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Diffstat (limited to 'arch/xtensa/lib/checksum.S')
| -rw-r--r-- | arch/xtensa/lib/checksum.S | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/arch/xtensa/lib/checksum.S b/arch/xtensa/lib/checksum.S new file mode 100644 index 00000000..df397f93 --- /dev/null +++ b/arch/xtensa/lib/checksum.S @@ -0,0 +1,409 @@ +/* + * 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 + * + * Xtensa version: Copyright (C) 2001 Tensilica, Inc. by Kevin Chea + * Optimized by Joe Taylor + * + * 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> +#include <linux/linkage.h> +#include <variant/core.h> + +/* + * computes a partial checksum, e.g. for TCP/UDP fragments + */ + +/* + * unsigned int csum_partial(const unsigned char *buf, int len, + * unsigned int sum); + * a2 = buf + * a3 = len + * a4 = sum + * + * This function assumes 2- or 4-byte alignment. Other alignments will fail! + */ + +/* ONES_ADD converts twos-complement math to ones-complement. */ +#define ONES_ADD(sum, val) \ + add sum, sum, val ; \ + bgeu sum, val, 99f ; \ + addi sum, sum, 1 ; \ +99: ; + +.text +ENTRY(csum_partial) + /* + * Experiments with Ethernet and SLIP connections show that buf + * is aligned on either a 2-byte or 4-byte boundary. + */ + entry sp, 32 + extui a5, a2, 0, 2 + bnez a5, 8f /* branch if 2-byte aligned */ + /* Fall-through on common case, 4-byte alignment */ +1: + srli a5, a3, 5 /* 32-byte chunks */ +#if XCHAL_HAVE_LOOPS + loopgtz a5, 2f +#else + beqz a5, 2f + slli a5, a5, 5 + add a5, a5, a2 /* a5 = end of last 32-byte chunk */ +.Loop1: +#endif + l32i a6, a2, 0 + l32i a7, a2, 4 + ONES_ADD(a4, a6) + ONES_ADD(a4, a7) + l32i a6, a2, 8 + l32i a7, a2, 12 + ONES_ADD(a4, a6) + ONES_ADD(a4, a7) + l32i a6, a2, 16 + l32i a7, a2, 20 + ONES_ADD(a4, a6) + ONES_ADD(a4, a7) + l32i a6, a2, 24 + l32i a7, a2, 28 + ONES_ADD(a4, a6) + ONES_ADD(a4, a7) + addi a2, a2, 4*8 +#if !XCHAL_HAVE_LOOPS + blt a2, a5, .Loop1 +#endif +2: + extui a5, a3, 2, 3 /* remaining 4-byte chunks */ +#if XCHAL_HAVE_LOOPS + loopgtz a5, 3f +#else + beqz a5, 3f + slli a5, a5, 2 + add a5, a5, a2 /* a5 = end of last 4-byte chunk */ +.Loop2: +#endif + l32i a6, a2, 0 + ONES_ADD(a4, a6) + addi a2, a2, 4 +#if !XCHAL_HAVE_LOOPS + blt a2, a5, .Loop2 +#endif +3: + _bbci.l a3, 1, 5f /* remaining 2-byte chunk */ + l16ui a6, a2, 0 + ONES_ADD(a4, a6) + addi a2, a2, 2 +5: + _bbci.l a3, 0, 7f /* remaining 1-byte chunk */ +6: l8ui a6, a2, 0 +#ifdef __XTENSA_EB__ + slli a6, a6, 8 /* load byte into bits 8..15 */ +#endif + ONES_ADD(a4, a6) +7: + mov a2, a4 + retw + + /* uncommon case, buf is 2-byte aligned */ +8: + beqz a3, 7b /* branch if len == 0 */ + beqi a3, 1, 6b /* branch if len == 1 */ + + extui a5, a2, 0, 1 + bnez a5, 8f /* branch if 1-byte aligned */ + + l16ui a6, a2, 0 /* common case, len >= 2 */ + ONES_ADD(a4, a6) + addi a2, a2, 2 /* adjust buf */ + addi a3, a3, -2 /* adjust len */ + j 1b /* now buf is 4-byte aligned */ + + /* case: odd-byte aligned, len > 1 + * This case is dog slow, so don't give us an odd address. + * (I don't think this ever happens, but just in case.) + */ +8: + srli a5, a3, 2 /* 4-byte chunks */ +#if XCHAL_HAVE_LOOPS + loopgtz a5, 2f +#else + beqz a5, 2f + slli a5, a5, 2 + add a5, a5, a2 /* a5 = end of last 4-byte chunk */ +.Loop3: +#endif + l8ui a6, a2, 0 /* bits 24..31 */ + l16ui a7, a2, 1 /* bits 8..23 */ + l8ui a8, a2, 3 /* bits 0.. 8 */ +#ifdef __XTENSA_EB__ + slli a6, a6, 24 +#else + slli a8, a8, 24 +#endif + slli a7, a7, 8 + or a7, a7, a6 + or a7, a7, a8 + ONES_ADD(a4, a7) + addi a2, a2, 4 +#if !XCHAL_HAVE_LOOPS + blt a2, a5, .Loop3 +#endif +2: + _bbci.l a3, 1, 3f /* remaining 2-byte chunk, still odd addr */ + l8ui a6, a2, 0 + l8ui a7, a2, 1 +#ifdef __XTENSA_EB__ + slli a6, a6, 8 +#else + slli a7, a7, 8 +#endif + or a7, a7, a6 + ONES_ADD(a4, a7) + addi a2, a2, 2 +3: + j 5b /* branch to handle the remaining byte */ + + + +/* + * 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 each access type. + */ + +#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 + +/* +unsigned int csum_partial_copy_generic (const char *src, char *dst, int len, + int sum, int *src_err_ptr, int *dst_err_ptr) + a2 = src + a3 = dst + a4 = len + a5 = sum + a6 = src_err_ptr + a7 = dst_err_ptr + a8 = temp + a9 = temp + a10 = temp + a11 = original len for exception handling + a12 = original dst for exception handling + + This function is optimized for 4-byte aligned addresses. Other + alignments work, but not nearly as efficiently. + */ + +ENTRY(csum_partial_copy_generic) + entry sp, 32 + mov a12, a3 + mov a11, a4 + or a10, a2, a3 + + /* We optimize the following alignment tests for the 4-byte + aligned case. Two bbsi.l instructions might seem more optimal + (commented out below). However, both labels 5: and 3: are out + of the imm8 range, so the assembler relaxes them into + equivalent bbci.l, j combinations, which is actually + slower. */ + + extui a9, a10, 0, 2 + beqz a9, 1f /* branch if both are 4-byte aligned */ + bbsi.l a10, 0, 5f /* branch if one address is odd */ + j 3f /* one address is 2-byte aligned */ + +/* _bbsi.l a10, 0, 5f */ /* branch if odd address */ +/* _bbsi.l a10, 1, 3f */ /* branch if 2-byte-aligned address */ + +1: + /* src and dst are both 4-byte aligned */ + srli a10, a4, 5 /* 32-byte chunks */ +#if XCHAL_HAVE_LOOPS + loopgtz a10, 2f +#else + beqz a10, 2f + slli a10, a10, 5 + add a10, a10, a2 /* a10 = end of last 32-byte src chunk */ +.Loop5: +#endif +SRC( l32i a9, a2, 0 ) +SRC( l32i a8, a2, 4 ) +DST( s32i a9, a3, 0 ) +DST( s32i a8, a3, 4 ) + ONES_ADD(a5, a9) + ONES_ADD(a5, a8) +SRC( l32i a9, a2, 8 ) +SRC( l32i a8, a2, 12 ) +DST( s32i a9, a3, 8 ) +DST( s32i a8, a3, 12 ) + ONES_ADD(a5, a9) + ONES_ADD(a5, a8) +SRC( l32i a9, a2, 16 ) +SRC( l32i a8, a2, 20 ) +DST( s32i a9, a3, 16 ) +DST( s32i a8, a3, 20 ) + ONES_ADD(a5, a9) + ONES_ADD(a5, a8) +SRC( l32i a9, a2, 24 ) +SRC( l32i a8, a2, 28 ) +DST( s32i a9, a3, 24 ) +DST( s32i a8, a3, 28 ) + ONES_ADD(a5, a9) + ONES_ADD(a5, a8) + addi a2, a2, 32 + addi a3, a3, 32 +#if !XCHAL_HAVE_LOOPS + blt a2, a10, .Loop5 +#endif +2: + extui a10, a4, 2, 3 /* remaining 4-byte chunks */ + extui a4, a4, 0, 2 /* reset len for general-case, 2-byte chunks */ +#if XCHAL_HAVE_LOOPS + loopgtz a10, 3f +#else + beqz a10, 3f + slli a10, a10, 2 + add a10, a10, a2 /* a10 = end of last 4-byte src chunk */ +.Loop6: +#endif +SRC( l32i a9, a2, 0 ) +DST( s32i a9, a3, 0 ) + ONES_ADD(a5, a9) + addi a2, a2, 4 + addi a3, a3, 4 +#if !XCHAL_HAVE_LOOPS + blt a2, a10, .Loop6 +#endif +3: + /* + Control comes to here in two cases: (1) It may fall through + to here from the 4-byte alignment case to process, at most, + one 2-byte chunk. (2) It branches to here from above if + either src or dst is 2-byte aligned, and we process all bytes + here, except for perhaps a trailing odd byte. It's + inefficient, so align your addresses to 4-byte boundaries. + + a2 = src + a3 = dst + a4 = len + a5 = sum + */ + srli a10, a4, 1 /* 2-byte chunks */ +#if XCHAL_HAVE_LOOPS + loopgtz a10, 4f +#else + beqz a10, 4f + slli a10, a10, 1 + add a10, a10, a2 /* a10 = end of last 2-byte src chunk */ +.Loop7: +#endif +SRC( l16ui a9, a2, 0 ) +DST( s16i a9, a3, 0 ) + ONES_ADD(a5, a9) + addi a2, a2, 2 + addi a3, a3, 2 +#if !XCHAL_HAVE_LOOPS + blt a2, a10, .Loop7 +#endif +4: + /* This section processes a possible trailing odd byte. */ + _bbci.l a4, 0, 8f /* 1-byte chunk */ +SRC( l8ui a9, a2, 0 ) +DST( s8i a9, a3, 0 ) +#ifdef __XTENSA_EB__ + slli a9, a9, 8 /* shift byte to bits 8..15 */ +#endif + ONES_ADD(a5, a9) +8: + mov a2, a5 + retw + +5: + /* Control branch to here when either src or dst is odd. We + process all bytes using 8-bit accesses. Grossly inefficient, + so don't feed us an odd address. */ + + srli a10, a4, 1 /* handle in pairs for 16-bit csum */ +#if XCHAL_HAVE_LOOPS + loopgtz a10, 6f +#else + beqz a10, 6f + slli a10, a10, 1 + add a10, a10, a2 /* a10 = end of last odd-aligned, 2-byte src chunk */ +.Loop8: +#endif +SRC( l8ui a9, a2, 0 ) +SRC( l8ui a8, a2, 1 ) +DST( s8i a9, a3, 0 ) +DST( s8i a8, a3, 1 ) +#ifdef __XTENSA_EB__ + slli a9, a9, 8 /* combine into a single 16-bit value */ +#else /* for checksum computation */ + slli a8, a8, 8 +#endif + or a9, a9, a8 + ONES_ADD(a5, a9) + addi a2, a2, 2 + addi a3, a3, 2 +#if !XCHAL_HAVE_LOOPS + blt a2, a10, .Loop8 +#endif +6: + j 4b /* process the possible trailing odd byte */ + + +# Exception handler: +.section .fixup, "ax" +/* + a6 = src_err_ptr + a7 = dst_err_ptr + a11 = original len for exception handling + a12 = original dst for exception handling +*/ + +6001: + _movi a2, -EFAULT + s32i a2, a6, 0 /* src_err_ptr */ + + # clear the complete destination - computing the rest + # is too much work + movi a2, 0 +#if XCHAL_HAVE_LOOPS + loopgtz a11, 2f +#else + beqz a11, 2f + add a11, a11, a12 /* a11 = ending address */ +.Leloop: +#endif + s8i a2, a12, 0 + addi a12, a12, 1 +#if !XCHAL_HAVE_LOOPS + blt a12, a11, .Leloop +#endif +2: + retw + +6002: + movi a2, -EFAULT + s32i a2, a7, 0 /* dst_err_ptr */ + movi a2, 0 + retw + +.previous + |