/* * Copyright (c) 2003 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * The contents of this file constitute Original Code as defined in and * are subject to the Apple Public Source License Version 1.1 (the * "License"). You may not use this file except in compliance with the * License. Please obtain a copy of the License at * http://www.apple.com/publicsource and read it before using this file. * * This Original Code and all software distributed under the License are * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the * License for the specific language governing rights and limitations * under the License. * * @APPLE_LICENSE_HEADER_END@ */ #include #include #include #include #include // commpage_time_dcba() uses a stack frame as follows: #define kBufSiz 1024 // Size of the buffer we use to do DCBA timing on G4 #define kSFSize (kBufSiz+128+16) // Stack frame size, which contains the 128-byte-aligned buffer #define kLoopCnt 5 // Iterations of the timing loop #define kDCBA 22 // Bit in cr5 used as a flag in timing loop // commpage_set_timestamp() uses the red zone for temporary storage: #define rzSaveF1 -8 // caller's FPR1 #define rzSaveF2 -16 // caller's FPR2 #define rzSaveF3 -24 // caller's FPR3 #define rzSaveF4 -32 // caller's FPR4 #define rzSaveF5 -40 // caller's FPR5 #define rzNewTimeBase -48 // used to load 64-bit TBR into a FPR // commpage_set_timestamp() uses the following data. kkTicksPerSec remembers // the number used to compute _COMM_PAGE_SEC_PER_TICK. Since this constant // rarely changes, we use it to avoid needless recomputation. It is a double // value, pre-initialize with an exponent of 2**52. #define kkBinary0 0 // offset in data to long long 0 (a constant) #define kkDouble1 8 // offset in data to double 1.0 (a constant) #define kkTicksPerSec 16 // offset in data to double(ticks_per_sec) .data .align 3 // three doubleword fields Ldata: .long 0 // kkBinary0 .long 0 .double 1.0e0 // kkDouble1 .long 0x43300000 // kkTicksPerSec (plus 2**52) .long 0 // this is where we store ticks_per_sec, to float .text .align 2 .globl EXT(commpage_time_dcba) .globl EXT(commpage_set_timestamp) /* *********************************************** * * C O M M P A G E _ S E T _ T I M E S T A M P * * *********************************************** * * Update the gettimeofday() shared data on the commpage, as follows: * _COMM_PAGE_TIMESTAMP = a BSD-style pair of uint_32's for secs and usecs * _COMM_PAGE_TIMEBASE = the timebase at which the timestamp was valid * _COMM_PAGE_SEC_PER_TICK = multiply timebase ticks by this to get seconds (double) * The convention is that if the timebase is 0, the data is invalid. Because other * CPUs are reading the three values asynchronously and must get a consistent set, * it is critical that we update them with the following protocol: * 1. set timebase to 0 (atomically), to invalidate all three values * 2. eieio (to create a barrier in stores to cacheable memory) * 3. change timestamp and "secs per tick" * 4. eieio * 5. set timebase nonzero (atomically) * This works because readers read the timebase, then the timestamp and divisor, sync * if MP, then read the timebase a second time and check to be sure it is equal to the first. * * We could save a few cycles on 64-bit machines by special casing them, but it probably * isn't necessary because this routine shouldn't be called very often. * * When called: * r3 = upper half of timebase (timebase is disabled if 0) * r4 = lower half of timebase * r5 = seconds part of timestamp * r6 = useconds part of timestamp * r7 = divisor (ie, timebase ticks per sec) * We set up: * r8 = ptr to our static data (kkBinary0, kkDouble1, kkTicksPerSec) * r9 = ptr to comm page in kernel map * * --> Interrupts must be disabled and rtclock locked when called. <-- */ .align 5 LEXT(commpage_set_timestamp) // void commpage_set_timestamp(tbr,secs,usecs,divisor) mfmsr r11 // get MSR ori r2,r11,MASK(MSR_FP) // turn FP on mtmsr r2 isync // wait until MSR changes take effect or. r0,r3,r4 // is timebase 0? (thus disabled) lis r8,hi16(Ldata) // point to our data lis r9,ha16(EXT(commPagePtr)) // get ptr to address of commpage in kernel map stfd f1,rzSaveF1(r1) // save a FPR in the red zone ori r8,r8,lo16(Ldata) lwz r9,lo16(EXT(commPagePtr))(r9) // r9 <- commPagePtr lfd f1,kkBinary0(r8) // get fixed 0s li r0,_COMM_PAGE_BASE_ADDRESS // get va in user space of commpage cmpwi cr1,r9,0 // is commpage allocated yet? sub r9,r9,r0 // r9 <- commpage address, biased by user va beq-- cr1,3f // skip if not allocated stfd f1,_COMM_PAGE_TIMEBASE(r9) // turn off the timestamp (atomically) eieio // make sure all CPUs see it is off beq 3f // all we had to do is turn off timestamp lwz r0,kkTicksPerSec+4(r8) // get last ticks_per_sec (or 0 if first) stw r3,rzNewTimeBase(r1) // store new timebase so we can lfd stw r4,rzNewTimeBase+4(r1) cmpw r0,r7 // do we need to recompute _COMM_PAGE_SEC_PER_TICK? stw r5,_COMM_PAGE_TIMESTAMP(r9) // store the new timestamp stw r6,_COMM_PAGE_TIMESTAMP+4(r9) lfd f1,rzNewTimeBase(r1) // get timebase in a FPR so we can store atomically beq++ 2f // same ticks_per_sec, no need to recompute stw r7,kkTicksPerSec+4(r8) // must recompute SEC_PER_TICK stfd f2,rzSaveF2(r1) // we'll need a few more temp FPRs stfd f3,rzSaveF3(r1) stfd f4,rzSaveF4(r1) stfd f5,rzSaveF5(r1) lfd f2,_COMM_PAGE_2_TO_52(r9) // f2 <- double(2**52) lfd f3,kkTicksPerSec(r8) // float new ticks_per_sec + 2**52 lfd f4,kkDouble1(r8) // f4 <- double(1.0) mffs f5 // save caller's FPSCR mtfsfi 7,0 // clear Inexeact Exception bit, set round-to-nearest fsub f3,f3,f2 // get ticks_per_sec fdiv f3,f4,f3 // divide 1 by ticks_per_sec to get SEC_PER_TICK stfd f3,_COMM_PAGE_SEC_PER_TICK(r9) mtfsf 0xFF,f5 // restore FPSCR lfd f2,rzSaveF2(r1) // restore FPRs lfd f3,rzSaveF3(r1) lfd f4,rzSaveF4(r1) lfd f5,rzSaveF5(r1) 2: // f1 == new timestamp eieio // wait until the stores take stfd f1,_COMM_PAGE_TIMEBASE(r9) // then turn the timestamp back on (atomically) 3: // here once all fields updated lfd f1,rzSaveF1(r1) // restore last FPR mtmsr r11 // turn FP back off isync blr /* *************************************** * * C O M M P A G E _ T I M E _ D C B A * * *************************************** * * Not all processors that support the DCBA opcode actually benefit from it. * Some store-gather and read-cancel well enough that there is no need to use * DCBA to avoid fetching cache lines that will be completely overwritten, while * others have this feature disabled (to work around errata etc), and so benefit * from DCBA. Since it is hard to tell the one group from the other, we just * time loops with and without DCBA, and pick the fastest. Thus we avoid * delicate dependence on processor and/or platform revisions. * * We return either kDcbaRecommended or zero. * * int commpage_time_dcba( void ); */ LEXT(commpage_time_dcba) mflr r12 // get return stw r12,8(r1) // save stwu r1,-kSFSize(r1) // carve our temp buffer from the stack addi r11,r1,127+16 // get base address... rlwinm r11,r11,0,0,24 // ...of our buffer, 128-byte aligned crset kDCBA // first, use DCBA bl LTest // time it with DCBA srwi r0,r3,3 // bias 12 pct in favor of not using DCBA... add r10,r3,r0 // ...because DCBA is always slower with warm cache crclr kDCBA bl LTest // time without DCBA cmplw r10,r3 // which is better? mtlr r12 // restore return lwz r1,0(r1) // pop off our stack frame li r3,kDcbaRecommended // assume using DCBA is faster bltlr li r3,0 // no DCBA is faster blr // Subroutine to time a loop with or without DCBA. // kDCBA = set if we should use DCBA // r11 = base of buffer to use for test (kBufSiz bytes) // // We return TBR ticks in r3. // We use r0,r3-r9. LTest: li r4,kLoopCnt // number of times to loop li r3,-1 // initialize fastest time 1: mr r6,r11 // initialize buffer ptr li r0,kBufSiz/32 // r0 <- cache blocks to test mtctr r0 2: dcbf 0,r6 // first, force the blocks out of the cache addi r6,r6,32 bdnz 2b sync // make sure all the flushes take mr r6,r11 // re-initialize buffer ptr mtctr r0 // reset cache-block count mftbu r7 // remember upper half so we can check for carry mftb r8 // start the timer 3: // loop over cache blocks bf kDCBA,4f // should we DCBA? dcba 0,r6 4: stw r0,0(r6) // store the entire cache block stw r0,4(r6) stw r0,8(r6) stw r0,12(r6) stw r0,16(r6) stw r0,20(r6) stw r0,24(r6) stw r0,28(r6) addi r6,r6,32 bdnz 3b mftb r9 mftbu r0 cmpw r0,r7 // did timebase carry? bne 1b // yes, retest rather than fuss sub r9,r9,r8 // r9 <- time for this loop cmplw r9,r3 // faster than current best? bge 5f // no mr r3,r9 // remember fastest time through loop 5: subi r4,r4,1 // decrement outer loop count cmpwi r4,0 // more to go? bne 1b // loop if so blr // return fastest time in r3