diff options
| -rw-r--r-- | include/linux/time.h | 6 | ||||
| -rw-r--r-- | include/vdso/datapage.h | 19 | ||||
| -rw-r--r-- | init/Kconfig | 1 | ||||
| -rw-r--r-- | lib/vdso/Kconfig | 6 | ||||
| -rw-r--r-- | lib/vdso/gettimeofday.c | 142 |
5 files changed, 169 insertions, 5 deletions
diff --git a/include/linux/time.h b/include/linux/time.h index 8e10b9dbd8c2..8ef5e5cc9f57 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -110,4 +110,10 @@ static inline bool itimerspec64_valid(const struct itimerspec64 *its) * Equivalent to !(time_before32(@t, @l) || time_after32(@t, @h)). */ #define time_between32(t, l, h) ((u32)(h) - (u32)(l) >= (u32)(t) - (u32)(l)) + +struct timens_offset { + s64 sec; + u64 nsec; +}; + #endif diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h index 2e302c0f41f7..c5f347cc5e55 100644 --- a/include/vdso/datapage.h +++ b/include/vdso/datapage.h @@ -21,6 +21,8 @@ #define CS_RAW 1 #define CS_BASES (CS_RAW + 1) +#define VCLOCK_TIMENS UINT_MAX + /** * struct vdso_timestamp - basetime per clock_id * @sec: seconds @@ -48,6 +50,7 @@ struct vdso_timestamp { * @mult: clocksource multiplier * @shift: clocksource shift * @basetime[clock_id]: basetime per clock_id + * @offset[clock_id]: time namespace offset per clock_id * @tz_minuteswest: minutes west of Greenwich * @tz_dsttime: type of DST correction * @hrtimer_res: hrtimer resolution @@ -55,6 +58,17 @@ struct vdso_timestamp { * * vdso_data will be accessed by 64 bit and compat code at the same time * so we should be careful before modifying this structure. + * + * @basetime is used to store the base time for the system wide time getter + * VVAR page. + * + * @offset is used by the special time namespace VVAR pages which are + * installed instead of the real VVAR page. These namespace pages must set + * @seq to 1 and @clock_mode to VLOCK_TIMENS to force the code into the + * time namespace slow path. The namespace aware functions retrieve the + * real system wide VVAR page, read host time and add the per clock offset. + * For clocks which are not affected by time namespace adjustment the + * offset must be zero. */ struct vdso_data { u32 seq; @@ -65,7 +79,10 @@ struct vdso_data { u32 mult; u32 shift; - struct vdso_timestamp basetime[VDSO_BASES]; + union { + struct vdso_timestamp basetime[VDSO_BASES]; + struct timens_offset offset[VDSO_BASES]; + }; s32 tz_minuteswest; s32 tz_dsttime; diff --git a/init/Kconfig b/init/Kconfig index b34314fc75f7..9b7f144a6d35 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1082,6 +1082,7 @@ config UTS_NS config TIME_NS bool "TIME namespace" + depends on GENERIC_VDSO_TIME_NS default y help In this namespace boottime and monotonic clocks can be set. diff --git a/lib/vdso/Kconfig b/lib/vdso/Kconfig index 9fe698ff62ec..d883ac299508 100644 --- a/lib/vdso/Kconfig +++ b/lib/vdso/Kconfig @@ -24,4 +24,10 @@ config GENERIC_COMPAT_VDSO help This config option enables the compat VDSO layer. +config GENERIC_VDSO_TIME_NS + bool + help + Selected by architectures which support time namespaces in the + VDSO + endif diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c index b453d2469b63..f342ac1fce77 100644 --- a/lib/vdso/gettimeofday.c +++ b/lib/vdso/gettimeofday.c @@ -38,15 +38,89 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult) } #endif +#ifdef CONFIG_TIME_NS +static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk, + struct __kernel_timespec *ts) +{ + const struct vdso_data *vd = __arch_get_timens_vdso_data(); + const struct timens_offset *offs = &vdns->offset[clk]; + const struct vdso_timestamp *vdso_ts; + u64 cycles, last, ns; + u32 seq; + s64 sec; + + if (clk != CLOCK_MONOTONIC_RAW) + vd = &vd[CS_HRES_COARSE]; + else + vd = &vd[CS_RAW]; + vdso_ts = &vd->basetime[clk]; + + do { + seq = vdso_read_begin(vd); + cycles = __arch_get_hw_counter(vd->clock_mode); + ns = vdso_ts->nsec; + last = vd->cycle_last; + if (unlikely((s64)cycles < 0)) + return -1; + + ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult); + ns >>= vd->shift; + sec = vdso_ts->sec; + } while (unlikely(vdso_read_retry(vd, seq))); + + /* Add the namespace offset */ + sec += offs->sec; + ns += offs->nsec; + + /* + * Do this outside the loop: a race inside the loop could result + * in __iter_div_u64_rem() being extremely slow. + */ + ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); + ts->tv_nsec = ns; + + return 0; +} +#else +static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void) +{ + return NULL; +} + +static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk, + struct __kernel_timespec *ts) +{ + return -EINVAL; +} +#endif + static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk, - struct __kernel_timespec *ts) + struct __kernel_timespec *ts) { const struct vdso_timestamp *vdso_ts = &vd->basetime[clk]; u64 cycles, last, sec, ns; u32 seq; do { - seq = vdso_read_begin(vd); + /* + * Open coded to handle VCLOCK_TIMENS. Time namespace + * enabled tasks have a special VVAR page installed which + * has vd->seq set to 1 and vd->clock_mode set to + * VCLOCK_TIMENS. For non time namespace affected tasks + * this does not affect performance because if vd->seq is + * odd, i.e. a concurrent update is in progress the extra + * check for vd->clock_mode is just a few extra + * instructions while spin waiting for vd->seq to become + * even again. + */ + while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) { + if (IS_ENABLED(CONFIG_TIME_NS) && + vd->clock_mode == VCLOCK_TIMENS) + return do_hres_timens(vd, clk, ts); + cpu_relax(); + } + smp_rmb(); + cycles = __arch_get_hw_counter(vd->clock_mode); ns = vdso_ts->nsec; last = vd->cycle_last; @@ -68,6 +142,43 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk, return 0; } +#ifdef CONFIG_TIME_NS +static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk, + struct __kernel_timespec *ts) +{ + const struct vdso_data *vd = __arch_get_timens_vdso_data(); + const struct vdso_timestamp *vdso_ts = &vd->basetime[clk]; + const struct timens_offset *offs = &vdns->offset[clk]; + u64 nsec; + s64 sec; + s32 seq; + + do { + seq = vdso_read_begin(vd); + sec = vdso_ts->sec; + nsec = vdso_ts->nsec; + } while (unlikely(vdso_read_retry(vd, seq))); + + /* Add the namespace offset */ + sec += offs->sec; + nsec += offs->nsec; + + /* + * Do this outside the loop: a race inside the loop could result + * in __iter_div_u64_rem() being extremely slow. + */ + ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec); + ts->tv_nsec = nsec; + return 0; +} +#else +static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk, + struct __kernel_timespec *ts) +{ + return -1; +} +#endif + static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk, struct __kernel_timespec *ts) { @@ -75,7 +186,18 @@ static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk, u32 seq; do { - seq = vdso_read_begin(vd); + /* + * Open coded to handle VCLOCK_TIMENS. See comment in + * do_hres(). + */ + while ((seq = READ_ONCE(vd->seq)) & 1) { + if (IS_ENABLED(CONFIG_TIME_NS) && + vd->clock_mode == VCLOCK_TIMENS) + return do_coarse_timens(vd, clk, ts); + cpu_relax(); + } + smp_rmb(); + ts->tv_sec = vdso_ts->sec; ts->tv_nsec = vdso_ts->nsec; } while (unlikely(vdso_read_retry(vd, seq))); @@ -156,6 +278,10 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) } if (unlikely(tz != NULL)) { + if (IS_ENABLED(CONFIG_TIME_NS) && + vd->clock_mode == VCLOCK_TIMENS) + vd = __arch_get_timens_vdso_data(); + tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest; tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime; } @@ -167,7 +293,12 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time) { const struct vdso_data *vd = __arch_get_vdso_data(); - __kernel_old_time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec); + __kernel_old_time_t t; + + if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS) + vd = __arch_get_timens_vdso_data(); + + t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec); if (time) *time = t; @@ -189,6 +320,9 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res) if (unlikely((u32) clock >= MAX_CLOCKS)) return -1; + if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS) + vd = __arch_get_timens_vdso_data(); + hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res); /* * Convert the clockid to a bitmask and use it to check which |