csum_partial_copy.c (8504B)
1// SPDX-License-Identifier: GPL-2.0 2/* 3 * csum_partial_copy - do IP checksumming and copy 4 * 5 * (C) Copyright 1996 Linus Torvalds 6 * accelerated versions (and 21264 assembly versions ) contributed by 7 * Rick Gorton <rick.gorton@alpha-processor.com> 8 * 9 * Don't look at this too closely - you'll go mad. The things 10 * we do for performance.. 11 */ 12 13#include <linux/types.h> 14#include <linux/string.h> 15#include <linux/uaccess.h> 16#include <net/checksum.h> 17 18 19#define ldq_u(x,y) \ 20__asm__ __volatile__("ldq_u %0,%1":"=r" (x):"m" (*(const unsigned long *)(y))) 21 22#define stq_u(x,y) \ 23__asm__ __volatile__("stq_u %1,%0":"=m" (*(unsigned long *)(y)):"r" (x)) 24 25#define extql(x,y,z) \ 26__asm__ __volatile__("extql %1,%2,%0":"=r" (z):"r" (x),"r" (y)) 27 28#define extqh(x,y,z) \ 29__asm__ __volatile__("extqh %1,%2,%0":"=r" (z):"r" (x),"r" (y)) 30 31#define mskql(x,y,z) \ 32__asm__ __volatile__("mskql %1,%2,%0":"=r" (z):"r" (x),"r" (y)) 33 34#define mskqh(x,y,z) \ 35__asm__ __volatile__("mskqh %1,%2,%0":"=r" (z):"r" (x),"r" (y)) 36 37#define insql(x,y,z) \ 38__asm__ __volatile__("insql %1,%2,%0":"=r" (z):"r" (x),"r" (y)) 39 40#define insqh(x,y,z) \ 41__asm__ __volatile__("insqh %1,%2,%0":"=r" (z):"r" (x),"r" (y)) 42 43#define __get_word(insn,x,ptr) \ 44({ \ 45 long __guu_err; \ 46 __asm__ __volatile__( \ 47 "1: "#insn" %0,%2\n" \ 48 "2:\n" \ 49 EXC(1b,2b,%0,%1) \ 50 : "=r"(x), "=r"(__guu_err) \ 51 : "m"(__m(ptr)), "1"(0)); \ 52 __guu_err; \ 53}) 54 55static inline unsigned short from64to16(unsigned long x) 56{ 57 /* Using extract instructions is a bit more efficient 58 than the original shift/bitmask version. */ 59 60 union { 61 unsigned long ul; 62 unsigned int ui[2]; 63 unsigned short us[4]; 64 } in_v, tmp_v, out_v; 65 66 in_v.ul = x; 67 tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1]; 68 69 /* Since the bits of tmp_v.sh[3] are going to always be zero, 70 we don't have to bother to add that in. */ 71 out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1] 72 + (unsigned long) tmp_v.us[2]; 73 74 /* Similarly, out_v.us[2] is always zero for the final add. */ 75 return out_v.us[0] + out_v.us[1]; 76} 77 78 79 80/* 81 * Ok. This isn't fun, but this is the EASY case. 82 */ 83static inline unsigned long 84csum_partial_cfu_aligned(const unsigned long __user *src, unsigned long *dst, 85 long len) 86{ 87 unsigned long checksum = ~0U; 88 unsigned long carry = 0; 89 90 while (len >= 0) { 91 unsigned long word; 92 if (__get_word(ldq, word, src)) 93 return 0; 94 checksum += carry; 95 src++; 96 checksum += word; 97 len -= 8; 98 carry = checksum < word; 99 *dst = word; 100 dst++; 101 } 102 len += 8; 103 checksum += carry; 104 if (len) { 105 unsigned long word, tmp; 106 if (__get_word(ldq, word, src)) 107 return 0; 108 tmp = *dst; 109 mskql(word, len, word); 110 checksum += word; 111 mskqh(tmp, len, tmp); 112 carry = checksum < word; 113 *dst = word | tmp; 114 checksum += carry; 115 } 116 return checksum; 117} 118 119/* 120 * This is even less fun, but this is still reasonably 121 * easy. 122 */ 123static inline unsigned long 124csum_partial_cfu_dest_aligned(const unsigned long __user *src, 125 unsigned long *dst, 126 unsigned long soff, 127 long len) 128{ 129 unsigned long first; 130 unsigned long word, carry; 131 unsigned long lastsrc = 7+len+(unsigned long)src; 132 unsigned long checksum = ~0U; 133 134 if (__get_word(ldq_u, first,src)) 135 return 0; 136 carry = 0; 137 while (len >= 0) { 138 unsigned long second; 139 140 if (__get_word(ldq_u, second, src+1)) 141 return 0; 142 extql(first, soff, word); 143 len -= 8; 144 src++; 145 extqh(second, soff, first); 146 checksum += carry; 147 word |= first; 148 first = second; 149 checksum += word; 150 *dst = word; 151 dst++; 152 carry = checksum < word; 153 } 154 len += 8; 155 checksum += carry; 156 if (len) { 157 unsigned long tmp; 158 unsigned long second; 159 if (__get_word(ldq_u, second, lastsrc)) 160 return 0; 161 tmp = *dst; 162 extql(first, soff, word); 163 extqh(second, soff, first); 164 word |= first; 165 mskql(word, len, word); 166 checksum += word; 167 mskqh(tmp, len, tmp); 168 carry = checksum < word; 169 *dst = word | tmp; 170 checksum += carry; 171 } 172 return checksum; 173} 174 175/* 176 * This is slightly less fun than the above.. 177 */ 178static inline unsigned long 179csum_partial_cfu_src_aligned(const unsigned long __user *src, 180 unsigned long *dst, 181 unsigned long doff, 182 long len, 183 unsigned long partial_dest) 184{ 185 unsigned long carry = 0; 186 unsigned long word; 187 unsigned long second_dest; 188 unsigned long checksum = ~0U; 189 190 mskql(partial_dest, doff, partial_dest); 191 while (len >= 0) { 192 if (__get_word(ldq, word, src)) 193 return 0; 194 len -= 8; 195 insql(word, doff, second_dest); 196 checksum += carry; 197 stq_u(partial_dest | second_dest, dst); 198 src++; 199 checksum += word; 200 insqh(word, doff, partial_dest); 201 carry = checksum < word; 202 dst++; 203 } 204 len += 8; 205 if (len) { 206 checksum += carry; 207 if (__get_word(ldq, word, src)) 208 return 0; 209 mskql(word, len, word); 210 len -= 8; 211 checksum += word; 212 insql(word, doff, second_dest); 213 len += doff; 214 carry = checksum < word; 215 partial_dest |= second_dest; 216 if (len >= 0) { 217 stq_u(partial_dest, dst); 218 if (!len) goto out; 219 dst++; 220 insqh(word, doff, partial_dest); 221 } 222 doff = len; 223 } 224 ldq_u(second_dest, dst); 225 mskqh(second_dest, doff, second_dest); 226 stq_u(partial_dest | second_dest, dst); 227out: 228 checksum += carry; 229 return checksum; 230} 231 232/* 233 * This is so totally un-fun that it's frightening. Don't 234 * look at this too closely, you'll go blind. 235 */ 236static inline unsigned long 237csum_partial_cfu_unaligned(const unsigned long __user * src, 238 unsigned long * dst, 239 unsigned long soff, unsigned long doff, 240 long len, unsigned long partial_dest) 241{ 242 unsigned long carry = 0; 243 unsigned long first; 244 unsigned long lastsrc; 245 unsigned long checksum = ~0U; 246 247 if (__get_word(ldq_u, first, src)) 248 return 0; 249 lastsrc = 7+len+(unsigned long)src; 250 mskql(partial_dest, doff, partial_dest); 251 while (len >= 0) { 252 unsigned long second, word; 253 unsigned long second_dest; 254 255 if (__get_word(ldq_u, second, src+1)) 256 return 0; 257 extql(first, soff, word); 258 checksum += carry; 259 len -= 8; 260 extqh(second, soff, first); 261 src++; 262 word |= first; 263 first = second; 264 insql(word, doff, second_dest); 265 checksum += word; 266 stq_u(partial_dest | second_dest, dst); 267 carry = checksum < word; 268 insqh(word, doff, partial_dest); 269 dst++; 270 } 271 len += doff; 272 checksum += carry; 273 if (len >= 0) { 274 unsigned long second, word; 275 unsigned long second_dest; 276 277 if (__get_word(ldq_u, second, lastsrc)) 278 return 0; 279 extql(first, soff, word); 280 extqh(second, soff, first); 281 word |= first; 282 first = second; 283 mskql(word, len-doff, word); 284 checksum += word; 285 insql(word, doff, second_dest); 286 carry = checksum < word; 287 stq_u(partial_dest | second_dest, dst); 288 if (len) { 289 ldq_u(second_dest, dst+1); 290 insqh(word, doff, partial_dest); 291 mskqh(second_dest, len, second_dest); 292 stq_u(partial_dest | second_dest, dst+1); 293 } 294 checksum += carry; 295 } else { 296 unsigned long second, word; 297 unsigned long second_dest; 298 299 if (__get_word(ldq_u, second, lastsrc)) 300 return 0; 301 extql(first, soff, word); 302 extqh(second, soff, first); 303 word |= first; 304 ldq_u(second_dest, dst); 305 mskql(word, len-doff, word); 306 checksum += word; 307 mskqh(second_dest, len, second_dest); 308 carry = checksum < word; 309 insql(word, doff, word); 310 stq_u(partial_dest | word | second_dest, dst); 311 checksum += carry; 312 } 313 return checksum; 314} 315 316static __wsum __csum_and_copy(const void __user *src, void *dst, int len) 317{ 318 unsigned long soff = 7 & (unsigned long) src; 319 unsigned long doff = 7 & (unsigned long) dst; 320 unsigned long checksum; 321 322 if (!doff) { 323 if (!soff) 324 checksum = csum_partial_cfu_aligned( 325 (const unsigned long __user *) src, 326 (unsigned long *) dst, len-8); 327 else 328 checksum = csum_partial_cfu_dest_aligned( 329 (const unsigned long __user *) src, 330 (unsigned long *) dst, 331 soff, len-8); 332 } else { 333 unsigned long partial_dest; 334 ldq_u(partial_dest, dst); 335 if (!soff) 336 checksum = csum_partial_cfu_src_aligned( 337 (const unsigned long __user *) src, 338 (unsigned long *) dst, 339 doff, len-8, partial_dest); 340 else 341 checksum = csum_partial_cfu_unaligned( 342 (const unsigned long __user *) src, 343 (unsigned long *) dst, 344 soff, doff, len-8, partial_dest); 345 } 346 return (__force __wsum)from64to16 (checksum); 347} 348 349__wsum 350csum_and_copy_from_user(const void __user *src, void *dst, int len) 351{ 352 if (!access_ok(src, len)) 353 return 0; 354 return __csum_and_copy(src, dst, len); 355} 356 357__wsum 358csum_partial_copy_nocheck(const void *src, void *dst, int len) 359{ 360 return __csum_and_copy((__force const void __user *)src, 361 dst, len); 362} 363EXPORT_SYMBOL(csum_partial_copy_nocheck);