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Subject[RFC 03/20] timens: Introduce CLOCK_MONOTONIC offsets
Date
From: Andrei Vagin <avagin@openvz.org>

Adds monotonic time virtualisation for time namespace.
Provide clock_set() API to set monotonic time inside ns.

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/timens_offsets.h | 1 +
kernel/time/posix-timers.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)

diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index 7d7cb68ea778..248b0c0bb92a 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -3,6 +3,7 @@
#define _LINUX_TIME_OFFSETS_H

struct timens_offsets {
+ struct timespec64 monotonic_time_offset;
};

#endif
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 4b9127e95430..3c1f98760dec 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -51,6 +51,7 @@
#include <linux/hashtable.h>
#include <linux/compat.h>
#include <linux/nospec.h>
+#include <linux/time_namespace.h>

#include "timekeeping.h"
#include "posix-timers.h"
@@ -205,12 +206,40 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
return do_adjtimex(t);
}

+static void timens_adjust_monotonic(struct timespec64 *tp)
+{
+ struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
+
+ if (ns_offsets)
+ *tp = timespec64_add(*tp, ns_offsets->monotonic_time_offset);
+}
+
+static int posix_ktime_set_ts(clockid_t which_clock,
+ const struct timespec64 *tp)
+{
+ struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
+ struct timespec64 ktp;
+
+ if (!ns_capable(current->nsproxy->time_ns->user_ns, CAP_SYS_TIME))
+ return -EPERM;
+
+ ktime_get_ts64(&ktp);
+
+ if (ns_offsets)
+ ns_offsets->monotonic_time_offset = timespec64_sub(*tp, ktp);
+ else
+ return -EINVAL;
+
+ return 0;
+}
+
/*
* Get monotonic time for posix timers
*/
static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
{
ktime_get_ts64(tp);
+ timens_adjust_monotonic(tp);
return 0;
}

@@ -220,6 +249,7 @@ static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
{
ktime_get_raw_ts64(tp);
+ timens_adjust_monotonic(tp);
return 0;
}

@@ -234,6 +264,7 @@ static int posix_get_monotonic_coarse(clockid_t which_clock,
struct timespec64 *tp)
{
ktime_get_coarse_ts64(tp);
+ timens_adjust_monotonic(tp);
return 0;
}

@@ -1283,6 +1314,7 @@ 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_set = posix_ktime_set_ts,
.nsleep = common_nsleep,
.timer_create = common_timer_create,
.timer_set = common_timer_set,
@@ -1298,6 +1330,7 @@ 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_set = posix_ktime_set_ts,
};

static const struct k_clock clock_realtime_coarse = {
@@ -1308,6 +1341,7 @@ static const struct k_clock clock_realtime_coarse = {
static const struct k_clock clock_monotonic_coarse = {
.clock_getres = posix_get_coarse_res,
.clock_get = posix_get_monotonic_coarse,
+ .clock_set = posix_ktime_set_ts,
};

static const struct k_clock clock_tai = {
--
2.13.6
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