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_data(struct vdso_data *vdata, 19 struct timekeeper *tk) 20 { 21 struct vdso_timestamp *vdso_ts; 22 u64 nsec, sec; 23 24 vdata[CS_HRES_COARSE].cycle_last = tk->tkr_mono.cycle_last; 25 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT 26 vdata[CS_HRES_COARSE].max_cycles = tk->tkr_mono.clock->max_cycles; 27 #endif 28 vdata[CS_HRES_COARSE].mask = tk->tkr_mono.mask; 29 vdata[CS_HRES_COARSE].mult = tk->tkr_mono.mult; 30 vdata[CS_HRES_COARSE].shift = tk->tkr_mono.shift; 31 vdata[CS_RAW].cycle_last = tk->tkr_raw.cycle_last; 32 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT 33 vdata[CS_RAW].max_cycles = tk->tkr_raw.clock->max_cycles; 34 #endif 35 vdata[CS_RAW].mask = tk->tkr_raw.mask; 36 vdata[CS_RAW].mult = tk->tkr_raw.mult; 37 vdata[CS_RAW].shift = tk->tkr_raw.shift; 38 39 /* CLOCK_MONOTONIC */ 40 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC]; 41 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 42 43 nsec = tk->tkr_mono.xtime_nsec; 44 nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift); 45 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { 46 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift); 47 vdso_ts->sec++; 48 } 49 vdso_ts->nsec = nsec; 50 51 /* Copy MONOTONIC time for BOOTTIME */ 52 sec = vdso_ts->sec; 53 /* Add the boot offset */ 54 sec += tk->monotonic_to_boot.tv_sec; 55 nsec += (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift; 56 57 /* CLOCK_BOOTTIME */ 58 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME]; 59 vdso_ts->sec = sec; 60 61 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { 62 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift); 63 vdso_ts->sec++; 64 } 65 vdso_ts->nsec = nsec; 66 67 /* CLOCK_MONOTONIC_RAW */ 68 vdso_ts = &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW]; 69 vdso_ts->sec = tk->raw_sec; 70 vdso_ts->nsec = tk->tkr_raw.xtime_nsec; 71 72 /* CLOCK_TAI */ 73 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI]; 74 vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset; 75 vdso_ts->nsec = tk->tkr_mono.xtime_nsec; 76 } 77 78 void update_vsyscall(struct timekeeper *tk) 79 { 80 struct vdso_data *vdata = __arch_get_k_vdso_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 vdata[CS_HRES_COARSE].clock_mode = clock_mode; 90 vdata[CS_RAW].clock_mode = clock_mode; 91 92 /* CLOCK_REALTIME also required for time() */ 93 vdso_ts = &vdata[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 = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE]; 99 vdso_ts->sec = tk->xtime_sec; 100 vdso_ts->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; 101 102 /* CLOCK_MONOTONIC_COARSE */ 103 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE]; 104 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 105 nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; 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 * Note: No need to have a second copy. 112 */ 113 WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution); 114 115 /* 116 * If the current clocksource is not VDSO capable, then spare the 117 * update of the high resolution parts. 118 */ 119 if (clock_mode != VDSO_CLOCKMODE_NONE) 120 update_vdso_data(vdata, tk); 121 122 __arch_update_vsyscall(vdata, tk); 123 124 vdso_write_end(vdata); 125 126 __arch_sync_vdso_data(vdata); 127 } 128 129 void update_vsyscall_tz(void) 130 { 131 struct vdso_data *vdata = __arch_get_k_vdso_data(); 132 133 vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest; 134 vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime; 135 136 __arch_sync_vdso_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_data *vdata = __arch_get_k_vdso_data(); 154 unsigned long flags; 155 156 raw_spin_lock_irqsave(&timekeeper_lock, flags); 157 vdso_write_begin(vdata); 158 return flags; 159 } 160 161 /** 162 * vdso_update_end - End of a VDSO update section 163 * @flags: Interrupt flags as returned from vdso_update_begin() 164 * 165 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data 166 * synchronization if the architecture requires it, drops timekeeper lock 167 * and restores interrupt flags. 168 */ 169 void vdso_update_end(unsigned long flags) 170 { 171 struct vdso_data *vdata = __arch_get_k_vdso_data(); 172 173 vdso_write_end(vdata); 174 __arch_sync_vdso_data(vdata); 175 raw_spin_unlock_irqrestore(&timekeeper_lock, flags); 176 } 177