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Date: Mon, 20 Nov 2017 14:52:55 +0100
From: Romain Perier <romain.perier@...il.com>
To: John Stultz <john.stultz@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <sboyd@...eaurora.org>
Cc: linux-api@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Romain Perier <romain.perier@...il.com>
Subject: Re: [PATCH] time: Make NTP optionnal
Hi,
No feedback regarding this patch ?
Thanks,
Romain
2017-11-02 19:29 GMT+01:00 Romain Perier <romain.perier@...il.com>:
> On embedded systems with limited space, synchronizing system clock via
> NTP might be not needed.
>
> This commit introduces a new Kconfig entry. When disabled, it compiles
> out the adjtimex and clock_adjtimes system calls. The corresponding NTP
> accessors are also disabled from timekeeping.c and their declaration are
> replaced by no_op static inline functions in time.h
>
> The bloat-o-meter output is the following:
>
> add/remove: 1/35 grow/shrink: 2/9 up/down: 170/-3760 (-3590)
> function old new delta
> tk_set_wall_to_mono.constprop - 164 +164
> tk_xtime_add.constprop 200 204 +4
> timespec_trunc 60 62 +2
> ntp_notify_cmos_timer 2 - -2
> k_itimer_rcu_free 18 16 -2
> timekeeping_forward_now.constprop 256 252 -4
> time_status 4 - -4
> time_state 4 - -4
> time_maxerror 4 - -4
> time_esterror 4 - -4
> time_constant 4 - -4
> time_adjust 4 - -4
> tick_usec 4 - -4
> tick_nsec 4 - -4
> ntp_init 4 - -4
> posix_clock_realtime_adj 6 - -6
> time_reftime 8 - -8
> time_offset 8 - -8
> time_freq 8 - -8
> tick_length_base 8 - -8
> tick_length 8 - -8
> ntp_tick_adj 8 - -8
> ntp_next_leap_sec 8 - -8
> mask_to_bit_num 8 - -8
> mask_to_allowed_status 8 - -8
> ntp_tick_length 12 - -12
> __setup_ntp_tick_adj_setup 12 - -12
> __setup_str_ntp_tick_adj_setup 14 - -14
> timekeeping_resume 614 598 -16
> timekeeping_inject_offset 352 336 -16
> timekeeping_init 400 384 -16
> do_settimeofday64 342 326 -16
> ntp_tick_adj_setup 28 - -28
> timekeeping_update 236 206 -30
> branch_table 32 - -32
> sys_adjtimex 42 - -42
> sys_clock_adjtime 64 - -64
> ntp_clear 72 - -72
> ntp_get_next_leap 76 - -76
> ntp_validate_timex 78 - -78
> tk_set_wall_to_mono 166 - -166
> ntp_update_frequency 180 - -180
> update_wall_time 1846 1590 -256
> do_adjtimex 272 - -272
> second_overflow 476 - -476
> bcj_apply 1100 224 -876
> __do_adjtimex 888 - -888
>
> Signed-off-by: Romain Perier <romain.perier@...il.com>
> ---
> include/linux/timex.h | 14 +++++++++++---
> init/Kconfig | 9 +++++++++
> kernel/compat.c | 2 ++
> kernel/sys_ni.c | 6 ++++++
> kernel/time/Makefile | 6 +++++-
> kernel/time/ntp_internal.h | 29 +++++++++++++++++++++++++++++
> kernel/time/posix-timers.c | 13 ++++++++-----
> kernel/time/time.c | 4 ++--
> kernel/time/timekeeping.c | 2 ++
> 9 files changed, 74 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/timex.h b/include/linux/timex.h
> index 39c25dbebfe8..5906b654821a 100644
> --- a/include/linux/timex.h
> +++ b/include/linux/timex.h
> @@ -151,12 +151,20 @@ extern unsigned long tick_nsec; /* SHIFTED_HZ period (nsec) */
> #define NTP_INTERVAL_FREQ (HZ)
> #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
>
> +#ifdef CONFIG_NTP
> extern int do_adjtimex(struct timex *);
> extern void hardpps(const struct timespec64 *, const struct timespec64 *);
> -
> -int read_current_timer(unsigned long *timer_val);
> void ntp_notify_cmos_timer(void);
> -
> +#else
> +static inline int do_adjtimex(struct timex *txc)
> +{
> + return TIME_OK;
> +}
> +static inline void hardpps(const struct timespec64 *phase_ts,
> + const struct timespec64 *raw_ts)
> +{}
> +#endif
> +int read_current_timer(unsigned long *timer_val);
> /* The clock frequency of the i8253/i8254 PIT */
> #define PIT_TICK_RATE 1193182ul
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 3c1faaa2af4a..d4b0b33f7e91 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1332,6 +1332,15 @@ config EVENTFD
>
> If unsure, say Y.
>
> +config NTP
> + bool "Enable NTP support" if EXPERT
> + default y
> + help
> + This enables support for synchronizing system clock with NTP
> + and its corresponding syscalls adjtimex and clock_adjtimex.
> +
> + If unsure, say Y.
> +
> # syscall, maps, verifier
> config BPF_SYSCALL
> bool "Enable bpf() system call"
> diff --git a/kernel/compat.c b/kernel/compat.c
> index 772e038d04d9..12945ae5ae94 100644
> --- a/kernel/compat.c
> +++ b/kernel/compat.c
> @@ -30,6 +30,7 @@
>
> #include <linux/uaccess.h>
>
> +#ifdef CONFIG_NTP
> int compat_get_timex(struct timex *txc, const struct compat_timex __user *utp)
> {
> struct compat_timex tx32;
> @@ -91,6 +92,7 @@ int compat_put_timex(struct compat_timex __user *utp, const struct timex *txc)
> return -EFAULT;
> return 0;
> }
> +#endif
>
> static int __compat_get_timeval(struct timeval *tv, const struct compat_timeval __user *ctv)
> {
> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> index 8acef8576ce9..f854d24b813c 100644
> --- a/kernel/sys_ni.c
> +++ b/kernel/sys_ni.c
> @@ -258,3 +258,9 @@ cond_syscall(sys_membarrier);
> cond_syscall(sys_pkey_mprotect);
> cond_syscall(sys_pkey_alloc);
> cond_syscall(sys_pkey_free);
> +#ifndef CONFIG_NTP
> +cond_syscall(sys_adjtimex);
> +cond_syscall(sys_clock_adjtime);
> +cond_syscall(compat_sys_adjtimex);
> +cond_syscall(compat_sys_clock_adjtime);
> +#endif
> diff --git a/kernel/time/Makefile b/kernel/time/Makefile
> index 938dbf33ef49..44bd321e4560 100644
> --- a/kernel/time/Makefile
> +++ b/kernel/time/Makefile
> @@ -1,7 +1,11 @@
> obj-y += time.o timer.o hrtimer.o
> -obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o
> +obj-y += timekeeping.o clocksource.o jiffies.o timer_list.o
> obj-y += timeconv.o timecounter.o alarmtimer.o
>
> +ifeq ($(CONFIG_NTP),y)
> + obj-y += ntp.o
> +endif
> +
> ifeq ($(CONFIG_POSIX_TIMERS),y)
> obj-y += posix-timers.o posix-cpu-timers.o posix-clock.o itimer.o
> else
> diff --git a/kernel/time/ntp_internal.h b/kernel/time/ntp_internal.h
> index d8a7c11fa71a..9d1ebc042968 100644
> --- a/kernel/time/ntp_internal.h
> +++ b/kernel/time/ntp_internal.h
> @@ -1,6 +1,7 @@
> #ifndef _LINUX_NTP_INTERNAL_H
> #define _LINUX_NTP_INTERNAL_H
>
> +#ifdef CONFIG_NTP
> extern void ntp_init(void);
> extern void ntp_clear(void);
> /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
> @@ -10,4 +11,32 @@ extern int second_overflow(time64_t secs);
> extern int ntp_validate_timex(struct timex *);
> extern int __do_adjtimex(struct timex *, struct timespec64 *, s32 *);
> extern void __hardpps(const struct timespec64 *, const struct timespec64 *);
> +#else
> +static inline void ntp_init(void)
> +{}
> +static inline void ntp_clear(void)
> +{}
> +static inline u64 ntp_tick_length(void)
> +{
> + return 0;
> +}
> +static inline ktime_t ntp_get_next_leap(void)
> +{
> + return KTIME_MAX;
> +}
> +static inline int second_overflow(time64_t secs)
> +{
> + return 0;
> +}
> +static inline int ntp_validate_timex(struct timex *txc)
> +{
> + return 0;
> +}
> +static inline int __do_adjtimex(struct timex *txc, struct timespec64 *ts,
> + s32 *time_tai)
> +{
> + return TIME_OK;
> +}
> +#endif
> +
> #endif /* _LINUX_NTP_INTERNAL_H */
> diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
> index 13d6881f908b..dd31eaddc196 100644
> --- a/kernel/time/posix-timers.c
> +++ b/kernel/time/posix-timers.c
> @@ -207,12 +207,13 @@ static int posix_clock_realtime_set(const clockid_t which_clock,
> return do_sys_settimeofday64(tp, NULL);
> }
>
> +#ifdef CONFIG_NTP
> static int posix_clock_realtime_adj(const clockid_t which_clock,
> struct timex *t)
> {
> return do_adjtimex(t);
> }
> -
> +#endif
> /*
> * Get monotonic time for posix timers
> */
> @@ -1065,7 +1066,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
>
> return error;
> }
> -
> +#ifdef CONFIG_NTP
> SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
> struct timex __user *, utx)
> {
> @@ -1088,7 +1089,7 @@ SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
>
> return err;
> }
> -
> +#endif
> SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
> struct timespec __user *, tp)
> {
> @@ -1141,7 +1142,7 @@ COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
>
> return err;
> }
> -
> +#ifdef CONFIG_NTP
> COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
> struct compat_timex __user *, utp)
> {
> @@ -1165,7 +1166,7 @@ COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
>
> return err;
> }
> -
> +#endif
> COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
> struct compat_timespec __user *, tp)
> {
> @@ -1252,7 +1253,9 @@ static const struct k_clock clock_realtime = {
> .clock_getres = posix_get_hrtimer_res,
> .clock_get = posix_clock_realtime_get,
> .clock_set = posix_clock_realtime_set,
> +#ifdef CONFIG_NTP
> .clock_adj = posix_clock_realtime_adj,
> +#endif
> .nsleep = common_nsleep,
> .timer_create = common_timer_create,
> .timer_set = common_timer_set,
> diff --git a/kernel/time/time.c b/kernel/time/time.c
> index 44a8c1402133..413eca43a09c 100644
> --- a/kernel/time/time.c
> +++ b/kernel/time/time.c
> @@ -297,7 +297,7 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct compat_timeval __user *, tv,
> return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
> }
> #endif
> -
> +#ifdef CONFIG_NTP
> SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
> {
> struct timex txc; /* Local copy of parameter */
> @@ -333,7 +333,7 @@ COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp)
> return ret;
> }
> #endif
> -
> +#endif
> /*
> * Convert jiffies to milliseconds and back.
> *
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index 2cafb49aa65e..223fe15daa75 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -2247,6 +2247,7 @@ ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
> return base;
> }
>
> +#ifdef CONFIG_NTP
> /**
> * do_adjtimex() - Accessor function to NTP __do_adjtimex function
> */
> @@ -2317,6 +2318,7 @@ void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
> }
> EXPORT_SYMBOL(hardpps);
> #endif /* CONFIG_NTP_PPS */
> +#endif /* CONFIG_NTP */
>
> /**
> * xtime_update() - advances the timekeeping infrastructure
> --
> 2.14.1
>
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