[PATCH 5/8] posix-timers: Use get_timepsec64() and put_timespec64()

[Deepa Dinamani]

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.kernel@xxxxxxxxx>
---
 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