talos-op-linux/kernel/time/time.c, branch v4.17

y2038: Introduce struct __kernel_old_timeval

2018-03-19T14:23:03+00:00

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 Signed-off-by: Thomas Gleixner Cc: Stephen Boyd Cc: John Stultz Cc: Al Viro Link: https://lkml.kernel.org/r/20180315161739.576085-1-arnd@arndb.de

Merge branch 'fortglx/4.15/time' of https://git.linaro.org/people/john.stultz/linux into timers/core

2017-10-31T22:17:28+00:00

Pull timekeeping updates from John Stultz: - More y2038 work from Arnd Bergmann - A new mechanism to allow RTC drivers to specify the resolution of the RTC so the suspend/resume code can make informed decisions whether to inject the suspended time or not in case of fast suspend/resume cycles.

time: Move time_t conversion helpers to time32.h

2017-10-30T22:17:19+00:00

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 Cc: Ingo Molnar Cc: Miroslav Lichvar Cc: Richard Cochran Cc: Prarit Bhargava Cc: Stephen Boyd Signed-off-by: Arnd Bergmann Signed-off-by: John Stultz

time: Remove unused functions

2017-10-30T22:14:18+00:00

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 Cc: Ingo Molnar Cc: Miroslav Lichvar Cc: Richard Cochran Cc: Prarit Bhargava Cc: Stephen Boyd Signed-off-by: Arnd Bergmann Signed-off-by: John Stultz

timekeeping: Consolidate timekeeping_inject_offset code

2017-10-30T22:13:35+00:00

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 Cc: Ingo Molnar Cc: Miroslav Lichvar Cc: Richard Cochran Cc: Prarit Bhargava Cc: Stephen Boyd Signed-off-by: Arnd Bergmann [jstultz: Whitespace fixup] Signed-off-by: John Stultz

time: Use do_settimeofday64() internally

2017-10-17T15:22:28+00:00

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 Signed-off-by: Thomas Gleixner Cc: y2038@lists.linaro.org Cc: Frederic Weisbecker Cc: Stephen Boyd Cc: John Stultz Cc: Al Viro Cc: Deepa Dinamani Link: https://lkml.kernel.org/r/20171013183452.3635956-1-arnd@arndb.de

time: introduce {get,put}_itimerspec64

2017-06-26T01:58:46+00:00

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 Signed-off-by: Deepa Dinamani Signed-off-by: Al Viro

time: add get_timespec64 and put_timespec64

2017-06-26T01:58:46+00:00

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 Signed-off-by: Deepa Dinamani Signed-off-by: Al Viro

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

2017-06-13T22:00:46+00:00

Signed-off-by: Al Viro Signed-off-by: Thomas Gleixner Cc: John Stultz Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170607084241.28657-16-viro@ZenIV.linux.org.uk

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

2017-06-13T22:00:45+00:00

Signed-off-by: Al Viro Signed-off-by: Thomas Gleixner Cc: John Stultz Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170607084241.28657-15-viro@ZenIV.linux.org.uk