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| author |   Andrei Vagin <avagin@gmail.com> | 2019-11-12 01:27:01 +0000 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2020-01-14 12:20:53 +0100 |
| commit | 89dd8eecfe961fab4924dcd14f80cf2ab2820044 (patch) | |
| tree | fcc408a7d8f1bc04818a7ef436791e14d8a38092 /kernel/time | |
| parent | posix-clocks: Wire up clock_gettime() with timens offsets (diff) | |
| download | linux-dev-89dd8eecfe961fab4924dcd14f80cf2ab2820044.tar.xz linux-dev-89dd8eecfe961fab4924dcd14f80cf2ab2820044.zip | |
time: Add do_timens_ktime_to_host() helper
The helper subtracts namespace's clock offset from the given time
and ensures that the result is within [0, KTIME_MAX].
Co-developed-by: Dmitry Safonov <dima@arista.com>
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/20191112012724.250792-13-dima@arista.com
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/namespace.c | 36 |
1 files changed, 36 insertions, 0 deletions
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); |