vsyscall.c (5066B)
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 18static 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 vdata[CS_HRES_COARSE].mask = tk->tkr_mono.mask; 26 vdata[CS_HRES_COARSE].mult = tk->tkr_mono.mult; 27 vdata[CS_HRES_COARSE].shift = tk->tkr_mono.shift; 28 vdata[CS_RAW].cycle_last = tk->tkr_raw.cycle_last; 29 vdata[CS_RAW].mask = tk->tkr_raw.mask; 30 vdata[CS_RAW].mult = tk->tkr_raw.mult; 31 vdata[CS_RAW].shift = tk->tkr_raw.shift; 32 33 /* CLOCK_MONOTONIC */ 34 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC]; 35 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 36 37 nsec = tk->tkr_mono.xtime_nsec; 38 nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift); 39 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { 40 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift); 41 vdso_ts->sec++; 42 } 43 vdso_ts->nsec = nsec; 44 45 /* Copy MONOTONIC time for BOOTTIME */ 46 sec = vdso_ts->sec; 47 /* Add the boot offset */ 48 sec += tk->monotonic_to_boot.tv_sec; 49 nsec += (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift; 50 51 /* CLOCK_BOOTTIME */ 52 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME]; 53 vdso_ts->sec = sec; 54 55 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { 56 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift); 57 vdso_ts->sec++; 58 } 59 vdso_ts->nsec = nsec; 60 61 /* CLOCK_MONOTONIC_RAW */ 62 vdso_ts = &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW]; 63 vdso_ts->sec = tk->raw_sec; 64 vdso_ts->nsec = tk->tkr_raw.xtime_nsec; 65 66 /* CLOCK_TAI */ 67 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI]; 68 vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset; 69 vdso_ts->nsec = tk->tkr_mono.xtime_nsec; 70} 71 72void update_vsyscall(struct timekeeper *tk) 73{ 74 struct vdso_data *vdata = __arch_get_k_vdso_data(); 75 struct vdso_timestamp *vdso_ts; 76 s32 clock_mode; 77 u64 nsec; 78 79 /* copy vsyscall data */ 80 vdso_write_begin(vdata); 81 82 clock_mode = tk->tkr_mono.clock->vdso_clock_mode; 83 vdata[CS_HRES_COARSE].clock_mode = clock_mode; 84 vdata[CS_RAW].clock_mode = clock_mode; 85 86 /* CLOCK_REALTIME also required for time() */ 87 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME]; 88 vdso_ts->sec = tk->xtime_sec; 89 vdso_ts->nsec = tk->tkr_mono.xtime_nsec; 90 91 /* CLOCK_REALTIME_COARSE */ 92 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE]; 93 vdso_ts->sec = tk->xtime_sec; 94 vdso_ts->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; 95 96 /* CLOCK_MONOTONIC_COARSE */ 97 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE]; 98 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; 99 nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; 100 nsec = nsec + tk->wall_to_monotonic.tv_nsec; 101 vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec); 102 103 /* 104 * Read without the seqlock held by clock_getres(). 105 * Note: No need to have a second copy. 106 */ 107 WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution); 108 109 /* 110 * If the current clocksource is not VDSO capable, then spare the 111 * update of the high resolution parts. 112 */ 113 if (clock_mode != VDSO_CLOCKMODE_NONE) 114 update_vdso_data(vdata, tk); 115 116 __arch_update_vsyscall(vdata, tk); 117 118 vdso_write_end(vdata); 119 120 __arch_sync_vdso_data(vdata); 121} 122 123void update_vsyscall_tz(void) 124{ 125 struct vdso_data *vdata = __arch_get_k_vdso_data(); 126 127 vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest; 128 vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime; 129 130 __arch_sync_vdso_data(vdata); 131} 132 133/** 134 * vdso_update_begin - Start of a VDSO update section 135 * 136 * Allows architecture code to safely update the architecture specific VDSO 137 * data. Disables interrupts, acquires timekeeper lock to serialize against 138 * concurrent updates from timekeeping and invalidates the VDSO data 139 * sequence counter to prevent concurrent readers from accessing 140 * inconsistent data. 141 * 142 * Returns: Saved interrupt flags which need to be handed in to 143 * vdso_update_end(). 144 */ 145unsigned long vdso_update_begin(void) 146{ 147 struct vdso_data *vdata = __arch_get_k_vdso_data(); 148 unsigned long flags; 149 150 raw_spin_lock_irqsave(&timekeeper_lock, flags); 151 vdso_write_begin(vdata); 152 return flags; 153} 154 155/** 156 * vdso_update_end - End of a VDSO update section 157 * @flags: Interrupt flags as returned from vdso_update_begin() 158 * 159 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data 160 * synchronization if the architecture requires it, drops timekeeper lock 161 * and restores interrupt flags. 162 */ 163void vdso_update_end(unsigned long flags) 164{ 165 struct vdso_data *vdata = __arch_get_k_vdso_data(); 166 167 vdso_write_end(vdata); 168 __arch_sync_vdso_data(vdata); 169 raw_spin_unlock_irqrestore(&timekeeper_lock, flags); 170}