1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright 2019 ARM Ltd. 4 * 5 * Generic implementation of update_vsyscall and update_vsyscall_tz. 6 * 7 * Based on the x86 specific implementation. 8 */ 9 10 #include <linux/hrtimer.h> 11 #include <linux/timekeeper_internal.h> 12 #include <vdso/datapage.h> 13 #include <vdso/helpers.h> 14 #include <vdso/vsyscall.h> 15 16 #include "timekeeping_internal.h" 17 18 static inline void fill_clock_configuration(struct vdso_clock *vc, const struct tk_read_base *base) 19 { 20 vc->cycle_last = base->cycle_last; 21 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT 22 vc->max_cycles = base->clock->max_cycles; 23 #endif 24 vc->mask = base->mask; 25 vc->mult = base->mult; 26 vc->shift = base->shift; 27 } 28 29 static inline void update_vdso_time_data(struct vdso_time_data *vdata, struct timekeeper *tk) 30 { 31 struct vdso_clock *vc = vdata->clock_data; 32 struct vdso_timestamp *vdso_ts; 33 u64 nsec, sec; 34 35 fill_clock_configuration(&vc[CS_HRES_COARSE], &tk->tkr_mono); 36 fill_clock_configuration(&vc[CS_RAW], &tk->tkr_raw); 37 38 /* CLOCK_MONOTONIC */ 39 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC]; 40 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 41 42 nsec = tk->tkr_mono.xtime_nsec; 43 nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift); 44 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { 45 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift); 46 vdso_ts->sec++; 47 } 48 vdso_ts->nsec = nsec; 49 50 /* Copy MONOTONIC time for BOOTTIME */ 51 sec = vdso_ts->sec; 52 /* Add the boot offset */ 53 sec += tk->monotonic_to_boot.tv_sec; 54 nsec += (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift; 55 56 /* CLOCK_BOOTTIME */ 57 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME]; 58 vdso_ts->sec = sec; 59 60 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { 61 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift); 62 vdso_ts->sec++; 63 } 64 vdso_ts->nsec = nsec; 65 66 /* CLOCK_MONOTONIC_RAW */ 67 vdso_ts = &vc[CS_RAW].basetime[CLOCK_MONOTONIC_RAW]; 68 vdso_ts->sec = tk->raw_sec; 69 vdso_ts->nsec = tk->tkr_raw.xtime_nsec; 70 71 /* CLOCK_TAI */ 72 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_TAI]; 73 vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset; 74 vdso_ts->nsec = tk->tkr_mono.xtime_nsec; 75 } 76 77 void update_vsyscall(struct timekeeper *tk) 78 { 79 struct vdso_time_data *vdata = vdso_k_time_data; 80 struct vdso_clock *vc = vdata->clock_data; 81 struct vdso_timestamp *vdso_ts; 82 s32 clock_mode; 83 u64 nsec; 84 85 /* copy vsyscall data */ 86 vdso_write_begin(vdata); 87 88 clock_mode = tk->tkr_mono.clock->vdso_clock_mode; 89 vc[CS_HRES_COARSE].clock_mode = clock_mode; 90 vc[CS_RAW].clock_mode = clock_mode; 91 92 /* CLOCK_REALTIME also required for time() */ 93 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME]; 94 vdso_ts->sec = tk->xtime_sec; 95 vdso_ts->nsec = tk->tkr_mono.xtime_nsec; 96 97 /* CLOCK_REALTIME_COARSE */ 98 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE]; 99 vdso_ts->sec = tk->xtime_sec; 100 vdso_ts->nsec = tk->coarse_nsec; 101 102 /* CLOCK_MONOTONIC_COARSE */ 103 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE]; 104 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 105 nsec = tk->coarse_nsec; 106 nsec = nsec + tk->wall_to_monotonic.tv_nsec; 107 vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec); 108 109 /* 110 * Read without the seqlock held by clock_getres(). 111 */ 112 WRITE_ONCE(vdata->hrtimer_res, hrtimer_resolution); 113 114 /* 115 * If the current clocksource is not VDSO capable, then spare the 116 * update of the high resolution parts. 117 */ 118 if (clock_mode != VDSO_CLOCKMODE_NONE) 119 update_vdso_time_data(vdata, tk); 120 121 __arch_update_vdso_clock(&vc[CS_HRES_COARSE]); 122 __arch_update_vdso_clock(&vc[CS_RAW]); 123 124 vdso_write_end(vdata); 125 126 __arch_sync_vdso_time_data(vdata); 127 } 128 129 void update_vsyscall_tz(void) 130 { 131 struct vdso_time_data *vdata = vdso_k_time_data; 132 133 vdata->tz_minuteswest = sys_tz.tz_minuteswest; 134 vdata->tz_dsttime = sys_tz.tz_dsttime; 135 136 __arch_sync_vdso_time_data(vdata); 137 } 138 139 /** 140 * vdso_update_begin - Start of a VDSO update section 141 * 142 * Allows architecture code to safely update the architecture specific VDSO 143 * data. Disables interrupts, acquires timekeeper lock to serialize against 144 * concurrent updates from timekeeping and invalidates the VDSO data 145 * sequence counter to prevent concurrent readers from accessing 146 * inconsistent data. 147 * 148 * Returns: Saved interrupt flags which need to be handed in to 149 * vdso_update_end(). 150 */ 151 unsigned long vdso_update_begin(void) 152 { 153 struct vdso_time_data *vdata = vdso_k_time_data; 154 unsigned long flags = timekeeper_lock_irqsave(); 155 156 vdso_write_begin(vdata); 157 return flags; 158 } 159 160 /** 161 * vdso_update_end - End of a VDSO update section 162 * @flags: Interrupt flags as returned from vdso_update_begin() 163 * 164 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data 165 * synchronization if the architecture requires it, drops timekeeper lock 166 * and restores interrupt flags. 167 */ 168 void vdso_update_end(unsigned long flags) 169 { 170 struct vdso_time_data *vdata = vdso_k_time_data; 171 172 vdso_write_end(vdata); 173 __arch_sync_vdso_time_data(vdata); 174 timekeeper_unlock_irqrestore(flags); 175 } 176