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Diffstat (limited to 'arch/ia64/lib/do_csum.S')
| -rw-r--r-- | arch/ia64/lib/do_csum.S | 324 |
1 files changed, 0 insertions, 324 deletions
diff --git a/arch/ia64/lib/do_csum.S b/arch/ia64/lib/do_csum.S deleted file mode 100644 index 6004dad259..0000000000 --- a/arch/ia64/lib/do_csum.S +++ /dev/null @@ -1,324 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* - * - * Optmized version of the standard do_csum() function - * - * Return: a 64bit quantity containing the 16bit Internet checksum - * - * Inputs: - * in0: address of buffer to checksum (char *) - * in1: length of the buffer (int) - * - * Copyright (C) 1999, 2001-2002 Hewlett-Packard Co - * Stephane Eranian <eranian@hpl.hp.com> - * - * 02/04/22 Ken Chen <kenneth.w.chen@intel.com> - * Data locality study on the checksum buffer. - * More optimization cleanup - remove excessive stop bits. - * 02/04/08 David Mosberger <davidm@hpl.hp.com> - * More cleanup and tuning. - * 01/04/18 Jun Nakajima <jun.nakajima@intel.com> - * Clean up and optimize and the software pipeline, loading two - * back-to-back 8-byte words per loop. Clean up the initialization - * for the loop. Support the cases where load latency = 1 or 2. - * Set CONFIG_IA64_LOAD_LATENCY to 1 or 2 (default). - */ - -#include <asm/asmmacro.h> - -// -// Theory of operations: -// The goal is to go as quickly as possible to the point where -// we can checksum 16 bytes/loop. Before reaching that point we must -// take care of incorrect alignment of first byte. -// -// The code hereafter also takes care of the "tail" part of the buffer -// before entering the core loop, if any. The checksum is a sum so it -// allows us to commute operations. So we do the "head" and "tail" -// first to finish at full speed in the body. Once we get the head and -// tail values, we feed them into the pipeline, very handy initialization. -// -// Of course we deal with the special case where the whole buffer fits -// into one 8 byte word. In this case we have only one entry in the pipeline. -// -// We use a (LOAD_LATENCY+2)-stage pipeline in the loop to account for -// possible load latency and also to accommodate for head and tail. -// -// The end of the function deals with folding the checksum from 64bits -// down to 16bits taking care of the carry. -// -// This version avoids synchronization in the core loop by also using a -// pipeline for the accumulation of the checksum in resultx[] (x=1,2). -// -// wordx[] (x=1,2) -// |---| -// | | 0 : new value loaded in pipeline -// |---| -// | | - : in transit data -// |---| -// | | LOAD_LATENCY : current value to add to checksum -// |---| -// | | LOAD_LATENCY+1 : previous value added to checksum -// |---| (previous iteration) -// -// resultx[] (x=1,2) -// |---| -// | | 0 : initial value -// |---| -// | | LOAD_LATENCY-1 : new checksum -// |---| -// | | LOAD_LATENCY : previous value of checksum -// |---| -// | | LOAD_LATENCY+1 : final checksum when out of the loop -// |---| -// -// -// See RFC1071 "Computing the Internet Checksum" for various techniques for -// calculating the Internet checksum. -// -// NOT YET DONE: -// - Maybe another algorithm which would take care of the folding at the -// end in a different manner -// - Work with people more knowledgeable than me on the network stack -// to figure out if we could not split the function depending on the -// type of packet or alignment we get. Like the ip_fast_csum() routine -// where we know we have at least 20bytes worth of data to checksum. -// - Do a better job of handling small packets. -// - Note on prefetching: it was found that under various load, i.e. ftp read/write, -// nfs read/write, the L1 cache hit rate is at 60% and L2 cache hit rate is at 99.8% -// on the data that buffer points to (partly because the checksum is often preceded by -// a copy_from_user()). This finding indiate that lfetch will not be beneficial since -// the data is already in the cache. -// - -#define saved_pfs r11 -#define hmask r16 -#define tmask r17 -#define first1 r18 -#define firstval r19 -#define firstoff r20 -#define last r21 -#define lastval r22 -#define lastoff r23 -#define saved_lc r24 -#define saved_pr r25 -#define tmp1 r26 -#define tmp2 r27 -#define tmp3 r28 -#define carry1 r29 -#define carry2 r30 -#define first2 r31 - -#define buf in0 -#define len in1 - -#define LOAD_LATENCY 2 // XXX fix me - -#if (LOAD_LATENCY != 1) && (LOAD_LATENCY != 2) -# error "Only 1 or 2 is supported/tested for LOAD_LATENCY." -#endif - -#define PIPE_DEPTH (LOAD_LATENCY+2) -#define ELD p[LOAD_LATENCY] // end of load -#define ELD_1 p[LOAD_LATENCY+1] // and next stage - -// unsigned long do_csum(unsigned char *buf,long len) - -GLOBAL_ENTRY(do_csum) - .prologue - .save ar.pfs, saved_pfs - alloc saved_pfs=ar.pfs,2,16,0,16 - .rotr word1[4], word2[4],result1[LOAD_LATENCY+2],result2[LOAD_LATENCY+2] - .rotp p[PIPE_DEPTH], pC1[2], pC2[2] - mov ret0=r0 // in case we have zero length - cmp.lt p0,p6=r0,len // check for zero length or negative (32bit len) - ;; - add tmp1=buf,len // last byte's address - .save pr, saved_pr - mov saved_pr=pr // preserve predicates (rotation) -(p6) br.ret.spnt.many rp // return if zero or negative length - - mov hmask=-1 // initialize head mask - tbit.nz p15,p0=buf,0 // is buf an odd address? - and first1=-8,buf // 8-byte align down address of first1 element - - and firstoff=7,buf // how many bytes off for first1 element - mov tmask=-1 // initialize tail mask - - ;; - adds tmp2=-1,tmp1 // last-1 - and lastoff=7,tmp1 // how many bytes off for last element - ;; - sub tmp1=8,lastoff // complement to lastoff - and last=-8,tmp2 // address of word containing last byte - ;; - sub tmp3=last,first1 // tmp3=distance from first1 to last - .save ar.lc, saved_lc - mov saved_lc=ar.lc // save lc - cmp.eq p8,p9=last,first1 // everything fits in one word ? - - ld8 firstval=[first1],8 // load, ahead of time, "first1" word - and tmp1=7, tmp1 // make sure that if tmp1==8 -> tmp1=0 - shl tmp2=firstoff,3 // number of bits - ;; -(p9) ld8 lastval=[last] // load, ahead of time, "last" word, if needed - shl tmp1=tmp1,3 // number of bits -(p9) adds tmp3=-8,tmp3 // effectively loaded - ;; -(p8) mov lastval=r0 // we don't need lastval if first1==last - shl hmask=hmask,tmp2 // build head mask, mask off [0,first1off[ - shr.u tmask=tmask,tmp1 // build tail mask, mask off ]8,lastoff] - ;; - .body -#define count tmp3 - -(p8) and hmask=hmask,tmask // apply tail mask to head mask if 1 word only -(p9) and word2[0]=lastval,tmask // mask last it as appropriate - shr.u count=count,3 // how many 8-byte? - ;; - // If count is odd, finish this 8-byte word so that we can - // load two back-to-back 8-byte words per loop thereafter. - and word1[0]=firstval,hmask // and mask it as appropriate - tbit.nz p10,p11=count,0 // if (count is odd) - ;; -(p8) mov result1[0]=word1[0] -(p9) add result1[0]=word1[0],word2[0] - ;; - cmp.ltu p6,p0=result1[0],word1[0] // check the carry - cmp.eq.or.andcm p8,p0=0,count // exit if zero 8-byte - ;; -(p6) adds result1[0]=1,result1[0] -(p8) br.cond.dptk .do_csum_exit // if (within an 8-byte word) -(p11) br.cond.dptk .do_csum16 // if (count is even) - - // Here count is odd. - ld8 word1[1]=[first1],8 // load an 8-byte word - cmp.eq p9,p10=1,count // if (count == 1) - adds count=-1,count // loaded an 8-byte word - ;; - add result1[0]=result1[0],word1[1] - ;; - cmp.ltu p6,p0=result1[0],word1[1] - ;; -(p6) adds result1[0]=1,result1[0] -(p9) br.cond.sptk .do_csum_exit // if (count == 1) exit - // Fall through to calculate the checksum, feeding result1[0] as - // the initial value in result1[0]. - // - // Calculate the checksum loading two 8-byte words per loop. - // -.do_csum16: - add first2=8,first1 - shr.u count=count,1 // we do 16 bytes per loop - ;; - adds count=-1,count - mov carry1=r0 - mov carry2=r0 - brp.loop.imp 1f,2f - ;; - mov ar.ec=PIPE_DEPTH - mov ar.lc=count // set lc - mov pr.rot=1<<16 - // result1[0] must be initialized in advance. - mov result2[0]=r0 - ;; - .align 32 -1: -(ELD_1) cmp.ltu pC1[0],p0=result1[LOAD_LATENCY],word1[LOAD_LATENCY+1] -(pC1[1])adds carry1=1,carry1 -(ELD_1) cmp.ltu pC2[0],p0=result2[LOAD_LATENCY],word2[LOAD_LATENCY+1] -(pC2[1])adds carry2=1,carry2 -(ELD) add result1[LOAD_LATENCY-1]=result1[LOAD_LATENCY],word1[LOAD_LATENCY] -(ELD) add result2[LOAD_LATENCY-1]=result2[LOAD_LATENCY],word2[LOAD_LATENCY] -2: -(p[0]) ld8 word1[0]=[first1],16 -(p[0]) ld8 word2[0]=[first2],16 - br.ctop.sptk 1b - ;; - // Since len is a 32-bit value, carry cannot be larger than a 64-bit value. -(pC1[1])adds carry1=1,carry1 // since we miss the last one -(pC2[1])adds carry2=1,carry2 - ;; - add result1[LOAD_LATENCY+1]=result1[LOAD_LATENCY+1],carry1 - add result2[LOAD_LATENCY+1]=result2[LOAD_LATENCY+1],carry2 - ;; - cmp.ltu p6,p0=result1[LOAD_LATENCY+1],carry1 - cmp.ltu p7,p0=result2[LOAD_LATENCY+1],carry2 - ;; -(p6) adds result1[LOAD_LATENCY+1]=1,result1[LOAD_LATENCY+1] -(p7) adds result2[LOAD_LATENCY+1]=1,result2[LOAD_LATENCY+1] - ;; - add result1[0]=result1[LOAD_LATENCY+1],result2[LOAD_LATENCY+1] - ;; - cmp.ltu p6,p0=result1[0],result2[LOAD_LATENCY+1] - ;; -(p6) adds result1[0]=1,result1[0] - ;; -.do_csum_exit: - // - // now fold 64 into 16 bits taking care of carry - // that's not very good because it has lots of sequentiality - // - mov tmp3=0xffff - zxt4 tmp1=result1[0] - shr.u tmp2=result1[0],32 - ;; - add result1[0]=tmp1,tmp2 - ;; - and tmp1=result1[0],tmp3 - shr.u tmp2=result1[0],16 - ;; - add result1[0]=tmp1,tmp2 - ;; - and tmp1=result1[0],tmp3 - shr.u tmp2=result1[0],16 - ;; - add result1[0]=tmp1,tmp2 - ;; - and tmp1=result1[0],tmp3 - shr.u tmp2=result1[0],16 - ;; - add ret0=tmp1,tmp2 - mov pr=saved_pr,0xffffffffffff0000 - ;; - // if buf was odd then swap bytes - mov ar.pfs=saved_pfs // restore ar.ec -(p15) mux1 ret0=ret0,@rev // reverse word - ;; - mov ar.lc=saved_lc -(p15) shr.u ret0=ret0,64-16 // + shift back to position = swap bytes - br.ret.sptk.many rp - -// I (Jun Nakajima) wrote an equivalent code (see below), but it was -// not much better than the original. So keep the original there so that -// someone else can challenge. -// -// shr.u word1[0]=result1[0],32 -// zxt4 result1[0]=result1[0] -// ;; -// add result1[0]=result1[0],word1[0] -// ;; -// zxt2 result2[0]=result1[0] -// extr.u word1[0]=result1[0],16,16 -// shr.u carry1=result1[0],32 -// ;; -// add result2[0]=result2[0],word1[0] -// ;; -// add result2[0]=result2[0],carry1 -// ;; -// extr.u ret0=result2[0],16,16 -// ;; -// add ret0=ret0,result2[0] -// ;; -// zxt2 ret0=ret0 -// mov ar.pfs=saved_pfs // restore ar.ec -// mov pr=saved_pr,0xffffffffffff0000 -// ;; -// // if buf was odd then swap bytes -// mov ar.lc=saved_lc -//(p15) mux1 ret0=ret0,@rev // reverse word -// ;; -//(p15) shr.u ret0=ret0,64-16 // + shift back to position = swap bytes -// br.ret.sptk.many rp - -END(do_csum) |