1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Optmized version of the ip_fast_csum() function 4 * Used for calculating IP header checksum 5 * 6 * Return: 16bit checksum, complemented 7 * 8 * Inputs: 9 * in0: address of buffer to checksum (char *) 10 * in1: length of the buffer (int) 11 * 12 * Copyright (C) 2002, 2006 Intel Corp. 13 * Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com> 14 */ 15 16 #include <linux/export.h> 17 #include <asm/asmmacro.h> 18 19 /* 20 * Since we know that most likely this function is called with buf aligned 21 * on 4-byte boundary and 20 bytes in length, we can execution rather quickly 22 * versus calling generic version of do_csum, which has lots of overhead in 23 * handling various alignments and sizes. However, due to lack of constrains 24 * put on the function input argument, cases with alignment not on 4-byte or 25 * size not equal to 20 bytes will be handled by the generic do_csum function. 26 */ 27 28 #define in0 r32 29 #define in1 r33 30 #define in2 r34 31 #define in3 r35 32 #define in4 r36 33 #define ret0 r8 34 35 GLOBAL_ENTRY(ip_fast_csum) 36 .prologue 37 .body 38 cmp.ne p6,p7=5,in1 // size other than 20 byte? 39 and r14=3,in0 // is it aligned on 4-byte? 40 add r15=4,in0 // second source pointer 41 ;; 42 cmp.ne.or.andcm p6,p7=r14,r0 43 ;; 44 (p7) ld4 r20=[in0],8 45 (p7) ld4 r21=[r15],8 46 (p6) br.spnt .generic 47 ;; 48 ld4 r22=[in0],8 49 ld4 r23=[r15],8 50 ;; 51 ld4 r24=[in0] 52 add r20=r20,r21 53 add r22=r22,r23 54 ;; 55 add r20=r20,r22 56 ;; 57 add r20=r20,r24 58 ;; 59 shr.u ret0=r20,16 // now need to add the carry 60 zxt2 r20=r20 61 ;; 62 add r20=ret0,r20 63 ;; 64 shr.u ret0=r20,16 // add carry again 65 zxt2 r20=r20 66 ;; 67 add r20=ret0,r20 68 ;; 69 shr.u ret0=r20,16 70 zxt2 r20=r20 71 ;; 72 add r20=ret0,r20 73 mov r9=0xffff 74 ;; 75 andcm ret0=r9,r20 76 .restore sp // reset frame state 77 br.ret.sptk.many b0 78 ;; 79 80 .generic: 81 .prologue 82 .save ar.pfs, r35 83 alloc r35=ar.pfs,2,2,2,0 84 .save rp, r34 85 mov r34=b0 86 .body 87 dep.z out1=in1,2,30 88 mov out0=in0 89 ;; 90 br.call.sptk.many b0=do_csum 91 ;; 92 andcm ret0=-1,ret0 93 mov ar.pfs=r35 94 mov b0=r34 95 br.ret.sptk.many b0 96 END(ip_fast_csum) 97 EXPORT_SYMBOL(ip_fast_csum) 98 99 GLOBAL_ENTRY(csum_ipv6_magic) 100 ld4 r20=[in0],4 101 ld4 r21=[in1],4 102 zxt4 in2=in2 103 ;; 104 ld4 r22=[in0],4 105 ld4 r23=[in1],4 106 dep r15=in3,in2,32,16 107 ;; 108 ld4 r24=[in0],4 109 ld4 r25=[in1],4 110 mux1 r15=r15,@rev 111 add r16=r20,r21 112 add r17=r22,r23 113 zxt4 in4=in4 114 ;; 115 ld4 r26=[in0],4 116 ld4 r27=[in1],4 117 shr.u r15=r15,16 118 add r18=r24,r25 119 add r8=r16,r17 120 ;; 121 add r19=r26,r27 122 add r8=r8,r18 123 ;; 124 add r8=r8,r19 125 add r15=r15,in4 126 ;; 127 add r8=r8,r15 128 ;; 129 shr.u r10=r8,32 // now fold sum into short 130 zxt4 r11=r8 131 ;; 132 add r8=r10,r11 133 ;; 134 shr.u r10=r8,16 // yeah, keep it rolling 135 zxt2 r11=r8 136 ;; 137 add r8=r10,r11 138 ;; 139 shr.u r10=r8,16 // three times lucky 140 zxt2 r11=r8 141 ;; 142 add r8=r10,r11 143 mov r9=0xffff 144 ;; 145 andcm r8=r9,r8 146 br.ret.sptk.many b0 147 END(csum_ipv6_magic) 148 EXPORT_SYMBOL(csum_ipv6_magic) 149