mirror of https://github.com/ipxe/ipxe.git
[arm] Add optimised TCP/IP checksumming for 64-bit ARM
Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/54/head^2
Michael Brown
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/*
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* Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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/** @file
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*
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* TCP/IP checksum
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*
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*/
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#include <strings.h>
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#include <ipxe/tcpip.h>
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/** Alignment used by main checksumming loop */
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#define TCPIP_CHKSUM_ALIGN 16
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/** Number of steps in each iteration of the unrolled main checksumming loop */
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#define TCPIP_CHKSUM_UNROLL 4
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/**
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* Calculate continued TCP/IP checkum
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*
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* @v sum Checksum of already-summed data, in network byte order
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* @v data Data buffer
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* @v len Length of data buffer
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* @ret sum Updated checksum, in network byte order
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*/
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uint16_t tcpip_continue_chksum ( uint16_t sum, const void *data,
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size_t len ) {
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intptr_t start;
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intptr_t end;
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intptr_t mid;
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unsigned int pre;
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unsigned int post;
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unsigned int first;
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uint64_t discard_low;
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uint64_t discard_high;
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/* Avoid potentially undefined shift operation */
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if ( len == 0 )
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return sum;
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/* Find maximally-aligned midpoint. For short blocks of data,
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* this may be aligned to fewer than 16 bytes.
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*/
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start = ( ( intptr_t ) data );
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end = ( start + len );
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mid = ( end &
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~( ( ~( 1UL << 63 ) ) >> ( 64 - flsl ( start ^ end ) ) ) );
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/* Calculate pre- and post-alignment lengths */
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pre = ( ( mid - start ) & ( TCPIP_CHKSUM_ALIGN - 1 ) );
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post = ( ( end - mid ) & ( TCPIP_CHKSUM_ALIGN - 1 ) );
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/* Calculate number of steps in first iteration of unrolled loop */
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first = ( ( ( len - pre - post ) / TCPIP_CHKSUM_ALIGN ) &
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( TCPIP_CHKSUM_UNROLL - 1 ) );
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/* Calculate checksum */
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__asm__ ( /* Invert sum */
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"eor %w0, %w0, #0xffff\n\t"
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/* Clear carry flag */
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"cmn xzr, xzr\n\t"
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/* Byteswap and sum pre-alignment byte, if applicable */
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"tbz %w4, #0, 1f\n\t"
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"ldrb %w2, [%1], #1\n\t"
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"rev16 %w0, %w0\n\t"
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"rev16 %w2, %w2\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Sum pre-alignment halfword, if applicable */
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"tbz %w4, #1, 1f\n\t"
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"ldrh %w2, [%1], #2\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Sum pre-alignment word, if applicable */
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"tbz %w4, #2, 1f\n\t"
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"ldr %w2, [%1], #4\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Sum pre-alignment doubleword, if applicable */
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"tbz %w4, #3, 1f\n\t"
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"ldr %2, [%1], #8\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Jump into unrolled (x4) main loop */
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"adr %2, 2f\n\t"
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"sub %2, %2, %5, lsl #3\n\t"
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"sub %2, %2, %5, lsl #2\n\t"
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"br %2\n\t"
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"\n1:\n\t"
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"ldp %2, %3, [%1], #16\n\t"
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"adcs %0, %0, %2\n\t"
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"adcs %0, %0, %3\n\t"
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"ldp %2, %3, [%1], #16\n\t"
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"adcs %0, %0, %2\n\t"
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"adcs %0, %0, %3\n\t"
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"ldp %2, %3, [%1], #16\n\t"
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"adcs %0, %0, %2\n\t"
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"adcs %0, %0, %3\n\t"
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"ldp %2, %3, [%1], #16\n\t"
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"adcs %0, %0, %2\n\t"
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"adcs %0, %0, %3\n\t"
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"\n2:\n\t"
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"sub %2, %1, %6\n\t"
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"cbnz %2, 1b\n\t"
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/* Sum post-alignment doubleword, if applicable */
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"tbz %w7, #3, 1f\n\t"
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"ldr %2, [%1], #8\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Sum post-alignment word, if applicable */
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"tbz %w7, #2, 1f\n\t"
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"ldr %w2, [%1], #4\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Sum post-alignment halfword, if applicable */
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"tbz %w7, #1, 1f\n\t"
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"ldrh %w2, [%1], #2\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Sum post-alignment byte, if applicable */
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"tbz %w7, #0, 1f\n\t"
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"ldrb %w2, [%1], #1\n\t"
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"adcs %0, %0, %2\n\t"
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"\n1:\n\t"
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/* Fold down to a uint32_t plus carry flag */
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"lsr %2, %0, #32\n\t"
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"adcs %w0, %w0, %w2\n\t"
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/* Fold down to a uint16_t plus carry in bit 16 */
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"ubfm %2, %0, #0, #15\n\t"
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"ubfm %3, %0, #16, #31\n\t"
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"adc %w0, %w2, %w3\n\t"
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/* Fold down to a uint16_t */
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"tbz %w0, #16, 1f\n\t"
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"mov %w2, #0xffff\n\t"
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"sub %w0, %w0, %w2\n\t"
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"tbz %w0, #16, 1f\n\t"
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"sub %w0, %w0, %w2\n\t"
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"\n1:\n\t"
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/* Byteswap back, if applicable */
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"tbz %w4, #0, 1f\n\t"
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"rev16 %w0, %w0\n\t"
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"\n1:\n\t"
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/* Invert sum */
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"eor %w0, %w0, #0xffff\n\t"
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: "+r" ( sum ), "+r" ( data ), "=&r" ( discard_low ),
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"=&r" ( discard_high )
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: "r" ( pre ), "r" ( first ), "r" ( end - post ),
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"r" ( post )
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: "cc" );
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return sum;
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}
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@ -0,0 +1,15 @@
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#ifndef _BITS_TCPIP_H
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#define _BITS_TCPIP_H
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/** @file
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*
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* Transport-network layer interface
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*
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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extern uint16_t tcpip_continue_chksum ( uint16_t sum, const void *data,
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size_t len );
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#endif /* _BITS_TCPIP_H */
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