Skip to content

L
linux
Commit 1c41006f authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files
Options

[PATCH] Time changes for x86-64 

Some timer updates from Vojtech Pavlik for x86-64.  In theory support
HPET timing now, but the support is disabled.

Would actually need vxtime_lock() macros in the generic timer code to
protect xtime updates, but I'm leaving that out now because it's only
needed for vsyscalls and they're currently disabled.
parent 15aed72d
Hide whitespace changes
Inline Side-by-side
Showing with 270 additions and 452 deletions
arch/x86_64/kernel/time.c
View file @ 1c41006f
/*
* linux/arch/x86-64/kernel/time.c
*
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
* "High Precision Event Timer" based timekeeping.
*
* Copyright (c) 1991,1992,1995 Linus Torvalds
* Copyright (c) 1994 Alan Modra
* Copyright (c) 1995 Markus Kuhn
* Copyright (c) 1996 Ingo Molnar
* Copyright (c) 1998 Andrea Arcangeli
* Copyright (c) 2002 Vojtech Pavlik
*
* This file contains the PC-specific time handling details:
* reading the RTC at bootup, etc..
* 1994-07-02 Alan Modra
* fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
* 1995-03-26 Markus Kuhn
* fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
* precision CMOS clock update
* 1996-05-03 Ingo Molnar
* fixed time warps in do_[slow|fast]_gettimeoffset()
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
* 1998-09-05 (Various)
* More robust do_fast_gettimeoffset() algorithm implemented
* (works with APM, Cyrix 6x86MX and Centaur C6),
* monotonic gettimeofday() with fast_get_timeoffset(),
* drift-proof precision TSC calibration on boot
* (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
* Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
* ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
* 1998-12-16 Andrea Arcangeli
* Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
* because was not accounting lost_ticks.
* 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
* Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
* serialize accesses to xtime/lost_ticks).
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/device.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/irq.h>
#include <asm/msr.h>
#include <asm/delay.h>
#include <asm/mpspec.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <linux/mc146818rtc.h>
#include <linux/timex.h>
#include <linux/config.h>
#include <asm/fixmap.h>
#include <linux/irq.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/device.h>
#include <asm/vsyscall.h>
#include <asm/timex.h>
unsigned int cpu_khz; /* Detected as we calibrate the TSC */
/* Number of usecs that the last interrupt was delayed */
int __delay_at_last_interrupt __section_delay_at_last_interrupt;
unsigned int __last_tsc_low __section_last_tsc_low; /* lsb 32 bits of Time Stamp Counter */
/* Cached *multiplier* to convert TSC counts to microseconds.
* (see the equation below).
* Equal to 2^32 * (1 / (clocks per usec) ).
* Initialized in time_init.
*/
unsigned int __fast_gettimeoffset_quotient __section_fast_gettimeoffset_quotient;
u64 jiffies_64;
extern rwlock_t xtime_lock;
struct timeval __xtime __section_xtime;
unsigned long __wall_jiffies __section_wall_jiffies;
struct timezone __sys_tz __section_sys_tz;
volatile unsigned long __jiffies __section_jiffies;
spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
inline unsigned long do_gettimeoffset(void)
{
register unsigned int eax, edx;
/* Read the Time Stamp Counter */
unsigned int cpu_khz; /* TSC clocks / usec, not used here */
unsigned long hpet_period; /* fsecs / HPET clock */
unsigned long hpet_tick; /* HPET clocks / interrupt */
int hpet_report_lost_ticks; /* command line option */
rdtsc(eax,edx);
struct hpet_data __hpet __section_hpet; /* address, quotient, trigger, hz */
/* .. relative to previous jiffy (32 bits is enough) */
eax -= last_tsc_low; /* tsc_low delta */
volatile unsigned long __jiffies __section_jiffies;
unsigned long __wall_jiffies __section_wall_jiffies;
struct timespec __xtime __section_xtime;
struct timezone __sys_tz __section_sys_tz;
/*
* Time offset = (tsc_low delta) * fast_gettimeoffset_quotient
* = (tsc_low delta) * (usecs_per_clock)
* = (tsc_low delta) * (usecs_per_jiffy / clocks_per_jiffy)
*
* Using a mull instead of a divl saves up to 31 clock cycles
* in the critical path.
/*
* do_gettimeoffset() returns microseconds since last timer interrupt was
* triggered by hardware. A memory read of HPET is slower than a register read
* of TSC, but much more reliable. It's also synchronized to the timer
* interrupt. Note that do_gettimeoffset() may return more than hpet_tick, if a
* timer interrupt has happened already, but hpet.trigger wasn't updated yet.
* This is not a problem, because jiffies hasn't updated either. They are bound
* together by xtime_lock.
*/
__asm__("mull %2"
:"=a" (eax), "=d" (edx)
:"rm" (fast_gettimeoffset_quotient),
"0" (eax));
static spinlock_t time_offset_lock = SPIN_LOCK_UNLOCKED;
static unsigned long timeoffset = 0;
/* our adjusted time offset in microseconds */
return delay_at_last_interrupt + edx;
inline unsigned int do_gettimeoffset(void)
{
unsigned long t;
rdtscll(t);
return (t - hpet.last_tsc) * (1000000L / HZ) / hpet.ticks + hpet.offset;
}
#define TICK_SIZE tick
spinlock_t i8253_lock = SPIN_LOCK_UNLOCKED;
extern spinlock_t i8259A_lock;
/*
* This version of gettimeofday has microsecond resolution
* and better than microsecond precision on fast x86 machines with TSC.
* This version of gettimeofday() has microsecond resolution and better than
* microsecond precision, as we're using at least a 10 MHz (usually 14.31818
* MHz) HPET timer.
*/
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
unsigned long usec, sec;
unsigned long flags, t;
unsigned int sec, usec;
read_lock_irqsave(&xtime_lock, flags);
usec = do_gettimeoffset();
{
unsigned long lost = jiffies - wall_jiffies;
if (lost)
usec += lost * (1000000 / HZ);
}
spin_lock(&time_offset_lock);
sec = xtime.tv_sec;
usec += xtime.tv_usec;
read_unlock_irqrestore(&xtime_lock, flags);
usec = xtime.tv_nsec / 1000;
while (usec >= 1000000) {
usec -= 1000000;
sec++;
}
t = (jiffies - wall_jiffies) * (1000000L / HZ) + do_gettimeoffset();
if (t > timeoffset) timeoffset = t;
usec += timeoffset;
tv->tv_sec = sec;
tv->tv_usec = usec;
spin_unlock(&time_offset_lock);
read_unlock_irqrestore(&xtime_lock, flags);
tv->tv_sec = sec + usec / 1000000;
tv->tv_usec = usec % 1000000;
}
/*
* settimeofday() first undoes the correction that gettimeofday would do
* on the time, and then saves it. This is ugly, but has been like this for
* ages already.
*/
void do_settimeofday(struct timeval *tv)
{
write_lock_irq(&xtime_lock);
vxtime_lock();
/*
* This is revolting. We need to set "xtime" correctly. However, the
* value in this location is the value at the most recent update of
* wall time. Discover what correction gettimeofday() would have
* made, and then undo it!
*/
tv->tv_usec -= do_gettimeoffset();
tv->tv_usec -= (jiffies - wall_jiffies) * (1000000 / HZ);
tv->tv_usec -= do_gettimeoffset() +
(jiffies - wall_jiffies) * tick_usec;
while (tv->tv_usec < 0) {
tv->tv_usec += 1000000;
tv->tv_sec--;
}
xtime = *tv;
xtime.tv_sec = tv->tv_sec;
xtime.tv_nsec = (tv->tv_usec * 1000);
vxtime_unlock();
time_adjust = 0; /* stop active adjtime() */
time_status |= STA_UNSYNC;
time_maxerror = NTP_PHASE_LIMIT;
time_esterror = NTP_PHASE_LIMIT;
write_unlock_irq(&xtime_lock);
}
/*
* In order to set the CMOS clock precisely, set_rtc_mmss has to be
* called 500 ms after the second nowtime has started, because when
* nowtime is written into the registers of the CMOS clock, it will
* jump to the next second precisely 500 ms later. Check the Motorola
* MC146818A or Dallas DS12887 data sheet for details.
*
* BUG: This routine does not handle hour overflow properly; it just
* sets the minutes. Usually you'll only notice that after reboot!
* In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
* ms after the second nowtime has started, because when nowtime is written
* into the registers of the CMOS clock, it will jump to the next second
* precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
* sheet for details.
*/
static int set_rtc_mmss(unsigned long nowtime)
static void set_rtc_mmss(unsigned long nowtime)
{
int retval = 0;
int real_seconds, real_minutes, cmos_minutes;
unsigned char save_control, save_freq_select;
unsigned char control, freq_select;
/*
* IRQs are disabled when we're called from the timer interrupt,
* no need for spin_lock_irqsave()
*/
/* gets recalled with irq locally disabled */
spin_lock(&rtc_lock);
save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
/*
* Tell the clock it's being set and stop it.
*/
control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE(control | RTC_SET, RTC_CONTROL);
freq_select = CMOS_READ(RTC_FREQ_SELECT);
CMOS_WRITE(freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);
cmos_minutes = CMOS_READ(RTC_MINUTES);
if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
BCD_TO_BIN(cmos_minutes);
/*
* since we're only adjusting minutes and seconds,
* don't interfere with hour overflow. This avoids
* messing with unknown time zones but requires your
* RTC not to be off by more than 15 minutes
/*
* since we're only adjusting minutes and seconds, don't interfere with hour
* overflow. This avoids messing with unknown time zones but requires your RTC
* not to be off by more than 15 minutes. Since we're calling it only when
* our clock is externally synchronized using NTP, this shouldn't be a problem.
*/
real_seconds = nowtime % 60;
real_minutes = nowtime / 60;
if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
real_minutes += 30; /* correct for half hour time zone */
real_minutes %= 60;
if (abs(real_minutes - cmos_minutes) < 30) {
if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
BIN_TO_BCD(real_seconds);
BIN_TO_BCD(real_minutes);
}
CMOS_WRITE(real_seconds,RTC_SECONDS);
CMOS_WRITE(real_minutes,RTC_MINUTES);
} else {
printk(KERN_WARNING
"set_rtc_mmss: can't update from %d to %d\n",
CMOS_WRITE(real_seconds, RTC_SECONDS);
CMOS_WRITE(real_minutes, RTC_MINUTES);
} else
printk(KERN_WARNING "time.c: can't update CMOS clock from %d to %d\n",
cmos_minutes, real_minutes);
retval = -1;
}
/* The following flags have to be released exactly in this order,
* otherwise the DS12887 (popular MC146818A clone with integrated
* battery and quartz) will not reset the oscillator and will not
* update precisely 500 ms later. You won't find this mentioned in
* the Dallas Semiconductor data sheets, but who believes data
* sheets anyway ... -- Markus Kuhn
*/
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
spin_unlock(&rtc_lock);
return retval;
}
/* last time the cmos clock got updated */
static long last_rtc_update;
int timer_ack;
/*
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
* The following flags have to be released exactly in this order, otherwise the
* DS12887 (popular MC146818A clone with integrated battery and quartz) will
* not reset the oscillator and will not update precisely 500 ms later. You
* won't find this mentioned in the Dallas Semiconductor data sheets, but who
* believes data sheets anyway ... -- Markus Kuhn
*/
static inline void do_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
#ifdef CONFIG_X86_IO_APIC
if (timer_ack) {
/*
* Subtle, when I/O APICs are used we have to ack timer IRQ
* manually to reset the IRR bit for do_slow_gettimeoffset().
* This will also deassert NMI lines for the watchdog if run
* on an 82489DX-based system.
*/
spin_lock(&i8259A_lock);
outb(0x0c, 0x20);
/* Ack the IRQ; AEOI will end it automatically. */
inb(0x20);
spin_unlock(&i8259A_lock);
}
#endif
do_timer(regs);
/*
* In the SMP case we use the local APIC timer interrupt to do the
* profiling, except when we simulate SMP mode on a uniprocessor
* system, in that case we have to call the local interrupt handler.
*/
#ifndef CONFIG_X86_LOCAL_APIC
if (!user_mode(regs))
x86_do_profile(regs->rip);
#else
if (!using_apic_timer)
smp_local_timer_interrupt(regs);
#endif
/*
* If we have an externally synchronized Linux clock, then update
* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
* called as close as possible to 500 ms before the new second starts.
*/
if ((time_status & STA_UNSYNC) == 0 &&
xtime.tv_sec > last_rtc_update + 660 &&
xtime.tv_usec >= 500000 - ((unsigned) tick) / 2 &&
xtime.tv_usec <= 500000 + ((unsigned) tick) / 2) {
if (set_rtc_mmss(xtime.tv_sec) == 0)
last_rtc_update = xtime.tv_sec;
else
last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
}
}
CMOS_WRITE(control, RTC_CONTROL);
CMOS_WRITE(freq_select, RTC_FREQ_SELECT);
static int use_tsc;
spin_unlock(&rtc_lock);
}
/*
* This is the same as the above, except we _also_ save the current
* Time Stamp Counter value at the time of the timer interrupt, so that
* we later on can estimate the time of day more exactly.
*/
static void timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
int count;
/*
* Here we are in the timer irq handler. We just have irqs locally
* disabled but we don't know if the timer_bh is running on the other
* CPU. We need to avoid to SMP race with it. NOTE: we don' t need
* the irq version of write_lock because as just said we have irq
* locally disabled. -arca
static unsigned long rtc_update = 0;
/*
* Here we are in the timer irq handler. We have irqs locally disabled (so we
* don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
* on the other CPU, so we need a lock. We also need to lock the vsyscall
* variables, because both do_timer() and us change them -arca+vojtech
*/
write_lock(&xtime_lock);
vxtime_lock();
if (use_tsc)
{
/*
* It is important that these two operations happen almost at
* the same time. We do the RDTSC stuff first, since it's
* faster. To avoid any inconsistencies, we need interrupts
* disabled locally.
*/
/*
* Interrupts are just disabled locally since the timer irq
* has the SA_INTERRUPT flag set. -arca
*/
/* read Pentium cycle counter */
unsigned long t;
rdtscll(t);
hpet.offset = (t - hpet.last_tsc) * (1000000L / HZ) / hpet.ticks + hpet.offset - 1000000L / HZ;
if (hpet.offset >= 1000000L / HZ)
hpet.offset = 0;
hpet.ticks = min_t(long, max_t(long, (t - hpet.last_tsc) * (1000000L / HZ) / (1000000L / HZ - hpet.offset),
cpu_khz * 1000/HZ * 15 / 16), cpu_khz * 1000/HZ * 16 / 15);
hpet.last_tsc = t;
}
rdtscl(last_tsc_low);
/*
* Do the timer stuff.
*/
spin_lock(&i8253_lock);
outb_p(0x00, 0x43); /* latch the count ASAP */
do_timer(regs);
count = inb_p(0x40); /* read the latched count */
count |= inb(0x40) << 8;
spin_unlock(&i8253_lock);
/*
* If we have an externally synchronized Linux clock, then update CMOS clock
* accordingly every ~11 minutes. set_rtc_mmss() will be called in the jiffy
* closest to exactly 500 ms before the next second. If the update fails, we
* don'tcare, as it'll be updated on the next turn, and the problem (time way
* off) isn't likely to go away much sooner anyway.
*/
count = ((LATCH-1) - count) * TICK_SIZE;
delay_at_last_interrupt = (count + LATCH/2) / LATCH;
if ((~time_status & STA_UNSYNC) && xtime.tv_sec > rtc_update &&
abs(xtime.tv_nsec - 500000000) <= tick_nsec / 2) {
set_rtc_mmss(xtime.tv_sec);
rtc_update = xtime.tv_sec + 660;
}
do_timer_interrupt(irq, NULL, regs);
vxtime_unlock();
write_unlock(&xtime_lock);
}
/* not static: needed by APM */
unsigned long get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
int i;
unsigned int timeout, year, mon, day, hour, min, sec;
unsigned char last, this;
/*
* The Linux interpretation of the CMOS clock register contents: When the
* Update-In-Progress (UIP) flag goes from 1 to 0, the RTC registers show the
* second which has precisely just started. Waiting for this can take up to 1
* second, we timeout approximately after 2.4 seconds on a machine with
* standard 8.3 MHz ISA bus.
*/
spin_lock(&rtc_lock);
/* The Linux interpretation of the CMOS clock register contents:
* When the Update-In-Progress (UIP) flag goes from 1 to 0, the
* RTC registers show the second which has precisely just started.
* Let's hope other operating systems interpret the RTC the same way.
timeout = 1000000;
last = this = 0;
while (timeout && last && !this) {
last = this;
this = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP;
timeout--;
}
/*
* Here we are safe to assume the registers won't change for a whole second, so
* we just go ahead and read them.
*/
/* read RTC exactly on falling edge of update flag */
for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
break;
for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
break;
do { /* Isn't this overkill ? UIP above should guarantee consistency */
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
} while (sec != CMOS_READ(RTC_SECONDS));
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
spin_unlock(&rtc_lock);
/*
* We know that x86-64 always uses BCD format, no need to check the config
* register.
*/
BCD_TO_BIN(sec);
BCD_TO_BIN(min);
BCD_TO_BIN(hour);
BCD_TO_BIN(day);
BCD_TO_BIN(mon);
BCD_TO_BIN(year);
}
spin_unlock(&rtc_lock);
/*
* This will work up to Dec 31, 2069.
*/
if ((year += 1900) < 1970)
year += 100;
return mktime(year, mon, day, hour, min, sec);
}
static struct irqaction irq0 = { timer_interrupt, SA_INTERRUPT, 0, "timer", NULL, NULL};
/* ------ Calibrate the TSC -------
* Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
* Too much 64-bit arithmetic here to do this cleanly in C, and for
* accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
* output busy loop as low as possible. We avoid reading the CTC registers
* directly because of the awkward 8-bit access mechanism of the 82C54
* device.
/*
* calibrate_tsc() calibrates the processor TSC in a very simple way, comparing
* it to the HPET timer of known frequency.
*/
#define CALIBRATE_LATCH (5 * LATCH)
#define CALIBRATE_TIME (5 * 1000020/HZ)
#define TICK_COUNT 100000000
/*
* pit_calibrate_tsc() uses the speaker output (channel 2) of
* the PIT. This is better than using the timer interrupt output,
* because we can read the value of the speaker with just one inb(),
* where we need three i/o operations for the interrupt channel.
* We count how many ticks the TSC does in 50 ms.
*/
/* Could use 64bit arithmetic on x86-64, but the code is too fragile */
static unsigned long __init calibrate_tsc(void)
static unsigned int __init pit_calibrate_tsc(void)
{
/* Set the Gate high, disable speaker */
unsigned long start, end;
unsigned long flags;
outb((inb(0x61) & ~0x02) | 0x01, 0x61);
/*
* Now let's take care of CTC channel 2
*
* Set the Gate high, program CTC channel 2 for mode 0,
* (interrupt on terminal count mode), binary count,
* load 5 * LATCH count, (LSB and MSB) to begin countdown.
*/
outb(0xb0, 0x43); /* binary, mode 0, LSB/MSB, Ch 2 */
outb(CALIBRATE_LATCH & 0xff, 0x42); /* LSB of count */
outb(CALIBRATE_LATCH >> 8, 0x42); /* MSB of count */
local_irq_save(flags);
local_irq_disable();
{
unsigned int startlow, starthigh;
unsigned int endlow, endhigh;
unsigned int count;
rdtsc(startlow,starthigh);
count = 0;
do {
count++;
} while ((inb(0x61) & 0x20) == 0);
rdtsc(endlow,endhigh);
last_tsc_low = endlow;
/* Error: ECTCNEVERSET */
if (count <= 1)
goto bad_ctc;
__asm__("subl %2,%0\n\t"
"sbbl %3,%1"
:"=a" (endlow), "=d" (endhigh)
:"g" (startlow), "g" (starthigh),
"0" (endlow), "1" (endhigh));
/* Error: ECPUTOOFAST */
if (endhigh)
goto bad_ctc;
/* Error: ECPUTOOSLOW */
if (endlow <= CALIBRATE_TIME)
goto bad_ctc;
__asm__("divl %2"
:"=a" (endlow), "=d" (endhigh)
:"r" (endlow), "0" (0), "1" (CALIBRATE_TIME));
outb(0xb0, 0x43);
outb((1193182 / (1000 / 50)) & 0xff, 0x42);
outb((1193182 / (1000 / 50)) >> 8, 0x42);
rdtscll(start);
return endlow;
}
while ((inb(0x61) & 0x20) == 0);
rdtscll(end);
/*
* The CTC wasn't reliable: we got a hit on the very first read,
* or the CPU was so fast/slow that the quotient wouldn't fit in
* 32 bits..
*/
bad_ctc:
return 0;
}
void __init time_init(void)
{
extern int x86_udelay_tsc;
local_irq_restore(flags);
xtime.tv_sec = get_cmos_time();
xtime.tv_usec = 0;
/*
* If we have APM enabled or the CPU clock speed is variable
* (CPU stops clock on HLT or slows clock to save power)
* then the TSC timestamps may diverge by up to 1 jiffy from
* 'real time' but nothing will break.
* The most frequent case is that the CPU is "woken" from a halt
* state by the timer interrupt itself, so we get 0 error. In the
* rare cases where a driver would "wake" the CPU and request a
* timestamp, the maximum error is < 1 jiffy. But timestamps are
* still perfectly ordered.
*/
return (end - start) / 50;
}
if (cpu_has_tsc) {
unsigned int tsc_quotient = calibrate_tsc();
if (tsc_quotient) {
fast_gettimeoffset_quotient = tsc_quotient;
use_tsc = 1;
/*
* We could be more selective here I suspect
* and just enable this for the next intel chips ?
*/
x86_udelay_tsc = 1;
/* report CPU clock rate in Hz.
* The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
* clock/second. Our precision is about 100 ppm.
*/
{ unsigned int eax=0, edx=1000;
__asm__("divl %2"
:"=a" (cpu_khz), "=d" (edx)
:"r" (tsc_quotient),
"0" (eax), "1" (edx));
printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
}
}
void __init pit_init(void)
{
outb_p(0x34, 0x43); /* binary, mode 2, LSB/MSB, ch 0 */
outb_p(LATCH & 0xff, 0x40); /* LSB */
outb_p(LATCH >> 8, 0x40); /* MSB */
}
setup_irq(0, &irq0);
int __init time_setup(char *str)
{
hpet_report_lost_ticks = 1;
return 1;
}
static struct device device_i8253 = {
name: "i8253",
bus_id: "0040",
};
static struct irqaction irq0 = { timer_interrupt, SA_INTERRUPT, 0, "timer", NULL, NULL};
extern void __init config_acpi_tables(void);
static int time_init_driverfs(void)
void __init time_init(void)
{
return register_sys_device(&device_i8253);
xtime.tv_sec = get_cmos_time();
xtime.tv_nsec = 0;
pit_init();
printk(KERN_INFO "time.c: Using 1.1931816 MHz PIT timer.\n");
setup_irq(0, &irq0);
cpu_khz = pit_calibrate_tsc();
printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
hpet.ticks = cpu_khz * (1000 / HZ);
rdtscll(hpet.last_tsc);
}
__initcall(time_init_driverfs);
__setup("report_lost_ticks", time_setup);
arch/x86_64/kernel/vsyscall.c
View file @ 1c41006f
......@@ -47,7 +47,7 @@
#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
//#define NO_VSYSCALL 1
#define NO_VSYSCALL 1
#ifdef NO_VSYSCALL
#include <asm/unistd.h>
......@@ -71,51 +71,27 @@ static inline void timeval_normalize(struct timeval * tv)
long __vxtime_sequence[2] __section_vxtime_sequence;
static inline void do_vgettimeofday(struct timeval * tv)
{
long sequence;
unsigned long usec, sec;
long sequence, t;
unsigned long sec, usec;
do {
unsigned long eax, edx;
sequence = __vxtime_sequence[1];
rmb();
/* Read the Time Stamp Counter */
rdtsc(eax,edx);
/* .. relative to previous jiffy (32 bits is enough) */
eax -= __last_tsc_low; /* tsc_low delta */
/*
* Time offset = (tsc_low delta) * fast_gettimeoffset_quotient
* = (tsc_low delta) * (usecs_per_clock)
* = (tsc_low delta) * (usecs_per_jiffy / clocks_per_jiffy)
*
* Using a mull instead of a divl saves up to 31 clock cycles
* in the critical path.
*/
edx = (eax*__fast_gettimeoffset_quotient) >> 32;
/* our adjusted time offset in microseconds */
usec = __delay_at_last_interrupt + edx;
{
unsigned long lost = __jiffies - __wall_jiffies;
if (lost)
usec += lost * (1000000 / HZ);
}
rdtscll(t);
sec = __xtime.tv_sec;
usec += __xtime.tv_usec;
usec = __xtime.tv_usec +
(__jiffies - __wall_jiffies) * (1000000 / HZ) +
(t - __hpet.last_tsc) * (1000000 / HZ) / __hpet.ticks + __hpet.offset;
rmb();
} while (sequence != __vxtime_sequence[0]);
tv->tv_sec = sec;
tv->tv_usec = usec;
timeval_normalize(tv);
tv->tv_sec = sec + usec / 1000000;
tv->tv_usec = usec % 1000000;
}
static inline void do_get_tz(struct timezone * tz)
......
include/asm-x86_64/timex.h
View file @ 1c41006f
......@@ -36,16 +36,14 @@ extern cycles_t cacheflush_time;
static inline cycles_t get_cycles (void)
{
#ifndef CONFIG_X86_TSC
return 0;
#else
unsigned long long ret;
rdtscll(ret);
return ret;
#endif
}
extern unsigned int cpu_khz;
extern struct hpet_data hpet;
#endif
include/asm-x86_64/vsyscall.h
View file @ 1c41006f
#ifndef _ASM_X86_64_VSYSCALL_H_
#define _ASM_X86_64_VSYSCALL_H_
#include <linux/time.h>
enum vsyscall_num {
__NR_vgettimeofday,
__NR_vtime,
......@@ -13,32 +15,39 @@ enum vsyscall_num {
#ifdef __KERNEL__
#define __section_last_tsc_low __attribute__ ((unused, __section__ (".last_tsc_low")))
#define __section_delay_at_last_interrupt __attribute__ ((unused, __section__ (".delay_at_last_interrupt")))
#define __section_fast_gettimeoffset_quotient __attribute__ ((unused, __section__ (".fast_gettimeoffset_quotient")))
#define __section_wall_jiffies __attribute__ ((unused, __section__ (".wall_jiffies")))
#define __section_jiffies __attribute__ ((unused, __section__ (".jiffies")))
#define __section_sys_tz __attribute__ ((unused, __section__ (".sys_tz")))
#define __section_xtime __attribute__ ((unused, __section__ (".xtime")))
#define __section_vxtime_sequence __attribute__ ((unused, __section__ (".vxtime_sequence")))
#define __section_hpet __attribute__ ((unused, __section__ (".hpet"), aligned(16)))
#define __section_wall_jiffies __attribute__ ((unused, __section__ (".wall_jiffies"), aligned(16)))
#define __section_jiffies __attribute__ ((unused, __section__ (".jiffies"), aligned(16)))
#define __section_sys_tz __attribute__ ((unused, __section__ (".sys_tz"), aligned(16)))
#define __section_xtime __attribute__ ((unused, __section__ (".xtime"), aligned(16)))
#define __section_vxtime_sequence __attribute__ ((unused, __section__ (".vxtime_sequence"), aligned(16)))
struct hpet_data {
long address; /* base address */
unsigned long hz; /* HPET clocks / sec */
int trigger; /* value at last interrupt */
int last;
int offset;
unsigned long last_tsc;
long ticks;
};
#define hpet_readl(a) readl(fix_to_virt(FIX_HPET_BASE) + a)
#define hpet_writel(d,a) writel(d, fix_to_virt(FIX_HPET_BASE) + a)
/* vsyscall space (readonly) */
extern long __vxtime_sequence[2];
extern int __delay_at_last_interrupt;
extern unsigned int __last_tsc_low;
extern unsigned int __fast_gettimeoffset_quotient;
extern struct timeval __xtime;
extern struct hpet_data __hpet;
extern struct timespec __xtime;
extern volatile unsigned long __jiffies;
extern unsigned long __wall_jiffies;
extern struct timezone __sys_tz;
/* kernel space (writeable) */
extern unsigned long last_tsc_low;
extern int delay_at_last_interrupt;
extern unsigned int fast_gettimeoffset_quotient;
extern long vxtime_sequence[2];
extern struct hpet_data hpet;
extern unsigned long wall_jiffies;
extern struct timezone sys_tz;
extern long vxtime_sequence[2];
#define vxtime_lock() do { vxtime_sequence[0]++; wmb(); } while(0)
#define vxtime_unlock() do { wmb(); vxtime_sequence[1]++; } while (0)
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7