- 14 Jan, 2020 38 commits
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Dmitry Safonov authored
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> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20191112012724.250792-29-dima@arista.com
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Andrei Vagin authored
API to set time namespace offsets for children processes, i.e.: echo "$clockid $offset_sec $offset_nsec" > /proc/self/timens_offsets Co-developed-by:
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Dmitry Safonov authored
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 be re-faulted with a corresponding layout. Co-developed-by:
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Dmitry Safonov authored
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:
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Dmitry Safonov authored
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:
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Dmitry Safonov authored
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 setup and to freeze offsets when the first task joins the new time namespace. That is better in terms of memory usage compared to having a per namespace mutex that's used only during the setup period. Suggested-by:
Andy Lutomirski <luto@kernel.org> Based-on-work-by:
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Dmitry Safonov authored
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 the time namespace 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:
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Dmitry Safonov authored
VDSO support for time namespaces 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 the time namespace page the kernel needs to know the vdso_data offset. Provide arch_get_vdso_data() helper for locating vdso_data on VVAR page. Co-developed-by:
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Thomas Gleixner authored
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. [avagin: Make do_hres_timens() work with raw clocks too: choose vdso_data pointer by CS_RAW offset.] Suggested-by:
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Dmitry Safonov authored
Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the amount of corner-cases to consider while working further on VDSO time namespace support. As the 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:
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Dmitry Safonov authored
Make sure that /proc/uptime is adjusted to the tasks time namespace. Co-developed-by:
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Andrei Vagin authored
clock_nanosleep() accepts absolute values of expiration time, if the TIMER_ABSTIME flag is set. This value is in the tasks time namespace, which has to be converted to the host time namespace. Co-developed-by:
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Andrei Vagin authored
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. Co-developed-by:
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Andrei Vagin authored
clock_nanosleep() accepts absolute values of expiration time when the 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. Co-developed-by:
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Andrei Vagin authored
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. The user-supplied expiry 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 differs by a fixed offset from a user-supplied time, but only absolute values (TIMER_ABSTIME) must be converted. Co-developed-by:
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Andrei Vagin authored
timerfd_settime() accepts an absolute value of the expiration time if TFD_TIMER_ABSTIME is specified. This value is in the task's time namespace and has to be converted to the host's time namespace. Co-developed-by:
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Andrei Vagin authored
The helper subtracts namespace's clock offset from the given time and ensures that the result is within [0, KTIME_MAX]. Co-developed-by:
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Andrei Vagin authored
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 when the namespace was created Note that applications usually go through vDSO to get time, which is not yet adjusted. Further changes will complete time namespace virtualisation with vDSO support. Co-developed-by:
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Andrei Vagin authored
Now, when the clock_get_ktime() callback exists, the suboptimal timespec64-based conversion can be removed from common_timer_get(). Suggested-by:
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Andrei Vagin authored
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: -
Andrei Vagin authored
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:
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Andrei Vagin authored
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 naming convention, so rename .gettime() callback into get_ktime() as a preparation for introducing get_timespec(). Suggested-by:
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Andrei Vagin authored
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 the callback implementations. Suggested-by:
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Andrei Vagin authored
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:
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Andrei Vagin authored
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. Co-developed-by:
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Andrei Vagin authored
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). Providing per namespace notions of CLOCK_REALTIME would be complex with a massive overhead, but has a dubious value. But in the context of checkpoint/restore functionality, monotonic and boottime clocks become interesting. Both clocks are monotonic with unspecified starting points. These clocks are widely used to measure time slices and set timers. After restoring or migrating processes, it has to be guaranteed 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 it is required to set CLOCK_MONOTONIC and CLOCK_BOOTTIME clocks, which can be achieved by adding per-namespace offsets for clocks. A time namespace is similar to a pid namespace in the 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 it can be used only with the unshare() and the clone3() system calls. [ tglx: Adjusted paragraph about clone3() to reality and massaged the changelog a bit. ] Co-developed-by: -
Andrei Vagin authored
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% The improvement for arm64 for monotonic and boottime is around 3.5%. 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% [ tglx: Avoid the goto ] Signed-off-by:
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Andrei Vagin authored
Place the branch with no concurrent write before the 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 Co-developed-by:Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by:
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Christophe Leroy authored
VDSO_HRES and VDSO_RAW clocks are handled the same way. Avoid the code duplication. Signed-off-by:
Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by:
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Christophe Leroy authored
do_coarse() is similar to do_hres() except that it never fails. Change its type to int instead of void and let it always return success (0) to simplify the call site. Signed-off-by:
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Vincenzo Frascino authored
VDSO_HAS_32BIT_FALLBACK has been removed from the core since the architectures that support the generic vDSO library have been converted to support the 32 bit fallbacks. Remove unused VDSO_HAS_32BIT_FALLBACK from x86 vdso. Signed-off-by:
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Vincenzo Frascino authored
VDSO_HAS_32BIT_FALLBACK has been removed from the core since the architectures that support the generic vDSO library have been converted to support the 32 bit fallbacks. Remove unused VDSO_HAS_32BIT_FALLBACK from mips vdso. Signed-off-by:
Paul Burton <paul.burton@mips.com> Link: https://lore.kernel.org/r/20190830135902.20861-8-vincenzo.frascino@arm.com
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Vincenzo Frascino authored
VDSO_HAS_32BIT_FALLBACK has been removed from the core since the architectures that support the generic vDSO library have been converted to support the 32 bit fallbacks. Remove unused VDSO_HAS_32BIT_FALLBACK from arm64 compat vdso. Signed-off-by:
Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20190830135902.20861-7-vincenzo.frascino@arm.com
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Vincenzo Frascino authored
Since all the architectures that support the generic vDSO library have been converted to support the 32 bit fallbacks it is not required anymore to check the return value of __cvdso_clock_get*time32_common() before updating the old_timespec fields. Remove the related checks from the generic vdso library. References: c60a32ea ("lib/vdso/32: Provide legacy syscall fallbacks") Signed-off-by:
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Vincenzo Frascino authored
VDSO_HAS_32BIT_FALLBACK was introduced to address a regression which caused seccomp to deny access to the applications to clock_gettime64() and clock_getres64() because they are not enabled in the existing filters. The purpose of VDSO_HAS_32BIT_FALLBACK was to simplify the conditional implementation of __cvdso_clock_get*time32() variants. Now that all the architectures that support the generic vDSO library have been converted to support the 32 bit fallbacks the conditional can be removed. Signed-off-by:
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Vincenzo Frascino authored
clock_gettime32 and clock_getres_time32 should be compiled only with a 32 bit vdso library. Exclude these symbols when BUILD_VDSO32 is not defined. Signed-off-by:
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Thomas Gleixner authored
Setting BUILD_VDSO32 is required to expose the legacy 32bit interfaces in the generic VDSO code which are going to be hidden behind an #ifdef BUILD_VDSO32. The 32bit fallbacks are necessary to remove the existing VDSO_HAS_32BIT_FALLBACK hackery. Signed-off-by:
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Vincenzo Frascino authored
clock_gettime32 and clock_getres_time32 should be compiled only with the 32 bit vdso library. Expose BUILD_VDSO32 when arm64 compat is compiled, to provide an indication to the generic library to include these symbols. Signed-off-by:
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- 10 Jan, 2020 2 commits
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Thomas Gleixner authored
Pick up upstream VDSO fix before adding more VDSO changes.
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Vincenzo Frascino authored
Fix the following sparse warning in the generic vDSO library: linux/lib/vdso/gettimeofday.c:224:5: warning: symbol '__cvdso_clock_getres' was not declared. Should it be static? Make it static and also mark it __maybe_unsed. Fixes: 502a590a ("lib/vdso: Move fallback invocation to the callers") Reported-by:
Marc Gonzalez <marc.w.gonzalez@free.fr> Signed-off-by:
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