title "Interval Clock Interrupt"
;++
;
; Copyright (c) 1989 Microsoft Corporation
;
; Module Name:
;
; spclock.asm
;
; Abstract:
;
; This module implements the code necessary to field and process the
; interval clock interrupt.
;
; Author:
;
; Shie-Lin Tzong (shielint) 12-Jan-1990
;
; Environment:
;
; Kernel mode only.
;
; Revision History:
;
; bryanwi 20-Sep-90
;
; Add KiSetProfileInterval, KiStartProfileInterrupt,
; KiStopProfileInterrupt procedures.
; KiProfileInterrupt ISR.
; KiProfileList, KiProfileLock are delcared here.
;
; shielint 10-Dec-90
; Add performance counter support.
; Move system clock to irq8, ie we now use RTC to generate system
; clock. Performance count and Profile use timer 1 counter 0.
; The interval of the irq0 interrupt can be changed by
; KiSetProfileInterval. Performance counter does not care about the
; interval of the interrupt as long as it knows the rollover count.
; Note: Currently I implemented 1 performance counter for the whole
; i386 NT. It works on UP and SystemPro.
;
; John Vert (jvert) 11-Jul-1991
; Moved from ke\i386 to hal\i386. Removed non-HAL stuff
;
; shie-lin tzong (shielint) 13-March-92
; Move System clock back to irq0 and use RTC (irq8) to generate
; profile interrupt. Performance counter and system clock use time1
; counter 0 of 8254.
;
;
;--
.386p
.xlist
include callconv.inc
include hal386.inc
include i386\ix8259.inc
include i386\ixcmos.inc
include i386\kimacro.inc
include mac386.inc
include i386\spmp.inc
.list
EXTRNP _DbgBreakPoint,0,IMPORT
extrn KiI8259MaskTable:DWORD
EXTRNP _KeUpdateSystemTime,0
EXTRNP _KeUpdateRunTime,1,IMPORT
EXTRNP Kei386EoiHelper,0,IMPORT
EXTRNP _HalEndSystemInterrupt,2
EXTRNP _HalBeginSystemInterrupt,3
EXTRNP _HalRequestIpi,1
EXTRNP _HalpAcquireCmosSpinLock ,0
EXTRNP _HalpReleaseCmosSpinLock ,0
EXTRNP _KeStallExecutionProcessor, 1
extrn _HalpProcessorPCR:DWORD
extrn _HalpSystemHardwareLock:DWORD
extrn _HalpFindFirstSetRight:BYTE
extrn _Sp8259PerProcessorMode:BYTE
EXTRNP _KeSetTimeIncrement,2,IMPORT
EXTRNP _HalpMcaQueueDpc, 0
extrn _SpType:BYTE
;
; Constants used to initialize timer 0
;
TIMER1_DATA_PORT0 EQU 40H ; Timer1, channel 0 data port
TIMER1_CONTROL_PORT0 EQU 43H ; Timer1, channel 0 control port
TIMER1_IRQ EQU 0 ; Irq 0 for timer1 interrupt
COMMAND_8254_COUNTER0 EQU 00H ; Select count 0
COMMAND_8254_RW_16BIT EQU 30H ; Read/Write LSB firt then MSB
COMMAND_8254_MODE2 EQU 4 ; Use mode 2
COMMAND_8254_BCD EQU 0 ; Binary count down
COMMAND_8254_LATCH_READ EQU 0 ; Latch read command
PERFORMANCE_FREQUENCY EQU 1193182
;
; ==== Values used for System Clock ====
;
;
; Convert the interval to rollover count for 8254 Timer1 device.
; Timer1 counts down a 16 bit value at a rate of 1.193181667M counts-per-sec.
;
;
; The best fit value closest to 10ms (but not below) is 10.0144012689ms:
; ROLLOVER_COUNT 11949
; TIME_INCREMENT 100144
; Calculated error is -.0109472 s/day
;
; The best fit value closest to 15ms (but not above) is 14.9952019ms:
; ROLLOVER_COUNT 17892
; TIME_INCREMENT 149952
; Calculated error is -.0109472 s/day
;
; On 486 class machines or better we use a 10ms tick, on 386
; class machines we use a 15ms tick
;
ROLLOVER_COUNT_10MS EQU 11949
TIME_INCREMENT_10MS EQU 100144
;
; Value for KeQueryPerf retries.
;
MAX_PERF_RETRY equ 3 ; Odly enough 3 is plenty.
_DATA SEGMENT DWORD PUBLIC 'DATA'
;
; The following array stores the per microsecond loop count for each
; central processor.
;
public _HalpIpiClock
_HalpIpiClock dd 0 ; Processors to IPI clock pulse to
public HalpPerfCounterLow
public HalpPerfCounterHigh
HalpPerfCounterLow dd 0
HalpPerfCounterHigh dd 0
HalpPerfP0Value dd 0
HalpCalibrateFlag db 0
db 0
dw 0
HalpRollOverCount dd 0
public _HalpClockWork, _HalpClockSetMSRate, _HalpClockMcaQueueDpc
_HalpClockWork label dword
_HalpClockSetMSRate db 0
_HalpClockMcaQueueDpc db 0
_bReserved1 db 0
_bReserved2 db 0
;
; Storage for variable to ensure that queries are always
; greater than the last.
;
HalpLastQueryLowValue dd 0
HalpLastQueryHighValue dd 0
HalpForceDataLock dd 0
; endmod
_DATA ends
_TEXT SEGMENT DWORD PUBLIC 'CODE'
ASSUME DS:FLAT, ES:FLAT, SS:NOTHING, FS:NOTHING, GS:NOTHING
page ,132
subttl "Initialize Clock"
;++
;
; VOID
; HalpInitializeClock (
; )
;
; Routine Description:
;
; This routine initialize system time clock using 8254 timer1 counter 0
; to generate an interrupt at every 15ms interval at 8259 irq0
;
; See the definition of TIME_INCREMENT and ROLLOVER_COUNT if clock rate
; needs to be changed.
;
; Arguments:
;
; None
;
; Return Value:
;
; None.
;
;--
cPublicProc _HalpInitializeClock ,0
;
; Use 15ms or 10ms clock tick?
;
mov edx, TIME_INCREMENT_10MS ; yes, use 10ms clock
mov ecx, ROLLOVER_COUNT_10MS
;
; Fill in PCR value with TIME_INCREMENT
; (edx) = TIME_INCREMENT
; (ecx) = ROLLOVER_COUNT
;
cmp byte ptr PCR[PcHal.PcrNumber], 0
jne short icl_10
push ecx
stdCall _KeSetTimeIncrement, <edx, edx>
pop ecx
pushfd ; save caller's eflag
cli ; make sure interrupts are disabled
;
; Set clock rate
; (ecx) = RollOverCount
;
mov al,COMMAND_8254_COUNTER0+COMMAND_8254_RW_16BIT+COMMAND_8254_MODE2
out TIMER1_CONTROL_PORT0, al ;program count mode of timer 0
IoDelay
mov al, cl
out TIMER1_DATA_PORT0, al ; program timer 0 LSB count
IoDelay
mov al,ch
out TIMER1_DATA_PORT0, al ; program timer 0 MSB count
popfd ; restore caller's eflag
mov HalpRollOverCount, ecx ; Set RollOverCount & initialized
stdRET _HalpInitializeClock
icl_10:
pushfd ; save caller's eflag
cli ; make sure interrupts are disabled
;
; initialize clock, non-p0
; (ecx) = ROLLOVER_COUNT
;
mov al,COMMAND_8254_COUNTER0+COMMAND_8254_RW_16BIT+COMMAND_8254_MODE2
out TIMER1_CONTROL_PORT0, al ;program count mode of timer 0
IoDelay
mov al, cl
out TIMER1_DATA_PORT0, al ; program timer 0 LSB count
IoDelay
mov al,ch
out TIMER1_DATA_PORT0, al ; program timer 0 MSB count
popfd ; restore caller's eflag
stdRET _HalpInitializeClock
stdENDP _HalpInitializeClock
;++
;
; VOID
; HalCalibratePerformanceCounter (
; IN LONG volatile *Number,
; IN ULONGLONG NewCount
; )
;
; /*++
;
; Routine Description:
;
; This routine calibrates the performance counter value for a
; multiprocessor system. The calibration can be done by zeroing
; the current performance counter, or by calculating a per-processor
; skewing between each processors counter.
;
; Arguments:
;
; Number - Supplies a pointer to count of the number of processors in
; the configuration.
;
; NewCount - Supplies the value to synchronize the counter too
;
; Return Value:
;
; None.
;--
cPublicProc _HalCalibratePerformanceCounter,3
mov eax, [esp+4] ; ponter to Number
pushfd ; save previous interrupt state
cli ; disable interrupts (go to high_level)
lock dec dword ptr [eax] ; count down
@@: cmp dword ptr [eax], 0 ; wait for all processors to signal
jnz short @b
test _Sp8259PerProcessorMode, SP_SMPCLOCK
jz short cal_exit ; 8254 per processor?
xor ecx, ecx
mov al, COMMAND_8254_LATCH_READ+COMMAND_8254_COUNTER0
; Latch PIT Ctr 0 command.
out TIMER1_CONTROL_PORT0, al
IODelay
in al, TIMER1_DATA_PORT0 ; Read PIT Ctr 0, LSByte.
IODelay
movzx ecx, al
in al, TIMER1_DATA_PORT0 ; Read PIT Ctr 0, MSByte.
mov ch, al ; (CX) = PIT Ctr 0 count.
cmp byte ptr PCR[PcHal.PcrNumber], 0 ; is this the processor
jz short cal_p0 ; which updates HalpPerfCounter?
@@: cmp HalpCalibrateFlag, 0 ; wait for P0 to post it's counter
jz short @b
sub ecx, HalpPerfP0Value ; compute difference
neg ecx
mov PCR[PcHal.PcrPerfSkew], ecx
cal_exit:
popfd
stdRET _HalCalibratePerformanceCounter
cal_p0: mov HalpPerfP0Value, ecx ; post our timer value
mov HalpCalibrateFlag, 1 ; signal we are done
jmp short cal_exit
stdENDP _HalCalibratePerformanceCounter
page ,132
subttl "Query Performance Counter"
;++
;
; LARGE_INTEGER
; KeQueryPerformanceCounter (
; OUT PLARGE_INTEGER PerformanceFrequency OPTIONAL
; )
;
; Routine Description:
;
; This routine returns current 64-bit performance counter and,
; optionally, the Performance Frequency.
;
; Note this routine can NOT be called at Profiling interrupt
; service routine. Because this routine depends on IRR0 to determine
; the actual count.
;
; Also note that the performace counter returned by this routine
; is not necessary the value when this routine is just entered.
; The value returned is actually the counter value at any point
; between the routine is entered and is exited.
;
; Arguments:
;
; PerformanceFrequency [TOS+4] - optionally, supplies the address
; of a variable to receive the performance counter frequency.
;
; Return Value:
;
; Current value of the performance counter will be returned.
;
;--
;
; Parameter definitions
;
KqpcFrequency EQU [esp+20] ; User supplied Performance Frequence
RetryPerfCount EQU [esp] ; Local retry variable
cPublicProc _KeQueryPerformanceCounter ,1
push ebx
push esi
push edi
push 0 ; make space for RetryPerfCount
;
; First check to see if the performance counter has been initialized yet.
; Since the kernel debugger calls KeQueryPerformanceCounter to support the
; !timer command, we need to return something reasonable before 8254
; initialization has occured. Reading garbage off the 8254 is not reasonable.
;
cmp HalpRollOverCount, 0
jne short Kqpc11 ; ok, perf counter has been initialized
;
; Initialization hasn't occured yet, so just return zeroes.
;
mov eax, 0
mov edx, 0
jmp Kqpc50
Kqpc11: pushfd
cli
Kqpc20:
lea eax, _HalpSystemHardwareLock
ACQUIRE_SPINLOCK eax, Kqpc198
;
; Fetch the base value. Note that interrupts are off.
;
; NOTE:
; Need to watch for Px reading the 'CounterLow', P0 updates both
; then Px finishes reading 'CounterHigh' [getting the wrong value].
; After reading both, make sure that 'CounterLow' didn't change.
; If it did, read it again. This way, we won't have to use a spinlock.
@@:
mov ebx, HalpPerfCounterLow
mov esi, HalpPerfCounterHigh ; [esi:ebx] = Performance counter
cmp ebx, HalpPerfCounterLow ;
jne short @b
;
; Fetch the current counter value from the hardware
;
;
; Background: Belize style systems have an 8254 per Processor.
;
; In short the original implementation kinda assumes that each
; timer on each processor will be in perfect sycnh with each other.
; This is a bad assumption, and the reason why we have attempted
; to use only the timer on P0.
;
; There is an existing window where the return value may not be accurate.
; The window will occur when multiple queries are made back to back
; in an MP environment, and there are a lot of IPIs going on. Intuitive,
; right. The problem is that this routine may return a value with the
; the hardware system timer on P0 that has already generated an interrupt
; and reset its rollover, but the software has yet to process the interrupt
; to update the performance counter value. When this occurs, the second
; querry will seem to have a lower value than the first.
;
; So, why don't I just fix it. Well the cause of the problem is the
; overhead associated with handling the interrupt, and the fact that
; the IPI has a higher IRQL. In addition, a busy system could be
; issueing multiple IPIs back to back, which could extend this window
; even further.
;
; I have managed to close the window most of the way for most normal
; conditions. It takes several minutes on a busy system, with
; multiple applications running with back to back queries to get
; an invalid value. It can happen though.
;
; A retry implementation has been instrumented on top off the
; Indexed IO implementation to finally close the window.
; It seems to work OK.
;
; In reality, I think the fix is sufficient. The performance counter
; is not designed propperly (via only software) to yield very accurate
; values on sub timer tic (10-15msec) ranges on multiprocessor systems.
;
; Problems with this design:
;
; On an idle system threads executing from P0 will always
; use less overhead than threads executing on P1.
; On a ProLiant 2000 with 2 P5-66s the difference in 2
; consecutive KeQueryPerformanceCounter calls from P0
; is about 14, while from P1 is about 22. Unfortunately
; on a busy system P0 performs about the same, but P1
; is much slower due to the overhead involved in performing
; an Indexed_IO. This means the busyier your system gets
; the less accurate your performance values will become.
;
; The solution:
;
; A system wide hardware timer needs to be used. This is about the
; only way to get accurate performance numbers from multiple
; processors without causing unnecessary software overhead.
;
; Supposedly there is a 48 bit counter that we may be able to use
; with SystemPro XL, and ProLiant systems, unfortunately it does
; not appear that any OS is currently using this feature, so
; its dependability may be suspect.
;
; JSL
;
;
; Essentially all we are doing is always using the timer value on P0.
; The indexed_io is a mechanism for one processor to access IOSPACE
; on another processor's IOSPACE. I suspect this will have a greater
; impact on performance than just reading the timer locally.
; By using the indexed_io you are gauranteed of going out on the bus.
;
; But, hey if the user understands anything about performance, they
; know that there will be some amount of overhead each time you make
; this KeQueryPerformanceCounter call.
;
;
; Increment the Retry counter now for convenience
;
inc dword ptr RetryPerfCount+4
;
; This is Belize specific.
;
cmp _SpType, SMP_SYSPRO2
jne timer_p0
;
; Only use Indexed_IO on a nonP0 processor
;
cmp byte ptr PCR[PcHal.PcrNumber], 0 ; is this the processor
je timer_p0 ; which updates HalpPerfCounter?
;
; So read the timer of P0.
;
push ebx
mov bl, 0
mov al, COMMAND_8254_LATCH_READ+COMMAND_8254_COUNTER0
; Latch PIT Ctr 0 command.
INDEXED_IO_WRITE bl,TIMER1_CONTROL_PORT0,al
IODelay
INDEXED_IO_READ bl,TIMER1_DATA_PORT0 ; Read PIT Ctr 0, LSByte.
movzx ecx, al
INDEXED_IO_READ bl,TIMER1_DATA_PORT0 ; Read PIT Ctr 0, MSByte.
IODelay
mov ch,al ; (CX) = PIT Ctr 0 count.
pop ebx
lea eax, _HalpSystemHardwareLock
RELEASE_SPINLOCK eax
jmp short TimerValDone
timer_p0:
mov al, COMMAND_8254_LATCH_READ+COMMAND_8254_COUNTER0
;Latch PIT Ctr 0 command.
out TIMER1_CONTROL_PORT0, al
IODelay
in al, TIMER1_DATA_PORT0 ;Read PIT Ctr 0, LSByte.
IODelay
movzx ecx,al ;Zero upper bytes of (ECX).
in al, TIMER1_DATA_PORT0 ;Read PIT Ctr 0, MSByte.
mov ch, al ;(CX) = PIT Ctr 0 count.
lea eax, _HalpSystemHardwareLock
RELEASE_SPINLOCK eax
TimerValDone:
mov al, PCR[PcHal.PcrNumber] ; get current processor #
;
; This is Belize specific.
;
cmp _SpType, SMP_SYSPRO2
je NoCPU0Update
;
; If not on P0 then make sure P0 isn't in the process of
; of updating its timer. Do this by checking the status
; of the PIC using indexed_io.
; Make sure that only one thread at time reads P0 PIC.
;
cmp al, 0 ; Are we p0
je NoCPU0Update
;
; Check IRQL at PO before going any further
;
push edx
mov edx, _HalpProcessorPCR[0] ; PCR of processor 0
cmp byte ptr ds:[edx].PcIrql,CLOCK2_LEVEL
pop edx
jb short NoCPU0Update
push ebx
Kqpc11p:
;
; Check P0 PIC and confirm Timer Interrupt status.
; Perform Spin Lock before reading P0 PIC.
;
pushfd
cli
lea ebx, _HalpSystemHardwareLock
ACQUIRE_SPINLOCK ebx, Kqpc198p ; Spin if another thread is here
INDEXED_IO_READ 0,PIC1_PORT1 ; read CPU 0 port 21 for masks
RELEASE_SPINLOCK ebx
popfd
pop ebx
test al, 1h ; check for IRQ 0 masked off
mov al, PCR[PcHal.PcrNumber] ; get current processor #
jz short NoCPU0Update
;
; Try ReadAgain if below retry count.
;
cmp RetryPerfCount+4, MAX_PERF_RETRY
ja short NoCPU0Update
ReadAgain:
;
; This readagain is only executed when P0 is
; at CLOCK2_LEVEL or greater.
; AND when Timer IRQ is active (ie interrupt in progress).
; This is done to close the window of an interrupt
; occuring and the irql hasn't been raised yet.
;
popfd
jmp Kqpc11 ; go back and read again
NoCPU0Update:
;
; Now enable interrupts such that if timer interrupt is pending, it can
; be serviced and update the PerformanceCounter. Note that there could
; be a long time between the sti and cli because ANY interrupt could come
; in in between.
;
popfd ; don't re-enable interrupts if
nop ; the caller had them off!
jmp $+2 ; allow interrupt in case counter
; has wrapped
pushfd
cli
;
; In Belize mode we do not care about this since we use the P0 clock.
;
cmp _SpType, SMP_SYSPRO2
je short Kqpc35
;
; If we moved processors while interrupts were enabled, start over
;
cmp al, PCR[PcHal.PcrNumber]
jne Kqpc20
Kqpc35:
;
; Fetch the base value again.
;
@@: mov eax, HalpPerfCounterLow
mov edx, HalpPerfCounterHigh ; [edx:eax] = new counter value
cmp eax, HalpPerfCounterLow ; did it move?
jne short @b ; re-read
;
; Compare the two reads of Performance counter. If they are different,
; start over
;
cmp eax, ebx
jne Kqpc20
cmp edx, esi
jne Kqpc20
neg ecx ; PIT counts down from 0h
add ecx, HalpRollOverCount
;
; In Belize mode we do not care about this since we use the P0 clock.
;
cmp _SpType, SMP_SYSPRO2
je short Kqpc37
add ecx, PCR[PcHal.PcrPerfSkew]
Kqpc37:
popfd ; restore interrupt flag
xchg ecx, eax
mov ebx, edx
cdq
add eax, ecx
adc edx, ebx ; [edx:eax] = Final result
;
; We only want to execute this code In Belize mode.
;
cmp _SpType, SMP_SYSPRO2
jne Kqpc50
;
; Ok compare this result with the last result.
; We will force the value to be greater than the last value,
; after we have used up all of our retry counts.
;
; This should slam shut that annoying Window that causes
; applications to recieve a 2nd query less then the first.
;
; This is not an most elegant solution, but fortunately
; this situation is hit only on a rare occasions.
;
; Yeah, I know that this value can roll over
; if someone runs some perf tests, and comes back in a
; few weeks and wants to run some more. In this situation
; the the very first call to this function will yield an
; invalid value. This is the price of the fix.
;
;
; Protect the global data with a spinlock
;
push ebx
Kqpc42: pushfd
cli
lea ebx, HalpForceDataLock
ACQUIRE_SPINLOCK ebx, Kqpc199 ; Spin if another thread is here
;
; Compare this value to the last value, if less then
; fix it up.
;
cmp edx, HalpLastQueryHighValue
ja short Kqpc44
cmp eax, HalpLastQueryLowValue
ja short Kqpc44
;
; Release the spinlock.
;
RELEASE_SPINLOCK ebx
popfd
pop ebx
;
; Try Again if below count.
;
cmp RetryPerfCount, MAX_PERF_RETRY
jbe Kqpc11 ; go back and read again
;
; Exhausted retry count so Fix up the values and leave.
;
mov eax, HalpLastQueryLowValue
inc eax
mov edx, HalpLastQueryHighValue
jmp short Kqpc50
Kqpc44:
;
; Save off the perf values for next time.
;
mov HalpLastQueryLowValue, eax
mov HalpLastQueryHighValue, edx
;
; Release the spinlock.
;
RELEASE_SPINLOCK ebx
popfd
pop ebx
;
; Return the counter
;
Kqpc50:
; return value is in edx:eax
;
; Return the freq. if caller wants it.
;
or dword ptr KqpcFrequency, 0 ; is it a NULL variable?
jz short Kqpc99 ; if z, yes, go exit
mov ecx, KqpcFrequency ; (ecx)-> Frequency variable
mov DWORD PTR [ecx], PERFORMANCE_FREQUENCY ; Set frequency
mov DWORD PTR [ecx+4], 0
Kqpc99:
pop edi ; remove locals
pop edi ; restore regs
pop esi
pop ebx
stdRET _KeQueryPerformanceCounter
Kqpc198: popfd
SPIN_ON_SPINLOCK eax,<Kqpc11>
;
; This is just where we are spinning while we are waiting to read the PIC
;
Kqpc198p: popfd
SPIN_ON_SPINLOCK ebx,<Kqpc11p>
;
; This is just where we are spinning while waiting global last perf data
;
Kqpc199: popfd
SPIN_ON_SPINLOCK ebx,<Kqpc42>
stdENDP _KeQueryPerformanceCounter
; endmod
page ,132
subttl "System Clock Interrupt"
;++
;
; Routine Description:
;
;
; This routine is entered as the result of an interrupt generated by CLOCK2.
; Its function is to dismiss the interrupt, raise system Irql to
; CLOCK2_LEVEL, update performance counter and transfer control to the
; standard system routine to update the system time and the execution
; time of the current thread
; and process.
;
;
; Arguments:
;
; None
; Interrupt is disabled
;
; Return Value:
;
; Does not return, jumps directly to KeUpdateSystemTime, which returns
;
; Sets Irql = CLOCK2_LEVEL and dismisses the interrupt
;
;--
ENTER_DR_ASSIST Hci_a, Hci_t
cPublicProc _HalpClockInterrupt ,0
;
; Save machine state in trap frame
;
ENTER_INTERRUPT Hci_a, Hci_t
;
; (esp) - base of trap frame
;
;
; dismiss interrupt and raise Irql
;
Hci10:
push CLOCK_VECTOR
sub esp, 4 ; allocate space to save OldIrql
stdCall _HalBeginSystemInterrupt, <CLOCK2_LEVEL,CLOCK_VECTOR,esp>
or al,al ; check for spurious interrupt
jz Hci100
;
; Update performance counter
;
mov eax, HalpRollOverCount
xor ebx, ebx
add HalpPerfCounterLow, eax ; update performace counter
adc HalpPerfCounterHigh, ebx
cmp _HalpClockWork, ebx
jz short Hci20
cmp _HalpClockMcaQueueDpc, bl
jz short Hci20
mov _HalpClockMcaQueueDpc, bl
;
; Queue MCA Dpc
;
stdCall _HalpMcaQueueDpc
Hci20:
;
; (esp) = OldIrql
; (esp+4) = Vector
; (esp+8) = base of trap frame
; (ebp) = address of trap frame
; (eax) = time increment
;
mov eax, TIME_INCREMENT_10MS
mov ebx, _HalpIpiClock ; Emulate clock ticks to any processors?
or ebx, ebx
jz _KeUpdateSystemTime@0
;
; On the SystemPro we know the processor which needs an emulated clock tick.
; Just set that processors bit and IPI him
;
@@:
movzx ecx, _HalpFindFirstSetRight[ebx] ; lookup first processor
btr ebx, ecx
mov ecx, _HalpProcessorPCR[ecx*4] ; PCR of processor
mov [ecx].PcHal.PcrIpiClockTick, 1 ; Set internal IPI event
or ebx, ebx ; any other processors?
jnz short @b ; yes, loop
stdCall _HalRequestIpi, <_HalpIpiClock> ; IPI the processor(s)
mov eax, TIME_INCREMENT_10MS
jmp _KeUpdateSystemTime@0
Hci100:
add esp, 8
SPURIOUS_INTERRUPT_EXIT
stdENDP _HalpClockInterrupt
page ,132
subttl "NonPrimaryClockTick"
;++
;
; VOID
; HalpNonPrimaryClockInterrupt (
; );
;
; Routine Description:
; ISR for clock interrupts for every processor except one.
;
; Arguments:
;
; None.
; Interrupt is dismissed
;
; Return Value:
;
; None.
;
;--
ENTER_DR_ASSIST Hni_a, Hni_t
cPublicProc _HalpNonPrimaryClockInterrupt ,0
ENTER_INTERRUPT Hni_a, Hni_t
; Dismiss interrupt and raise irql
push CLOCK_VECTOR
sub esp, 4 ; allocate space to save OldIrql
stdCall _HalBeginSystemInterrupt, <CLOCK2_LEVEL,CLOCK_VECTOR,esp>
or al,al ; check for spurious interrupt
jz Hni100
; TOS const PreviousIrql
stdCall _KeUpdateRunTime,<dword ptr [esp]>
INTERRUPT_EXIT ; will do an iret
Hni100:
add esp, 8
SPURIOUS_INTERRUPT_EXIT
stdENDP _HalpNonPrimaryClockInterrupt
page ,132
subttl "Emulate NonPrimaryClockTick"
;++
;
; VOID
; HalpSWNonPrimaryClockTick (
; );
;
; Routine Description:
; On the SystemPro the second processor does not get it's own clock
; ticks. The HAL emulates them by sending an IPI which sets an overloaded
; software interrupt level of SWCLOCK_LEVEL. When the processor attempts
; to lower it's irql level below SWCLOCK_LEVEL the soft interrupt code
; lands us here as if an interrupt occured.
;
; Arguments:
;
; None.
; Interrupt is dismissed
;
; Return Value:
;
; None.
;
ENTER_DR_ASSIST Hsi_a, Hsi_t
public _HalpSWNonPrimaryClockTick
_HalpSWNonPrimaryClockTick proc
;
; Create IRET frame on stack
;
pop eax
pushfd
push cs
push eax
;
; Save machine state in trap frame
;
ENTER_INTERRUPT Hsi_a, Hsi_t
public _HalpSWNonPrimaryClockTick2ndEntry
_HalpSWNonPrimaryClockTick2ndEntry:
; Save previous IRQL and set new priority level
push fs:PcIrql ; save previous IRQL
mov byte ptr fs:PcIrql, SWCLOCK_LEVEL ; set new irql
btr dword ptr fs:PcIRR, SWCLOCK_LEVEL ; clear the pending bit in IRR
sti
; TOS const PreviousIrql
stdCall _KeUpdateRunTime,<dword ptr [esp]>
SOFT_INTERRUPT_EXIT ; will do an iret
_HalpSWNonPrimaryClockTick endp
;++
;
; ULONG
; HalSetTimeIncrement (
; IN ULONG DesiredIncrement
; )
;
; /*++
;
; Routine Description:
;
; This routine initialize system time clock to generate an
; interrupt at every DesiredIncrement interval.
;
; Arguments:
;
; DesiredIncrement - desired interval between every timer tick (in
; 100ns unit.)
;
; Return Value:
;
; The *REAL* time increment set.
;--
cPublicProc _HalSetTimeIncrement,1
mov eax, TIME_INCREMENT_10MS ; yes, use 10ms clock
stdRET _HalSetTimeIncrement
stdENDP _HalSetTimeIncrement
_TEXT ends
end