diff options
Diffstat (limited to 'kernel/time/jiffies.c')
| -rw-r--r-- | kernel/time/jiffies.c | 221 |
1 files changed, 159 insertions, 62 deletions
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index 7a925ba456fb..d31a6d40d38d 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -1,84 +1,59 @@ -/*********************************************************************** -* linux/kernel/time/jiffies.c -* -* This file contains the jiffies based clocksource. -* -* Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) -* -* This program is free software; you can redistribute it and/or modify -* it under the terms of the GNU General Public License as published by -* the Free Software Foundation; either version 2 of the License, or -* (at your option) any later version. -* -* This program is distributed in the hope that it will be useful, -* but WITHOUT ANY WARRANTY; without even the implied warranty of -* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -* GNU General Public License for more details. -* -* You should have received a copy of the GNU General Public License -* along with this program; if not, write to the Free Software -* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. -* -************************************************************************/ +// SPDX-License-Identifier: GPL-2.0+ +/* + * This file contains the jiffies based clocksource. + * + * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) + */ #include <linux/clocksource.h> #include <linux/jiffies.h> #include <linux/module.h> #include <linux/init.h> +#include "timekeeping.h" #include "tick-internal.h" -/* The Jiffies based clocksource is the lowest common + +static u64 jiffies_read(struct clocksource *cs) +{ + return (u64) jiffies; +} + +/* + * The Jiffies based clocksource is the lowest common * denominator clock source which should function on * all systems. It has the same coarse resolution as * the timer interrupt frequency HZ and it suffers * inaccuracies caused by missed or lost timer * interrupts and the inability for the timer - * interrupt hardware to accuratly tick at the + * interrupt hardware to accurately tick at the * requested HZ value. It is also not recommended * for "tick-less" systems. */ -#define NSEC_PER_JIFFY ((NSEC_PER_SEC+HZ/2)/HZ) - -/* Since jiffies uses a simple NSEC_PER_JIFFY multiplier - * conversion, the .shift value could be zero. However - * this would make NTP adjustments impossible as they are - * in units of 1/2^.shift. Thus we use JIFFIES_SHIFT to - * shift both the nominator and denominator the same - * amount, and give ntp adjustments in units of 1/2^8 - * - * The value 8 is somewhat carefully chosen, as anything - * larger can result in overflows. NSEC_PER_JIFFY grows as - * HZ shrinks, so values greater than 8 overflow 32bits when - * HZ=100. - */ -#define JIFFIES_SHIFT 8 - -static cycle_t jiffies_read(struct clocksource *cs) -{ - return (cycle_t) jiffies; -} - static struct clocksource clocksource_jiffies = { - .name = "jiffies", - .rating = 1, /* lowest valid rating*/ - .read = jiffies_read, - .mask = 0xffffffff, /*32bits*/ - .mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */ - .shift = JIFFIES_SHIFT, + .name = "jiffies", + .rating = 1, /* lowest valid rating*/ + .uncertainty_margin = 32 * NSEC_PER_MSEC, + .read = jiffies_read, + .mask = CLOCKSOURCE_MASK(32), + .mult = TICK_NSEC << JIFFIES_SHIFT, /* details above */ + .shift = JIFFIES_SHIFT, + .max_cycles = 10, }; -__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock); +__cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock); +__cacheline_aligned_in_smp seqcount_raw_spinlock_t jiffies_seq = + SEQCNT_RAW_SPINLOCK_ZERO(jiffies_seq, &jiffies_lock); #if (BITS_PER_LONG < 64) u64 get_jiffies_64(void) { - unsigned long seq; + unsigned int seq; u64 ret; do { - seq = read_seqbegin(&jiffies_lock); + seq = read_seqcount_begin(&jiffies_seq); ret = jiffies_64; - } while (read_seqretry(&jiffies_lock, seq)); + } while (read_seqcount_retry(&jiffies_seq, seq)); return ret; } EXPORT_SYMBOL(get_jiffies_64); @@ -88,7 +63,7 @@ EXPORT_SYMBOL(jiffies); static int __init init_jiffies_clocksource(void) { - return clocksource_register(&clocksource_jiffies); + return __clocksource_register(&clocksource_jiffies); } core_initcall(init_jiffies_clocksource); @@ -98,15 +73,13 @@ struct clocksource * __init __weak clocksource_default_clock(void) return &clocksource_jiffies; } -struct clocksource refined_jiffies; +static struct clocksource refined_jiffies; -int register_refined_jiffies(long cycles_per_second) +void __init register_refined_jiffies(long cycles_per_second) { u64 nsec_per_tick, shift_hz; long cycles_per_tick; - - refined_jiffies = clocksource_jiffies; refined_jiffies.name = "refined-jiffies"; refined_jiffies.rating++; @@ -124,6 +97,130 @@ int register_refined_jiffies(long cycles_per_second) refined_jiffies.mult = ((u32)nsec_per_tick) << JIFFIES_SHIFT; - clocksource_register(&refined_jiffies); - return 0; + __clocksource_register(&refined_jiffies); +} + +#define SYSCTL_CONV_MULT_HZ(val) ((val) * HZ) +#define SYSCTL_CONV_DIV_HZ(val) ((val) / HZ) + +static SYSCTL_USER_TO_KERN_INT_CONV(_hz, SYSCTL_CONV_MULT_HZ) +static SYSCTL_KERN_TO_USER_INT_CONV(_hz, SYSCTL_CONV_DIV_HZ) +static SYSCTL_USER_TO_KERN_INT_CONV(_userhz, clock_t_to_jiffies) +static SYSCTL_KERN_TO_USER_INT_CONV(_userhz, jiffies_to_clock_t) +static SYSCTL_USER_TO_KERN_INT_CONV(_ms, msecs_to_jiffies) +static SYSCTL_KERN_TO_USER_INT_CONV(_ms, jiffies_to_msecs) + +static SYSCTL_INT_CONV_CUSTOM(_jiffies, sysctl_user_to_kern_int_conv_hz, + sysctl_kern_to_user_int_conv_hz, false) +static SYSCTL_INT_CONV_CUSTOM(_userhz_jiffies, + sysctl_user_to_kern_int_conv_userhz, + sysctl_kern_to_user_int_conv_userhz, false) +static SYSCTL_INT_CONV_CUSTOM(_ms_jiffies, sysctl_user_to_kern_int_conv_ms, + sysctl_kern_to_user_int_conv_ms, false) +static SYSCTL_INT_CONV_CUSTOM(_ms_jiffies_minmax, + sysctl_user_to_kern_int_conv_ms, + sysctl_kern_to_user_int_conv_ms, true) + +/** + * proc_dointvec_jiffies - read a vector of integers as seconds + * @table: the sysctl table + * @dir: %TRUE if this is a write to the sysctl file + * @buffer: the user buffer + * @lenp: the size of the user buffer + * @ppos: file position + * + * Reads/writes up to table->maxlen/sizeof(unsigned int) integer + * values from/to the user buffer, treated as an ASCII string. + * The values read are assumed to be in seconds, and are converted into + * jiffies. + * + * Returns 0 on success. + */ +int proc_dointvec_jiffies(const struct ctl_table *table, int dir, + void *buffer, size_t *lenp, loff_t *ppos) +{ + return proc_dointvec_conv(table, dir, buffer, lenp, ppos, + do_proc_int_conv_jiffies); } +EXPORT_SYMBOL(proc_dointvec_jiffies); + +/** + * proc_dointvec_userhz_jiffies - read a vector of integers as 1/USER_HZ seconds + * @table: the sysctl table + * @dir: %TRUE if this is a write to the sysctl file + * @buffer: the user buffer + * @lenp: the size of the user buffer + * @ppos: pointer to the file position + * + * Reads/writes up to table->maxlen/sizeof(unsigned int) integer + * values from/to the user buffer, treated as an ASCII string. + * The values read are assumed to be in 1/USER_HZ seconds, and + * are converted into jiffies. + * + * Returns 0 on success. + */ +int proc_dointvec_userhz_jiffies(const struct ctl_table *table, int dir, + void *buffer, size_t *lenp, loff_t *ppos) +{ + if (SYSCTL_USER_TO_KERN(dir) && USER_HZ < HZ) + return -EINVAL; + return proc_dointvec_conv(table, dir, buffer, lenp, ppos, + do_proc_int_conv_userhz_jiffies); +} +EXPORT_SYMBOL(proc_dointvec_userhz_jiffies); + +/** + * proc_dointvec_ms_jiffies - read a vector of integers as 1 milliseconds + * @table: the sysctl table + * @dir: %TRUE if this is a write to the sysctl file + * @buffer: the user buffer + * @lenp: the size of the user buffer + * @ppos: the current position in the file + * + * Reads/writes up to table->maxlen/sizeof(unsigned int) integer + * values from/to the user buffer, treated as an ASCII string. + * The values read are assumed to be in 1/1000 seconds, and + * are converted into jiffies. + * + * Returns 0 on success. + */ +int proc_dointvec_ms_jiffies(const struct ctl_table *table, int dir, void *buffer, + size_t *lenp, loff_t *ppos) +{ + return proc_dointvec_conv(table, dir, buffer, lenp, ppos, + do_proc_int_conv_ms_jiffies); +} +EXPORT_SYMBOL(proc_dointvec_ms_jiffies); + +int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int dir, + void *buffer, size_t *lenp, loff_t *ppos) +{ + return proc_dointvec_conv(table, dir, buffer, lenp, ppos, + do_proc_int_conv_ms_jiffies_minmax); +} + +/** + * proc_doulongvec_ms_jiffies_minmax - read a vector of millisecond values with min/max values + * @table: the sysctl table + * @dir: %TRUE if this is a write to the sysctl file + * @buffer: the user buffer + * @lenp: the size of the user buffer + * @ppos: file position + * + * Reads/writes up to table->maxlen/sizeof(unsigned long) unsigned long + * values from/to the user buffer, treated as an ASCII string. The values + * are treated as milliseconds, and converted to jiffies when they are stored. + * + * This routine will ensure the values are within the range specified by + * table->extra1 (min) and table->extra2 (max). + * + * Returns 0 on success. + */ +int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int dir, + void *buffer, size_t *lenp, loff_t *ppos) +{ + return proc_doulongvec_minmax_conv(table, dir, buffer, lenp, ppos, + HZ, 1000l); +} +EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax); + |