset[CLOCK_MONOTONIC_RAW]	= monotonic;
+	offset[CLOCK_MONOTONIC_COARSE]	= monotonic;
+	offset[CLOCK_BOOTTIME]		= boottime;
+	offset[CLOCK_BOOTTIME_ALARM]	= boottime;
+}
+
+/*
+ * Protects possibly multiple offsets writers racing each other
+ * and tasks entering the namespace.
+ */
+static DEFINE_MUTEX(offset_lock);
+
+static void timens_set_vvar_page(struct task_struct *task,
+				struct time_namespace *ns)
+{
+	struct vdso_data *vdata;
+	unsigned int i;
+
+	if (ns == &init_time_ns)
+		return;
+
+	/* Fast-path, taken by every task in namespace except the first. */
+	if (likely(ns->frozen_offsets))
+		return;
+
+	mutex_lock(&offset_lock);
+	/* Nothing to-do: vvar_page has been already initialized. */
+	if (ns->frozen_offsets)
+		goto out;
+
+	ns->frozen_offsets = true;
+	vdata = arch_get_vdso_data(page_address(ns->vvar_page));
+
+	for (i = 0; i < CS_BASES; i++)
+		timens_setup_vdso_data(&vdata[i], ns);
+
+out:
+	mutex_unlock(&offset_lock);
+}
+
 void free_time_ns(struct kref *kref)
 {
 	struct time_namespace *ns;
@@ -136,6 +231,7 @@ void free_time_ns(struct kref *kref)
 	dec_time_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
 	ns_free_inum(&ns->ns);
+	__free_page(ns->vvar_page);
 	kfree(ns);
 }
 
@@ -192,6 +288,8 @@ static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
+	timens_set_vvar_page(current, ns);
+
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
 	nsproxy->time_ns = ns;
@@ -211,6 +309,8 @@ int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
 	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
 		return 0;
 
+	timens_set_vvar_page(tsk, ns);
+
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
 	nsproxy->time_ns = ns;
@@ -246,6 +346,7 @@ struct time_namespace init_time_ns = {
 	.user_ns	= &init_user_ns,
 	.ns.inum	= PROC_TIME_INIT_INO,
 	.ns.ops		= &timens_operations,
+	.frozen_offsets	= true,
 };
 
 static int __init time_ns_init(void)
-- 
2.23.0

[PATCHv7 23/33] x86/vdso: Handle faults on timens page

[Dmitry Safonov]

If a task belongs to a time namespace then the VVAR page which contains
the system wide VDSO data is replaced with a namespace specific page
which has the same layout as the VVAR page.

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 | 53 +++++++++++++++++++++++++++++++++++++--
 mm/mmap.c                 |  2 ++
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 5dab706aca2e..f6e13ab29d94 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -14,11 +14,13 @@
 #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>
 #include <asm/vdso.h>
 #include <asm/vvar.h>
+#include <asm/tlb.h>
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
@@ -107,10 +109,36 @@ static int vvar_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
+#ifdef CONFIG_TIME_NS
+static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+	if (likely(vma->vm_mm == current->mm))
+		return current->nsproxy->time_ns->vvar_page;
+
+	/*
+	 * VM_PFNMAP | VM_IO protect .fault() handler from being called
+	 * through interfaces like /proc/$pid/mem or
+	 * process_vm_{readv,writev}() as long as there's no .access()
+	 * in special_mapping_vmops().
+	 * For more details check_vma_flags() and __access_remote_vm()
+	 */
+
+	WARN(1, "vvar_page accessed remotely");
+
+	return NULL;
+}
+#else
+static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+	return NULL;
+}
+#endif
+
 static vm_fault_t vvar_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 pfn;
 	long sym_offset;
 
 	if (!image)
@@ -130,8 +158,21 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		return VM_FAULT_SIGBUS;
 
 	if (sym_offset == image->sym_vvar_page) {
-		return vmf_insert_pfn(vma, vmf->address,
-				__pa_symbol(&__vvar_page) >> PAGE_SHIFT);
+		struct page *timens_page = find_timens_vvar_page(vma);
+
+		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+
+		/*
+		 * If a task belongs to a time namespace then a namespace
+		 * specific VVAR is mapped with the sym_vvar_page offset and
+		 * the real VVAR page is mapped with the sym_timens_page
+		 * offset.
+		 * See also the comment near timens_setup_vdso_data().
+		 */
+		if (timens_page)
+			pfn = page_to_pfn(timens_page);
+
+		return vmf_insert_pfn(vma, vmf->address, pfn);
 	} else if (sym_offset == image->sym_pvclock_page) {
 		struct pvclock_vsyscall_time_info *pvti =
 			pvclock_get_pvti_cpu0_va();
@@ -146,6 +187,14 @@ 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,
 					virt_to_phys(tsc_pg) >> PAGE_SHIFT);
+	} else if (sym_offset == image->sym_timens_page) {
+		struct page *timens_page = find_timens_vvar_page(vma);
+
+		if (!timens_page)
+			return VM_FAULT_SIGBUS;
+
+		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+		return vmf_insert_pfn(vma, vmf->address, pfn);
 	}
 
 	return VM_FAULT_SIGBUS;
diff --git a/mm/mmap.c b/mm/mmap.c
index a7d8c84d19b7..af722a47db3c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3363,6 +3363,8 @@ static const struct vm_operations_struct special_mapping_vmops = {
 	.fault = special_mapping_fault,
 	.mremap = special_mapping_mremap,
 	.name = special_mapping_name,
+	/* vDSO code relies that VVAR can't be accessed remotely */
+	.access = NULL,
 };
 
 static const struct vm_operations_struct legacy_special_mapping_vmops = {
-- 
2.23.0

[PATCHv7 24/33] x86/vdso: On timens page fault prefault also VVAR page

[Dmitry Safonov]

As timens page has offsets to data on VVAR page VVAR is going
to be accessed shortly. Set it up with timens in one page fault
as optimization.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
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 | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index f6e13ab29d94..d6cb8a16f368 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -169,8 +169,23 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		 * offset.
 		 * See also the comment near timens_setup_vdso_data().
 		 */
-		if (timens_page)
+		if (timens_page) {
+			unsigned long addr;
+			vm_fault_t err;
+
+			/*
+			 * Optimization: inside time namespace pre-fault
+			 * VVAR page too. As on timens page there are only
+			 * offsets for clocks on VVAR, it'll be faulted
+			 * shortly by VDSO code.
+			 */
+			addr = vmf->address + (image->sym_timens_page - sym_offset);
+			err = vmf_insert_pfn(vma, addr, pfn);
+			if (unlikely(err & VM_FAULT_ERROR))
+				return err;
+
 			pfn = page_to_pfn(timens_page);
+		}
 
 		return vmf_insert_pfn(vma, vmf->address, pfn);
 	} else if (sym_offset == image->sym_pvclock_page) {
-- 
2.23.0

[PATCHv7 25/33] x86/vdso: Zap vvar pages on switch a time namspace

[Dmitry Safonov]

The VVAR page layout depends on whether a task belongs to the root or
non-root time namespace. Whenever a task changes its namespace, the VVAR
page tables are cleared and then they will re-faulted with a
corresponding layout.

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      | 27 +++++++++++++++++++++++++++
 include/linux/time_namespace.h |  3 +++
 kernel/time/namespace.c        | 10 ++++++++++
 3 files changed, 40 insertions(+)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index d6cb8a16f368..57ada3e95f8d 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -50,6 +50,7 @@ void __init init_vdso_image(const struct vdso_image *image)
 						image->alt_len));
 }
 
+static const struct vm_special_mapping vvar_mapping;
 struct linux_binprm;
 
 static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
@@ -127,6 +128,32 @@ static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
 
 	return NULL;
 }
+
+/*
+ * The vvar page layout depends on whether a task belongs to the root or
+ * non-root time namespace. Whenever a task changes its namespace, the VVAR
+ * page tables are cleared and then they will re-faulted with a
+ * corresponding layout.
+ * See also the comment near timens_setup_vdso_data() for details.
+ */
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+	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))
+			zap_page_range(vma, vma->vm_start, size);
+	}
+
+	up_write(&mm->mmap_sem);
+	return 0;
+}
 #else
 static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
 {
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index c479cfda2c3e..dcf3dbf2836b 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -30,6 +30,9 @@ struct time_namespace {
 extern struct time_namespace init_time_ns;
 
 #ifdef CONFIG_TIME_NS
+extern int vdso_join_timens(struct task_struct *task,
+			    struct time_namespace *ns);
+
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
 	kref_get(&ns->kref);
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index e14cd1ca387d..0dc0742ed1ee 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -280,6 +280,7 @@ 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 err;
 
 	if (!current_is_single_threaded())
 		return -EUSERS;
@@ -290,6 +291,10 @@ static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 
 	timens_set_vvar_page(current, ns);
 
+	err = vdso_join_timens(current, ns);
+	if (err)
+		return err;
+
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
 	nsproxy->time_ns = ns;
@@ -304,6 +309,7 @@ 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 err;
 
 	/* create_new_namespaces() already incremented the ref counter */
 	if (nsproxy->time_ns == nsproxy->time_ns_for_children)
@@ -311,6 +317,10 @@ int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
 
 	timens_set_vvar_page(tsk, ns);
 
+	err = vdso_join_timens(tsk, ns);
+	if (err)
+		return err;
+
 	get_time_ns(ns);
 	put_time_ns(nsproxy->time_ns);
 	nsproxy->time_ns = ns;
-- 
2.23.0

[PATCHv7 26/33] 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        | 100 +++++++++++++++++++++++++++++++++
 3 files changed, 205 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 dcf3dbf2836b..7cc80051cd17 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -50,6 +50,16 @@ 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 0dc0742ed1ee..267120f31699 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>
@@ -333,6 +334,105 @@ 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;
+
+	ns = timens_for_children_get(p);
+	if (!ns)
+		return;
+	time_ns = to_time_ns(ns);
+
+	show_offset(m, CLOCK_MONOTONIC, &time_ns->offsets.monotonic);
+	show_offset(m, CLOCK_BOOTTIME, &time_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 timespec64 tp;
+	int i, err;
+
+	ns = timens_for_children_get(p);
+	if (!ns)
+		return -ESRCH;
+	time_ns = to_time_ns(ns);
+
+	if (!file_ns_capable(file, time_ns->user_ns, CAP_SYS_TIME)) {
+		put_time_ns(time_ns);
+		return -EPERM;
+	}
+
+	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;
+	}
+
+	mutex_lock(&offset_lock);
+	if (time_ns->frozen_offsets) {
+		err = -EACCES;
+		goto out_unlock;
+	}
+
+	err = 0;
+	/* don't report errors after this line */
+	for (i = 0; i < noffsets; i++) {
+		struct proc_timens_offset *off = &offsets[i];
+		struct timespec64 *offset = NULL;
+
+		switch (off->clockid) {
+		case CLOCK_MONOTONIC:
+			offset = &time_ns->offsets.monotonic;
+			break;
+		case CLOCK_BOOTTIME:
+			offset = &time_ns->offsets.boottime;
+			break;
+		}
+
+		*offset = off->val;
+	}
+
+out_unlock:
+	mutex_unlock(&offset_lock);
+out:
+	put_time_ns(time_ns);
+
+	return err;
+}
+
 const struct proc_ns_operations timens_operations = {
 	.name		= "time",
 	.type		= CLONE_NEWTIME,
-- 
2.23.0

[PATCHv7 27/33] selftests/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.

Output on success:
 1..10
 ok 1 Passed for CLOCK_BOOTTIME (syscall)
 ok 2 Passed for CLOCK_BOOTTIME (vdso)
 ok 3 Passed for CLOCK_BOOTTIME_ALARM (syscall)
 ok 4 Passed for CLOCK_BOOTTIME_ALARM (vdso)
 ok 5 Passed for CLOCK_MONOTONIC (syscall)
 ok 6 Passed for CLOCK_MONOTONIC (vdso)
 ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall)
 ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso)
 ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall)
 ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso)
 # Pass 10 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output with lack of permissions:
 1..10
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..10
 not ok 1 # SKIP Time namespaces are not supported

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
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   |  73 +++++++++
 7 files changed, 292 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 4cdbae6f4e61..f6c3329946a6 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..9fc362d5a168
--- /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_timens())
+		return  -1;
+
+	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..0cba32fdaffd
--- /dev/null
+++ b/tools/testing/selftests/timens/timens.h
@@ -0,0 +1,73 @@
+/* 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 unshare_timens(void)
+{
+	if (unshare(CLONE_NEWTIME)) {
+		if (errno == EPERM)
+			ksft_exit_skip("need to run as root\n");
+		return pr_perror("Can't unshare() timens");
+	}
+	return 0;
+}
+
+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
-- 
2.23.0

[PATCHv7 28/33] selftests/timens: Add a test for timerfd

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Check that timerfd_create() takes into account clock offsets.

Output on success:
 1..3
 ok 1 clockid=7
 ok 2 clockid=1
 ok 3 clockid=9
 # Pass 3 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output on failure:
 1..3
 not ok 1 clockid: 7 elapsed: 0
 not ok 2 clockid: 1 elapsed: 0
 not ok 3 clockid: 9 elapsed: 0
 Bail out!

Output with lack of permissions:
 1..3
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..3
 not ok 1 # SKIP Time namespaces are not supported

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..619b096b7fe5
--- /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_timens())
+		return 1;
+
+	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;
+}
+
-- 
2.23.0

[PATCHv7 29/33] selftests/timens: Add a test for clock_nanosleep()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Check that clock_nanosleep() takes into account clock offsets.

Output on success:
 1..4
 ok 1 clockid: 1 abs:0
 ok 2 clockid: 1 abs:1
 ok 3 clockid: 9 abs:0
 ok 4 clockid: 9 abs:1

Output with lack of permissions:
 1..4
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..4
 not ok 1 # SKIP Time namespaces are not supported

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       |   4 +-
 .../selftests/timens/clock_nanosleep.c        | 143 ++++++++++++++++++
 3 files changed, 146 insertions(+), 2 deletions(-)
 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..801e7ab2f8bf 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,5 +1,5 @@
-TEST_GEN_PROGS := timens timerfd
+TEST_GEN_PROGS := timens timerfd clock_nanosleep
 
-CFLAGS := -Wall -Werror
+CFLAGS := -Wall -Werror -pthread
 
 include ../lib.mk
diff --git a/tools/testing/selftests/timens/clock_nanosleep.c b/tools/testing/selftests/timens/clock_nanosleep.c
new file mode 100644
index 000000000000..0f4eab6e4669
--- /dev/null
+++ b/tools/testing/selftests/timens/clock_nanosleep.c
@@ -0,0 +1,143 @@
+// 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 <pthread.h>
+#include <signal.h>
+#include <string.h>
+
+#include "log.h"
+#include "timens.h"
+
+void test_sig(int sig) {
+	if (sig == SIGUSR2)
+		pthread_exit(NULL);
+}
+
+struct thread_args {
+	struct timespec *now, *rem;
+	pthread_mutex_t *lock;
+	int clockid;
+	int abs;
+};
+
+void *call_nanosleep(void *_args)
+{
+	struct thread_args *args = _args;
+	clock_nanosleep(args->clockid, args->abs ? TIMER_ABSTIME : 0, args->now, args->rem);
+	pthread_mutex_unlock(args->lock);
+	return NULL;
+}
+
+int run_test(int clockid, int abs)
+{
+	struct timespec now = {}, rem;
+	struct thread_args args = { .now = &now, .rem = &rem, .clockid = clockid};
+	struct timespec start;
+	pthread_mutex_t lock;
+	pthread_t thread;
+	int j, ok, ret;
+
+	signal(SIGUSR1, test_sig);
+	signal(SIGUSR2, test_sig);
+
+	pthread_mutex_init(&lock, NULL);
+	pthread_mutex_lock(&lock);
+
+	if (clock_gettime(clockid, &start) == -1)
+		return pr_perror("clock_gettime");
+
+
+	if (abs) {
+		now.tv_sec = start.tv_sec;
+		now.tv_nsec = start.tv_nsec;
+	}
+
+	now.tv_sec += 3600;
+	args.abs = abs;
+	args.lock = &lock;
+	ret = pthread_create(&thread, NULL, call_nanosleep, &args);
+	if (ret != 0) {
+		pr_err("Unable to create a thread: %s", strerror(ret));
+		return 1;
+	}
+
+	/* Wait when the thread will call clock_nanosleep(). */
+	ok = 0;
+	for (j = 0; j < 8; j++) {
+		/* The maximum timeout is about 5 seconds. */
+		usleep(10000 << j);
+
+		/* Try to interrupt clock_nanosleep(). */
+		pthread_kill(thread, SIGUSR1);
+
+		usleep(10000 << j);
+		/* Check whether clock_nanosleep() has been interrupted or not. */
+		if (pthread_mutex_trylock(&lock) == 0) {
+			/**/
+			ok = 1;
+			break;
+		}
+	}
+	if (!ok)
+		pthread_kill(thread, SIGUSR2);
+	pthread_join(thread, NULL);
+	pthread_mutex_destroy(&lock);
+
+	if (!ok) {
+		ksft_test_result_pass("clockid: %d abs:%d timeout\n", clockid, abs);
+		return 1;
+	}
+
+	if (rem.tv_sec < 3300 || rem.tv_sec > 3900) {
+		pr_fail("clockid: %d abs: %d remain: %ld\n",
+			clockid, abs, rem.tv_sec);
+		return 1;
+	}
+	ksft_test_result_pass("clockid: %d abs:%d\n", clockid, abs);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, nsfd;
+
+	nscheck();
+
+	ksft_set_plan(4);
+
+	if (unshare_timens())
+		return 1;
+
+	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, 0);
+	ret |= run_test(CLOCK_MONOTONIC, 1);
+	ret |= run_test(CLOCK_BOOTTIME_ALARM, 0);
+	ret |= run_test(CLOCK_BOOTTIME_ALARM, 1);
+
+	if (ret)
+		ksft_exit_fail();
+	ksft_exit_pass();
+	return ret;
+}
+
-- 
2.23.0

[PATCHv7 30/33] selftests/timens: Add procfs selftest

[Dmitry Safonov]

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

Output on success:
 1..1
 ok 1 Passed for /proc/uptime
 # Pass 1 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output with lack of permissions:
 1..1
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..1
 not ok 1 # SKIP Time namespaces are not supported

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 801e7ab2f8bf..e4913f2991d4 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 -pthread
 
diff --git a/tools/testing/selftests/timens/procfs.c b/tools/testing/selftests/timens/procfs.c
new file mode 100644
index 000000000000..43d93f4006b9
--- /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_timens())
+		return -1;
+
+	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;
+}
-- 
2.23.0

[PATCHv7 31/33] selftests/timens: Add timer offsets test

[Dmitry Safonov]

From: Andrei Vagin <avagin@openvz.org>

Check that timer_create() takes into account clock offsets.

Output on success:
 1..3
 ok 1 clockid=7
 ok 2 clockid=1
 ok 3 clockid=9
 # Pass 3 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output with lack of permissions:
 1..3
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..3
 not ok 1 # SKIP Time namespaces are not supported

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 e4913f2991d4..08164548a49d 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 -pthread
+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..5164cafd408d
--- /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_timens())
+		return 1;
+
+	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;
+}
+
-- 
2.23.0

[PATCHv7 32/33] selftests/timens: Add a simple perf test for clock_gettime()

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Output on success:
1..4
 ok 1 host:	clock:  monotonic	cycles:	 148323947
 ok 2 host:	clock:   boottime	cycles:	 148577503
 ok 3 ns:	clock:  monotonic	cycles:	 137659217
 ok 4 ns:	clock:   boottime	cycles:	 137959154
 # Pass 4 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output with lack of permissions:
 1..4
 ok 1 host:	clock:  monotonic	cycles:	 145671139
 ok 2 host:	clock:   boottime	cycles:	 146958357
 not ok 3 # SKIP need to run as root

Output without support of time namespaces:
 1..4
 ok 1 host:	clock:  monotonic	cycles:	 145671139
 ok 2 host:	clock:   boottime	cycles:	 146958357
 not ok 3 # SKIP Time namespaces are not supported

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       |  3 +-
 tools/testing/selftests/timens/gettime_perf.c | 91 +++++++++++++++++++
 3 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/gettime_perf.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 08164548a49d..6aefcaccb8f4 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,6 +1,7 @@
 TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs
+TEST_GEN_PROGS_EXTENDED := gettime_perf
 
 CFLAGS := -Wall -Werror -pthread
-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..3a6d9c485de5
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf.c
@@ -0,0 +1,91 @@
+// 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"
+
+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;
+
+	vdso_clock_gettime(clockid, &start);
+	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++) {
+		vdso_clock_gettime(clockid, &tp);
+	}
+
+	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_timens())
+		return 1;
+
+	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;
+}
-- 
2.23.0

[PATCHv7 33/33] selftests/timens: Check for right timens offsets after fork and exec

[Dmitry Safonov]

From: Andrei Vagin <avagin@gmail.com>

Output on success:
 1..1
 ok 1 exec
 # Pass 1 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output on failure:
 1..1
 not ok 1 36016 16
 Bail out!

Output with lack of permissions:
 1..1
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..1
 not ok 1 # SKIP Time namespaces are not supported

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     | 94 +++++++++++++++++++++++
 3 files changed, 96 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 6aefcaccb8f4..e9fb30bd8aeb 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
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec
 TEST_GEN_PROGS_EXTENDED := gettime_perf
 
 CFLAGS := -Wall -Werror -pthread
diff --git a/tools/testing/selftests/timens/exec.c b/tools/testing/selftests/timens/exec.c
new file mode 100644
index 000000000000..87b47b557a7a
--- /dev/null
+++ b/tools/testing/selftests/timens/exec.c
@@ -0,0 +1,94 @@
+// 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);
+		}
+		return 0;
+	}
+
+	nscheck();
+
+	ksft_set_plan(1);
+
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	if (unshare_timens())
+		return 1;
+
+	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 for proper vvar offsets 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;
+}
-- 
2.23.0

Re: [PATCHv7 06/33] alarmtimer: Provide get_timespec() callback

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1213 bytes --]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.4.0-13) 7.4.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   ld: kernel/time/alarmtimer.o: in function `alarmtimer_init':
>> alarmtimer.c:(.init.text+0x26): undefined reference to `posix_get_realtime_timespec'
>> ld: alarmtimer.c:(.init.text+0x44): undefined reference to `posix_get_boottime_timespec'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 7207 bytes --]

Re: [PATCHv7 15/33] posix-timers: Make clock_nanosleep() time namespace aware

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 4759 bytes --]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.4.0-13) 7.4.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/time/posix-stubs.c: In function '__do_sys_clock_nanosleep':
>> kernel/time/posix-stubs.c:153:31: error: 'clockid' undeclared (first use in this function); did you mean 'clock_t'?
      texp = timens_ktime_to_host(clockid, texp);
                                  ^~~~~~~
                                  clock_t
   kernel/time/posix-stubs.c:153:31: note: each undeclared identifier is reported only once for each function it appears in
   kernel/time/posix-stubs.c: In function '__do_sys_clock_nanosleep_time32':
>> kernel/time/posix-stubs.c:222:2: error: unknown type name 'ktime'; did you mean 'ktime_t'?
     ktime texp;
     ^~~~~
     ktime_t
   kernel/time/posix-stubs.c:243:31: error: 'clockid' undeclared (first use in this function); did you mean 'clock_t'?
      texp = timens_ktime_to_host(clockid, texp);
                                  ^~~~~~~
                                  clock_t

vim +153 kernel/time/posix-stubs.c

   126	
   127	SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
   128			const struct __kernel_timespec __user *, rqtp,
   129			struct __kernel_timespec __user *, rmtp)
   130	{
   131		struct timespec64 t;
   132		ktime_t texp;
   133	
   134		switch (which_clock) {
   135		case CLOCK_REALTIME:
   136		case CLOCK_MONOTONIC:
   137		case CLOCK_BOOTTIME:
   138			break;
   139		default:
   140			return -EINVAL;
   141		}
   142	
   143		if (get_timespec64(&t, rqtp))
   144			return -EFAULT;
   145		if (!timespec64_valid(&t))
   146			return -EINVAL;
   147		if (flags & TIMER_ABSTIME)
   148			rmtp = NULL;
   149		current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
   150		current->restart_block.nanosleep.rmtp = rmtp;
   151		texp = timespec64_to_ktime(t);
   152		if (flags & TIMER_ABSTIME)
 > 153			texp = timens_ktime_to_host(clockid, texp);
   154		return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
   155					 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
   156					 which_clock);
   157	}
   158	
   159	#ifdef CONFIG_COMPAT
   160	COMPAT_SYS_NI(timer_create);
   161	COMPAT_SYS_NI(getitimer);
   162	COMPAT_SYS_NI(setitimer);
   163	#endif
   164	
   165	#ifdef CONFIG_COMPAT_32BIT_TIME
   166	SYS_NI(timer_settime32);
   167	SYS_NI(timer_gettime32);
   168	
   169	SYSCALL_DEFINE2(clock_settime32, const clockid_t, which_clock,
   170			struct old_timespec32 __user *, tp)
   171	{
   172		struct timespec64 new_tp;
   173	
   174		if (which_clock != CLOCK_REALTIME)
   175			return -EINVAL;
   176		if (get_old_timespec32(&new_tp, tp))
   177			return -EFAULT;
   178	
   179		return do_sys_settimeofday64(&new_tp, NULL);
   180	}
   181	
   182	SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
   183			struct old_timespec32 __user *, tp)
   184	{
   185		int ret;
   186		struct timespec64 kernel_tp;
   187	
   188		ret = do_clock_gettime(which_clock, &kernel_tp);
   189		if (ret)
   190			return ret;
   191	
   192		if (put_old_timespec32(&kernel_tp, tp))
   193			return -EFAULT;
   194		return 0;
   195	}
   196	
   197	SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
   198			struct old_timespec32 __user *, tp)
   199	{
   200		struct timespec64 rtn_tp = {
   201			.tv_sec = 0,
   202			.tv_nsec = hrtimer_resolution,
   203		};
   204	
   205		switch (which_clock) {
   206		case CLOCK_REALTIME:
   207		case CLOCK_MONOTONIC:
   208		case CLOCK_BOOTTIME:
   209			if (put_old_timespec32(&rtn_tp, tp))
   210				return -EFAULT;
   211			return 0;
   212		default:
   213			return -EINVAL;
   214		}
   215	}
   216	
   217	SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
   218			struct old_timespec32 __user *, rqtp,
   219			struct old_timespec32 __user *, rmtp)
   220	{
   221		struct timespec64 t;
 > 222		ktime texp;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCHv7 22/33] time: Allocate per-timens vvar page

[kbuild test robot]

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Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191010]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: parisc-b180_defconfig (attached as .config)
compiler: hppa-linux-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=parisc 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/time/namespace.o: In function `timens_set_vvar_page.isra.8.part.9':
>> (.text+0x130): undefined reference to `arch_get_vdso_data'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
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Re: [PATCHv7 22/33] time: Allocate per-timens vvar page

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1255 bytes --]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: riscv-defconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/time/namespace.o: In function `.L0 ':
>> namespace.c:(.text+0xfc): undefined reference to `arch_get_vdso_data'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCHv7 25/33] x86/vdso: Zap vvar pages on switch a time namspace

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1514 bytes --]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191010]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: parisc-b180_defconfig (attached as .config)
compiler: hppa-linux-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=parisc 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/time/namespace.o: In function `timens_set_vvar_page.isra.8.part.9':
   (.text+0x130): undefined reference to `arch_get_vdso_data'
   kernel/time/namespace.o: In function `timens_install':
>> (.text+0x6e0): undefined reference to `vdso_join_timens'
   kernel/time/namespace.o: In function `timens_on_fork':
   (.text+0x804): undefined reference to `vdso_join_timens'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
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Re: [PATCHv7 25/33] x86/vdso: Zap vvar pages on switch a time namspace

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1457 bytes --]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: riscv-defconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/time/namespace.o: In function `.L0 ':
   namespace.c:(.text+0xfc): undefined reference to `arch_get_vdso_data'
   kernel/time/namespace.o: In function `timens_install':
>> namespace.c:(.text+0x41c): undefined reference to `vdso_join_timens'
   namespace.c:(.text+0x4ce): undefined reference to `vdso_join_timens'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 18632 bytes --]

Re: [PATCHv7 15/33] posix-timers: Make clock_nanosleep() time namespace aware

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 4611 bytes --]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: x86_64-randconfig-s1-201941 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.2-10+deb8u1) 4.9.2
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel//time/posix-stubs.c: In function '__do_sys_clock_nanosleep':
>> kernel//time/posix-stubs.c:153:31: error: 'clockid' undeclared (first use in this function)
      texp = timens_ktime_to_host(clockid, texp);
                                  ^
   kernel//time/posix-stubs.c:153:31: note: each undeclared identifier is reported only once for each function it appears in
   kernel//time/posix-stubs.c: In function '__do_sys_clock_nanosleep_time32':
>> kernel//time/posix-stubs.c:222:2: error: unknown type name 'ktime'
     ktime texp;
     ^
   kernel//time/posix-stubs.c:243:31: error: 'clockid' undeclared (first use in this function)
      texp = timens_ktime_to_host(clockid, texp);
                                  ^

vim +/clockid +153 kernel//time/posix-stubs.c

   126	
   127	SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
   128			const struct __kernel_timespec __user *, rqtp,
   129			struct __kernel_timespec __user *, rmtp)
   130	{
   131		struct timespec64 t;
   132		ktime_t texp;
   133	
   134		switch (which_clock) {
   135		case CLOCK_REALTIME:
   136		case CLOCK_MONOTONIC:
   137		case CLOCK_BOOTTIME:
   138			break;
   139		default:
   140			return -EINVAL;
   141		}
   142	
   143		if (get_timespec64(&t, rqtp))
   144			return -EFAULT;
   145		if (!timespec64_valid(&t))
   146			return -EINVAL;
   147		if (flags & TIMER_ABSTIME)
   148			rmtp = NULL;
   149		current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
   150		current->restart_block.nanosleep.rmtp = rmtp;
   151		texp = timespec64_to_ktime(t);
   152		if (flags & TIMER_ABSTIME)
 > 153			texp = timens_ktime_to_host(clockid, texp);
   154		return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
   155					 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
   156					 which_clock);
   157	}
   158	
   159	#ifdef CONFIG_COMPAT
   160	COMPAT_SYS_NI(timer_create);
   161	COMPAT_SYS_NI(getitimer);
   162	COMPAT_SYS_NI(setitimer);
   163	#endif
   164	
   165	#ifdef CONFIG_COMPAT_32BIT_TIME
   166	SYS_NI(timer_settime32);
   167	SYS_NI(timer_gettime32);
   168	
   169	SYSCALL_DEFINE2(clock_settime32, const clockid_t, which_clock,
   170			struct old_timespec32 __user *, tp)
   171	{
   172		struct timespec64 new_tp;
   173	
   174		if (which_clock != CLOCK_REALTIME)
   175			return -EINVAL;
   176		if (get_old_timespec32(&new_tp, tp))
   177			return -EFAULT;
   178	
   179		return do_sys_settimeofday64(&new_tp, NULL);
   180	}
   181	
   182	SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
   183			struct old_timespec32 __user *, tp)
   184	{
   185		int ret;
   186		struct timespec64 kernel_tp;
   187	
   188		ret = do_clock_gettime(which_clock, &kernel_tp);
   189		if (ret)
   190			return ret;
   191	
   192		if (put_old_timespec32(&kernel_tp, tp))
   193			return -EFAULT;
   194		return 0;
   195	}
   196	
   197	SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
   198			struct old_timespec32 __user *, tp)
   199	{
   200		struct timespec64 rtn_tp = {
   201			.tv_sec = 0,
   202			.tv_nsec = hrtimer_resolution,
   203		};
   204	
   205		switch (which_clock) {
   206		case CLOCK_REALTIME:
   207		case CLOCK_MONOTONIC:
   208		case CLOCK_BOOTTIME:
   209			if (put_old_timespec32(&rtn_tp, tp))
   210				return -EFAULT;
   211			return 0;
   212		default:
   213			return -EINVAL;
   214		}
   215	}
   216	
   217	SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
   218			struct old_timespec32 __user *, rqtp,
   219			struct old_timespec32 __user *, rmtp)
   220	{
   221		struct timespec64 t;
 > 222		ktime texp;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 30786 bytes --]

Re: [PATCHv7 15/33] posix-timers: Make clock_nanosleep() time namespace aware

[Andrey Vagin]

On Sun, Oct 13, 2019 at 9:28 PM kbuild test robot <lkp@intel.com> wrote:
>
> Hi Dmitry,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on linus/master]
> [cannot apply to v5.4-rc2 next-20191011]
> [if your patch is applied to the wrong git tree, please drop us a note to help
> improve the system. BTW, we also suggest to use '--base' option to specify the
> base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
>
> url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
> config: x86_64-randconfig-s1-201941 (attached as .config)
> compiler: gcc-4.9 (Debian 4.9.2-10+deb8u1) 4.9.2
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=x86_64
>
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>):
>
>    kernel//time/posix-stubs.c: In function '__do_sys_clock_nanosleep':
> >> kernel//time/posix-stubs.c:153:31: error: 'clockid' undeclared (first use in this function)
>       texp = timens_ktime_to_host(clockid, texp);

This is my fault. I forgot to compile it without CONFIG_POSIX_TIMERS.
Will fix this shortly. Sorry for inconvenience.

>                                   ^
>    kernel//time/posix-stubs.c:153:31: note: each undeclared identifier is reported only once for each function it appears in
>    kernel//time/posix-stubs.c: In function '__do_sys_clock_nanosleep_time32':
> >> kernel//time/posix-stubs.c:222:2: error: unknown type name 'ktime'
>      ktime texp;
>      ^
>    kernel//time/posix-stubs.c:243:31: error: 'clockid' undeclared (first use in this function)
>       texp = timens_ktime_to_host(clockid, texp);
>                                   ^
>
> vim +/clockid +153 kernel//time/posix-stubs.c
>
>    126
>    127  SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
>    128                  const struct __kernel_timespec __user *, rqtp,
>    129                  struct __kernel_timespec __user *, rmtp)
>    130  {
>    131          struct timespec64 t;
>    132          ktime_t texp;
>    133
>    134          switch (which_clock) {
>    135          case CLOCK_REALTIME:
>    136          case CLOCK_MONOTONIC:
>    137          case CLOCK_BOOTTIME:
>    138                  break;
>    139          default:
>    140                  return -EINVAL;
>    141          }
>    142
>    143          if (get_timespec64(&t, rqtp))
>    144                  return -EFAULT;
>    145          if (!timespec64_valid(&t))
>    146                  return -EINVAL;
>    147          if (flags & TIMER_ABSTIME)
>    148                  rmtp = NULL;
>    149          current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
>    150          current->restart_block.nanosleep.rmtp = rmtp;
>    151          texp = timespec64_to_ktime(t);
>    152          if (flags & TIMER_ABSTIME)
>  > 153                  texp = timens_ktime_to_host(clockid, texp);
>    154          return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
>    155                                   HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
>    156                                   which_clock);
>    157  }
>    158
>    159  #ifdef CONFIG_COMPAT
>    160  COMPAT_SYS_NI(timer_create);
>    161  COMPAT_SYS_NI(getitimer);
>    162  COMPAT_SYS_NI(setitimer);
>    163  #endif
>    164
>    165  #ifdef CONFIG_COMPAT_32BIT_TIME
>    166  SYS_NI(timer_settime32);
>    167  SYS_NI(timer_gettime32);
>    168
>    169  SYSCALL_DEFINE2(clock_settime32, const clockid_t, which_clock,
>    170                  struct old_timespec32 __user *, tp)
>    171  {
>    172          struct timespec64 new_tp;
>    173
>    174          if (which_clock != CLOCK_REALTIME)
>    175                  return -EINVAL;
>    176          if (get_old_timespec32(&new_tp, tp))
>    177                  return -EFAULT;
>    178
>    179          return do_sys_settimeofday64(&new_tp, NULL);
>    180  }
>    181
>    182  SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
>    183                  struct old_timespec32 __user *, tp)
>    184  {
>    185          int ret;
>    186          struct timespec64 kernel_tp;
>    187
>    188          ret = do_clock_gettime(which_clock, &kernel_tp);
>    189          if (ret)
>    190                  return ret;
>    191
>    192          if (put_old_timespec32(&kernel_tp, tp))
>    193                  return -EFAULT;
>    194          return 0;
>    195  }
>    196
>    197  SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
>    198                  struct old_timespec32 __user *, tp)
>    199  {
>    200          struct timespec64 rtn_tp = {
>    201                  .tv_sec = 0,
>    202                  .tv_nsec = hrtimer_resolution,
>    203          };
>    204
>    205          switch (which_clock) {
>    206          case CLOCK_REALTIME:
>    207          case CLOCK_MONOTONIC:
>    208          case CLOCK_BOOTTIME:
>    209                  if (put_old_timespec32(&rtn_tp, tp))
>    210                          return -EFAULT;
>    211                  return 0;
>    212          default:
>    213                  return -EINVAL;
>    214          }
>    215  }
>    216
>    217  SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
>    218                  struct old_timespec32 __user *, rqtp,
>    219                  struct old_timespec32 __user *, rmtp)
>    220  {
>    221          struct timespec64 t;
>  > 222          ktime texp;
>
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Vincenzo Frascino]

Hi Andrei and Dmitry,

On 10/11/19 2:23 AM, Dmitry Safonov wrote:
> 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@gmail.com>
> 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 |  66 ++++++++++
>  include/linux/user_namespace.h |   1 +
>  include/uapi/linux/sched.h     |   6 +
>  init/Kconfig                   |   7 ++
>  kernel/fork.c                  |  16 ++-
>  kernel/nsproxy.c               |  41 +++++--
>  kernel/time/Makefile           |   1 +
>  kernel/time/namespace.c        | 217 +++++++++++++++++++++++++++++++++
>  12 files changed, 356 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 d44d6732510d..cabe7bddbf69 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13009,6 +13009,8 @@ 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..873b908c9ba8
> --- /dev/null
> +++ b/include/linux/time_namespace.h
> @@ -0,0 +1,66 @@
> +/* 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;
> +} __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 99335e1f4a27..5b7511ac2005 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 */
> +
>  #ifndef __ASSEMBLY__
>  /**
>   * struct clone_args - arguments for the clone3 syscall
> diff --git a/init/Kconfig b/init/Kconfig
> index b4daad2bac23..bc2ee93408ad 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1096,6 +1096,13 @@ config UTS_NS
>  	  In this namespace tasks see different info provided with the
>  	  uname() system call
>  
> +config TIME_NS
> +	bool "TIME namespace"
> +	default y

Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
the architectures that have no support for time namespaces.
The direct consequence is that the fallbacks defined in this patch are never
selected and this ends up in kernel compilation errors due to missing symbols.

The error below shows what happens on arm64 (similar behavior on other
architectures):

aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'

aarch64-linux-gnu-ld: kernel/time/namespace.o: in function
`timens_set_vvar_page': kernel/time/namespace.c:218: undefined reference to
`arch_get_vdso_
data'

aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_install':
/data1/Projects/LinuxKernel/linux/kernel/time/namespace.c:295: undefined
reference to `vdso_join_time
ns'
/data1/Projects/LinuxKernel/linux/Makefile:1074: recipe for target 'vmlinux'
failed
make[1]: *** [vmlinux] Error 1
make[1]: Leaving directory '/data1/Projects/LinuxKernel/linux-out'
                    Makefile:179: recipe for target 'sub-make' failed
make: *** [sub-make] Error 2

My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
architectures that enable time namespaces select it and make CONFIG_TIME_NS
select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.

What do you think?

Thanks,
Vincenzo

> +	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/fork.c b/kernel/fork.c
> index bcdf53125210..aa65333dbc45 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1772,6 +1772,7 @@ 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
> @@ -1814,8 +1815,16 @@ 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);
>  	}
>  
> @@ -2703,7 +2712,8 @@ 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/Makefile b/kernel/time/Makefile
> index 1867044800bb..c8f00168afe8 100644
> --- a/kernel/time/Makefile
> +++ b/kernel/time/Makefile
> @@ -19,3 +19,4 @@ obj-$(CONFIG_TICK_ONESHOT)			+= tick-oneshot.o tick-sched.o
>  obj-$(CONFIG_HAVE_GENERIC_VDSO)			+= vsyscall.o
>  obj-$(CONFIG_DEBUG_FS)				+= timekeeping_debug.o
>  obj-$(CONFIG_TEST_UDELAY)			+= test_udelay.o
> +obj-$(CONFIG_TIME_NS)				+= namespace.o
> diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
> new file mode 100644
> index 000000000000..2662a69e0382
> --- /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);
> +}
> +
> +/**
> + * clone_time_ns - Clone a time namespace
> + * @user_ns:	User namespace which owns a new namespace.
> + * @old_ns:	Namespace to clone
> + *
> + * Clone @old_ns and set the clone refcount to 1
> + *
> + * Return: The new namespace 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 = kmalloc(sizeof(*ns), GFP_KERNEL);
> +	if (!ns)
> +		goto fail_dec;
> +
> +	kref_init(&ns->kref);
> +
> +	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);
> +}
> +
> +/**
> + * copy_time_ns - Create timens_for_children from @old_ns
> + * @flags:	Cloning flags
> + * @user_ns:	User namespace which owns a new namespace.
> + * @old_ns:	Namespace to clone
> + *
> + * If CLONE_NEWTIME specified in @flags, creates a new timens_for_children;
> + * adds a refcounter to @old_ns otherwise.
> + *
> + * Return: timens_for_children namespace or ERR_PTR.
> + */
> +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);
> +	put_time_ns(nsproxy->time_ns);
> +	nsproxy->time_ns = ns;
> +
> +	get_time_ns(ns);
> +	put_time_ns(nsproxy->time_ns_for_children);
> +	nsproxy->time_ns_for_children = ns;
> +	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);
> +
> +	/* create_new_namespaces() already incremented the ref counter */
> +	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;
> +
> +	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);
> 

-- 
Regards,
Vincenzo

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Thomas Gleixner]

On Wed, 16 Oct 2019, Vincenzo Frascino wrote:

< Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons >

> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -1096,6 +1096,13 @@ config UTS_NS
> >  	  In this namespace tasks see different info provided with the
> >  	  uname() system call
> >  
> > +config TIME_NS
> > +	bool "TIME namespace"
> > +	default y
> 
> Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
> the architectures that have no support for time namespaces.
> The direct consequence is that the fallbacks defined in this patch are never
> selected and this ends up in kernel compilation errors due to missing symbols.
> 
> The error below shows what happens on arm64 (similar behavior on other
> architectures):
> 
> aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
> kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'
> 
> My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
> architectures that enable time namespaces select it and make CONFIG_TIME_NS
> select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.

Nah.

config TIME_NS
	bool "TIME namespace"
	depends on GENERIC_VDSO_TIME_NS
	default y

and in lib/vdso/Kconfig

config GENERIC_VDSO_TIME_NS
	bool

and let architectures which have support for the VDSO bits select it.

< Trim another gazillion of useless lines >

See: https://people.kernel.org/tglx/notes-about-netiquette

Thanks,

	tglx

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Vincenzo Frascino]

On 10/16/19 11:39 AM, Thomas Gleixner wrote:
> On Wed, 16 Oct 2019, Vincenzo Frascino wrote:
> 
> < Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons >
> 
>>> --- a/init/Kconfig
>>> +++ b/init/Kconfig
>>> @@ -1096,6 +1096,13 @@ config UTS_NS
>>>  	  In this namespace tasks see different info provided with the
>>>  	  uname() system call
>>>  
>>> +config TIME_NS
>>> +	bool "TIME namespace"
>>> +	default y
>>
>> Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
>> the architectures that have no support for time namespaces.
>> The direct consequence is that the fallbacks defined in this patch are never
>> selected and this ends up in kernel compilation errors due to missing symbols.
>>
>> The error below shows what happens on arm64 (similar behavior on other
>> architectures):
>>
>> aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
>> kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'
>>
>> My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
>> architectures that enable time namespaces select it and make CONFIG_TIME_NS
>> select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.
> 
> Nah.
> 
> config TIME_NS
> 	bool "TIME namespace"
> 	depends on GENERIC_VDSO_TIME_NS
> 	default y
> 
> and in lib/vdso/Kconfig
> 
> config GENERIC_VDSO_TIME_NS
> 	bool
> 
> and let architectures which have support for the VDSO bits select it.
>

Agreed, this is even better.

> < Trim another gazillion of useless lines >
> 
> See: https://people.kernel.org/tglx/notes-about-netiquette
> 
> Thanks,
> 
> 	tglx
> 

-- 
Regards,
Vincenzo

Re: [PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()

[Vincenzo Frascino]

On 10/11/19 2:23 AM, Dmitry Safonov wrote:
> From: Andrei Vagin <avagin@gmail.com>
> 
> Place the branch with no concurrent write before contended case.
> 
> Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
> (more clock_gettime() cycles - the better):
>         | before    | after
> -----------------------------------
>         | 150252214 | 153242367
>         | 150301112 | 153324800
>         | 150392773 | 153125401
>         | 150373957 | 153399355
>         | 150303157 | 153489417
>         | 150365237 | 153494270
> -----------------------------------
> avg     | 150331408 | 153345935
> diff %  | 2	    | 0
> -----------------------------------
> stdev % | 0.3	    | 0.1
> 
> Signed-off-by: Andrei Vagin <avagin@gmail.com>
> Co-developed-by: Dmitry Safonov <dima@arista.com>
> Signed-off-by: Dmitry Safonov <dima@arista.com>

Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

> ---
>  include/vdso/helpers.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
> index 01641dbb68ef..9a2af9fca45e 100644
> --- a/include/vdso/helpers.h
> +++ b/include/vdso/helpers.h
> @@ -10,7 +10,7 @@ static __always_inline u32 vdso_read_begin(const struct vdso_data *vd)
>  {
>  	u32 seq;
>  
> -	while ((seq = READ_ONCE(vd->seq)) & 1)
> +	while (unlikely((seq = READ_ONCE(vd->seq)) & 1))
>  		cpu_relax();
>  
>  	smp_rmb();
> 

-- 
Regards,
Vincenzo

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Dmitry Safonov]

On 10/16/19 11:44 AM, Vincenzo Frascino wrote:
> On 10/16/19 11:39 AM, Thomas Gleixner wrote:
[..]
>> config TIME_NS
>> 	bool "TIME namespace"
>> 	depends on GENERIC_VDSO_TIME_NS
>> 	default y
>>
>> and in lib/vdso/Kconfig
>>
>> config GENERIC_VDSO_TIME_NS
>> 	bool
>>
>> and let architectures which have support for the VDSO bits select it.
>>
> 
> Agreed, this is even better.

Thanks, will fix in v8,
          Dmitry

Re: [PATCHv7 19/33] lib/vdso: Prepare for time namespace support

[Vincenzo Frascino]

Hi Dmitry,

On 10/11/19 2:23 AM, Dmitry Safonov wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> To support time namespaces in the vdso with a minimal impact on regular non
> time namespace affected tasks, the namespace handling needs to be hidden in
> a slow path.
> 
> The most obvious place is vdso_seq_begin(). If a task belongs to a time
> namespace then the VVAR page which contains the system wide vdso data is
> replaced with a namespace specific page which has the same layout as the
> VVAR page. That page has vdso_data->seq set to 1 to enforce the slow path
> and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time
> namespace handling path.
> 
> The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
> update of the vdso data is in progress, is not really affecting regular
> tasks which are not part of a time namespace as the task is spin waiting
> for the update to finish and vdso_data->seq to become even again.
> 
> If a time namespace task hits that code path, it invokes the corresponding
> time getter function which retrieves the real VVAR page, reads host time
> and then adds the offset for the requested clock which is stored in the
> special VVAR page.
> 
> If VDSO time namespace support is disabled the whole magic is compiled out.
> 
> Initial testing shows that the disabled case is almost identical to the
> host case which does not take the slow timens path. With the special timens
> page installed the performance hit is constant time and in the range of
> 5-7%.
> 
> For the vdso functions which are not using the sequence count an
> unconditional check for vdso_data->clock_mode is added which switches to
> the real vdso when the clock_mode is VCLOCK_TIMENS.
> 
> Suggested-by: Andy Lutomirski <luto@kernel.org>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Andrei Vagin <avagin@gmail.com>
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> ---
>  include/linux/time.h    |   6 ++
>  include/vdso/datapage.h |  19 +++++-
>  lib/vdso/Kconfig        |   6 ++
>  lib/vdso/gettimeofday.c | 128 +++++++++++++++++++++++++++++++++++++++-
>  4 files changed, 155 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/time.h b/include/linux/time.h
> index 27d83fd2ae61..b1a592638d7d 100644
> --- a/include/linux/time.h
> +++ b/include/linux/time.h
> @@ -96,4 +96,10 @@ static inline bool itimerspec64_valid(const struct itimerspec64 *its)
>   */
>  #define time_after32(a, b)	((s32)((u32)(b) - (u32)(a)) < 0)
>  #define time_before32(b, a)	time_after32(a, b)
> +
> +struct timens_offset {
> +	s64	sec;
> +	u64	nsec;
> +};
> +
>  #endif
> diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
> index 2e302c0f41f7..65a38acce27e 100644
> --- a/include/vdso/datapage.h
> +++ b/include/vdso/datapage.h
> @@ -21,6 +21,8 @@
>  #define CS_RAW		1
>  #define CS_BASES	(CS_RAW + 1)
>  
> +#define VCLOCK_TIMENS	UINT_MAX
> +
>  /**
>   * struct vdso_timestamp - basetime per clock_id
>   * @sec:	seconds
> @@ -48,6 +50,7 @@ struct vdso_timestamp {
>   * @mult:		clocksource multiplier
>   * @shift:		clocksource shift
>   * @basetime[clock_id]:	basetime per clock_id
> + * @offset[clock_id]:	time namespace offset per clock_id
>   * @tz_minuteswest:	minutes west of Greenwich
>   * @tz_dsttime:		type of DST correction
>   * @hrtimer_res:	hrtimer resolution
> @@ -55,6 +58,17 @@ struct vdso_timestamp {
>   *
>   * vdso_data will be accessed by 64 bit and compat code at the same time
>   * so we should be careful before modifying this structure.
> + *
> + * @basetime is used to store the base time for the system wide time getter
> + * VVAR page.
> + *
> + * @offset is used by the special time namespace VVAR pages which are
> + * installed instead of the real VVAR page. These namespace pages must set
> + * @seq to 1 and @clock_mode to VLOCK_TIMENS to force the code into the
> + * time namespace slow path. The namespace aware functions retrieve the
> + * real system wide VVAR page, read host time and add the per clock offset.
> + * For clocks which are not affected by time namespace adjustement the
> + * offset must be zero.
>   */
>  struct vdso_data {
>  	u32			seq;
> @@ -65,7 +79,10 @@ struct vdso_data {
>  	u32			mult;
>  	u32			shift;
>  
> -	struct vdso_timestamp	basetime[VDSO_BASES];
> +	union {
> +		struct vdso_timestamp	basetime[VDSO_BASES];
> +		struct timens_offset	offset[VDSO_BASES];
> +	};
>  
>  	s32			tz_minuteswest;
>  	s32			tz_dsttime;
> diff --git a/lib/vdso/Kconfig b/lib/vdso/Kconfig
> index 9fe698ff62ec..85276de70dba 100644
> --- a/lib/vdso/Kconfig
> +++ b/lib/vdso/Kconfig
> @@ -24,4 +24,10 @@ config GENERIC_COMPAT_VDSO
>  	help
>  	  This config option enables the compat VDSO layer.
>  
> +config VDSO_TIMENS

To uniform the naming with the rest of the file and with CONFIG_TIME_NS, can we
please change the name of this config option in GENERIC_VDSO_TIME_NS? And then
follow the logic explained by Thomas in patch 1 of this series.

Thanks,
Vincenzo

> +	bool
> +	help
> +	  Selected by architectures which support time namespaces in the
> +	  VDSO
> +
>  endif
> diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
> index e630e7ff57f1..25244b677823 100644
> --- a/lib/vdso/gettimeofday.c
> +++ b/lib/vdso/gettimeofday.c
> @@ -38,6 +38,51 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
>  }
>  #endif
>  
> +#ifndef CONFIG_VDSO_TIMENS
> +static __always_inline
> +const struct vdso_data *__arch_get_timens_vdso_data(void)
> +{
> +	return NULL;
> +}
> +#endif
> +
> +static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
> +		      struct __kernel_timespec *ts)
> +{
> +	const struct vdso_data *vd = __arch_get_timens_vdso_data();
> +	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
> +	const struct timens_offset *offs = &vdns->offset[clk];
> +	u64 cycles, last, ns;
> +	s64 sec;
> +	u32 seq;
> +
> +	do {
> +		seq = vdso_read_begin(vd);
> +		cycles = __arch_get_hw_counter(vd->clock_mode);
> +		ns = vdso_ts->nsec;
> +		last = vd->cycle_last;
> +		if (unlikely((s64)cycles < 0))
> +			return -1;
> +
> +		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
> +		ns >>= vd->shift;
> +		sec = vdso_ts->sec;
> +	} while (unlikely(vdso_read_retry(vd, seq)));
> +
> +	/* Add the namespace offset */
> +	sec += offs->sec;
> +	ns += offs->nsec;
> +
> +	/*
> +	 * Do this outside the loop: a race inside the loop could result
> +	 * in __iter_div_u64_rem() being extremely slow.
> +	 */
> +	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
> +	ts->tv_nsec = ns;
> +
> +	return 0;
> +}
> +
>  static int do_hres(const struct vdso_data *vd, clockid_t clk,
>  		   struct __kernel_timespec *ts)
>  {
> @@ -46,7 +91,28 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
>  	u32 seq;
>  
>  	do {
> -		seq = vdso_read_begin(vd);
> +		/*
> +		 * Open coded to handle VCLOCK_TIMENS. Time namespace
> +		 * enabled tasks have a special VVAR page installed which
> +		 * has vd->seq set to 1 and vd->clock_mode set to
> +		 * VCLOCK_TIMENS. For non time namespace affected tasks
> +		 * this does not affect performance because if vd->seq is
> +		 * odd, i.e. a concurrent update is in progress the extra
> +		 * check for vd->clock_mode is just a few extra
> +		 * instructions while spin waiting for vd->seq to become
> +		 * even again.
> +		 */
> +		while (1) {
> +			seq = READ_ONCE(vd->seq);
> +			if (likely(!(seq & 1)))
> +				break;
> +			if (IS_ENABLED(CONFIG_VDSO_TIMENS) &&
> +			    vd->clock_mode == VCLOCK_TIMENS)
> +				return do_hres_timens(vd, clk, ts);
> +			cpu_relax();
> +		}
> +		smp_rmb();
> +
>  		cycles = __arch_get_hw_counter(vd->clock_mode);
>  		ns = vdso_ts->nsec;
>  		last = vd->cycle_last;
> @@ -68,6 +134,34 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
>  	return 0;
>  }
>  
> +static void do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
> +			 struct __kernel_timespec *ts)
> +{
> +	const struct vdso_data *vd = __arch_get_timens_vdso_data();
> +	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
> +	const struct timens_offset *offs = &vdns->offset[clk];
> +	u64 nsec;
> +	s64 sec;
> +	s32 seq;
> +
> +	do {
> +		seq = vdso_read_begin(vd);
> +		sec = vdso_ts->sec;
> +		nsec = vdso_ts->nsec;
> +	} while (unlikely(vdso_read_retry(vd, seq)));
> +
> +	/* Add the namespace offset */
> +	sec += offs->sec;
> +	nsec += offs->nsec;
> +
> +	/*
> +	 * Do this outside the loop: a race inside the loop could result
> +	 * in __iter_div_u64_rem() being extremely slow.
> +	 */
> +	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
> +	ts->tv_nsec = nsec;
> +}
> +
>  static void do_coarse(const struct vdso_data *vd, clockid_t clk,
>  		      struct __kernel_timespec *ts)
>  {
> @@ -75,7 +169,23 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
>  	u32 seq;
>  
>  	do {
> -		seq = vdso_read_begin(vd);
> +		/*
> +		 * Open coded to handle VCLOCK_TIMENS. See comment in
> +		 * do_hres().
> +		 */
> +		while (1) {
> +			seq = READ_ONCE(vd->seq);
> +			if (likely(!(seq & 1)))
> +				break;
> +			if (IS_ENABLED(CONFIG_VDSO_TIMENS) &&
> +			    vd->clock_mode == VCLOCK_TIMENS) {
> +				do_coarse_timens(vd, clk, ts);
> +				return;
> +			}
> +			cpu_relax();
> +		}
> +		smp_rmb();
> +
>  		ts->tv_sec = vdso_ts->sec;
>  		ts->tv_nsec = vdso_ts->nsec;
>  	} while (unlikely(vdso_read_retry(vd, seq)));
> @@ -156,6 +266,10 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
>  	}
>  
>  	if (unlikely(tz != NULL)) {
> +		if (IS_ENABLED(CONFIG_VDSO_TIMENS) &&
> +		    vd->clock_mode == VCLOCK_TIMENS)
> +			vd = __arch_get_timens_vdso_data();
> +
>  		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
>  		tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
>  	}
> @@ -167,7 +281,12 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
>  static __maybe_unused time_t __cvdso_time(time_t *time)
>  {
>  	const struct vdso_data *vd = __arch_get_vdso_data();
> -	time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
> +	time_t t;
> +
> +	if (IS_ENABLED(CONFIG_VDSO_TIMENS) && vd->clock_mode == VCLOCK_TIMENS)
> +		vd = __arch_get_timens_vdso_data();
> +
> +	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
>  
>  	if (time)
>  		*time = t;
> @@ -189,6 +308,9 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
>  	if (unlikely((u32) clock >= MAX_CLOCKS))
>  		return -1;
>  
> +	if (IS_ENABLED(CONFIG_VDSO_TIMENS) && vd->clock_mode == VCLOCK_TIMENS)
> +		vd = __arch_get_timens_vdso_data();
> +
>  	hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
>  	/*
>  	 * Convert the clockid to a bitmask and use it to check which
> 

-- 
Regards,
Vincenzo

Re: [PATCHv7 19/33] lib/vdso: Prepare for time namespace support

[Thomas Gleixner]

On Wed, 16 Oct 2019, Vincenzo Frascino wrote:

< SNIP >

> > --- a/lib/vdso/Kconfig
> > +++ b/lib/vdso/Kconfig
> > @@ -24,4 +24,10 @@ config GENERIC_COMPAT_VDSO
> >  	help
> >  	  This config option enables the compat VDSO layer.
> >  
> > +config VDSO_TIMENS
> 
> To uniform the naming with the rest of the file and with CONFIG_TIME_NS, can we
> please change the name of this config option in GENERIC_VDSO_TIME_NS? And then
> follow the logic explained by Thomas in patch 1 of this series.

Can you pretty please finally start to trim your replies?

If you didn't read the link I sent you earlier, then here is the relevant
paragraph:

  It's an annoyance to have to scroll down through several pages of quoted
  text to find a single line of reply or to figure out that after that
  reply the rest of the e-mail is just useless ballast.

I know that corporate mail style does not care about that, but I pretty
much care.

Thanks,

	tglx

Re: [PATCHv7 19/33] lib/vdso: Prepare for time namespace support

[Vincenzo Frascino]

Hi Thomas,

On 10/16/19 4:07 PM, Thomas Gleixner wrote:
[...]

> Can you pretty please finally start to trim your replies?

I really apologize. I can't explain to myself how did I miss the information. It
will not happen again.

-- 
Regards,
Vincenzo

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Andrei Vagin]

On Wed, Oct 16, 2019 at 12:39:11PM +0200, Thomas Gleixner wrote:
> On Wed, 16 Oct 2019, Vincenzo Frascino wrote:
> 
> < Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons >
> 
> > > --- a/init/Kconfig
> > > +++ b/init/Kconfig
> > > @@ -1096,6 +1096,13 @@ config UTS_NS
> > >  	  In this namespace tasks see different info provided with the
> > >  	  uname() system call
> > >  
> > > +config TIME_NS
> > > +	bool "TIME namespace"
> > > +	default y
> > 
> > Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
> > the architectures that have no support for time namespaces.
> > The direct consequence is that the fallbacks defined in this patch are never
> > selected and this ends up in kernel compilation errors due to missing symbols.
> > 
> > The error below shows what happens on arm64 (similar behavior on other
> > architectures):
> > 
> > aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
> > kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'
> > 
> > My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
> > architectures that enable time namespaces select it and make CONFIG_TIME_NS
> > select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.
> 
> Nah.
> 
> config TIME_NS
> 	bool "TIME namespace"
> 	depends on GENERIC_VDSO_TIME_NS

I was thinking to fix this by the same way with a small difference.

If GENERIC_GETTIMEOFDAY isn't set, it should be safe to allow enabling
TIME_NS. In this case, clock_gettime works via system call and we don't
have arch-specific code in this case. Does this sound reasonable?

        depends on (!GENERIC_GETTIMEOFDAY || GENERIC_VDSO_TIME_NS)

Thanks,
Andrei

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Thomas Gleixner]

Andrei!

On Wed, 16 Oct 2019, Andrei Vagin wrote:
> On Wed, Oct 16, 2019 at 12:39:11PM +0200, Thomas Gleixner wrote:
> > Nah.
> > 
> > config TIME_NS
> > 	bool "TIME namespace"
> > 	depends on GENERIC_VDSO_TIME_NS
> 
> I was thinking to fix this by the same way with a small difference.
> 
> If GENERIC_GETTIMEOFDAY isn't set, it should be safe to allow enabling
> TIME_NS. In this case, clock_gettime works via system call and we don't
> have arch-specific code in this case. Does this sound reasonable?
> 
>         depends on (!GENERIC_GETTIMEOFDAY || GENERIC_VDSO_TIME_NS)

No, that's wrong. If GENERIC_GETTIMEOFDAY is not set, then the architecture
still might have its own VDSO implementation and we agreed in Vancouver a
year ago that we are not going to support per architecture time namespace
VDSO implementations.

So if at all then you want:

   depends on HAVE_GENERIC_VDSO && (!GENERIC_GETTIMEOFDAY || GENERIC_VDSO_TIME_NS)

But that's crap, really.

The reason why HAVE_GENERIC_VDSO and GENERIC_GETTIMEOFDAY exist as separate
config items is not a functional issue. It's there to ease the migration to
the generic VDSO implementation. Having generic VDSO in production without
implementing GENERIC_GETTIMEOFDAY does not make any sense at all.

The architectures which implement VDSO are:

    arm, arm64, mips, nds32, powerpc, riscv, s390, sparc, x86, um

arm64, mips, x86 use the generic VDSO. Patches for arm are floating
around. UM is special as it just traps into the syscalls. No idea about the
rest. Vincenzo might know.

The bad news is that we have no information (except on arm which has a
config switch for VDSO) whether an architecture provides VDSO support or
not.

So unless you add something like

   config HAS_VDSO
   	  bool

which is selected by all architectures which provide VDSO support, the only
sane solution is to depend on GENERIC_VDSO_TIME_NS.

TBH, I would not even bother. The architectures which matter and are going
to use time namespaces already support VDSO and they need to move to the
generic implementation anyway as we discussed and agreed on in Vancouver.

Providing time name spaces for the non VDSO archs is a purely academic
exercise.

Thanks,

	tglx

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Vincenzo Frascino]

Hi Andrei,

On 10/17/19 12:33 AM, Andrei Vagin wrote:
>>> Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
>>> the architectures that have no support for time namespaces.
>>> The direct consequence is that the fallbacks defined in this patch are never
>>> selected and this ends up in kernel compilation errors due to missing symbols.
>>>
>>> The error below shows what happens on arm64 (similar behavior on other
>>> architectures):
>>>
>>> aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
>>> kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'
>>>
>>> My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
>>> architectures that enable time namespaces select it and make CONFIG_TIME_NS
>>> select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.
>> Nah.
>>
>> config TIME_NS
>> 	bool "TIME namespace"
>> 	depends on GENERIC_VDSO_TIME_NS
> I was thinking to fix this by the same way with a small difference.
> 
> If GENERIC_GETTIMEOFDAY isn't set, it should be safe to allow enabling
> TIME_NS. In this case, clock_gettime works via system call and we don't
> have arch-specific code in this case. Does this sound reasonable?
> 
>         depends on (!GENERIC_GETTIMEOFDAY || GENERIC_VDSO_TIME_NS)

This option would not work because not all the architectures have been converted
to the unified vdso approach. For example if you try to build ppc64 that does
not set GENERIC_GETTIMEOFDAY but has vdso support you would get:

powerpc64-linux-ld: warning: orphan section `.gnu.hash' from `linker stubs'
being placed in section `.gnu.hash'.
kernel/time/namespace.o: In function `.timens_set_vvar_page.isra.2.part.3':
namespace.c:(.text+0x178): undefined reference to `.arch_get_vdso_data'
kernel/time/namespace.o: In function `.timens_install':
namespace.c:(.text+0x798): undefined reference to `.vdso_join_timens'
kernel/time/namespace.o: In function `.timens_on_fork':
namespace.c:(.text+0x90c): undefined reference to `.vdso_join_timens'
/home/vinfra01/Projects/linux/Makefile:1074: recipe for target 'vmlinux' failed
make[1]: *** [vmlinux] Error 1
make[1]: Leaving directory '/home/vinfra01/Projects/linux-out'
Makefile:179: recipe for target 'sub-make' failed
make: *** [sub-make] Error 2

-- 
Regards,
Vincenzo

Re: [PATCHv7 00/33] kernel: Introduce Time Namespace

[Thomas Gleixner]

On Fri, 11 Oct 2019, Dmitry Safonov wrote:
> 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
> --------------------------------------------------------------
>         | 153242367 | 153567617        | 150933203 | 139310914
>         | 153324800 | 153115132        | 150919828 | 139299761
>         | 153125401 | 153686868        | 150930471 | 139273917
>         | 153399355 | 153694866        | 151083410 | 139286081
>         | 153489417 | 153739716        | 150997262 | 139146403
>         | 153494270 | 153724332        | 150035651 | 138835612
> -----------------------------------------------------------
> avg     | 153345935 | 153588088        | 150816637 | 139192114
> diff %  | 100       | 100.1            | 98.3      | 90.7


That host 98.3% number is weird and does not match the tests I did with the
fallback code I provided you. On my limited testing that fallback hidden in
the slowpath did not show any difference to the TIME_NS=n case when not
inside a time namespace.

Thanks,

	tglx

Re: [PATCHv7 01/33] ns: Introduce Time Namespace

[Vincenzo Frascino]

On 10/17/19 10:20 AM, Thomas Gleixner wrote:

[...]

> The architectures which implement VDSO are:
> 
>     arm, arm64, mips, nds32, powerpc, riscv, s390, sparc, x86, um
> 
> arm64, mips, x86 use the generic VDSO. Patches for arm are floating
> around. UM is special as it just traps into the syscalls. No idea about the
> rest. Vincenzo might know.
> 

There a couple of cases: hexagon and csky that have vDSOs for signal trampolines
if I recall correctly, but they do not fall into the category we are exploring
at the moment.

> The bad news is that we have no information (except on arm which has a
> config switch for VDSO) whether an architecture provides VDSO support or
> not.
> 
> So unless you add something like
> 
>    config HAS_VDSO
>    	  bool
> 
> which is selected by all architectures which provide VDSO support, the only
> sane solution is to depend on GENERIC_VDSO_TIME_NS.
> 
> TBH, I would not even bother. The architectures which matter and are going
> to use time namespaces already support VDSO and they need to move to the
> generic implementation anyway as we discussed and agreed on in Vancouver.
> 
> Providing time name spaces for the non VDSO archs is a purely academic
> exercise.

I totally agree with this.

-- 
Regards,
Vincenzo

Re: [PATCHv7 00/33] kernel: Introduce Time Namespace

[Andrei Vagin]

On Thu, Oct 17, 2019 at 11:24:45AM +0200, Thomas Gleixner wrote:
> On Fri, 11 Oct 2019, Dmitry Safonov wrote:
> > 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
> > --------------------------------------------------------------
> >         | 153242367 | 153567617        | 150933203 | 139310914
> >         | 153324800 | 153115132        | 150919828 | 139299761
> >         | 153125401 | 153686868        | 150930471 | 139273917
> >         | 153399355 | 153694866        | 151083410 | 139286081
> >         | 153489417 | 153739716        | 150997262 | 139146403
> >         | 153494270 | 153724332        | 150035651 | 138835612
> > -----------------------------------------------------------
> > avg     | 153345935 | 153588088        | 150816637 | 139192114
> > diff %  | 100       | 100.1            | 98.3      | 90.7
> 
> 
> That host 98.3% number is weird and does not match the tests I did with the
> fallback code I provided you. On my limited testing that fallback hidden in
> the slowpath did not show any difference to the TIME_NS=n case when not
> inside a time namespace.

You did your experiments without a small optimization that we introduced
in the 18-th patch:

[PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()

When I did my measurements in the first time, I found that with this
timens change clock_gettime() shows a better performance when
CONFIG_TIME_NS isn't set. This looked weird for me, because I don't
expect to see this improvement. After analyzing a disassembled code of
vdso.so, I found that we can add the unlikely() hint into
vdso_read_begin() and this gives us 2% improvement of clock_gettime
performance on the upsteam kernel.

In my table, the "before" column is actually for the upstream kernel
with the 18-th patch. Here is the table with the real "before" column:

        | before    | with 18/33 | CONFIG_TIME_NS=n | host      | inside timens
------------------------------------------------------------------------------
avg     | 150331408 | 153345935  | 153588088        | 150816637 | 139192114
------------------------------------------------------------------------------
diff %  |       98  |      100   | 100.1            | 98.3      | 90.7
------------------------------------------------------------------------------
stdev % |       0.3 |     0.09   | 0.15             | 0.25      | 0.13

If we compare numbers in "before", "host" and "inside timens" columns, we
see the same results that you had. clock_gettime() works with the
same performance in the host namespace and 7% slower in a time
namespace.

Now let's look why we have these 2% degradation in the host time
namespace. For that, we cat look at disassembled code of do_hres:

Before:
   0:   55                      push   %rbp
   1:   48 63 f6                movslq %esi,%rsi
   4:   49 89 d1                mov    %rdx,%r9
   7:   49 89 c8                mov    %rcx,%r8
   a:   48 c1 e6 04             shl    $0x4,%rsi
   e:   48 01 fe                add    %rdi,%rsi
  11:   48 89 e5                mov    %rsp,%rbp
  14:   41 54                   push   %r12
  16:   53                      push   %rbx
  17:   44 8b 17                mov    (%rdi),%r10d
  1a:   41 f6 c2 01             test   $0x1,%r10b
  1e:   0f 85 fb 00 00 00       jne    11f <do_hres.isra.0+0x11f>
  24:   8b 47 04                mov    0x4(%rdi),%eax
  27:   83 f8 01                cmp    $0x1,%eax
  2a:   74 0f                   je     3b <do_hres.isra.0+0x3b>
  2c:   83 f8 02                cmp    $0x2,%eax
  2f:   74 72                   je     a3 <do_hres.isra.0+0xa3>
  31:   5b                      pop    %rbx
  32:   b8 ff ff ff ff          mov    $0xffffffff,%eax
  37:   41 5c                   pop    %r12
  39:   5d                      pop    %rbp
  3a:   c3                      retq
...

After:
   0:   55                      push   %rbp
   1:   4c 63 ce                movslq %esi,%r9
   4:   49 89 d0                mov    %rdx,%r8
   7:   49 c1 e1 04             shl    $0x4,%r9
   b:   49 01 f9                add    %rdi,%r9
   e:   48 89 e5                mov    %rsp,%rbp
  11:   41 56                   push   %r14
  13:   41 55                   push   %r13
  15:   41 54                   push   %r12
  17:   53                      push   %rbx
  18:   44 8b 17                mov    (%rdi),%r10d
  1b:   44 89 d0                mov    %r10d,%eax
  1e:   f7 d0                   not    %eax
  20:   83 e0 01                and    $0x1,%eax
  23:   89 c3                   mov    %eax,%ebx
  25:   0f 84 03 01 00 00       je     12e <do_hres+0x12e>
  2b:   8b 47 04                mov    0x4(%rdi),%eax
  2e:   83 f8 01                cmp    $0x1,%eax
  31:   74 13                   je     46 <do_hres+0x46>
  33:   83 f8 02                cmp    $0x2,%eax
  36:   74 7b                   je     b3 <do_hres+0xb3>
  38:   b8 ff ff ff ff          mov    $0xffffffff,%eax
  3d:   5b                      pop    %rbx
  3e:   41 5c                   pop    %r12
  40:   41 5d                   pop    %r13
  42:   41 5e                   pop    %r14
  44:   5d                      pop    %rbp
  45:   c3                      retq
...

So I think we see these 2% degradation in the host time namespace,
because we need to save to extra registers on stack. If we want to avoid
this degradation, we can mark do_hres_timens as noinline. In this case,
the disassembled code will be the same as before these changes:

  0000000000000160 <do_hres>:
  do_hres():
   160:   55                      push   %rbp
   161:   4c 63 ce                movslq %esi,%r9
   164:   49 89 d0                mov    %rdx,%r8
   167:   49 c1 e1 04             shl    $0x4,%r9
   16b:   49 01 f9                add    %rdi,%r9
   16e:   48 89 e5                mov    %rsp,%rbp
   171:   41 54                   push   %r12
   173:   53                      push   %rbx
   174:   44 8b 17                mov    (%rdi),%r10d
   177:   41 f6 c2 01             test   $0x1,%r10b
   17b:   0f 85 fc 00 00 00       jne    27d <do_hres+0x11d>
   181:   8b 47 04                mov    0x4(%rdi),%eax
   184:   83 f8 01                cmp    $0x1,%eax
   187:   74 0f                   je     198 <do_hres+0x38>
   189:   83 f8 02                cmp    $0x2,%eax
   18c:   74 73                   je     201 <do_hres+0xa1>
   18e:   5b                      pop    %rbx
   18f:   b8 ff ff ff ff          mov    $0xffffffff,%eax
   194:   41 5c                   pop    %r12
   196:   5d                      pop    %rbp
   197:   c3                      retq
...

But this change will affect the performance of clock_gettime in a time
namespace.

My experiments shows that with the noinline annotation for
do_hres_timens, clock_gettime will work with the same performance in the
host time namespace, but it will be slower on 11% in a time namespace.

Thomas, what do you think about this? Do we need to mark do_hres_timens
as noinline?

Thanks,
Andrei

Re: [PATCHv7 00/33] kernel: Introduce Time Namespace

[Andrei Vagin]

On Thu, Oct 17, 2019 at 04:47:48PM -0700, Andrei Vagin wrote:
> 
> In my table, the "before" column is actually for the upstream kernel
> with the 18-th patch. Here is the table with the real "before" column:
> 
>         | before    | with 18/33 | CONFIG_TIME_NS=n | host      | inside timens
> ------------------------------------------------------------------------------
> avg     | 150331408 | 153345935  | 153588088        | 150816637 | 139192114
> ------------------------------------------------------------------------------
> diff %  |       98  |      100   | 100.1            | 98.3      | 90.7
> ------------------------------------------------------------------------------
> stdev % |       0.3 |     0.09   | 0.15             | 0.25      | 0.13
> 
> If we compare numbers in "before", "host" and "inside timens" columns, we
> see the same results that you had. clock_gettime() works with the
> same performance in the host namespace and 7% slower in a time
> namespace.
> 

I played with this a bit more and I've found that we can speed up
clock_gettime on 5% more if we mark do_hres and do_coarse as
__always_inline.

With the unlikely hint in vdso_read_begin and noinline for
do_hres_timens and do_coarse_timens:
1..8
ok 1 host:      clock:  monotonic       cycles:  155278332
ok 2 host:      clock: monotonic-coarse cycles:  662067077
ok 3 host:      clock: monotonic-raw    cycles:  151218057
ok 4 host:      clock:   boottime       cycles:  154907635
ok 5 ns:        clock:  monotonic       cycles:  133100433
ok 6 host:      clock: monotonic-coarse cycles:  444170219
ok 7 host:      clock: monotonic-raw    cycles:  129550178
ok 8 ns:        clock:   boottime       cycles:  130167136


With __always_inline for do_hres and do_coarse:
1..8
ok 1 host:      clock:  monotonic       cycles:  163691015
ok 2 host:      clock: monotonic-coarse cycles:  641443397
ok 3 host:      clock: monotonic-raw    cycles:  163649270
ok 4 host:      clock:   boottime       cycles:  163682242
ok 5 ns:        clock:  monotonic       cycles:  138759212
ok 6 host:      clock: monotonic-coarse cycles:  486149502
ok 7 host:      clock: monotonic-raw    cycles:  134801053
ok 8 ns:        clock:   boottime       cycles:  138675460
# Pass 8 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

With __always_inline for do_hres, do_coarse, do_hres_timens,
do_coarse_timens:
1..8
ok 1 host:	clock:  monotonic	cycles:	 158984538
ok 2 host:	clock: monotonic-coarse	cycles:	 594932695
ok 3 host:	clock: monotonic-raw	cycles:	 157834511
ok 4 host:	clock:   boottime	cycles:	 158297691
ok 5 ns:	clock:  monotonic	cycles:	 148559612
ok 6 host:	clock: monotonic-coarse	cycles:	 468505657
ok 7 host:	clock: monotonic-raw	cycles:	 146366575
ok 8 ns:	clock:   boottime	cycles:	 148573015
# Pass 8 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Thanks,
Andrei

Re: [PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()

[Andrei Vagin]

[-- Attachment #1: Type: text/plain, Size: 1415 bytes --]

On Wed, Oct 16, 2019 at 12:24:14PM +0100, Vincenzo Frascino wrote:
> On 10/11/19 2:23 AM, Dmitry Safonov wrote:
> > From: Andrei Vagin <avagin@gmail.com>
> > 
> > Place the branch with no concurrent write before contended case.
> > 
> > Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
> > (more clock_gettime() cycles - the better):
> >         | before    | after
> > -----------------------------------
> >         | 150252214 | 153242367
> >         | 150301112 | 153324800
> >         | 150392773 | 153125401
> >         | 150373957 | 153399355
> >         | 150303157 | 153489417
> >         | 150365237 | 153494270
> > -----------------------------------
> > avg     | 150331408 | 153345935
> > diff %  | 2	    | 0
> > -----------------------------------
> > stdev % | 0.3	    | 0.1
> > 
> > Signed-off-by: Andrei Vagin <avagin@gmail.com>
> > Co-developed-by: Dmitry Safonov <dima@arista.com>
> > Signed-off-by: Dmitry Safonov <dima@arista.com>
> 
> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

Hello Vincenzo,

Could you test the attached patch on aarch64? On x86, it gives about 9%
performance improvement for CLOCK_MONOTONIC and CLOCK_BOOTTIME.

Here is my test:
https://github.com/avagin/vdso-perf

It is calling clock_gettime() in a loop for three seconds and then
reports a number of iterations.

Thanks,
Andrei

[-- Attachment #2: 0001-lib-vdso-make-do_hres-and-do_coarse-as-__always_inli.patch --]
[-- Type: text/plain, Size: 2207 bytes --]

From 5252093fec4c74802e5ef501b9f1db3369430c80 Mon Sep 17 00:00:00 2001
From: Andrei Vagin <avagin@gmail.com>
Date: Tue, 22 Oct 2019 18:23:17 -0700
Subject: [PATCH] lib/vdso: make do_hres and do_coarse as __always_inline

Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
(more clock_gettime() cycles - the better):

clock            | before     | after      | diff
----------------------------------------------------------
monotonic        |  153222105 |  166775025 | 8.8%
monotonic-coarse |  671557054 |  691513017 | 3.0%
monotonic-raw    |  147116067 |  161057395 | 9.5%
boottime         |  153446224 |  166962668 | 9.1%

Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
 lib/vdso/gettimeofday.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index e630e7ff57f1..b4f7f0f246af 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -38,7 +38,7 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 }
 #endif
 
-static int do_hres(const struct vdso_data *vd, clockid_t clk,
+static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 		   struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
@@ -68,7 +68,7 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	return 0;
 }
 
-static void do_coarse(const struct vdso_data *vd, clockid_t clk,
+static __always_inline void do_coarse(const struct vdso_data *vd, clockid_t clk,
 		      struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
@@ -97,12 +97,16 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
 	 */
 	msk = 1U << clock;
 	if (likely(msk & VDSO_HRES)) {
-		return do_hres(&vd[CS_HRES_COARSE], clock, ts);
+		vd = &vd[CS_HRES_COARSE];
+out_hres:
+		return do_hres(vd, clock, ts);
 	} else if (msk & VDSO_COARSE) {
 		do_coarse(&vd[CS_HRES_COARSE], clock, ts);
 		return 0;
 	} else if (msk & VDSO_RAW) {
-		return do_hres(&vd[CS_RAW], clock, ts);
+		vd = &vd[CS_RAW];
+		/* goto allows to avoid extra inlining of do_hres. */
+		goto out_hres;
 	}
 	return -1;
 }
-- 
2.21.0

Re: [PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()

[Vincenzo Frascino]

Hi Andrei,

On 10/24/19 7:13 AM, Andrei Vagin wrote:
> On Wed, Oct 16, 2019 at 12:24:14PM +0100, Vincenzo Frascino wrote:
>> On 10/11/19 2:23 AM, Dmitry Safonov wrote:
>>> From: Andrei Vagin <avagin@gmail.com>
>>>
>>> Place the branch with no concurrent write before contended case.
>>>
>>> Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
>>> (more clock_gettime() cycles - the better):
>>>         | before    | after
>>> -----------------------------------
>>>         | 150252214 | 153242367
>>>         | 150301112 | 153324800
>>>         | 150392773 | 153125401
>>>         | 150373957 | 153399355
>>>         | 150303157 | 153489417
>>>         | 150365237 | 153494270
>>> -----------------------------------
>>> avg     | 150331408 | 153345935
>>> diff %  | 2	    | 0
>>> -----------------------------------
>>> stdev % | 0.3	    | 0.1
>>>
>>> Signed-off-by: Andrei Vagin <avagin@gmail.com>
>>> Co-developed-by: Dmitry Safonov <dima@arista.com>
>>> Signed-off-by: Dmitry Safonov <dima@arista.com>
>>
>> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> 
> Hello Vincenzo,
> 
> Could you test the attached patch on aarch64? On x86, it gives about 9%
> performance improvement for CLOCK_MONOTONIC and CLOCK_BOOTTIME.
> 

I did run similar tests in past with a previous version of the unified vDSO
library and what I can tell based on the results of those is that the impact of
"__always_inline" alone was around 7% on arm64, in fact I had a comment stating
"To improve performances, in this file, __always_inline it is used for the
functions called multiple times." in my implementation [1].

[1] https://bit.ly/2W9zMxB

I spent some time yesterday trying to dig out why the approach did not make the
cut but I could not infer it from the review process.

> Here is my test:
> https://github.com/avagin/vdso-perf
> 
> It is calling clock_gettime() in a loop for three seconds and then
> reports a number of iterations.
> 

I am happy to run the test on arm64 and provide some results.

> Thanks,
> Andrei
> 

-- 
Regards,
Vincenzo

Re: [PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()

[Vincenzo Frascino]

Hi Andrei,

On 10/24/19 10:30 AM, Vincenzo Frascino wrote:
[...]
>> Here is my test:
>> https://github.com/avagin/vdso-perf
>>
>> It is calling clock_gettime() in a loop for three seconds and then
>> reports a number of iterations.
>>
> 
> I am happy to run the test on arm64 and provide some results.
>

Please find below the results:

clock            | before     | after      | diff
==================================================
monotonic          17326692     17951770     3.6%
monotonic-coarse   43624027     44215292     1.3%
monotonic-raw      17541809     17554932     0.1%
boottime           17334982     17954361     3.5%

The improvement for arm64 for monotonic and boottime is around 3.5%.

I created a pull request on github to send to you back the changes I had
to do to vdso-perf to cross-compile it on arm64 [1].

[1] https://github.com/avagin/vdso-perf/pull/1


>> Thanks,
>> Andrei
>>
> 

-- 
Regards,
Vincenzo