Usage of these apis and their compat versions makes
the syscalls: clock_gettime, clock_settime, clock_getres
and their compat implementations simpler.

This is a preparatory patch to isolate data conversions to
struct timespec64 at userspace boundaries. This helps contain
the changes needed to transition to new y2038 safe types.

Signed-off-by: Deepa Dinamani <deepa.ker...@gmail.com>
---
 kernel/time/posix-stubs.c  | 111 ++++++++++++++++++++++++---------------------
 kernel/time/posix-timers.c |  75 +++++++++++++-----------------
 2 files changed, 91 insertions(+), 95 deletions(-)

diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 61daf3576e85..da3fa8f9181a 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -53,40 +53,52 @@ SYS_NI(alarm);
 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
                const struct timespec __user *, tp)
 {
-       struct timespec64 new_tp64;
-       struct timespec new_tp;
+       struct timespec64 new_tp;
 
        if (which_clock != CLOCK_REALTIME)
                return -EINVAL;
-       if (copy_from_user(&new_tp, tp, sizeof (*tp)))
+       if (get_timespec64(&new_tp, tp))
                return -EFAULT;
 
-       new_tp64 = timespec_to_timespec64(new_tp);
-       return do_sys_settimeofday64(&new_tp64, NULL);
+       return do_sys_settimeofday64(&new_tp, NULL);
 }
 
-SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
-               struct timespec __user *,tp)
+int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 {
-       struct timespec64 kernel_tp64;
-       struct timespec kernel_tp;
-
        switch (which_clock) {
-       case CLOCK_REALTIME: ktime_get_real_ts64(&kernel_tp64); break;
-       case CLOCK_MONOTONIC: ktime_get_ts64(&kernel_tp64); break;
-       case CLOCK_BOOTTIME: get_monotonic_boottime64(&kernel_tp64); break;
-       default: return -EINVAL;
+       case CLOCK_REALTIME:
+               ktime_get_real_ts64(tp);
+               break;
+       case CLOCK_MONOTONIC:
+               ktime_get_ts64(tp);
+               break;
+       case CLOCK_BOOTTIME:
+               get_monotonic_boottime64(tp);
+               break;
+       default:
+               return -EINVAL;
        }
 
-       kernel_tp = timespec64_to_timespec(kernel_tp64);
-       if (copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
+       return 0;
+}
+SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
+               struct timespec __user *, tp)
+{
+       int ret;
+       struct timespec64 kernel_tp;
+
+       ret = do_clock_gettime(which_clock, &kernel_tp);
+       if (ret)
+               return ret;
+
+       if (put_timespec64(&kernel_tp, tp))
                return -EFAULT;
        return 0;
 }
 
 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock, struct timespec 
__user *, tp)
 {
-       struct timespec rtn_tp = {
+       struct timespec64 rtn_tp = {
                .tv_sec = 0,
                .tv_nsec = hrtimer_resolution,
        };
@@ -95,7 +107,7 @@ SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock, 
struct timespec __us
        case CLOCK_REALTIME:
        case CLOCK_MONOTONIC:
        case CLOCK_BOOTTIME:
-               if (copy_to_user(tp, &rtn_tp, sizeof(rtn_tp)))
+               if (put_timespec64(&rtn_tp, tp))
                        return -EFAULT;
                return 0;
        default:
@@ -151,52 +163,49 @@ COMPAT_SYS_NI(timer_settime);
 COMPAT_SYSCALL_DEFINE2(clock_settime, clockid_t, which_clock,
                       struct compat_timespec __user *, tp)
 {
-       long err;
-       mm_segment_t oldfs;
-       struct timespec ts;
+       struct timespec64 new_tp;
 
-       if (compat_get_timespec(&ts, tp))
+       if (which_clock != CLOCK_REALTIME)
+               return -EINVAL;
+       if (compat_get_timespec64(&new_tp, tp))
                return -EFAULT;
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       err = sys_clock_settime(which_clock,
-                               (struct timespec __user *) &ts);
-       set_fs(oldfs);
-       return err;
+
+       return do_sys_settimeofday64(&new_tp, NULL);
 }
 
 COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
                       struct compat_timespec __user *, tp)
 {
-       long err;
-       mm_segment_t oldfs;
-       struct timespec ts;
-
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       err = sys_clock_gettime(which_clock,
-                               (struct timespec __user *) &ts);
-       set_fs(oldfs);
-       if (!err && compat_put_timespec(&ts, tp))
+       int ret;
+       struct timespec64 kernel_tp;
+
+       ret = do_clock_gettime(which_clock, &kernel_tp);
+       if (ret)
+               return ret;
+
+       if (compat_put_timespec64(&kernel_tp, tp))
                return -EFAULT;
-       return err;
+       return 0;
 }
 
 COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
                       struct compat_timespec __user *, tp)
 {
-       long err;
-       mm_segment_t oldfs;
-       struct timespec ts;
-
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       err = sys_clock_getres(which_clock,
-                              (struct timespec __user *) &ts);
-       set_fs(oldfs);
-       if (!err && tp && compat_put_timespec(&ts, tp))
-               return -EFAULT;
-       return err;
+       struct timespec64 rtn_tp = {
+               .tv_sec = 0,
+               .tv_nsec = hrtimer_resolution,
+       };
+
+       switch (which_clock) {
+       case CLOCK_REALTIME:
+       case CLOCK_MONOTONIC:
+       case CLOCK_BOOTTIME:
+               if (compat_put_timespec64(&rtn_tp, tp))
+                       return -EFAULT;
+               return 0;
+       default:
+               return -EINVAL;
+       }
 }
 
 COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 58c2f9c2c2c8..58ed4e759485 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -949,34 +949,30 @@ SYSCALL_DEFINE2(clock_settime, const clockid_t, 
which_clock,
                const struct timespec __user *, tp)
 {
        const struct k_clock *kc = clockid_to_kclock(which_clock);
-       struct timespec64 new_tp64;
-       struct timespec new_tp;
+       struct timespec64 new_tp;
 
        if (!kc || !kc->clock_set)
                return -EINVAL;
 
-       if (copy_from_user(&new_tp, tp, sizeof (*tp)))
+       if (get_timespec64(&new_tp, tp))
                return -EFAULT;
-       new_tp64 = timespec_to_timespec64(new_tp);
 
-       return kc->clock_set(which_clock, &new_tp64);
+       return kc->clock_set(which_clock, &new_tp);
 }
 
 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
                struct timespec __user *,tp)
 {
        const struct k_clock *kc = clockid_to_kclock(which_clock);
-       struct timespec64 kernel_tp64;
-       struct timespec kernel_tp;
+       struct timespec64 kernel_tp;
        int error;
 
        if (!kc)
                return -EINVAL;
 
-       error = kc->clock_get(which_clock, &kernel_tp64);
-       kernel_tp = timespec64_to_timespec(kernel_tp64);
+       error = kc->clock_get(which_clock, &kernel_tp);
 
-       if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
+       if (!error && put_timespec64(&kernel_tp, tp))
                error = -EFAULT;
 
        return error;
@@ -1009,17 +1005,15 @@ SYSCALL_DEFINE2(clock_getres, const clockid_t, 
which_clock,
                struct timespec __user *, tp)
 {
        const struct k_clock *kc = clockid_to_kclock(which_clock);
-       struct timespec64 rtn_tp64;
-       struct timespec rtn_tp;
+       struct timespec64 rtn_tp;
        int error;
 
        if (!kc)
                return -EINVAL;
 
-       error = kc->clock_getres(which_clock, &rtn_tp64);
-       rtn_tp = timespec64_to_timespec(rtn_tp64);
+       error = kc->clock_getres(which_clock, &rtn_tp);
 
-       if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
+       if (!error && tp && put_timespec64(&rtn_tp, tp))
                error = -EFAULT;
 
        return error;
@@ -1265,51 +1259,44 @@ COMPAT_SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
 COMPAT_SYSCALL_DEFINE2(clock_settime, clockid_t, which_clock,
                       struct compat_timespec __user *, tp)
 {
-       long err;
-       mm_segment_t oldfs;
-       struct timespec ts;
+       const struct k_clock *kc = clockid_to_kclock(which_clock);
+       struct timespec64 ts;
 
-       if (compat_get_timespec(&ts, tp))
+       if (compat_get_timespec64(&ts, tp))
                return -EFAULT;
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       err = sys_clock_settime(which_clock,
-                               (struct timespec __user *) &ts);
-       set_fs(oldfs);
-       return err;
+
+       return kc->clock_set(which_clock, &ts);
 }
 
 COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
                       struct compat_timespec __user *, tp)
 {
-       long err;
-       mm_segment_t oldfs;
-       struct timespec ts;
+       const struct k_clock *kc = clockid_to_kclock(which_clock);
+       struct timespec64 ts;
+       int err;
+
+       if (!kc)
+               return -EINVAL;
+
+       err = kc->clock_get(which_clock, &ts);
+
+       if (!err && compat_put_timespec64(&ts, tp))
+               err = -EFAULT;
 
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       err = sys_clock_gettime(which_clock,
-                               (struct timespec __user *) &ts);
-       set_fs(oldfs);
-       if (!err && compat_put_timespec(&ts, tp))
-               return -EFAULT;
        return err;
 }
 
 COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
                       struct compat_timespec __user *, tp)
 {
-       long err;
-       mm_segment_t oldfs;
-       struct timespec ts;
+       const struct k_clock *kc = clockid_to_kclock(which_clock);
+       struct timespec64 ts;
+       int err;
 
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       err = sys_clock_getres(which_clock,
-                              (struct timespec __user *) &ts);
-       set_fs(oldfs);
-       if (!err && tp && compat_put_timespec(&ts, tp))
+       err = kc->clock_getres(which_clock, &ts);
+       if (!err && tp && compat_put_timespec64(&ts, tp))
                return -EFAULT;
+
        return err;
 }
 #endif
-- 
2.11.0

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