linux/arch/ia64/lib/do_csum.S
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

325 lines
10 KiB
ArmAsm

/* 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)