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SubjectRe: 2.1.128 / current EGCS
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In article <Pine.GSO.4.02A.9811132159510.2863-100000@jennifer.informatik.rwth-aachen.de>,
Bernd Schmidt <crux@pool.informatik.rwth-aachen.de> writes:
>> There's still a problem (last time I had forgotten to change the compiler
>> in the arch/i386/Makefile... Guess I should stop trying stuff after being
>> at the computer for 18 hours continually ;) ):
>>
>> gcc -D__KERNEL__ -I/usr/src/linux-AC/include -Wall -Wstrict-prototypes -O2
>> -fomit-frame-pointer -pipe -s -fno-exceptions -pipe -s
>> -fomit-frame-pointer -mk6 -march=k6 -DCPU=686 -c -o checksum.o
>> checksum.c
>> checksum.c: In function `csum_partial':
>> checksum.c:200: Invalid `asm' statement:
>> checksum.c:200: fixed or forbidden register 2 (cx) was spilled for class
>> CREG.
>> checksum.c: In function `csum_partial_copy_generic':
>> checksum.c:538: Invalid `asm' statement:
>> checksum.c:538: fixed or forbidden register 4 (si) was spilled for class
>> SIREG.

> That's a known problem; I didn't fix it yet in the patch I sent to Alan. The
> asms in checksum.c are rather hard to convert as they'd need too many
> operands if they were done properly. IMO the whole file should be replaced
> with a new file checksum.S which is entirely in assembler - the only C code
> in that file has a comment saying "old compatibility stuff, will be removed
> soon".

I did the conversion work, unfortunately it is not tested because the
resulting kernel crashes during boot. Tabs might be messed up a bit.

/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* IP/TCP/UDP checksumming routines
*
* Authors: Jorge Cwik, <jorge@laser.satlink.net>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Tom May, <ftom@netcom.com>
* Pentium Pro/II routines:
* Alexander Kjeldaas <astor@guardian.no>
* Finn Arne Gangstad <finnag@guardian.no>
* Lots of code moved from tcp.c and ip.c; see those files
* for more names.
*
* Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
* handling.
* Andi Kleen, add zeroing on error
* converted to pure assembler
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/errno.h>

/*
* computes a partial checksum, e.g. for TCP/UDP fragments
*/
/*
unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
*/
.text
.align 4
.globl csum_partial

#if CPU!=686

/*
* Experiments with Ethernet and SLIP connections show that buff
* is aligned on either a 2-byte or 4-byte boundary. We get at
* least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
* Fortunately, it is easy to convert 2-byte alignment to 4-byte
* alignment for the unrolled loop.
*/
csum_partial:
pushl %esi
pushl %ebx
movl 20(%esp),%eax
movl 16(%esp),%ecx
movl 12(%esp),%esi
testl $2, %esi # Check alignment.
jz 2f # Jump if alignment is ok.
subl $2, %ecx # Alignment uses up two bytes.
jae 1f # Jump if we had at least two bytes.
addl $2, %ecx # ecx was < 2. Deal with it.
jmp 4f
1: movw (%esi), %bx
addl $2, %esi
addw %bx, %ax
adcl $0, %eax
2:
movl %ecx, %edx
shrl $5, %ecx
jz 2f
testl %esi, %esi
1: movl (%esi), %ebx
adcl %ebx, %eax
movl 4(%esi), %ebx
adcl %ebx, %eax
movl 8(%esi), %ebx
adcl %ebx, %eax
movl 12(%esi), %ebx
adcl %ebx, %eax
movl 16(%esi), %ebx
adcl %ebx, %eax
movl 20(%esi), %ebx
adcl %ebx, %eax
movl 24(%esi), %ebx
adcl %ebx, %eax
movl 28(%esi), %ebx
adcl %ebx, %eax
lea 32(%esi), %esi
dec %ecx
jne 1b
adcl $0, %eax
2: movl %edx, %ecx
andl $0x1c, %edx
je 4f
shrl $2, %edx # This clears CF
3: adcl (%esi), %eax
lea 4(%esi), %esi
dec %edx
jne 3b
adcl $0, %eax
4: andl $3, %ecx
jz 7f
cmpl $2, %ecx
jb 5f
movw (%esi),%cx
leal 2(%esi),%esi
je 6f
shll $16,%ecx
5: movb (%esi),%cl
6: addl %ecx,%eax
adcl $0, %eax
7:
popl %ebx
popl %esi
ret
#else /* CPU==686 */
csum_partial:
movl 12(%esp),%eax #sum
movl 8(%esp),%ecx #len
movl 4(%esp),%esi #buff

testl $2, %esi
jnz 30f
10:
movl %ecx, %edx
movl %ecx, %ebx
andl $0x7c, %ebx
shrl $7, %ecx
addl %ebx,%esi
shrl $2, %ebx
negl %ebx
lea 45f(%ebx,%ebx,2), %ebx
testl %esi, %esi
jmp *%ebx

# Handle 2-byte-aligned regions
20: addw (%esi), %ax
lea 2(%esi), %esi
adcl $0, %eax
jmp 10b

30: subl $2, %ecx
ja 20b
je 32f
movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
addl %ebx, %eax
adcl $0, %eax
jmp 80f
32:
addw (%esi), %ax # csumming 2 bytes, 2-aligned
adcl $0, %eax
jmp 80f

40:
addl -128(%esi), %eax
adcl -124(%esi), %eax
adcl -120(%esi), %eax
adcl -116(%esi), %eax
adcl -112(%esi), %eax
adcl -108(%esi), %eax
adcl -104(%esi), %eax
adcl -100(%esi), %eax
adcl -96(%esi), %eax
adcl -92(%esi), %eax
adcl -88(%esi), %eax
adcl -84(%esi), %eax
adcl -80(%esi), %eax
adcl -76(%esi), %eax
adcl -72(%esi), %eax
adcl -68(%esi), %eax
adcl -64(%esi), %eax
adcl -60(%esi), %eax
adcl -56(%esi), %eax
adcl -52(%esi), %eax
adcl -48(%esi), %eax
adcl -44(%esi), %eax
adcl -40(%esi), %eax
adcl -36(%esi), %eax
adcl -32(%esi), %eax
adcl -28(%esi), %eax
adcl -24(%esi), %eax
adcl -20(%esi), %eax
adcl -16(%esi), %eax
adcl -12(%esi), %eax
adcl -8(%esi), %eax
adcl -4(%esi), %eax
45:
lea 128(%esi), %esi
adcl $0, %eax
dec %ecx
jge 40b
movl %edx, %ecx
50: andl $3, %ecx
jz 80f

# Handle the last 1-3 bytes without jumping
notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
movl $0xffffff,%ebx # by the shll and shrl instructions
shll $3,%ecx
shrl %cl,%ebx
andl -128(%esi),%ebx # esi is 4-aligned so should be ok
addl %ebx,%eax
adcl $0,%eax
80:
ret
#endif /* CPU==686 */
/*
unsigned int csum_partial_copy_generic (const char *src, char *dst,
int len, int sum, int *src_err_ptr, int *dst_err_ptr)
*/
/*
* Copy from ds while checksumming, otherwise like csum_partial
*
* The macros SRC and DST specify the type of access for the instruction.
* thus we can call a custom exception handler for all access types.
*
* FIXME: could someone double-check whether I haven't mixed up some SRC and
* DST definitions? It's damn hard to trigger all cases. I hope I got
* them all but there's no guarantee.
*/
#define SRC(y...) \
9999: y; \
.section __ex_table, "a" ;\
.long 9999b, 6001f ;\
.previous
#define DST(y...) \
9999: y; \
.section __ex_table,"a" ;\
.long 9999b, 6002f ;\
.previous
.align 4
.globl csum_partial_copy_generic

#if CPU!=686

#define ARGBASE 16
#define FP 12

csum_partial_copy_generic:
subl $4,%esp
pushl %edi
pushl %esi
pushl %ebx
movl ARGBASE+16(%esp),%eax # sum
movl ARGBASE+12(%esp),%ecx # len
movl ARGBASE+4(%esp),%esi # src
movl ARGBASE+8,%edi # dst
testl $2, %edi # Check alignment.
jz 2f # Jump if alignment is ok.
subl $2, %ecx # Alignment uses up two bytes.
jae 1f # Jump if we had at least two bytes.
addl $2, %ecx # ecx was < 2. Deal with it.
jmp 4f
SRC( 1: movw (%esi), %bx )
addl $2, %esi
DST( movw %bx, (%edi) )
addl $2, %edi
addw %bx, %ax
adcl $0, %eax
2:
movl %ecx, FP(%esp)
shrl $5, %ecx
jz 2f
testl %esi, %esi
SRC(1: movl (%esi), %ebx )
SRC( movl 4(%esi), %edx )
adcl %ebx, %eax
DST( movl %ebx, (%edi) )
adcl %edx, %eax
DST( movl %edx, 4(%edi) )

SRC( movl 8(%esi), %ebx )
SRC( movl 12(%esi), %edx )
adcl %ebx, %eax
DST( movl %ebx, 8(%edi) )
adcl %edx, %eax
DST( movl %edx, 12(%edi) )

SRC( movl 16(%esi), %ebx )
SRC( movl 20(%esi), %edx )
adcl %ebx, %eax
DST( movl %ebx, 16(%edi) )
adcl %edx, %eax
DST( movl %edx, 20(%edi) )

SRC( movl 24(%esi), %ebx )
SRC( movl 28(%esi), %edx )
adcl %ebx, %eax
DST( movl %ebx, 24(%edi) )
adcl %edx, %eax
DST( movl %edx, 28(%edi) )

SRC( lea 32(%esi), %esi )
DST( lea 32(%edi), %edi )
dec %ecx
jne 1b
adcl $0, %eax
2: movl FP(%esp), %edx
movl %edx, %ecx
andl $0x1c, %edx
je 4f
shrl $2, %edx # This clears CF
SRC( 3: movl (%esi), %ebx )
adcl %ebx, %eax
DST( movl %ebx, (%edi) )
SRC( lea 4(%esi), %esi )
DST( lea 4(%edi), %edi )
dec %edx
jne 3b
adcl $0, %eax
4: andl $3, %ecx
jz 7f
cmpl $2, %ecx
jb 5f
SRC( movw (%esi), %cx )
SRC( leal 2(%esi), %esi )
DST( movw %cx, (%edi) )
DST( leal 2(%edi), %edi )
je 6f
shll $16,%ecx
SRC(5: movb (%esi), %cl )
DST( movb %cl, (%edi) )
6: addl %ecx, %eax
adcl $0, %eax
7:
5000:
popl %ebx
popl %esi
popl %edi
ret

# Exception handler:
.section .fixup, "ax"
6000:

movl $-EFAULT, (%ebx)

# zero the complete destination - computing the rest
# is too much work
movl ARGBASE+8(%esp), %edi # dst
movl ARGBASE+12(%esp), %ecx
xorl %eax,%eax
rep ; stosb

jmp 5000b

6001:
movl ARGBASE+20(%esp), %ebx # src_err_ptr
jmp 6000b

6002:
movl ARGBASE+24(%esp), %ebx # dst_err_ptr
jmp 6000b

.previous

#else

/* Version for PentiumII/PPro */
#define ROUND1(x) \
SRC(movl x(%esi), %ebx ) ; \
addl %ebx, %eax\n ; \
DST(movl %ebx, x(%edi) ) ;
#define ROUND(x) \
SRC(movl x(%esi), %ebx ) ; \
adcl %ebx, %eax ; \
DST(movl %ebx, x(%edi) )

#define ARGBASE 16

csum_partial_copy_generic:
pushl %ebx
pushl %edi
pushl %esi
movl ARGBASE+4(%esp),%esi #len
movl ARGBASE+8(%esp),%edi #dst
movl ARGBASE+12(%esp),%ecx #len
movl ARGBASE+16(%esp),%eax #sum
movl %ecx, %edx
movl %ecx, %ebx
shrl $6, %ecx
andl $0x3c, %ebx
negl %ebx
subl %ebx, %esi
subl %ebx, %edi
lea 3f(%ebx,%ebx), %ebx
testl %esi, %esi
jmp *%ebx
1: addl $64,%esi
addl $64,%edi
ROUND1(-64) ROUND(-60) ROUND(-56) ROUND(-52)
ROUND (-48) ROUND(-44) ROUND(-40) ROUND(-36)
ROUND (-32) ROUND(-28) ROUND(-24) ROUND(-20)
ROUND (-16) ROUND(-12) ROUND(-8) ROUND(-4)
3: adcl $0,%eax
dec %ecx
jge 1b
4: andl $3, %edx
jz 7f
cmpl $2, %edx
jb 5f
SRC(movw (%esi), %dx )
leal 2(%esi), %esi
DST(movw %dx, (%edi) )
leal 2(%edi), %edi
je 6f
shll $16,%edx
5: SRC(movb (%esi), %dl )
DST(movb %dl, (%edi) )
6: addl %edx, %eax
adcl $0, %eax
7:
popl %esi
popl %edi
popl %ebx
ret

.section .fixup, "ax"
6000: movl $-EFAULT, (%ebx)
# zero the complete destination (computing the rest is too much work)
movl ARGBASE+8(%esp),%edi
movl ARGBASE+12(%esp),%ecx
xorl %eax,%eax
rep ; stosb
jmp 7b
6001: movl ARGBASE+20(%esp), %ebx
jmp 6000b
6002: movl ARGBASE+24(%esp), %ebx
jmp 6000b
.previous

#undef ROUND
#undef ROUND1

#endif /* CPU==i686 */
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