powerpc: Use rol32() instead of opencoding in csum_fold()

rol32(x, 16) will do the rotate using rlwinm.

No need to open code using inline assembly.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/794337eff7bb803d2c4e67d9eee635390c4c48fe.1646812553.git.christophe.leroy@csgroup.eu

powerpc: Reduce csum_add() complexity for PPC64

PPC64 does everything in C, gcc is able to skip calculation
when one of the operands in zero.

Move the constant folding in PPC32 part.

This helps GCC and reduces ppc64_defconfig by 170 bytes.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a4ca63dd4c4b09e1906d08fb814af5a41d0f3fcb.1644651363.git.christophe.leroy@csgroup.eu

powerpc/net: Implement powerpc specific csum_shift() to remove branch

Today's implementation of csum_shift() leads to branching based on
parity of 'offset'

000002f8 <csum_block_add>:
2f8: 70 a5 00 01 andi. r5,r5,1
2fc: 41 a2 00 08 beq 304 <csum_block_add+0xc>
300: 54 84 c0 3e rotlwi r4,r4,24
304: 7c 63 20 14 addc r3,r3,r4
308: 7c 63 01 94 addze r3,r3
30c: 4e 80 00 20 blr

Use first bit of 'offset' directly as input of the rotation instead of
branching.

000002f8 <csum_block_add>:
2f8: 54 a5 1f 38 rlwinm r5,r5,3,28,28
2fc: 20 a5 00 20 subfic r5,r5,32
300: 5c 84 28 3e rotlw r4,r4,r5
304: 7c 63 20 14 addc r3,r3,r4
308: 7c 63 01 94 addze r3,r3
30c: 4e 80 00 20 blr

And change to left shift instead of right shift to skip one more
instruction. This has no impact on the final sum.

000002f8 <csum_block_add>:
2f8: 54 a5 1f 38 rlwinm r5,r5,3,28,28
2fc: 5c 84 28 3e rotlw r4,r4,r5
300: 7c 63 20 14 addc r3,r3,r4
304: 7c 63 01 94 addze r3,r3
308: 4e 80 00 20 blr

Seems like only powerpc benefits from a branchless implementation.
Other main architectures like ARM or X86 get better code with
the generic implementation and its branch.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

powerpc: Force inlining of csum_add()

Commit 328e7e487a46 ("powerpc: force inlining of csum_partial() to
avoid multiple csum_partial() with GCC10") inlined csum_partial().

Now that csum_partial() is inlined, GCC outlines csum_add() when
called by csum_partial().

c064fb28 <csum_add>:
c064fb28: 7c 63 20 14 addc r3,r3,r4
c064fb2c: 7c 63 01 94 addze r3,r3
c064fb30: 4e 80 00 20 blr

c0665fb8 <csum_add>:
c0665fb8: 7c 63 20 14 addc r3,r3,r4
c0665fbc: 7c 63 01 94 addze r3,r3
c0665fc0: 4e 80 00 20 blr

c066719c: 7c 9a c0 2e lwzx r4,r26,r24
c06671a0: 38 60 00 00 li r3,0
c06671a4: 7f 1a c2 14 add r24,r26,r24
c06671a8: 4b ff ee 11 bl c0665fb8 <csum_add>
c06671ac: 80 98 00 04 lwz r4,4(r24)
c06671b0: 4b ff ee 09 bl c0665fb8 <csum_add>
c06671b4: 80 98 00 08 lwz r4,8(r24)
c06671b8: 4b ff ee 01 bl c0665fb8 <csum_add>
c06671bc: a0 98 00 0c lhz r4,12(r24)
c06671c0: 4b ff ed f9 bl c0665fb8 <csum_add>
c06671c4: 7c 63 18 f8 not r3,r3
c06671c8: 81 3f 00 68 lwz r9,104(r31)
c06671cc: 81 5f 00 a0 lwz r10,160(r31)
c06671d0: 7d 29 18 14 addc r9,r9,r3
c06671d4: 7d 29 01 94 addze r9,r9
c06671d8: 91 3f 00 68 stw r9,104(r31)
c06671dc: 7d 1a 50 50 subf r8,r26,r10
c06671e0: 83 01 00 10 lwz r24,16(r1)
c06671e4: 83 41 00 18 lwz r26,24(r1)

The sum with 0 is useless, should have been skipped.
And there is even one completely unused instance of csum_add().

In file included from ./include/net/checksum.h:22,
from ./include/linux/skbuff.h:28,
from ./include/linux/icmp.h:16,
from net/ipv6/ip6_tunnel.c:23:
./arch/powerpc/include/asm/checksum.h: In function '__ip6_tnl_rcv':
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:172:31: note: called from here
172 | sum = csum_add(sum, (__force __wsum)*(const u32 *)buff);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:177:31: note: called from here
177 | sum = csum_add(sum, (__force __wsum)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
178 | *(const u32 *)(buff + 4));
| ~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:183:31: note: called from here
183 | sum = csum_add(sum, (__force __wsum)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
184 | *(const u32 *)(buff + 8));
| ~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:186:31: note: called from here
186 | sum = csum_add(sum, (__force __wsum)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
187 | *(const u16 *)(buff + 12));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~

Force inlining of csum_add().

94c: 80 df 00 a0 lwz r6,160(r31)
950: 7d 28 50 2e lwzx r9,r8,r10
954: 7d 48 52 14 add r10,r8,r10
958: 80 aa 00 04 lwz r5,4(r10)
95c: 80 ff 00 68 lwz r7,104(r31)
960: 7d 29 28 14 addc r9,r9,r5
964: 7d 29 01 94 addze r9,r9
968: 7d 08 30 50 subf r8,r8,r6
96c: 80 aa 00 08 lwz r5,8(r10)
970: a1 4a 00 0c lhz r10,12(r10)
974: 7d 29 28 14 addc r9,r9,r5
978: 7d 29 01 94 addze r9,r9
97c: 7d 29 50 14 addc r9,r9,r10
980: 7d 29 01 94 addze r9,r9
984: 7d 29 48 f8 not r9,r9
988: 7c e7 48 14 addc r7,r7,r9
98c: 7c e7 01 94 addze r7,r7
990: 90 ff 00 68 stw r7,104(r31)

In the non-inlined version, the first sum with 0 was performed.
Here it is skipped.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f7f4d4e364de6e473da874468b903da6e5d97adc.1620713272.git.christophe.leroy@csgroup.eu

powerpc: force inlining of csum_partial() to avoid multiple csum_partial() with GCC10

ppc-linux-objdump -d vmlinux | grep -e "<csum_partial>" -e "<__csum_partial>"

With gcc9 I get:

c0017ef8 <__csum_partial>:
c00182fc: 4b ff fb fd bl c0017ef8 <__csum_partial>
c0018478: 4b ff fa 80 b c0017ef8 <__csum_partial>
c03e8458: 4b c2 fa a0 b c0017ef8 <__csum_partial>
c03e8518: 4b c2 f9 e1 bl c0017ef8 <__csum_partial>
c03ef410: 4b c2 8a e9 bl c0017ef8 <__csum_partial>
c03f0b24: 4b c2 73 d5 bl c0017ef8 <__csum_partial>
c04279a4: 4b bf 05 55 bl c0017ef8 <__csum_partial>
c0429820: 4b be e6 d9 bl c0017ef8 <__csum_partial>
c0429944: 4b be e5 b5 bl c0017ef8 <__csum_partial>
c042b478: 4b be ca 81 bl c0017ef8 <__csum_partial>
c042b554: 4b be c9 a5 bl c0017ef8 <__csum_partial>
c045f15c: 4b bb 8d 9d bl c0017ef8 <__csum_partial>
c0492190: 4b b8 5d 69 bl c0017ef8 <__csum_partial>
c0492310: 4b b8 5b e9 bl c0017ef8 <__csum_partial>
c0495594: 4b b8 29 65 bl c0017ef8 <__csum_partial>
c049c420: 4b b7 ba d9 bl c0017ef8 <__csum_partial>
c049c870: 4b b7 b6 89 bl c0017ef8 <__csum_partial>
c049c930: 4b b7 b5 c9 bl c0017ef8 <__csum_partial>
c04a9ca0: 4b b6 e2 59 bl c0017ef8 <__csum_partial>
c04bdde4: 4b b5 a1 15 bl c0017ef8 <__csum_partial>
c04be480: 4b b5 9a 79 bl c0017ef8 <__csum_partial>
c04be710: 4b b5 97 e9 bl c0017ef8 <__csum_partial>
c04c969c: 4b b4 e8 5d bl c0017ef8 <__csum_partial>
c04ca2fc: 4b b4 db fd bl c0017ef8 <__csum_partial>
c04cf5bc: 4b b4 89 3d bl c0017ef8 <__csum_partial>
c04d0440: 4b b4 7a b9 bl c0017ef8 <__csum_partial>

With gcc10 I get:

c0018d08 <__csum_partial>:
c0019020 <csum_partial>:
c0019020: 4b ff fc e8 b c0018d08 <__csum_partial>
c001914c: 4b ff fe d4 b c0019020 <csum_partial>
c0019250: 4b ff fd d1 bl c0019020 <csum_partial>
c03e404c <csum_partial>:
c03e404c: 4b c3 4c bc b c0018d08 <__csum_partial>
c03e4050: 4b ff ff fc b c03e404c <csum_partial>
c03e40fc: 4b ff ff 51 bl c03e404c <csum_partial>
c03e6680: 4b ff d9 cd bl c03e404c <csum_partial>
c03e68c4: 4b ff d7 89 bl c03e404c <csum_partial>
c03e7934: 4b ff c7 19 bl c03e404c <csum_partial>
c03e7bf8: 4b ff c4 55 bl c03e404c <csum_partial>
c03eb148: 4b ff 8f 05 bl c03e404c <csum_partial>
c03ecf68: 4b c2 bd a1 bl c0018d08 <__csum_partial>
c04275b8 <csum_partial>:
c04275b8: 4b bf 17 50 b c0018d08 <__csum_partial>
c0427884: 4b ff fd 35 bl c04275b8 <csum_partial>
c0427b18: 4b ff fa a1 bl c04275b8 <csum_partial>
c0427bd8: 4b ff f9 e1 bl c04275b8 <csum_partial>
c0427cd4: 4b ff f8 e5 bl c04275b8 <csum_partial>
c0427e34: 4b ff f7 85 bl c04275b8 <csum_partial>
c045a1c0: 4b bb eb 49 bl c0018d08 <__csum_partial>
c0489464 <csum_partial>:
c0489464: 4b b8 f8 a4 b c0018d08 <__csum_partial>
c04896b0: 4b ff fd b5 bl c0489464 <csum_partial>
c048982c: 4b ff fc 39 bl c0489464 <csum_partial>
c0490158: 4b b8 8b b1 bl c0018d08 <__csum_partial>
c0492f0c <csum_partial>:
c0492f0c: 4b b8 5d fc b c0018d08 <__csum_partial>
c049326c: 4b ff fc a1 bl c0492f0c <csum_partial>
c049333c: 4b ff fb d1 bl c0492f0c <csum_partial>
c0493b18: 4b ff f3 f5 bl c0492f0c <csum_partial>
c0493f50: 4b ff ef bd bl c0492f0c <csum_partial>
c0493ffc: 4b ff ef 11 bl c0492f0c <csum_partial>
c04a0f78: 4b b7 7d 91 bl c0018d08 <__csum_partial>
c04b3e3c: 4b b6 4e cd bl c0018d08 <__csum_partial>
c04b40d0 <csum_partial>:
c04b40d0: 4b b6 4c 38 b c0018d08 <__csum_partial>
c04b4448: 4b ff fc 89 bl c04b40d0 <csum_partial>
c04b46f4: 4b ff f9 dd bl c04b40d0 <csum_partial>
c04bf448: 4b b5 98 c0 b c0018d08 <__csum_partial>
c04c5264: 4b b5 3a a5 bl c0018d08 <__csum_partial>
c04c61e4: 4b b5 2b 25 bl c0018d08 <__csum_partial>

gcc10 defines multiple versions of csum_partial() which are just
an unconditionnal branch to __csum_partial().

To enforce inlining of that branch to __csum_partial(),
mark csum_partial() as __always_inline.

With this patch with gcc10:

c0018d08 <__csum_partial>:
c0019148: 4b ff fb c0 b c0018d08 <__csum_partial>
c001924c: 4b ff fa bd bl c0018d08 <__csum_partial>
c03e40ec: 4b c3 4c 1d bl c0018d08 <__csum_partial>
c03e4120: 4b c3 4b e8 b c0018d08 <__csum_partial>
c03eb004: 4b c2 dd 05 bl c0018d08 <__csum_partial>
c03ecef4: 4b c2 be 15 bl c0018d08 <__csum_partial>
c0427558: 4b bf 17 b1 bl c0018d08 <__csum_partial>
c04286e4: 4b bf 06 25 bl c0018d08 <__csum_partial>
c0428cd8: 4b bf 00 31 bl c0018d08 <__csum_partial>
c0428d84: 4b be ff 85 bl c0018d08 <__csum_partial>
c045a17c: 4b bb eb 8d bl c0018d08 <__csum_partial>
c0489450: 4b b8 f8 b9 bl c0018d08 <__csum_partial>
c0491860: 4b b8 74 a9 bl c0018d08 <__csum_partial>
c0492eec: 4b b8 5e 1d bl c0018d08 <__csum_partial>
c04a0eac: 4b b7 7e 5d bl c0018d08 <__csum_partial>
c04b3e34: 4b b6 4e d5 bl c0018d08 <__csum_partial>
c04b426c: 4b b6 4a 9d bl c0018d08 <__csum_partial>
c04b463c: 4b b6 46 cd bl c0018d08 <__csum_partial>
c04c004c: 4b b5 8c bd bl c0018d08 <__csum_partial>
c04c0368: 4b b5 89 a1 bl c0018d08 <__csum_partial>
c04c5254: 4b b5 3a b5 bl c0018d08 <__csum_partial>
c04c60d4: 4b b5 2c 35 bl c0018d08 <__csum_partial>

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a1d31f84ddb0926813b17fcd5cc7f3fa7b4deac2.1602759123.git.christophe.leroy@csgroup.eu

ppc: propagate the calling conventions change down to csum_partial_copy_generic()

... and get rid of the pointless fallback in the wrappers. On error it used
to zero the unwritten area and calculate the csum of the entire thing. Not
wanting to do it in assembler part had been very reasonable; doing that in
the first place, OTOH... In case of an error the caller discards the data
we'd copied, along with whatever checksum it might've had.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

saner calling conventions for csum_and_copy_..._user()

All callers of these primitives will
* discard anything we might've copied in case of error
* ignore the csum value in case of error
* always pass 0xffffffff as the initial sum, so the
resulting csum value (in case of success, that is) will never be 0.

That suggest the following calling conventions:
* don't pass err_ptr - just return 0 on error.
* don't bother with zeroing destination, etc. in case of error
* don't pass the initial sum - just use 0xffffffff.

This commit does the minimal conversion in the instances of csum_and_copy_...();
the changes of actual asm code behind them are done later in the series.
Note that this asm code is often shared with csum_partial_copy_nocheck();
the difference is that csum_partial_copy_nocheck() passes 0 for initial
sum while csum_and_copy_..._user() pass 0xffffffff. Fortunately, we are
free to pass 0xffffffff in all cases and subsequent patches will use that
freedom without any special comments.

A part that could be split off: parisc and uml/i386 claimed to have
csum_and_copy_to_user() instances of their own, but those were identical
to the generic one, so we simply drop them. Not sure if it's worth
a separate commit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

csum_partial_copy_nocheck(): drop the last argument

It's always 0. Note that we theoretically could use ~0U as well -
result will be the same modulo 0xffff, _if_ the damn thing did the
right thing for any value of initial sum; later we'll make use of
that when convenient.

However, unlike csum_and_copy_..._user(), there are instances that
did not work for arbitrary initial sums; c6x is one such.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

unify generic instances of csum_partial_copy_nocheck()

quite a few architectures have the same csum_partial_copy_nocheck() -
simply memcpy() the data and then return the csum of the copy.

hexagon, parisc, ia64, s390, um: explicitly spelled out that way.

arc, arm64, csky, h8300, m68k/nommu, microblaze, mips/GENERIC_CSUM, nds32,
nios2, openrisc, riscv, unicore32: end up picking the same thing spelled
out in lib/checksum.h (with varying amounts of perversions along the way).

everybody else (alpha, arm, c6x, m68k/mmu, mips/!GENERIC_CSUM, powerpc,
sh, sparc, x86, xtensa) have non-generic variants. For all except c6x
the declaration is in their asm/checksum.h. c6x uses the wrapper
from asm-generic/checksum.h that would normally lead to the lib/checksum.h
instance, but in case of c6x we end up using an asm function from arch/c6x
instead.

Screw that mess - have architectures with private instances define
_HAVE_ARCH_CSUM_AND_COPY in their asm/checksum.h and have the default
one right in net/checksum.h conditional on _HAVE_ARCH_CSUM_AND_COPY
*not* defined.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

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

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc: drop unused GENERIC_CSUM Kconfig item

Commit d4fde568a34a ("powerpc/64: Use optimized checksum routines on
little-endian") converted last powerpc user of GENERIC_CSUM.

This patch does a final cleanup dropping the Kconfig GENERIC_CSUM
option which is always 'n', and associated piece of code in
asm/checksum.h

Fixes: d4fde568a34a ("powerpc/64: Use optimized checksum routines on little-endian")
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Implement csum_ipv6_magic in assembly

The generic csum_ipv6_magic() generates a pretty bad result

00000000 <csum_ipv6_magic>: (PPC32)
0: 81 23 00 00 lwz r9,0(r3)
4: 81 03 00 04 lwz r8,4(r3)
8: 7c e7 4a 14 add r7,r7,r9
c: 7d 29 38 10 subfc r9,r9,r7
10: 7d 4a 51 10 subfe r10,r10,r10
14: 7d 27 42 14 add r9,r7,r8
18: 7d 2a 48 50 subf r9,r10,r9
1c: 80 e3 00 08 lwz r7,8(r3)
20: 7d 08 48 10 subfc r8,r8,r9
24: 7d 4a 51 10 subfe r10,r10,r10
28: 7d 29 3a 14 add r9,r9,r7
2c: 81 03 00 0c lwz r8,12(r3)
30: 7d 2a 48 50 subf r9,r10,r9
34: 7c e7 48 10 subfc r7,r7,r9
38: 7d 4a 51 10 subfe r10,r10,r10
3c: 7d 29 42 14 add r9,r9,r8
40: 7d 2a 48 50 subf r9,r10,r9
44: 80 e4 00 00 lwz r7,0(r4)
48: 7d 08 48 10 subfc r8,r8,r9
4c: 7d 4a 51 10 subfe r10,r10,r10
50: 7d 29 3a 14 add r9,r9,r7
54: 7d 2a 48 50 subf r9,r10,r9
58: 81 04 00 04 lwz r8,4(r4)
5c: 7c e7 48 10 subfc r7,r7,r9
60: 7d 4a 51 10 subfe r10,r10,r10
64: 7d 29 42 14 add r9,r9,r8
68: 7d 2a 48 50 subf r9,r10,r9
6c: 80 e4 00 08 lwz r7,8(r4)
70: 7d 08 48 10 subfc r8,r8,r9
74: 7d 4a 51 10 subfe r10,r10,r10
78: 7d 29 3a 14 add r9,r9,r7
7c: 7d 2a 48 50 subf r9,r10,r9
80: 81 04 00 0c lwz r8,12(r4)
84: 7c e7 48 10 subfc r7,r7,r9
88: 7d 4a 51 10 subfe r10,r10,r10
8c: 7d 29 42 14 add r9,r9,r8
90: 7d 2a 48 50 subf r9,r10,r9
94: 7d 08 48 10 subfc r8,r8,r9
98: 7d 4a 51 10 subfe r10,r10,r10
9c: 7d 29 2a 14 add r9,r9,r5
a0: 7d 2a 48 50 subf r9,r10,r9
a4: 7c a5 48 10 subfc r5,r5,r9
a8: 7c 63 19 10 subfe r3,r3,r3
ac: 7d 29 32 14 add r9,r9,r6
b0: 7d 23 48 50 subf r9,r3,r9
b4: 7c c6 48 10 subfc r6,r6,r9
b8: 7c 63 19 10 subfe r3,r3,r3
bc: 7c 63 48 50 subf r3,r3,r9
c0: 54 6a 80 3e rotlwi r10,r3,16
c4: 7c 63 52 14 add r3,r3,r10
c8: 7c 63 18 f8 not r3,r3
cc: 54 63 84 3e rlwinm r3,r3,16,16,31
d0: 4e 80 00 20 blr

0000000000000000 <.csum_ipv6_magic>: (PPC64)
0: 81 23 00 00 lwz r9,0(r3)
4: 80 03 00 04 lwz r0,4(r3)
8: 81 63 00 08 lwz r11,8(r3)
c: 7c e7 4a 14 add r7,r7,r9
10: 7f 89 38 40 cmplw cr7,r9,r7
14: 7d 47 02 14 add r10,r7,r0
18: 7d 30 10 26 mfocrf r9,1
1c: 55 29 f7 fe rlwinm r9,r9,30,31,31
20: 7d 4a 4a 14 add r10,r10,r9
24: 7f 80 50 40 cmplw cr7,r0,r10
28: 7d 2a 5a 14 add r9,r10,r11
2c: 80 03 00 0c lwz r0,12(r3)
30: 81 44 00 00 lwz r10,0(r4)
34: 7d 10 10 26 mfocrf r8,1
38: 55 08 f7 fe rlwinm r8,r8,30,31,31
3c: 7d 29 42 14 add r9,r9,r8
40: 81 04 00 04 lwz r8,4(r4)
44: 7f 8b 48 40 cmplw cr7,r11,r9
48: 7d 29 02 14 add r9,r9,r0
4c: 7d 70 10 26 mfocrf r11,1
50: 55 6b f7 fe rlwinm r11,r11,30,31,31
54: 7d 29 5a 14 add r9,r9,r11
58: 7f 80 48 40 cmplw cr7,r0,r9
5c: 7d 29 52 14 add r9,r9,r10
60: 7c 10 10 26 mfocrf r0,1
64: 54 00 f7 fe rlwinm r0,r0,30,31,31
68: 7d 69 02 14 add r11,r9,r0
6c: 7f 8a 58 40 cmplw cr7,r10,r11
70: 7c 0b 42 14 add r0,r11,r8
74: 81 44 00 08 lwz r10,8(r4)
78: 7c f0 10 26 mfocrf r7,1
7c: 54 e7 f7 fe rlwinm r7,r7,30,31,31
80: 7c 00 3a 14 add r0,r0,r7
84: 7f 88 00 40 cmplw cr7,r8,r0
88: 7d 20 52 14 add r9,r0,r10
8c: 80 04 00 0c lwz r0,12(r4)
90: 7d 70 10 26 mfocrf r11,1
94: 55 6b f7 fe rlwinm r11,r11,30,31,31
98: 7d 29 5a 14 add r9,r9,r11
9c: 7f 8a 48 40 cmplw cr7,r10,r9
a0: 7d 29 02 14 add r9,r9,r0
a4: 7d 70 10 26 mfocrf r11,1
a8: 55 6b f7 fe rlwinm r11,r11,30,31,31
ac: 7d 29 5a 14 add r9,r9,r11
b0: 7f 80 48 40 cmplw cr7,r0,r9
b4: 7d 29 2a 14 add r9,r9,r5
b8: 7c 10 10 26 mfocrf r0,1
bc: 54 00 f7 fe rlwinm r0,r0,30,31,31
c0: 7d 29 02 14 add r9,r9,r0
c4: 7f 85 48 40 cmplw cr7,r5,r9
c8: 7c 09 32 14 add r0,r9,r6
cc: 7d 50 10 26 mfocrf r10,1
d0: 55 4a f7 fe rlwinm r10,r10,30,31,31
d4: 7c 00 52 14 add r0,r0,r10
d8: 7f 80 30 40 cmplw cr7,r0,r6
dc: 7d 30 10 26 mfocrf r9,1
e0: 55 29 ef fe rlwinm r9,r9,29,31,31
e4: 7c 09 02 14 add r0,r9,r0
e8: 54 03 80 3e rotlwi r3,r0,16
ec: 7c 03 02 14 add r0,r3,r0
f0: 7c 03 00 f8 not r3,r0
f4: 78 63 84 22 rldicl r3,r3,48,48
f8: 4e 80 00 20 blr

This patch implements it in assembly for both PPC32 and PPC64

Link: https://github.com/linuxppc/linux/issues/9
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64: optimises from64to32()

The current implementation of from64to32() gives a poor result:

0000000000000270 <.from64to32>:
270: 38 00 ff ff li r0,-1
274: 78 69 00 22 rldicl r9,r3,32,32
278: 78 00 00 20 clrldi r0,r0,32
27c: 7c 60 00 38 and r0,r3,r0
280: 7c 09 02 14 add r0,r9,r0
284: 78 09 00 22 rldicl r9,r0,32,32
288: 7c 00 4a 14 add r0,r0,r9
28c: 78 03 00 20 clrldi r3,r0,32
290: 4e 80 00 20 blr

This patch modifies from64to32() to operate in the same
spirit as csum_fold()

It swaps the two 32-bit halves of sum then it adds it with the
unswapped sum. If there is a carry from adding the two 32-bit halves,
it will carry from the lower half into the upper half, giving us the
correct sum in the upper half.

The resulting code is:

0000000000000260 <.from64to32>:
260: 78 60 00 02 rotldi r0,r3,32
264: 7c 60 1a 14 add r3,r0,r3
268: 78 63 00 22 rldicl r3,r3,32,32
26c: 4e 80 00 20 blr

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Revert "powerpc/64: Fix checksum folding in csum_add()"

This reverts commit 6ad966d7303b70165228dba1ee8da1a05c10eefe.

That commit was pointless, because csum_add() sums two 32 bits
values, so the sum is 0x1fffffffe at the maximum.
And then when adding upper part (1) and lower part (0xfffffffe),
the result is 0xffffffff which doesn't carry.
Any lower value will not carry either.

And behind the fact that this commit is useless, it also kills the
whole purpose of having an arch specific inline csum_add()
because the resulting code gets even worse than what is obtained
with the generic implementation of csum_add()

0000000000000240 <.csum_add>:
240: 38 00 ff ff li r0,-1
244: 7c 84 1a 14 add r4,r4,r3
248: 78 00 00 20 clrldi r0,r0,32
24c: 78 89 00 22 rldicl r9,r4,32,32
250: 7c 80 00 38 and r0,r4,r0
254: 7c 09 02 14 add r0,r9,r0
258: 78 09 00 22 rldicl r9,r0,32,32
25c: 7c 00 4a 14 add r0,r0,r9
260: 78 03 00 20 clrldi r3,r0,32
264: 4e 80 00 20 blr

In comparison, the generic implementation of csum_add() gives:

0000000000000290 <.csum_add>:
290: 7c 63 22 14 add r3,r3,r4
294: 7f 83 20 40 cmplw cr7,r3,r4
298: 7c 10 10 26 mfocrf r0,1
29c: 54 00 ef fe rlwinm r0,r0,29,31,31
2a0: 7c 60 1a 14 add r3,r0,r3
2a4: 78 63 00 20 clrldi r3,r3,32
2a8: 4e 80 00 20 blr

And the reverted implementation for PPC64 gives:

0000000000000240 <.csum_add>:
240: 7c 84 1a 14 add r4,r4,r3
244: 78 80 00 22 rldicl r0,r4,32,32
248: 7c 80 22 14 add r4,r0,r4
24c: 78 83 00 20 clrldi r3,r4,32
250: 4e 80 00 20 blr

Fixes: 6ad966d7303b7 ("powerpc/64: Fix checksum folding in csum_add()")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64: Fix checksum folding in csum_add()

Paul's patch to fix checksum folding, commit b492f7e4e07a ("powerpc/64:
Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold")
missed a case in csum_add(). Fix it.

Signed-off-by: Shile Zhang <shile.zhang@nokia.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64: Use optimized checksum routines on little-endian

Currently we have optimized hand-coded assembly checksum routines for
big-endian 64-bit systems, but for little-endian we use the generic C
routines. This modifies the optimized routines to work for
little-endian. With this, we no longer need to enable
CONFIG_GENERIC_CSUM. This also fixes a couple of comments in
checksum_64.S so they accurately reflect what the associated instruction
does.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
[mpe: Use the more common __BIG_ENDIAN__]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64: Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold

These functions compute an IP checksum by computing a 64-bit sum and
folding it to 32 bits (the "nofold" in their names refers to folding
down to 16 bits). However, doing (u32) (s + (s >> 32)) is not
sufficient to fold a 64-bit sum to 32 bits correctly. The addition
can produce a carry out from bit 31, which needs to be added in to
the sum to produce the correct result.

To fix this, we copy the from64to32() function from lib/checksum.c
and use that.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc: Update parameters for csum_tcpudp_magic & csum_tcpudp_nofold

Commit 01cfbad "ipv4: Update parameters for csum_tcpudp_magic to their
original types" changed parameters for csum_tcpudp_magic and
csum_tcpudp_nofold for many platforms but not for PowerPC.

Fixes: 01cfbad "ipv4: Update parameters for csum_tcpudp_magic to their original types"
Cc: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

powerpc: optimise csum_partial() call when len is constant

csum_partial is often called for small fixed length packets
for which it is suboptimal to use the generic csum_partial()
function.

For instance, in my configuration, I got:
* One place calling it with constant len 4
* Seven places calling it with constant len 8
* Three places calling it with constant len 14
* One place calling it with constant len 20
* One place calling it with constant len 24
* One place calling it with constant len 32

This patch renames csum_partial() to __csum_partial() and
implements csum_partial() as a wrapper inline function which
* uses csum_add() for small 16bits multiple constant length
* uses ip_fast_csum() for other 32bits multiple constant
* uses __csum_partial() in all other cases

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>

powerpc: simplify csum_add(a, b) in case a or b is constant 0

Simplify csum_add(a, b) in case a or b is constant 0

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>

powerpc: inline ip_fast_csum()

In several architectures, ip_fast_csum() is inlined
There are functions like ip_send_check() which do nothing
much more than calling ip_fast_csum().
Inlining ip_fast_csum() allows the compiler to optimise better

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[scottwood: whitespace and cast fixes]
Signed-off-by: Scott Wood <oss@buserror.net>

powerpc32: checksum_wrappers_64 becomes checksum_wrappers

The powerpc64 checksum wrapper functions adds csum_and_copy_to_user()
which otherwise is implemented in include/net/checksum.h by using
csum_partial() then copy_to_user()

Those two wrapper fonctions are also applicable to powerpc32 as it is
based on the use of csum_partial_copy_generic() which also
exists on powerpc32

This patch renames arch/powerpc/lib/checksum_wrappers_64.c to
arch/powerpc/lib/checksum_wrappers.c and
makes it non-conditional to CONFIG_WORD_SIZE

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>

powerpc: mark xer clobbered in csum_add()

addc uses carry so xer is clobbered in csum_add()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>

powerpc: add support for csum_add()

The C version of csum_add() as defined in include/net/checksum.h gives
the following assembly in ppc32:
0: 7c 04 1a 14 add r0,r4,r3
4: 7c 64 00 10 subfc r3,r4,r0
8: 7c 63 19 10 subfe r3,r3,r3
c: 7c 63 00 50 subf r3,r3,r0
and the following in ppc64:
0xc000000000001af8 <+0>: add r3,r3,r4
0xc000000000001afc <+4>: cmplw cr7,r3,r4
0xc000000000001b00 <+8>: mfcr r4
0xc000000000001b04 <+12>: rlwinm r4,r4,29,31,31
0xc000000000001b08 <+16>: add r3,r4,r3
0xc000000000001b0c <+20>: clrldi r3,r3,32
0xc000000000001b10 <+24>: blr

include/net/checksum.h also offers the possibility to define an arch
specific function. This patch provides a specific csum_add() inline
function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>

powerpc: put csum_tcpudp_magic inline

csum_tcpudp_magic() is only a few instructions, and does modify
really few registers. So it is not worth having it as a separate
function and suffer function branching and saving of volatile
registers.

This patch makes it inline by use of the already existing
csum_tcpudp_nofold() function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>

powerpc: Use generic checksum code in little endian

We need to fix some endian issues in our checksum code. For now
just enable the generic checksum routines for little endian builds.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Add 64bit csum_and_copy_to_user

This adds the equivalent of csum_and_copy_from_user for the receive side so we
can copy and checksum in one pass. It is modelled on the generic checksum
routine.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Optimise 64bit csum_partial_copy_generic and add csum_and_copy_from_user

We use the same core loop as the new csum_partial, adding in the
stores and exception handling code. To keep things simple we do all the
exception fixup in csum_and_copy_from_user. This wrapper function is
modelled on the generic checksum code and is careful to always calculate
a complete checksum even if we only copied part of the data to userspace.

To test this I forced checksumming on over loopback and ran socklib (a
simple TCP benchmark). On a POWER6 575 throughput improved by 19% with
this patch. If I forced both the sender and receiver onto the same cpu
(with the hope of shifting the benchmark from being cache bandwidth limited
to cpu limited), adding this patch improved performance by 55%

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Move include files to arch/powerpc/include/asm

from include/asm-powerpc. This is the result of a

mkdir arch/powerpc/include/asm
git mv include/asm-powerpc/* arch/powerpc/include/asm

Followed by a few documentation/comment fixups and a couple of places
where <asm-powepc/...> was being used explicitly. Of the latter only
one was outside the arch code and it is a driver only built for powerpc.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>