Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/xen/interface/io/ring.h
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /****************************************************************************** 2 * ring.h 3 * 4 * Shared producer-consumer ring macros. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to 8 * deal in the Software without restriction, including without limitation the 9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 10 * sell copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 22 * DEALINGS IN THE SOFTWARE. 23 * 24 * Tim Deegan and Andrew Warfield November 2004. 25 */ 26 27 #ifndef __XEN_PUBLIC_IO_RING_H__ 28 #define __XEN_PUBLIC_IO_RING_H__ 29 30 /* 31 * When #include'ing this header, you need to provide the following 32 * declaration upfront: 33 * - standard integers types (uint8_t, uint16_t, etc) 34 * They are provided by stdint.h of the standard headers. 35 * 36 * In addition, if you intend to use the FLEX macros, you also need to 37 * provide the following, before invoking the FLEX macros: 38 * - size_t 39 * - memcpy 40 * - grant_ref_t 41 * These declarations are provided by string.h of the standard headers, 42 * and grant_table.h from the Xen public headers. 43 */ 44 45 #include "../xen-compat.h" 46 47 #if __XEN_INTERFACE_VERSION__ < 0x00030208 48 #define xen_mb() mb() 49 #define xen_rmb() rmb() 50 #define xen_wmb() wmb() 51 #endif 52 53 typedef unsigned int RING_IDX; 54 55 /* Round a 32-bit unsigned constant down to the nearest power of two. */ 56 #define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) 57 #define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) 58 #define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) 59 #define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) 60 #define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) 61 62 /* 63 * Calculate size of a shared ring, given the total available space for the 64 * ring and indexes (_sz), and the name tag of the request/response structure. 65 * A ring contains as many entries as will fit, rounded down to the nearest 66 * power of two (so we can mask with (size-1) to loop around). 67 */ 68 #define __CONST_RING_SIZE(_s, _sz) \ 69 (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ 70 sizeof(((struct _s##_sring *)0)->ring[0]))) 71 /* 72 * The same for passing in an actual pointer instead of a name tag. 73 */ 74 #define __RING_SIZE(_s, _sz) \ 75 (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) 76 77 /* 78 * Macros to make the correct C datatypes for a new kind of ring. 79 * 80 * To make a new ring datatype, you need to have two message structures, 81 * let's say request_t, and response_t already defined. 82 * 83 * In a header where you want the ring datatype declared, you then do: 84 * 85 * DEFINE_RING_TYPES(mytag, request_t, response_t); 86 * 87 * These expand out to give you a set of types, as you can see below. 88 * The most important of these are: 89 * 90 * mytag_sring_t - The shared ring. 91 * mytag_front_ring_t - The 'front' half of the ring. 92 * mytag_back_ring_t - The 'back' half of the ring. 93 * 94 * To initialize a ring in your code you need to know the location and size 95 * of the shared memory area (PAGE_SIZE, for instance). To initialise 96 * the front half: 97 * 98 * mytag_front_ring_t front_ring; 99 * SHARED_RING_INIT((mytag_sring_t *)shared_page); 100 * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); 101 * 102 * Initializing the back follows similarly (note that only the front 103 * initializes the shared ring): 104 * 105 * mytag_back_ring_t back_ring; 106 * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); 107 */ 108 109 #define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ 110 \ 111 /* Shared ring entry */ \ 112 union __name##_sring_entry { \ 113 __req_t req; \ 114 __rsp_t rsp; \ 115 }; \ 116 \ 117 /* Shared ring page */ \ 118 struct __name##_sring { \ 119 RING_IDX req_prod, req_event; \ 120 RING_IDX rsp_prod, rsp_event; \ 121 union { \ 122 struct { \ 123 uint8_t smartpoll_active; \ 124 } netif; \ 125 struct { \ 126 uint8_t msg; \ 127 } tapif_user; \ 128 uint8_t pvt_pad[4]; \ 129 } pvt; \ 130 uint8_t __pad[44]; \ 131 union __name##_sring_entry ring[1]; /* variable-length */ \ 132 }; \ 133 \ 134 /* "Front" end's private variables */ \ 135 struct __name##_front_ring { \ 136 RING_IDX req_prod_pvt; \ 137 RING_IDX rsp_cons; \ 138 unsigned int nr_ents; \ 139 struct __name##_sring *sring; \ 140 }; \ 141 \ 142 /* "Back" end's private variables */ \ 143 struct __name##_back_ring { \ 144 RING_IDX rsp_prod_pvt; \ 145 RING_IDX req_cons; \ 146 unsigned int nr_ents; \ 147 struct __name##_sring *sring; \ 148 }; \ 149 \ 150 /* Syntactic sugar */ \ 151 typedef struct __name##_sring __name##_sring_t; \ 152 typedef struct __name##_front_ring __name##_front_ring_t; \ 153 typedef struct __name##_back_ring __name##_back_ring_t 154 155 /* 156 * Macros for manipulating rings. 157 * 158 * FRONT_RING_whatever works on the "front end" of a ring: here 159 * requests are pushed on to the ring and responses taken off it. 160 * 161 * BACK_RING_whatever works on the "back end" of a ring: here 162 * requests are taken off the ring and responses put on. 163 * 164 * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. 165 * This is OK in 1-for-1 request-response situations where the 166 * requestor (front end) never has more than RING_SIZE()-1 167 * outstanding requests. 168 */ 169 170 /* Initialising empty rings */ 171 #define SHARED_RING_INIT(_s) do { \ 172 (_s)->req_prod = (_s)->rsp_prod = 0; \ 173 (_s)->req_event = (_s)->rsp_event = 1; \ 174 (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ 175 (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ 176 } while(0) 177 178 #define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \ 179 (_r)->req_prod_pvt = (_i); \ 180 (_r)->rsp_cons = (_i); \ 181 (_r)->nr_ents = __RING_SIZE(_s, __size); \ 182 (_r)->sring = (_s); \ 183 } while (0) 184 185 #define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size) 186 187 #define BACK_RING_ATTACH(_r, _s, _i, __size) do { \ 188 (_r)->rsp_prod_pvt = (_i); \ 189 (_r)->req_cons = (_i); \ 190 (_r)->nr_ents = __RING_SIZE(_s, __size); \ 191 (_r)->sring = (_s); \ 192 } while (0) 193 194 #define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size) 195 196 /* How big is this ring? */ 197 #define RING_SIZE(_r) \ 198 ((_r)->nr_ents) 199 200 /* Number of free requests (for use on front side only). */ 201 #define RING_FREE_REQUESTS(_r) \ 202 (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) 203 204 /* Test if there is an empty slot available on the front ring. 205 * (This is only meaningful from the front. ) 206 */ 207 #define RING_FULL(_r) \ 208 (RING_FREE_REQUESTS(_r) == 0) 209 210 /* Test if there are outstanding messages to be processed on a ring. */ 211 #define RING_HAS_UNCONSUMED_RESPONSES(_r) \ 212 ((_r)->sring->rsp_prod - (_r)->rsp_cons) 213 214 #ifdef __GNUC__ 215 #define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ 216 unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ 217 unsigned int rsp = RING_SIZE(_r) - \ 218 ((_r)->req_cons - (_r)->rsp_prod_pvt); \ 219 req < rsp ? req : rsp; \ 220 }) 221 #else 222 /* Same as above, but without the nice GCC ({ ... }) syntax. */ 223 #define RING_HAS_UNCONSUMED_REQUESTS(_r) \ 224 ((((_r)->sring->req_prod - (_r)->req_cons) < \ 225 (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ 226 ((_r)->sring->req_prod - (_r)->req_cons) : \ 227 (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) 228 #endif 229 230 /* Direct access to individual ring elements, by index. */ 231 #define RING_GET_REQUEST(_r, _idx) \ 232 (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) 233 234 /* 235 * Get a local copy of a request. 236 * 237 * Use this in preference to RING_GET_REQUEST() so all processing is 238 * done on a local copy that cannot be modified by the other end. 239 * 240 * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this 241 * to be ineffective where _req is a struct which consists of only bitfields. 242 */ 243 #define RING_COPY_REQUEST(_r, _idx, _req) do { \ 244 /* Use volatile to force the copy into _req. */ \ 245 *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ 246 } while (0) 247 248 #define RING_GET_RESPONSE(_r, _idx) \ 249 (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) 250 251 /* Loop termination condition: Would the specified index overflow the ring? */ 252 #define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ 253 (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) 254 255 /* Ill-behaved frontend determination: Can there be this many requests? */ 256 #define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ 257 (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) 258 259 #define RING_PUSH_REQUESTS(_r) do { \ 260 xen_wmb(); /* back sees requests /before/ updated producer index */ \ 261 (_r)->sring->req_prod = (_r)->req_prod_pvt; \ 262 } while (0) 263 264 #define RING_PUSH_RESPONSES(_r) do { \ 265 xen_wmb(); /* front sees resps /before/ updated producer index */ \ 266 (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ 267 } while (0) 268 269 /* 270 * Notification hold-off (req_event and rsp_event): 271 * 272 * When queueing requests or responses on a shared ring, it may not always be 273 * necessary to notify the remote end. For example, if requests are in flight 274 * in a backend, the front may be able to queue further requests without 275 * notifying the back (if the back checks for new requests when it queues 276 * responses). 277 * 278 * When enqueuing requests or responses: 279 * 280 * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument 281 * is a boolean return value. True indicates that the receiver requires an 282 * asynchronous notification. 283 * 284 * After dequeuing requests or responses (before sleeping the connection): 285 * 286 * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). 287 * The second argument is a boolean return value. True indicates that there 288 * are pending messages on the ring (i.e., the connection should not be put 289 * to sleep). 290 * 291 * These macros will set the req_event/rsp_event field to trigger a 292 * notification on the very next message that is enqueued. If you want to 293 * create batches of work (i.e., only receive a notification after several 294 * messages have been enqueued) then you will need to create a customised 295 * version of the FINAL_CHECK macro in your own code, which sets the event 296 * field appropriately. 297 */ 298 299 #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ 300 RING_IDX __old = (_r)->sring->req_prod; \ 301 RING_IDX __new = (_r)->req_prod_pvt; \ 302 xen_wmb(); /* back sees requests /before/ updated producer index */ \ 303 (_r)->sring->req_prod = __new; \ 304 xen_mb(); /* back sees new requests /before/ we check req_event */ \ 305 (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ 306 (RING_IDX)(__new - __old)); \ 307 } while (0) 308 309 #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ 310 RING_IDX __old = (_r)->sring->rsp_prod; \ 311 RING_IDX __new = (_r)->rsp_prod_pvt; \ 312 xen_wmb(); /* front sees resps /before/ updated producer index */ \ 313 (_r)->sring->rsp_prod = __new; \ 314 xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ 315 (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ 316 (RING_IDX)(__new - __old)); \ 317 } while (0) 318 319 #define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ 320 (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ 321 if (_work_to_do) break; \ 322 (_r)->sring->req_event = (_r)->req_cons + 1; \ 323 xen_mb(); \ 324 (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ 325 } while (0) 326 327 #define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ 328 (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ 329 if (_work_to_do) break; \ 330 (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ 331 xen_mb(); \ 332 (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ 333 } while (0) 334 335 336 /* 337 * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and 338 * functions to check if there is data on the ring, and to read and 339 * write to them. 340 * 341 * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but 342 * does not define the indexes page. As different protocols can have 343 * extensions to the basic format, this macro allow them to define their 344 * own struct. 345 * 346 * XEN_FLEX_RING_SIZE 347 * Convenience macro to calculate the size of one of the two rings 348 * from the overall order. 349 * 350 * $NAME_mask 351 * Function to apply the size mask to an index, to reduce the index 352 * within the range [0-size]. 353 * 354 * $NAME_read_packet 355 * Function to read data from the ring. The amount of data to read is 356 * specified by the "size" argument. 357 * 358 * $NAME_write_packet 359 * Function to write data to the ring. The amount of data to write is 360 * specified by the "size" argument. 361 * 362 * $NAME_get_ring_ptr 363 * Convenience function that returns a pointer to read/write to the 364 * ring at the right location. 365 * 366 * $NAME_data_intf 367 * Indexes page, shared between frontend and backend. It also 368 * contains the array of grant refs. 369 * 370 * $NAME_queued 371 * Function to calculate how many bytes are currently on the ring, 372 * ready to be read. It can also be used to calculate how much free 373 * space is currently on the ring (XEN_FLEX_RING_SIZE() - 374 * $NAME_queued()). 375 */ 376 377 #ifndef XEN_PAGE_SHIFT 378 /* The PAGE_SIZE for ring protocols and hypercall interfaces is always 379 * 4K, regardless of the architecture, and page granularity chosen by 380 * operating systems. 381 */ 382 #define XEN_PAGE_SHIFT 12 383 #endif 384 #define XEN_FLEX_RING_SIZE(order) \ 385 (1UL << ((order) + XEN_PAGE_SHIFT - 1)) 386 387 #define DEFINE_XEN_FLEX_RING(name) \ 388 static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ 389 { \ 390 return idx & (ring_size - 1); \ 391 } \ 392 \ 393 static inline unsigned char *name##_get_ring_ptr(unsigned char *buf, \ 394 RING_IDX idx, \ 395 RING_IDX ring_size) \ 396 { \ 397 return buf + name##_mask(idx, ring_size); \ 398 } \ 399 \ 400 static inline void name##_read_packet(void *opaque, \ 401 const unsigned char *buf, \ 402 size_t size, \ 403 RING_IDX masked_prod, \ 404 RING_IDX *masked_cons, \ 405 RING_IDX ring_size) \ 406 { \ 407 if (*masked_cons < masked_prod || \ 408 size <= ring_size - *masked_cons) { \ 409 memcpy(opaque, buf + *masked_cons, size); \ 410 } else { \ 411 memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ 412 memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ 413 size - (ring_size - *masked_cons)); \ 414 } \ 415 *masked_cons = name##_mask(*masked_cons + size, ring_size); \ 416 } \ 417 \ 418 static inline void name##_write_packet(unsigned char *buf, \ 419 const void *opaque, \ 420 size_t size, \ 421 RING_IDX *masked_prod, \ 422 RING_IDX masked_cons, \ 423 RING_IDX ring_size) \ 424 { \ 425 if (*masked_prod < masked_cons || \ 426 size <= ring_size - *masked_prod) { \ 427 memcpy(buf + *masked_prod, opaque, size); \ 428 } else { \ 429 memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ 430 memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ 431 size - (ring_size - *masked_prod)); \ 432 } \ 433 *masked_prod = name##_mask(*masked_prod + size, ring_size); \ 434 } \ 435 \ 436 static inline RING_IDX name##_queued(RING_IDX prod, \ 437 RING_IDX cons, \ 438 RING_IDX ring_size) \ 439 { \ 440 RING_IDX size; \ 441 \ 442 if (prod == cons) \ 443 return 0; \ 444 \ 445 prod = name##_mask(prod, ring_size); \ 446 cons = name##_mask(cons, ring_size); \ 447 \ 448 if (prod == cons) \ 449 return ring_size; \ 450 \ 451 if (prod > cons) \ 452 size = prod - cons; \ 453 else \ 454 size = ring_size - (cons - prod); \ 455 return size; \ 456 } \ 457 \ 458 struct name##_data { \ 459 unsigned char *in; /* half of the allocation */ \ 460 unsigned char *out; /* half of the allocation */ \ 461 } 462 463 #define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ 464 struct name##_data_intf { \ 465 RING_IDX in_cons, in_prod; \ 466 \ 467 uint8_t pad1[56]; \ 468 \ 469 RING_IDX out_cons, out_prod; \ 470 \ 471 uint8_t pad2[56]; \ 472 \ 473 RING_IDX ring_order; \ 474 grant_ref_t ref[]; \ 475 }; \ 476 DEFINE_XEN_FLEX_RING(name) 477 478 #endif /* __XEN_PUBLIC_IO_RING_H__ */ 479 480 /* 481 * Local variables: 482 * mode: C 483 * c-file-style: "BSD" 484 * c-basic-offset: 4 485 * tab-width: 4 486 * indent-tabs-mode: nil 487 * End: 488 */
Cache object: c771c91806378f0aaf81bf15ec710ef3
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]