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 update_vdso_time_data(struct vdso_time_data *vdata, struct timekeeper *tk) 19 { 20 struct vdso_timestamp *vdso_ts; 21 u64 nsec, sec; 22 23 vdata[CS_HRES_COARSE].cycle_last = tk->tkr_mono.cycle_last; 24 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT 25 vdata[CS_HRES_COARSE].max_cycles = tk->tkr_mono.clock->max_cycles; 26 #endif 27 vdata[CS_HRES_COARSE].mask = tk->tkr_mono.mask; 28 vdata[CS_HRES_COARSE].mult = tk->tkr_mono.mult; 29 vdata[CS_HRES_COARSE].shift = tk->tkr_mono.shift; 30 vdata[CS_RAW].cycle_last = tk->tkr_raw.cycle_last; 31 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT 32 vdata[CS_RAW].max_cycles = tk->tkr_raw.clock->max_cycles; 33 #endif 34 vdata[CS_RAW].mask = tk->tkr_raw.mask; 35 vdata[CS_RAW].mult = tk->tkr_raw.mult; 36 vdata[CS_RAW].shift = tk->tkr_raw.shift; 37 38 /* CLOCK_MONOTONIC */ 39 vdso_ts = &vdata[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 = &vdata[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 = &vdata[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 = &vdata[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_timestamp *vdso_ts; 81 s32 clock_mode; 82 u64 nsec; 83 84 /* copy vsyscall data */ 85 vdso_write_begin(vdata); 86 87 clock_mode = tk->tkr_mono.clock->vdso_clock_mode; 88 vdata[CS_HRES_COARSE].clock_mode = clock_mode; 89 vdata[CS_RAW].clock_mode = clock_mode; 90 91 /* CLOCK_REALTIME also required for time() */ 92 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME]; 93 vdso_ts->sec = tk->xtime_sec; 94 vdso_ts->nsec = tk->tkr_mono.xtime_nsec; 95 96 /* CLOCK_REALTIME_COARSE */ 97 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE]; 98 vdso_ts->sec = tk->xtime_sec; 99 vdso_ts->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; 100 101 /* CLOCK_MONOTONIC_COARSE */ 102 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE]; 103 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 104 nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; 105 nsec = nsec + tk->wall_to_monotonic.tv_nsec; 106 vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec); 107 108 /* 109 * Read without the seqlock held by clock_getres(). 110 * Note: No need to have a second copy. 111 */ 112 WRITE_ONCE(vdata[CS_HRES_COARSE].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_vsyscall(vdata); 122 123 vdso_write_end(vdata); 124 125 __arch_sync_vdso_time_data(vdata); 126 } 127 128 void update_vsyscall_tz(void) 129 { 130 struct vdso_time_data *vdata = vdso_k_time_data; 131 132 vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest; 133 vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime; 134 135 __arch_sync_vdso_time_data(vdata); 136 } 137 138 /** 139 * vdso_update_begin - Start of a VDSO update section 140 * 141 * Allows architecture code to safely update the architecture specific VDSO 142 * data. Disables interrupts, acquires timekeeper lock to serialize against 143 * concurrent updates from timekeeping and invalidates the VDSO data 144 * sequence counter to prevent concurrent readers from accessing 145 * inconsistent data. 146 * 147 * Returns: Saved interrupt flags which need to be handed in to 148 * vdso_update_end(). 149 */ 150 unsigned long vdso_update_begin(void) 151 { 152 struct vdso_time_data *vdata = vdso_k_time_data; 153 unsigned long flags = timekeeper_lock_irqsave(); 154 155 vdso_write_begin(vdata); 156 return flags; 157 } 158 159 /** 160 * vdso_update_end - End of a VDSO update section 161 * @flags: Interrupt flags as returned from vdso_update_begin() 162 * 163 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data 164 * synchronization if the architecture requires it, drops timekeeper lock 165 * and restores interrupt flags. 166 */ 167 void vdso_update_end(unsigned long flags) 168 { 169 struct vdso_time_data *vdata = vdso_k_time_data; 170 171 vdso_write_end(vdata); 172 __arch_sync_vdso_time_data(vdata); 173 timekeeper_unlock_irqrestore(flags); 174 } 175