[PATCH V8 03/13] posix clocks: introduce a syscall for clock tuning.

Richard Cochran
2010-12-31T19:13:18Z

A new syscall is introduced that allows tuning of a POSIX clock. The
new call, clock_adjtime, takes two parameters, the clock ID and a
pointer to a struct timex. Any ADJTIMEX(2) operation may be requested
via this system call, but various POSIX clocks may or may not support
tuning.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
---
drivers/char/mmtimer.c | 1 +
include/linux/posix-timers.h | 4 +
include/linux/syscalls.h | 2 +
kernel/compat.c | 136 +++++++++++++++++++++++++++---------------
kernel/posix-cpu-timers.c | 6 ++
kernel/posix-timers.c | 35 +++++++++++
6 files changed, 136 insertions(+), 48 deletions(-)

diff --git a/drivers/char/mmtimer.c b/drivers/char/mmtimer.c
index e6d7562..98f2488 100644
--- a/drivers/char/mmtimer.c
+++ b/drivers/char/mmtimer.c
@@ -767,6 +767,7 @@ static struct k_clock sgi_clock = {
.res = 0,
.clock_set = sgi_clock_set,
.clock_get = sgi_clock_get,
+ .clock_adj = do_posix_clock_noadjtime,
.timer_create = sgi_timer_create,
.nsleep = do_posix_clock_nonanosleep,
.timer_set = sgi_timer_set,
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 3e23844..b05d9b8 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -4,6 +4,7 @@
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h>
+#include <linux/timex.h>

union cpu_time_count {
cputime_t cpu;
@@ -71,6 +72,7 @@ struct k_clock {
int (*clock_getres) (const clockid_t which_clock, struct timespec *tp);
int (*clock_set) (const clockid_t which_clock, struct timespec * tp);
int (*clock_get) (const clockid_t which_clock, struct timespec * tp);
+ int (*clock_adj) (const clockid_t which_clock, struct timex *tx);
int (*timer_create) (struct k_itimer *timer);
int (*nsleep) (const clockid_t which_clock, int flags,
struct timespec *, struct timespec __user *);
@@ -90,6 +92,7 @@ void register_posix_clock(const clockid_t clock_id, struct k_clock *new_clock);
int do_posix_clock_nonanosleep(const clockid_t, int flags, struct timespec *,
struct timespec __user *);
int do_posix_clock_nosettime(const clockid_t, struct timespec *tp);
+int do_posix_clock_noadjtime(const clockid_t, struct timex *tx);

/* function to call to trigger timer event */
int posix_timer_event(struct k_itimer *timr, int si_private);
@@ -97,6 +100,7 @@ int posix_timer_event(struct k_itimer *timr, int si_private);
int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *ts);
int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *ts);
int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *ts);
+int posix_cpu_clock_adj(const clockid_t which_clock, struct timex *tx);
int posix_cpu_timer_create(struct k_itimer *timer);
int posix_cpu_nsleep(const clockid_t which_clock, int flags,
struct timespec *rqtp, struct timespec __user *rmtp);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index cacc27a..c76cefb 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -313,6 +313,8 @@ asmlinkage long sys_clock_settime(clockid_t which_clock,
const struct timespec __user *tp);
asmlinkage long sys_clock_gettime(clockid_t which_clock,
struct timespec __user *tp);
+asmlinkage long sys_clock_adjtime(clockid_t which_clock,
+ struct timex __user *tx);
asmlinkage long sys_clock_getres(clockid_t which_clock,
struct timespec __user *tp);
asmlinkage long sys_clock_nanosleep(clockid_t which_clock, int flags,
diff --git a/kernel/compat.c b/kernel/compat.c
index c9e2ec0..38b1d2c 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -52,6 +52,64 @@ static int compat_put_timeval(struct compat_timeval __user *o,
put_user(i->tv_usec, &o->tv_usec)) ? -EFAULT : 0;
}

+static int compat_get_timex(struct timex *txc, struct compat_timex __user *utp)
+{
+ memset(txc, 0, sizeof(struct timex));
+
+ if (!access_ok(VERIFY_READ, utp, sizeof(struct compat_timex)) ||
+ __get_user(txc->modes, &utp->modes) ||
+ __get_user(txc->offset, &utp->offset) ||
+ __get_user(txc->freq, &utp->freq) ||
+ __get_user(txc->maxerror, &utp->maxerror) ||
+ __get_user(txc->esterror, &utp->esterror) ||
+ __get_user(txc->status, &utp->status) ||
+ __get_user(txc->constant, &utp->constant) ||
+ __get_user(txc->precision, &utp->precision) ||
+ __get_user(txc->tolerance, &utp->tolerance) ||
+ __get_user(txc->time.tv_sec, &utp->time.tv_sec) ||
+ __get_user(txc->time.tv_usec, &utp->time.tv_usec) ||
+ __get_user(txc->tick, &utp->tick) ||
+ __get_user(txc->ppsfreq, &utp->ppsfreq) ||
+ __get_user(txc->jitter, &utp->jitter) ||
+ __get_user(txc->shift, &utp->shift) ||
+ __get_user(txc->stabil, &utp->stabil) ||
+ __get_user(txc->jitcnt, &utp->jitcnt) ||
+ __get_user(txc->calcnt, &utp->calcnt) ||
+ __get_user(txc->errcnt, &utp->errcnt) ||
+ __get_user(txc->stbcnt, &utp->stbcnt))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int compat_put_timex(struct compat_timex __user *utp, struct timex *txc)
+{
+ if (!access_ok(VERIFY_WRITE, utp, sizeof(struct compat_timex)) ||
+ __put_user(txc->modes, &utp->modes) ||
+ __put_user(txc->offset, &utp->offset) ||
+ __put_user(txc->freq, &utp->freq) ||
+ __put_user(txc->maxerror, &utp->maxerror) ||
+ __put_user(txc->esterror, &utp->esterror) ||
+ __put_user(txc->status, &utp->status) ||
+ __put_user(txc->constant, &utp->constant) ||
+ __put_user(txc->precision, &utp->precision) ||
+ __put_user(txc->tolerance, &utp->tolerance) ||
+ __put_user(txc->time.tv_sec, &utp->time.tv_sec) ||
+ __put_user(txc->time.tv_usec, &utp->time.tv_usec) ||
+ __put_user(txc->tick, &utp->tick) ||
+ __put_user(txc->ppsfreq, &utp->ppsfreq) ||
+ __put_user(txc->jitter, &utp->jitter) ||
+ __put_user(txc->shift, &utp->shift) ||
+ __put_user(txc->stabil, &utp->stabil) ||
+ __put_user(txc->jitcnt, &utp->jitcnt) ||
+ __put_user(txc->calcnt, &utp->calcnt) ||
+ __put_user(txc->errcnt, &utp->errcnt) ||
+ __put_user(txc->stbcnt, &utp->stbcnt) ||
+ __put_user(txc->tai, &utp->tai))
+ return -EFAULT;
+ return 0;
+}
+
asmlinkage long compat_sys_gettimeofday(struct compat_timeval __user *tv,
struct timezone __user *tz)
{
@@ -617,6 +675,29 @@ long compat_sys_clock_gettime(clockid_t which_clock,
return err;
}

+long compat_sys_clock_adjtime(clockid_t which_clock,
+ struct compat_timex __user *utp)
+{
+ struct timex txc;
+ mm_segment_t oldfs;
+ int err, ret;
+
+ err = compat_get_timex(&txc, utp);
+ if (err)
+ return err;
+
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = sys_clock_adjtime(which_clock, (struct timex __user *) &txc);
+ set_fs(oldfs);
+
+ err = compat_put_timex(utp, &txc);
+ if (err)
+ return err;
+
+ return ret;
+}
+
long compat_sys_clock_getres(clockid_t which_clock,
struct compat_timespec __user *tp)
{
@@ -951,58 +1032,17 @@ asmlinkage long compat_sys_rt_sigsuspend(compat_sigset_t __user *unewset, compat
asmlinkage long compat_sys_adjtimex(struct compat_timex __user *utp)
{
struct timex txc;
- int ret;
-
- memset(&txc, 0, sizeof(struct timex));
+ int err, ret;

- if (!access_ok(VERIFY_READ, utp, sizeof(struct compat_timex)) ||
- __get_user(txc.modes, &utp->modes) ||
- __get_user(txc.offset, &utp->offset) ||
- __get_user(txc.freq, &utp->freq) ||
- __get_user(txc.maxerror, &utp->maxerror) ||
- __get_user(txc.esterror, &utp->esterror) ||
- __get_user(txc.status, &utp->status) ||
- __get_user(txc.constant, &utp->constant) ||
- __get_user(txc.precision, &utp->precision) ||
- __get_user(txc.tolerance, &utp->tolerance) ||
- __get_user(txc.time.tv_sec, &utp->time.tv_sec) ||
- __get_user(txc.time.tv_usec, &utp->time.tv_usec) ||
- __get_user(txc.tick, &utp->tick) ||
- __get_user(txc.ppsfreq, &utp->ppsfreq) ||
- __get_user(txc.jitter, &utp->jitter) ||
- __get_user(txc.shift, &utp->shift) ||
- __get_user(txc.stabil, &utp->stabil) ||
- __get_user(txc.jitcnt, &utp->jitcnt) ||
- __get_user(txc.calcnt, &utp->calcnt) ||
- __get_user(txc.errcnt, &utp->errcnt) ||
- __get_user(txc.stbcnt, &utp->stbcnt))
- return -EFAULT;
+ err = compat_get_timex(&txc, utp);
+ if (err)
+ return err;

ret = do_adjtimex(&txc);

- if (!access_ok(VERIFY_WRITE, utp, sizeof(struct compat_timex)) ||
- __put_user(txc.modes, &utp->modes) ||
- __put_user(txc.offset, &utp->offset) ||
- __put_user(txc.freq, &utp->freq) ||
- __put_user(txc.maxerror, &utp->maxerror) ||
- __put_user(txc.esterror, &utp->esterror) ||
- __put_user(txc.status, &utp->status) ||
- __put_user(txc.constant, &utp->constant) ||
- __put_user(txc.precision, &utp->precision) ||
- __put_user(txc.tolerance, &utp->tolerance) ||
- __put_user(txc.time.tv_sec, &utp->time.tv_sec) ||
- __put_user(txc.time.tv_usec, &utp->time.tv_usec) ||
- __put_user(txc.tick, &utp->tick) ||
- __put_user(txc.ppsfreq, &utp->ppsfreq) ||
- __put_user(txc.jitter, &utp->jitter) ||
- __put_user(txc.shift, &utp->shift) ||
- __put_user(txc.stabil, &utp->stabil) ||
- __put_user(txc.jitcnt, &utp->jitcnt) ||
- __put_user(txc.calcnt, &utp->calcnt) ||
- __put_user(txc.errcnt, &utp->errcnt) ||
- __put_user(txc.stbcnt, &utp->stbcnt) ||
- __put_user(txc.tai, &utp->tai))
- ret = -EFAULT;
+ err = compat_put_timex(utp, &txc);
+ if (err)
+ return err;

return ret;
}
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 05bb717..0206116 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -207,6 +207,10 @@ int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
return error;
}

+int posix_cpu_clock_adj(const clockid_t which_clock, struct timex *tx)
+{
+ return -EOPNOTSUPP;
+}

/*
* Sample a per-thread clock for the given task.
@@ -1610,6 +1614,7 @@ static __init int init_posix_cpu_timers(void)
.clock_getres = process_cpu_clock_getres,
.clock_get = process_cpu_clock_get,
.clock_set = do_posix_clock_nosettime,
+ .clock_adj = do_posix_clock_noadjtime,
.timer_create = process_cpu_timer_create,
.nsleep = process_cpu_nsleep,
.nsleep_restart = process_cpu_nsleep_restart,
@@ -1618,6 +1623,7 @@ static __init int init_posix_cpu_timers(void)
.clock_getres = thread_cpu_clock_getres,
.clock_get = thread_cpu_clock_get,
.clock_set = do_posix_clock_nosettime,
+ .clock_adj = do_posix_clock_noadjtime,
.timer_create = thread_cpu_timer_create,
.nsleep = thread_cpu_nsleep,
.nsleep_restart = thread_cpu_nsleep_restart,
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 9ca4973..502bde4 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -197,6 +197,11 @@ static int common_timer_create(struct k_itimer *new_timer)
return 0;
}

+static inline int common_clock_adj(const clockid_t which_clock, struct timex *t)
+{
+ return do_adjtimex(t);
+}
+
static int no_timer_create(struct k_itimer *new_timer)
{
return -EOPNOTSUPP;
@@ -273,11 +278,13 @@ static __init int init_posix_timers(void)
.clock_getres = hrtimer_get_res,
.clock_get = posix_ktime_get_ts,
.clock_set = do_posix_clock_nosettime,
+ .clock_adj = do_posix_clock_noadjtime,
};
struct k_clock clock_monotonic_raw = {
.clock_getres = hrtimer_get_res,
.clock_get = posix_get_monotonic_raw,
.clock_set = do_posix_clock_nosettime,
+ .clock_adj = do_posix_clock_noadjtime,
.timer_create = no_timer_create,
.nsleep = no_nsleep,
};
@@ -285,6 +292,7 @@ static __init int init_posix_timers(void)
.clock_getres = posix_get_coarse_res,
.clock_get = posix_get_realtime_coarse,
.clock_set = do_posix_clock_nosettime,
+ .clock_adj = do_posix_clock_noadjtime,
.timer_create = no_timer_create,
.nsleep = no_nsleep,
};
@@ -292,6 +300,7 @@ static __init int init_posix_timers(void)
.clock_getres = posix_get_coarse_res,
.clock_get = posix_get_monotonic_coarse,
.clock_set = do_posix_clock_nosettime,
+ .clock_adj = do_posix_clock_noadjtime,
.timer_create = no_timer_create,
.nsleep = no_nsleep,
};
@@ -928,6 +937,12 @@ int do_posix_clock_nosettime(const clockid_t clockid, struct timespec *tp)
}
EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);

+int do_posix_clock_noadjtime(const clockid_t which_clock, struct timex *t)
+{
+ return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(do_posix_clock_noadjtime);
+
int do_posix_clock_nonanosleep(const clockid_t clock, int flags,
struct timespec *t, struct timespec __user *r)
{
@@ -969,6 +984,26 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,

}

+SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
+ struct timex __user *, utx)
+{
+ struct timex ktx;
+ int err;
+
+ if (copy_from_user(&ktx, utx, sizeof(ktx)))
+ return -EFAULT;
+
+ if (invalid_clockid(which_clock))
+ return -EINVAL;
+
+ err = CLOCK_DISPATCH(which_clock, clock_adj, (which_clock, &ktx));
+
+ if (copy_to_user(utx, &ktx, sizeof(ktx)))
+ return -EFAULT;
+
+ return err;
+}
+
SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
struct timespec __user *, tp)
{
--
1.7.0.4