time: add kernel-doc in time.c

Add kernel-doc for all APIs that do not already have it.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: John Stultz <jstultz@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Acked-by: John Stultz <jstultz@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230704052405.5089-3-rdunlap@infradead.org

time: Fix various kernel-doc problems

Clean up kernel-doc complaints about function names and non-kernel-doc
comments in kernel/time/. Fixes these warnings:

kernel/time/time.c:479: warning: expecting prototype for set_normalized_timespec(). Prototype was for set_normalized_timespec64() instead
kernel/time/time.c:553: warning: expecting prototype for msecs_to_jiffies(). Prototype was for __msecs_to_jiffies() instead

kernel/time/timekeeping.c:1595: warning: contents before sections
kernel/time/timekeeping.c:1705: warning: This comment starts with '/**', but isn't a kernel-doc comment.
* We have three kinds of time sources to use for sleep time
kernel/time/timekeeping.c:1726: warning: This comment starts with '/**', but isn't a kernel-doc comment.
* 1) can be determined whether to use or not only when doing

kernel/time/tick-oneshot.c:21: warning: missing initial short description on line:
* tick_program_event
kernel/time/tick-oneshot.c:107: warning: expecting prototype for tick_check_oneshot_mode(). Prototype was for tick_oneshot_mode_active() instead

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230103032849.12723-1-rdunlap@infradead.org

time: Correct the prototype of ns_to_kernel_old_timeval and ns_to_timespec64

In ns_to_kernel_old_timeval() definition, the function argument is defined
with const identifier in kernel/time/time.c, but the prototype in
include/linux/time32.h looks different.

- The function is defined in kernel/time/time.c as below:
struct __kernel_old_timeval ns_to_kernel_old_timeval(const s64 nsec)

- The function is decalared in include/linux/time32.h as below:
extern struct __kernel_old_timeval ns_to_kernel_old_timeval(s64 nsec);

Because the variable of arithmethic types isn't modified in the calling scope,
there's no need to mark arguments as const, which was already mentioned during
review (Link[1) of the original patch.

Likewise remove the "const" keyword in both definition and declaration of
ns_to_timespec64() as requested by Arnd (Link[2]).

Fixes: a84d1169164b ("y2038: Introduce struct __kernel_old_timeval")
Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/all/20220712094715.2918823-1-youngmin.nam@samsung.com
Link[1]: https://lore.kernel.org/all/20180310081123.thin6wphgk7tongy@gmail.com/
Link[2]: https://lore.kernel.org/all/CAK8P3a3nknJgEDESGdJH91jMj6R_xydFqWASd8r5BbesdvMBgA@mail.gmail.com/

timekeeping, clocksource: Fix various typos in comments

Fix ~56 single-word typos in timekeeping & clocksource code comments.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-kernel@vger.kernel.org

y2038: remove unused time32 interfaces

No users remain, so kill these off before we grow new ones.

Link: http://lkml.kernel.org/r/20200110154232.4104492-3-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

y2038: remove obsolete jiffies conversion functions

Now that the last user of timespec_to_jiffies() is gone, these
can just be removed, everything else is using ktime_t or timespec64
already.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

time: Zero the upper 32-bits in __kernel_timespec on 32-bit

On compat interfaces, the high order bits of nanoseconds should be zeroed
out. This is because the application code or the libc do not guarantee
zeroing of these. If used without zeroing, kernel might be at risk of using
timespec values incorrectly.

Originally it was handled correctly, but lost during is_compat_syscall()
cleanup. Revert the condition back to check CONFIG_64BIT.

Fixes: 98f76206b335 ("compat: Cleanup in_compat_syscall() callers")
Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191121000303.126523-1-dima@arista.com

y2038: time: avoid timespec usage in settimeofday()

The compat_get_timeval() and timeval_valid() interfaces are deprecated
and getting removed along with the definition of struct timeval itself.

Change the two implementations of the settimeofday() system call to
open-code these helpers and completely avoid references to timeval.

The timeval_valid() call is not needed any more here, only a check to
avoid overflowing tv_nsec during the multiplication, as there is another
range check in do_sys_settimeofday64().

Tested-by: syzbot+dccce9b26ba09ca49966@syzkaller.appspotmail.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: syscalls: change remaining timeval to __kernel_old_timeval

All of the remaining syscalls that pass a timeval (gettimeofday, utime,
futimesat) can trivially be changed to pass a __kernel_old_timeval
instead, which has a compatible layout, but avoids ambiguity with
the timeval type in user space.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: uapi: change __kernel_time_t to __kernel_old_time_t

This is mainly a patch for clarification, and to let us remove
the time_t definition from the kernel to prevent new users from
creeping in that might not be y2038-safe.

All remaining uses of 'time_t' or '__kernel_time_t' are part of
the user API that cannot be changed by that either have a
replacement or that do not suffer from the y2038 overflow.

Acked-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: remove CONFIG_64BIT_TIME

The CONFIG_64BIT_TIME option is defined on all architectures, and can
be removed for simplicity now.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

time: Fix spelling mistake in comment

witin => within

Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1571124819-9639-1-git-send-email-mojha@codeaurora.org

time: Optimize ns_to_timespec64()

ns_to_timespec64() calls div_s64_rem(), which is a rather slow function on
32-bit architectures, as it cannot take advantage of the do_div()
optimizations for constant arguments.

Open-code the div_s64_rem() function in ns_to_timespec64(), so a constant
divider can be passed into the optimized div_u64_rem() function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191108203435.112759-3-arnd@arndb.de

time: Validate user input in compat_settimeofday()

The user value is validated after converting the timeval to a timespec, but
for a wide range of negative tv_usec values the multiplication overflow turns
them in positive numbers. So the 'validated later' is not catching the
invalid input.

Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1562460701-113301-1-git-send-email-zhengbin13@huawei.com

time: Introduce jiffies64_to_msecs()

there is a similar helper in net/netfilter/nf_tables_api.c,
this maybe become a common request someday, so move it to
time.c

Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

timekeeping: Force upper bound for setting CLOCK_REALTIME

Several people reported testing failures after setting CLOCK_REALTIME close
to the limits of the kernel internal representation in nanoseconds,
i.e. year 2262.

The failures are exposed in subsequent operations, i.e. when arming timers
or when the advancing CLOCK_MONOTONIC makes the calculation of
CLOCK_REALTIME overflow into negative space.

Now people start to paper over the underlying problem by clamping
calculations to the valid range, but that's just wrong because such
workarounds will prevent detection of real issues as well.

It is reasonable to force an upper bound for the various methods of setting
CLOCK_REALTIME. Year 2262 is the absolute upper bound. Assume a maximum
uptime of 30 years which is plenty enough even for esoteric embedded
systems. That results in an upper bound of year 2232 for setting the time.

Once that limit is reached in reality this limit is only a small part of
the problem space. But until then this stops people from trying to paper
over the problem at the wrong places.

Reported-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reported-by: Hongbo Yao <yaohongbo@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903231125480.2157@nanos.tec.linutronix.de

y2038: rename old time and utime syscalls

The time, stime, utime, utimes, and futimesat system calls are only
used on older architectures, and we do not provide y2038 safe variants
of them, as they are replaced by clock_gettime64, clock_settime64,
and utimensat_time64.

However, for consistency it seems better to have the 32-bit architectures
that still use them call the "time32" entry points (leaving the
traditional handlers for the 64-bit architectures), like we do for system
calls that now require two versions.

Note: We used to always define __ARCH_WANT_SYS_TIME and
__ARCH_WANT_SYS_UTIME and only set __ARCH_WANT_COMPAT_SYS_TIME and
__ARCH_WANT_SYS_UTIME32 for compat mode on 64-bit kernels. Now this is
reversed: only 64-bit architectures set __ARCH_WANT_SYS_TIME/UTIME, while
we need __ARCH_WANT_SYS_TIME32/UTIME32 for 32-bit architectures and compat
mode. The resulting asm/unistd.h changes look a bit counterintuitive.

This is only a cleanup patch and it should not change any behavior.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>

y2038: syscalls: rename y2038 compat syscalls

A lot of system calls that pass a time_t somewhere have an implementation
using a COMPAT_SYSCALL_DEFINEx() on 64-bit architectures, and have
been reworked so that this implementation can now be used on 32-bit
architectures as well.

The missing step is to redefine them using the regular SYSCALL_DEFINEx()
to get them out of the compat namespace and make it possible to build them
on 32-bit architectures.

Any system call that ends in 'time' gets a '32' suffix on its name for
that version, while the others get a '_time32' suffix, to distinguish
them from the normal version, which takes a 64-bit time argument in the
future.

In this step, only 64-bit architectures are changed, doing this rename
first lets us avoid touching the 32-bit architectures twice.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

timex: change syscalls to use struct __kernel_timex

struct timex is not y2038 safe.
Switch all the syscall apis to use y2038 safe __kernel_timex.

Note that sys_adjtimex() does not have a y2038 safe solution. C libraries
can implement it by calling clock_adjtime(CLOCK_REALTIME, ...).

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

timex: use __kernel_timex internally

struct timex is not y2038 safe.
Replace all uses of timex with y2038 safe __kernel_timex.

Note that struct __kernel_timex is an ABI interface definition.
We could define a new structure based on __kernel_timex that
is only available internally instead. Right now, there isn't
a strong motivation for this as the structure is isolated to
a few defined struct timex interfaces and such a structure would
be exactly the same as struct timex.

The patch was generated by the following coccinelle script:

virtual patch

@depends on patch forall@
identifier ts;
expression e;
@@
(
- struct timex ts;
+ struct __kernel_timex ts;
|
- struct timex ts = {};
+ struct __kernel_timex ts = {};
|
- struct timex ts = e;
+ struct __kernel_timex ts = e;
|
- struct timex *ts;
+ struct __kernel_timex *ts;
|
(memset \| copy_from_user \| copy_to_user \)(...,
- sizeof(struct timex))
+ sizeof(struct __kernel_timex))
)

@depends on patch forall@
identifier ts;
identifier fn;
@@
fn(...,
- struct timex *ts,
+ struct __kernel_timex *ts,
...) {
...
}

@depends on patch forall@
identifier ts;
identifier fn;
@@
fn(...,
- struct timex *ts) {
+ struct __kernel_timex *ts) {
...
}

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: linux-alpha@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

time: make adjtime compat handling available for 32 bit

We want to reuse the compat_timex handling on 32-bit architectures the
same way we are using the compat handling for timespec when moving to
64-bit time_t.

Move all definitions related to compat_timex out of the compat code
into the normal timekeeping code, along with a rename to old_timex32,
corresponding to the timespec/timeval structures, and make it controlled
by CONFIG_COMPAT_32BIT_TIME, which 32-bit architectures will then select.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

timekeeping: remove timespec_add/timespec_del

The last users were removed a while ago since everyone moved to ktime_t,
so we can remove the two unused interfaces for old timespec structures.

With those two gone, set_normalized_timespec() is also unused, so
remove that as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: John Stultz <john.stultz@linaro.org>

time: Add SPDX license identifiers

Update the time(r) core files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of the
full boiler plate text.

This work is based on a script and data from Philippe Ombredanne, Kate
Stewart and myself. The data has been created with two independent license
scanners and manual inspection.

The following files do not contain any direct license information and have
been omitted from the big initial SPDX changes:

timeconst.bc: The .bc files were not touched
time.c, timer.c, timekeeping.c: Licence was deduced from EXPORT_SYMBOL_GPL

As those files do not contain direct license references they fall under the
project license, i.e. GPL V2 only.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: https://lkml.kernel.org/r/20181031182252.879109557@linutronix.de

time: Remove useless filenames in top level comments

Remove the pointless filenames in the top level comments. They have no
value at all and just occupy space. While at it tidy up some of the
comments and remove a stale one.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Link: https://lkml.kernel.org/r/20181031182252.794898238@linutronix.de

compat: Cleanup in_compat_syscall() callers

Now that in_compat_syscall() is consistent on all architectures and does
not longer report true on native i686, the workarounds (ifdeffery and
helpers) can be removed.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-efi@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: https://lkml.kernel.org/r/20181012134253.23266-3-dima@arista.com

y2038: __get_old_timespec32() can be static

The kbuild test robot reports two new warnings with the previous
patch:

kernel/time/time.c:866:5: sparse: symbol '__get_old_timespec32' was not declared. Should it be static?
kernel/time/time.c:882:5: sparse: symbol '__put_old_timespec32' was not declared. Should it be static?

These are actually older bugs, but came up now after the
symbol got renamed. Fortunately, commit afef05cf238c ("time:
Enable get/put_compat_itimerspec64 always") makes the two functions
(__compat_get_timespec64/__compat_get_timespec64) local to time.c already,
so we can mark them as 'static'.

Fixes: ee16c8f415e4 ("y2038: Globally rename compat_time to old_time32")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
[arnd: added changelog text]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: globally rename compat_time to old_time32

Christoph Hellwig suggested a slightly different path for handling
backwards compatibility with the 32-bit time_t based system calls:

Rather than simply reusing the compat_sys_* entry points on 32-bit
architectures unchanged, we get rid of those entry points and the
compat_time types by renaming them to something that makes more sense
on 32-bit architectures (which don't have a compat mode otherwise),
and then share the entry points under the new name with the 64-bit
architectures that use them for implementing the compatibility.

The following types and interfaces are renamed here, and moved
from linux/compat_time.h to linux/time32.h:

old new
--- ---
compat_time_t old_time32_t
struct compat_timeval struct old_timeval32
struct compat_timespec struct old_timespec32
struct compat_itimerspec struct old_itimerspec32
ns_to_compat_timeval() ns_to_old_timeval32()
get_compat_itimerspec64() get_old_itimerspec32()
put_compat_itimerspec64() put_old_itimerspec32()
compat_get_timespec64() get_old_timespec32()
compat_put_timespec64() put_old_timespec32()

As we already have aliases in place, this patch addresses only the
instances that are relevant to the system call interface in particular,
not those that occur in device drivers and other modules. Those
will get handled separately, while providing the 64-bit version
of the respective interfaces.

I'm not renaming the timex, rusage and itimerval structures, as we are
still debating what the new interface will look like, and whether we
will need a replacement at all.

This also doesn't change the names of the syscall entry points, which can
be done more easily when we actually switch over the 32-bit architectures
to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to
SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: make do_gettimeofday() and get_seconds() inline

get_seconds() and do_gettimeofday() are only used by a few modules now any
more (waiting for the respective patches to get accepted), and they are
among the last holdouts of code that is not y2038 safe in the core kernel.

Move the implementation into the timekeeping32.h header to clean up
the core kernel and isolate the old interfaces further.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: remove unused time interfaces

After many small patches, at least some of the deprecated interfaces
have no remaining users any more and can be removed:

current_kernel_time
do_settimeofday
get_monotonic_boottime
get_monotonic_boottime64
get_monotonic_coarse
get_monotonic_coarse64
getrawmonotonic64
ktime_get_real_ts
timekeeping_clocktai
timespec_trunc
timespec_valid_strict
time_to_tm

For many of the remaining time functions, we are missing one or
two patches that failed to make it into 4.19, they will be removed
in the following merge window.

The replacement functions for the removed interfaces are documented in
Documentation/core-api/timekeeping.rst.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

time: Enable get/put_compat_itimerspec64 always

This will aid in enabling the compat syscalls on 32-bit architectures later
on.

Also move compat_itimerspec and related defines to compat_time.h. The
compat_time.h file will eventually be deleted.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: viro@zeniv.linux.org.uk
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: y2038@lists.linaro.org
Link: https://lkml.kernel.org/r/20180617051144.29756-3-deepa.kernel@gmail.com

time: Introduce struct __kernel_itimerspec

struct itimerspec is not y2038-safe.

Introduce a new struct __kernel_itimerspec based on the kernel internal
y2038-safe struct itimerspec64.

The definition of struct __kernel_itimerspec includes two struct
__kernel_timespec.

Since struct __kernel_timespec has the same representation in native and
compat modes, so does struct __kernel_itimerspec. This helps have a common
entry point for syscalls using struct __kernel_itimerspec.

New y2038-safe syscalls will use this new type. Since most of the new
syscalls are just an update to the native syscalls with the type update,
place the new definition under CONFIG_64BIT_TIME. This helps architectures
that do not support the above config to keep using the old definition of
struct itimerspec.

Also change the get/put_itimerspec64 to use struct__kernel_itimerspec.
This will help 32 bit architectures to use the new syscalls when
architectures select CONFIG_64BIT_TIME.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: viro@zeniv.linux.org.uk
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: y2038@lists.linaro.org
Link: https://lkml.kernel.org/r/20180617051144.29756-2-deepa.kernel@gmail.com

time: Make sure jiffies_to_msecs() preserves non-zero time periods

For the common cases where 1000 is a multiple of HZ, or HZ is a multiple of
1000, jiffies_to_msecs() never returns zero when passed a non-zero time
period.

However, if HZ > 1000 and not an integer multiple of 1000 (e.g. 1024 or
1200, as used on alpha and DECstation), jiffies_to_msecs() may return zero
for small non-zero time periods. This may break code that relies on
receiving back a non-zero value.

jiffies_to_usecs() does not need such a fix: one jiffy can only be less
than one µs if HZ > 1000000, and such large values of HZ are already
rejected at build time, twice:

- include/linux/jiffies.h does #error if HZ >= 12288,
- kernel/time/time.c has BUILD_BUG_ON(HZ > USEC_PER_SEC).

Broken since forever.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-alpha@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180622143357.7495-1-geert@linux-m68k.org

time: Use ktime_get_real_seconds() in time syscall

Both get_seconds() and do_gettimeofday() are deprecated. Change the time()
implementation to use the replacement function instead.

Obviously the system call will still overflow in 2038, but this gets us
closer to removing the old helper functions.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: y2038@lists.linaro.org
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lkml.kernel.org/r/20180618140811.2998503-2-arnd@arndb.de

timekeeping: Remove timespec64 hack

At this point, we have converted most of the kernel to use timespec64
consistently in place of timespec, so it seems it's time to make
timespec64 the native structure and define timespec in terms of that
one on 64-bit architectures.

Starting with gcc-5, the compiler can completely optimize away the
timespec_to_timespec64 and timespec64_to_timespec functions on 64-bit
architectures. With older compilers, we introduce a couple of extra
copies of local variables, but those are easily avoided by using
the timespec64 based interfaces consistently, as we do in most of the
important code paths already.

The main upside of removing the hack is that printing the tv_sec
field of a timespec64 structure can now use the %lld format
string on all architectures without a cast to time64_t. Without
this patch, the field is a 'long' type and would have to be printed
using %ld on 64-bit architectures.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180427134016.2525989-2-arnd@arndb.de

time: Fix get_timespec64() for y2038 safe compat interfaces

get/put_timespec64() interfaces will eventually be used for
conversions between the new y2038 safe struct __kernel_timespec
and struct timespec64.

The new y2038 safe syscalls have a common entry for native
and compat interfaces.
On compat interfaces, the high order bits of nanoseconds
should be zeroed out. This is because the application code
or the libc do not guarantee zeroing of these. If used without
zeroing, kernel might be at risk of using timespec values
incorrectly.

Note that clearing of bits is dependent on CONFIG_64BIT_TIME
for now. This is until COMPAT_USE_64BIT_TIME has been handled
correctly. x86 will be the first architecture that will use the
CONFIG_64BIT_TIME.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

compat: Enable compat_get/put_timespec64 always

These functions are used in the repurposed compat syscalls
to provide backward compatibility for using 32 bit time_t
on 32 bit systems.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

y2038: Introduce struct __kernel_old_timeval

Dealing with 'struct timeval' users in the y2038 series is a bit tricky:

We have two definitions of timeval that are visible to user space,
one comes from glibc (or some other C library), the other comes from
linux/time.h. The kernel copy is what we want to be used for a number of
structures defined by the kernel itself, e.g. elf_prstatus (used it core
dumps), sysinfo and rusage (used in system calls). These generally tend
to be used for passing time intervals rather than absolute (epoch-based)
times, so they do not suffer from the y2038 overflow. Some of them
could be changed to use 64-bit timestamps by creating new system calls,
others like the core files cannot easily be changed.

An application using these interfaces likely also uses gettimeofday()
or other interfaces that use absolute times, and pass 'struct timeval'
pointers directly into kernel interfaces, so glibc must redefine their
timeval based on a 64-bit time_t when they introduce their y2038-safe
interfaces.

The only reasonable way forward I see is to remove the 'timeval'
definion from the kernel's uapi headers, and change the interfaces that
we do not want to (or cannot) duplicate for 64-bit times to use a new
__kernel_old_timeval definition instead. This type should be avoided
for all new interfaces (those can use 64-bit nanoseconds, or the 64-bit
version of timespec instead), and should be used with great care when
converting existing interfaces from timeval, to be sure they don't suffer
from the y2038 overflow, and only with consensus for the particular user
that using __kernel_old_timeval is better than moving to a 64-bit based
interface. The structure name is intentionally chosen to not conflict
with user space types, and to be ugly enough to discourage its use.

Note that ioctl based interfaces that pass a bare 'timeval' pointer
cannot change to '__kernel_old_timeval' because the user space source
code refers to 'timeval' instead, and we don't want to modify the user
space sources if possible. However, any application that relies on a
structure to contain an embedded 'timeval' (e.g. by passing a pointer
to the member into a function call that expects a timeval pointer) is
broken when that structure gets converted to __kernel_old_timeval. I
don't see any way around that, and we have to rely on the compiler to
produce a warning or compile failure that will alert users when they
recompile their sources against a new libc.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lkml.kernel.org/r/20180315161739.576085-1-arnd@arndb.de

time: Move time_t conversion helpers to time32.h

On 64-bit architectures, the timespec64 based helpers in linux/time.h
are defined as macros pointing to their timespec based counterparts.
This made sense when they were first introduced, but as we are migrating
away from timespec in general, it's much less intuitive now.

This changes the macros to work in the exact opposite way: we always
provide the timespec64 based helpers and define the old interfaces as
macros for them. Now we can move those macros into linux/time32.h, which
already contains the respective helpers for 32-bit architectures.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Remove unused functions

The (slow but) ongoing work on conversion from timespec to timespec64
has led some timespec based helper functions to become unused.

No new code should use them, so we can remove the functions entirely.
I'm planning to obsolete additional interfaces next and remove
more of these.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

timekeeping: Consolidate timekeeping_inject_offset code

The code to check the adjtimex() or clock_adjtime() arguments is spread
out across multiple files for presumably only historic reasons. As a
preparatation for a rework to get rid of the use of 'struct timeval'
and 'struct timespec' in there, this moves all the portions into
kernel/time/timekeeping.c and marks them as 'static'.

The warp_clock() function here is not as closely related as the others,
but I feel it still makes sense to move it here in order to consolidate
all callers of timekeeping_inject_offset().

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[jstultz: Whitespace fixup]
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Use do_settimeofday64() internally

do_settimeofday() is a wrapper around do_settimeofday64(), so that function
can be called directly. The wrapper can be removed once the last user is
gone.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: y2038@lists.linaro.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Link: https://lkml.kernel.org/r/20171013183452.3635956-1-arnd@arndb.de

time: introduce {get,put}_itimerspec64

As we change the user space type for the timerfd and posix timer
functions to newer data types, we need some form of conversion
helpers to avoid duplicating that logic.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

time: add get_timespec64 and put_timespec64

Add helper functions to convert between struct timespec64 and
struct timespec at userspace boundaries.

This is a preparatory patch to use timespec64 as the basic type
internally in the kernel as timespec is not y2038 safe on 32 bit systems.
The patch helps the cause by containing all data conversions at the
userspace boundaries within these functions.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

time: Move compat_gettimeofday()/settimeofday() to native

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-16-viro@ZenIV.linux.org.uk

time: Move compat_time()/stime() to native

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-15-viro@ZenIV.linux.org.uk

ntp: Move adjtimex related compat syscalls to native counterparts

Get rid of set_fs() mess and sanitize compat_{get,put}_timex(),
while we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-9-viro@ZenIV.linux.org.uk

time: delete current_fs_time()

All uses of the current_fs_time() function have been replaced by other
time interfaces.

And, its use cases can be fulfilled by current_time() or ktime_get_*
variants.

Link: http://lkml.kernel.org/r/1491613030-11599-13-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

time: Delete do_sys_setimeofday()

struct timespec is not y2038 safe on 32 bit machines and needs to be
replaced with struct timespec64.

do_sys_timeofday() is just a wrapper function. Replace all calls to this
function with direct calls to do_sys_timeofday64() instead and delete
do_sys_timeofday().

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: y2038@lists.linaro.org
Cc: john.stultz@linaro.org
Cc: arnd@arndb.de
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/r/1490555058-4603-2-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

time: Introduce jiffies64_to_nsecs()

This will be needed for the cputime_t to nsec conversion.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Replace <asm/uaccess.h> with <linux/uaccess.h> globally

This was entirely automated, using the script by Al:

PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

time: Avoid undefined behaviour in timespec64_add_safe()

I ran into this:

================================================================================
UBSAN: Undefined behaviour in kernel/time/time.c:783:2
signed integer overflow:
5273 + 9223372036854771711 cannot be represented in type 'long int'
CPU: 0 PID: 17363 Comm: trinity-c0 Not tainted 4.8.0-rc1+ #88
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org
04/01/2014
0000000000000000 ffff88011457f8f0 ffffffff82344f50 0000000041b58ab3
ffffffff84f98080 ffffffff82344ea4 ffff88011457f918 ffff88011457f8c8
ffff88011457f8e0 7fffffffffffefff ffff88011457f6d8 dffffc0000000000
Call Trace:
[<ffffffff82344f50>] dump_stack+0xac/0xfc
[<ffffffff82344ea4>] ? _atomic_dec_and_lock+0xc4/0xc4
[<ffffffff8242f4c8>] ubsan_epilogue+0xd/0x8a
[<ffffffff8242fc04>] handle_overflow+0x202/0x23d
[<ffffffff8242fa02>] ? val_to_string.constprop.6+0x11e/0x11e
[<ffffffff823c7837>] ? debug_smp_processor_id+0x17/0x20
[<ffffffff8131b581>] ? __sigqueue_free.part.13+0x51/0x70
[<ffffffff8146d4e0>] ? rcu_is_watching+0x110/0x110
[<ffffffff8242fc4d>] __ubsan_handle_add_overflow+0xe/0x10
[<ffffffff81476ef8>] timespec64_add_safe+0x298/0x340
[<ffffffff81476c60>] ? timespec_add_safe+0x330/0x330
[<ffffffff812f7990>] ? wait_noreap_copyout+0x1d0/0x1d0
[<ffffffff8184bf18>] poll_select_set_timeout+0xf8/0x170
[<ffffffff8184be20>] ? poll_schedule_timeout+0x2b0/0x2b0
[<ffffffff813aa9bb>] ? __might_sleep+0x5b/0x260
[<ffffffff833c8a87>] __sys_recvmmsg+0x107/0x790
[<ffffffff833c8980>] ? SyS_recvmsg+0x20/0x20
[<ffffffff81486378>] ? hrtimer_start_range_ns+0x3b8/0x1380
[<ffffffff845f8bfb>] ? _raw_spin_unlock_irqrestore+0x3b/0x60
[<ffffffff8148bcea>] ? do_setitimer+0x39a/0x8e0
[<ffffffff813aa9bb>] ? __might_sleep+0x5b/0x260
[<ffffffff833c9110>] ? __sys_recvmmsg+0x790/0x790
[<ffffffff833c91e9>] SyS_recvmmsg+0xd9/0x160
[<ffffffff833c9110>] ? __sys_recvmmsg+0x790/0x790
[<ffffffff823c7853>] ? __this_cpu_preempt_check+0x13/0x20
[<ffffffff8162f680>] ? __context_tracking_exit.part.3+0x30/0x1b0
[<ffffffff833c9110>] ? __sys_recvmmsg+0x790/0x790
[<ffffffff81007bd3>] do_syscall_64+0x1b3/0x4b0
[<ffffffff845f936a>] entry_SYSCALL64_slow_path+0x25/0x25
================================================================================

Line 783 is this:

783 set_normalized_timespec64(&res, lhs.tv_sec + rhs.tv_sec,
784 lhs.tv_nsec + rhs.tv_nsec);

In other words, since lhs.tv_sec and rhs.tv_sec are both time64_t, this
is a signed addition which will cause undefined behaviour on overflow.

Note that this is not currently a huge concern since the kernel should be
built with -fno-strict-overflow by default, but could be a problem in the
future, a problem with older compilers, or other compilers than gcc.

The easiest way to avoid the overflow is to cast one of the arguments to
unsigned (so the addition will be done using unsigned arithmetic).

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: remove timespec_add_safe()

All references to timespec_add_safe() now use timespec64_add_safe().

The plan is to replace struct timespec references with struct timespec64
throughout the kernel as timespec is not y2038 safe.

Drop timespec_add_safe() and use timespec64_add_safe() for all
architectures.

Link: http://lkml.kernel.org/r/1461947989-21926-4-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

time: add missing implementation for timespec64_add_safe()

timespec64_add_safe() has been defined in time64.h for 64 bit systems.
But, 32 bit systems only have an extern function prototype defined.
Provide a definition for the above function.

The function will be necessary as part of y2038 changes. struct
timespec is not y2038 safe. All references to timespec will be replaced
by struct timespec64. The function is meant to be a replacement for
timespec_add_safe().

The implementation is similar to timespec_add_safe().

Link: http://lkml.kernel.org/r/1461947989-21926-2-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

time: Introduce do_sys_settimeofday64()

The do_sys_settimeofday() function uses a timespec, which is not year
2038 safe on 32bit systems.

Thus this patch introduces do_sys_settimeofday64(), which allows us to
transition users of do_sys_settimeofday() to using 64bit time types.

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
[jstultz: Include errno-base.h to avoid build issue on some arches]
Signed-off-by: John Stultz <john.stultz@linaro.org>

Handle ISO 8601 leap seconds and encodings of midnight in mktime64()

Handle the following ISO 8601 features in mktime64():

(1) Leap seconds.

Leap seconds are indicated by the seconds parameter being the value
60. Handle this by treating it the same as 00 of the following
minute.

It has been pointed out that a minute may contain two leap seconds.
However, pending discussion of what that looks like and how to handle
it, I'm not going to concern myself with it.

(2) Alternate encodings of midnight.

Two different encodings of midnight are permitted - 00:00:00 and
24:00:00 - the first is midnight today and the second is midnight
tomorrow and is exactly equivalent to the first with tomorrow's date.

As it happens, we don't actually need to change mktime64() to handle either
of these - just comment them as valid parameters.

These facility will be used by the X.509 parser. Doing it in mktime64()
makes the policy common to the whole kernel and easier to find.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
cc: John Stultz <john.stultz@linaro.org>
cc: Rudolf Polzer <rpolzer@google.com>
cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>

time: Introduce timespec64_to_jiffies()/jiffies_to_timespec64()

The conversion between struct timespec and jiffies is not year 2038
safe on 32bit systems. Introduce timespec64_to_jiffies() and
jiffies_to_timespec64() functions which use struct timespec64 to
make it ready for 2038 issue.

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Fix nanosecond file time rounding in timespec_trunc()

timespec_trunc() avoids rounding if granularity <= nanoseconds-per-jiffie
(or TICK_NSEC). This optimization assumes that:

1. current_kernel_time().tv_nsec is already rounded to TICK_NSEC (i.e.
with HZ=1000 you'd get 1000000, 2000000, 3000000... but never 1000001).
This is no longer true (probably since hrtimers introduced in 2.6.16).

2. TICK_NSEC is evenly divisible by all possible granularities. This may
be true for HZ=100, 250, 1000, but obviously not for HZ=300 /
TICK_NSEC=3333333 (introduced in 2.6.20).

Thus, sub-second portions of in-core file times are not rounded to on-disk
granularity. I.e. file times may change when the inode is re-read from disk
or when the file system is remounted.

This affects all file systems with file time granularities > 1 ns and < 1s,
e.g. CEPH (1000 ns), UDF (1000 ns), CIFS (100 ns), NTFS (100 ns) and FUSE
(configurable from user mode via struct fuse_init_out.time_gran).

Steps to reproduce with e.g. UDF:

$ dd if=/dev/zero of=udfdisk count=10000 && mkudffs udfdisk
$ mkdir udf && mount udfdisk udf
$ touch udf/test && stat -c %y udf/test
2015-06-09 10:22:56.130006767 +0200
$ umount udf && mount udfdisk udf
$ stat -c %y udf/test
2015-06-09 10:22:56.130006000 +0200

Remounting truncates the mtime to 1 µs.

Fix the rounding in timespec_trunc() and update the documentation.

timespec_trunc() is exclusively used to calculate inode's [acm]time (mostly
via current_fs_time()), and always with super_block.s_time_gran as second
argument. So this can safely be changed without side effects.

Note: This does _not_ fix the issue for FAT's 2 second mtime resolution,
as super_block.s_time_gran isn't prepared to handle different ctime /
mtime / atime resolutions nor resolutions > 1 second.

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

jiffies: Remove HZ > USEC_PER_SEC special case

HZ never goes much further 1000 and a bit. And if we ever reach one tick
per microsecond, we might be having a problem.

Lets stop maintaining this special case, just leave a paranoid check.

Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc; John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

time: Refactor usecs_to_jiffies

Refactor the usecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability. This is analogous to the msecs_to_jiffies()
cleanup in commit ca42aaf0c861 ("time: Refactor msecs_to_jiffies")

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1432832996-12129-1-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

time: Make sure tz_minuteswest is set to a valid value when setting time

Invalid values may overflow later, leading to undefined behaviour when
multiplied by 60 to get the amount of seconds.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Refactor msecs_to_jiffies

Refactor the msecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability.

[ tglx: Verified that there is no binary code change ]

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-2-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

time: Move timeconst.h into include/generated

kernel/time/timeconst.h is moved to include/generated/ and generated
by the top level Kbuild. This allows using timeconst.h in an earlier
build stage.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-1-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

time: settimeofday: Validate the values of tv from user

An unvalidated user input is multiplied by a constant, which can result in
an undefined behaviour for large values. While this is validated later,
we should avoid triggering undefined behaviour.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
[jstultz: include trivial milisecond->microsecond correction noticed
by Andy]
Signed-off-by: John Stultz <john.stultz@linaro.org>

drm/i915: compute wait_ioctl timeout correctly

We've lost the +1 required for correct timeouts in

commit 5ed0bdf21a85d78e04f89f15ccf227562177cbd9
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Wed Jul 16 21:05:06 2014 +0000

drm: i915: Use nsec based interfaces

Use ktime_get_raw_ns() and get rid of the back and forth timespec
conversions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: John Stultz <john.stultz@linaro.org>

So fix this up by reinstating our handrolled _timeout function. While
at it bother with handling MAX_JIFFIES.

v2: Convert to usecs (we don't care about the accuracy anyway) first
to avoid overflow issues Dave Gordon spotted.

v3: Drop the explicit MAX_JIFFY_OFFSET check, usecs_to_jiffies should
take care of that already. It might be a bit too enthusiastic about it
though.

v4: Chris has a much nicer color, so use his implementation.

This requires to export nsec_to_jiffies from time.c.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82749
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

time: Provide y2038 safe mktime() replacement

As part of addressing "y2038 problem" for in-kernel uses, this
patch adds safe mktime64() using time64_t.

After this patch, mktime() is deprecated and all its call sites
will be fixed using mktime64(), after that it can be removed.

Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

jiffies: Fix timeval conversion to jiffies

timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:

setitimer(ITIMER_PROF, &val, NULL);
setitimer(ITIMER_PROF, NULL, &val);

would add a full tick to val, _even if it was exactly representable in
terms of jiffies_ (say, the result of a previous rounding.) Doing
this repeatedly would cause unbounded growth in val. So fix the math.

Here's what was wrong with the conversion: we essentially computed
(eliding seconds)

jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)

by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:

jiffies = (usec * x) >> USEC_JIFFIE_SC

and rounded this calculation up in the intermediate form (since we
can't necessarily exactly represent TICK_NSEC in usec.) But the
scaling arithmetic is a (very slight) *over*approximation of the true
value; that is, instead of dividing by (1 usec/ 1 jiffie), we
effectively divided by (1 usec/1 jiffie)-epsilon (rounding
down). This would normally be fine, but we want to round timeouts up,
and we did so by adding 2^USEC_JIFFIE_SC - 1 before the shift; this
would be fine if our division was exact, but dividing this by the
slightly smaller factor was equivalent to adding just _over_ 1 to the
final result (instead of just _under_ 1, as desired.)

In particular, with HZ=1000, we consistently computed that 10000 usec
was 11 jiffies; the same was true for any exact multiple of
TICK_NSEC.

We could possibly still round in the intermediate form, adding
something less than 2^USEC_JIFFIE_SC - 1, but easier still is to
convert usec->nsec, round in nanoseconds, and then convert using
time*spec*_to_jiffies. This adds one constant multiplication, and is
not observably slower in microbenchmarks on recent x86 hardware.

Tested: the following program:

int main() {
struct itimerval zero = {{0, 0}, {0, 0}};
/* Initially set to 10 ms. */
struct itimerval initial = zero;
initial.it_interval.tv_usec = 10000;
setitimer(ITIMER_PROF, &initial, NULL);
/* Save and restore several times. */
for (size_t i = 0; i < 10; ++i) {
struct itimerval prev;
setitimer(ITIMER_PROF, &zero, &prev);
/* on old kernels, this goes up by TICK_USEC every iteration */
printf("previous value: %ld %ld %ld %ld\n",
prev.it_interval.tv_sec, prev.it_interval.tv_usec,
prev.it_value.tv_sec, prev.it_value.tv_usec);
setitimer(ITIMER_PROF, &prev, NULL);
}
return 0;
}

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Reviewed-by: Paul Turner <pjt@google.com>
Reported-by: Aaron Jacobs <jacobsa@google.com>
Signed-off-by: Andrew Hunter <ahh@google.com>
[jstultz: Tweaked to apply to 3.17-rc]
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Export nsecs_to_jiffies()

Required for moving drivers to the nanosecond based interfaces.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Consolidate the time accessor prototypes

Right now we have time related prototypes in 3 different header
files. Move it to a single timekeeping header file and move the core
internal stuff into a core private header.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: More core infrastructure for timespec64

Helper and conversion functions for timespec64.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time/timers: Move all time(r) related files into kernel/time

Except for Kconfig.HZ. That needs a separate treatment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>