1 /* 2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/kern/lwkt_ipiq.c,v 1.27 2008/05/18 20:57:56 nth Exp $ 35 */ 36 37 /* 38 * This module implements IPI message queueing and the MI portion of IPI 39 * message processing. 40 */ 41 42 #include "opt_ddb.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kernel.h> 47 #include <sys/proc.h> 48 #include <sys/rtprio.h> 49 #include <sys/queue.h> 50 #include <sys/thread2.h> 51 #include <sys/sysctl.h> 52 #include <sys/ktr.h> 53 #include <sys/kthread.h> 54 #include <machine/cpu.h> 55 #include <sys/lock.h> 56 #include <sys/caps.h> 57 58 #include <vm/vm.h> 59 #include <vm/vm_param.h> 60 #include <vm/vm_kern.h> 61 #include <vm/vm_object.h> 62 #include <vm/vm_page.h> 63 #include <vm/vm_map.h> 64 #include <vm/vm_pager.h> 65 #include <vm/vm_extern.h> 66 #include <vm/vm_zone.h> 67 68 #include <machine/stdarg.h> 69 #include <machine/smp.h> 70 #include <machine/atomic.h> 71 72 #ifdef SMP 73 static __int64_t ipiq_count; /* total calls to lwkt_send_ipiq*() */ 74 static __int64_t ipiq_fifofull; /* number of fifo full conditions detected */ 75 static __int64_t ipiq_avoided; /* interlock with target avoids cpu ipi */ 76 static __int64_t ipiq_passive; /* passive IPI messages */ 77 static __int64_t ipiq_cscount; /* number of cpu synchronizations */ 78 static int ipiq_optimized = 1; /* XXX temporary sysctl */ 79 static int ipiq_debug; /* set to 1 for debug */ 80 #ifdef PANIC_DEBUG 81 static int panic_ipiq_cpu = -1; 82 static int panic_ipiq_count = 100; 83 #endif 84 #endif 85 86 #ifdef SMP 87 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_count, CTLFLAG_RW, &ipiq_count, 0, 88 "Number of IPI's sent"); 89 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_fifofull, CTLFLAG_RW, &ipiq_fifofull, 0, 90 "Number of fifo full conditions detected"); 91 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_avoided, CTLFLAG_RW, &ipiq_avoided, 0, 92 "Number of IPI's avoided by interlock with target cpu"); 93 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_passive, CTLFLAG_RW, &ipiq_passive, 0, 94 "Number of passive IPI messages sent"); 95 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_cscount, CTLFLAG_RW, &ipiq_cscount, 0, 96 "Number of cpu synchronizations"); 97 SYSCTL_INT(_lwkt, OID_AUTO, ipiq_optimized, CTLFLAG_RW, &ipiq_optimized, 0, 98 ""); 99 SYSCTL_INT(_lwkt, OID_AUTO, ipiq_debug, CTLFLAG_RW, &ipiq_debug, 0, 100 ""); 101 #ifdef PANIC_DEBUG 102 SYSCTL_INT(_lwkt, OID_AUTO, panic_ipiq_cpu, CTLFLAG_RW, &panic_ipiq_cpu, 0, ""); 103 SYSCTL_INT(_lwkt, OID_AUTO, panic_ipiq_count, CTLFLAG_RW, &panic_ipiq_count, 0, ""); 104 #endif 105 106 #define IPIQ_STRING "func=%p arg1=%p arg2=%d scpu=%d dcpu=%d" 107 #define IPIQ_ARG_SIZE (sizeof(void *) * 2 + sizeof(int) * 3) 108 109 #if !defined(KTR_IPIQ) 110 #define KTR_IPIQ KTR_ALL 111 #endif 112 KTR_INFO_MASTER(ipiq); 113 KTR_INFO(KTR_IPIQ, ipiq, send_norm, 0, IPIQ_STRING, IPIQ_ARG_SIZE); 114 KTR_INFO(KTR_IPIQ, ipiq, send_pasv, 1, IPIQ_STRING, IPIQ_ARG_SIZE); 115 KTR_INFO(KTR_IPIQ, ipiq, send_nbio, 2, IPIQ_STRING, IPIQ_ARG_SIZE); 116 KTR_INFO(KTR_IPIQ, ipiq, send_fail, 3, IPIQ_STRING, IPIQ_ARG_SIZE); 117 KTR_INFO(KTR_IPIQ, ipiq, receive, 4, IPIQ_STRING, IPIQ_ARG_SIZE); 118 KTR_INFO(KTR_IPIQ, ipiq, sync_start, 5, "cpumask=%08x", sizeof(cpumask_t)); 119 KTR_INFO(KTR_IPIQ, ipiq, sync_end, 6, "cpumask=%08x", sizeof(cpumask_t)); 120 KTR_INFO(KTR_IPIQ, ipiq, cpu_send, 7, IPIQ_STRING, IPIQ_ARG_SIZE); 121 KTR_INFO(KTR_IPIQ, ipiq, send_end, 8, IPIQ_STRING, IPIQ_ARG_SIZE); 122 123 #define logipiq(name, func, arg1, arg2, sgd, dgd) \ 124 KTR_LOG(ipiq_ ## name, func, arg1, arg2, sgd->gd_cpuid, dgd->gd_cpuid) 125 #define logipiq2(name, arg) \ 126 KTR_LOG(ipiq_ ## name, arg) 127 128 #endif /* SMP */ 129 130 #ifdef SMP 131 132 static int lwkt_process_ipiq_core(globaldata_t sgd, lwkt_ipiq_t ip, 133 struct intrframe *frame); 134 static void lwkt_cpusync_remote1(lwkt_cpusync_t cs); 135 static void lwkt_cpusync_remote2(lwkt_cpusync_t cs); 136 137 /* 138 * Send a function execution request to another cpu. The request is queued 139 * on the cpu<->cpu ipiq matrix. Each cpu owns a unique ipiq FIFO for every 140 * possible target cpu. The FIFO can be written. 141 * 142 * If the FIFO fills up we have to enable interrupts to avoid an APIC 143 * deadlock and process pending IPIQs while waiting for it to empty. 144 * Otherwise we may soft-deadlock with another cpu whos FIFO is also full. 145 * 146 * We can safely bump gd_intr_nesting_level because our crit_exit() at the 147 * end will take care of any pending interrupts. 148 * 149 * The actual hardware IPI is avoided if the target cpu is already processing 150 * the queue from a prior IPI. It is possible to pipeline IPI messages 151 * very quickly between cpus due to the FIFO hysteresis. 152 * 153 * Need not be called from a critical section. 154 */ 155 int 156 lwkt_send_ipiq3(globaldata_t target, ipifunc3_t func, void *arg1, int arg2) 157 { 158 lwkt_ipiq_t ip; 159 int windex; 160 struct globaldata *gd = mycpu; 161 162 logipiq(send_norm, func, arg1, arg2, gd, target); 163 164 if (target == gd) { 165 func(arg1, arg2, NULL); 166 logipiq(send_end, func, arg1, arg2, gd, target); 167 return(0); 168 } 169 crit_enter(); 170 ++gd->gd_intr_nesting_level; 171 #ifdef INVARIANTS 172 if (gd->gd_intr_nesting_level > 20) 173 panic("lwkt_send_ipiq: TOO HEAVILY NESTED!"); 174 #endif 175 KKASSERT(curthread->td_critcount); 176 ++ipiq_count; 177 ip = &gd->gd_ipiq[target->gd_cpuid]; 178 179 /* 180 * Do not allow the FIFO to become full. Interrupts must be physically 181 * enabled while we liveloop to avoid deadlocking the APIC. 182 * 183 * The target ipiq may have gotten filled up due to passive IPIs and thus 184 * not be aware that its queue is too full, so be sure to issue an 185 * ipiq interrupt to the target cpu. 186 */ 187 if (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 2) { 188 #if defined(__i386__) 189 unsigned int eflags = read_eflags(); 190 #elif defined(__x86_64__) 191 unsigned long rflags = read_rflags(); 192 #endif 193 194 cpu_enable_intr(); 195 ++ipiq_fifofull; 196 DEBUG_PUSH_INFO("send_ipiq3"); 197 while (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 4) { 198 if (atomic_poll_acquire_int(&ip->ip_npoll) || ipiq_optimized == 0) { 199 logipiq(cpu_send, func, arg1, arg2, gd, target); 200 cpu_send_ipiq(target->gd_cpuid); 201 } 202 KKASSERT(ip->ip_windex - ip->ip_rindex != MAXCPUFIFO - 1); 203 lwkt_process_ipiq(); 204 cpu_pause(); 205 } 206 DEBUG_POP_INFO(); 207 #if defined(__i386__) 208 write_eflags(eflags); 209 #elif defined(__x86_64__) 210 write_rflags(rflags); 211 #endif 212 } 213 214 /* 215 * Queue the new message 216 */ 217 windex = ip->ip_windex & MAXCPUFIFO_MASK; 218 ip->ip_func[windex] = func; 219 ip->ip_arg1[windex] = arg1; 220 ip->ip_arg2[windex] = arg2; 221 cpu_sfence(); 222 ++ip->ip_windex; 223 224 /* 225 * signal the target cpu that there is work pending. 226 */ 227 if (atomic_poll_acquire_int(&ip->ip_npoll) || ipiq_optimized == 0) { 228 logipiq(cpu_send, func, arg1, arg2, gd, target); 229 cpu_send_ipiq(target->gd_cpuid); 230 } else { 231 ++ipiq_avoided; 232 } 233 --gd->gd_intr_nesting_level; 234 crit_exit(); 235 logipiq(send_end, func, arg1, arg2, gd, target); 236 237 return(ip->ip_windex); 238 } 239 240 /* 241 * Similar to lwkt_send_ipiq() but this function does not actually initiate 242 * the IPI to the target cpu unless the FIFO has become too full, so it is 243 * very fast. 244 * 245 * This function is used for non-critical IPI messages, such as memory 246 * deallocations. The queue will typically be flushed by the target cpu at 247 * the next clock interrupt. 248 * 249 * Need not be called from a critical section. 250 */ 251 int 252 lwkt_send_ipiq3_passive(globaldata_t target, ipifunc3_t func, 253 void *arg1, int arg2) 254 { 255 lwkt_ipiq_t ip; 256 int windex; 257 struct globaldata *gd = mycpu; 258 259 KKASSERT(target != gd); 260 crit_enter(); 261 ++gd->gd_intr_nesting_level; 262 logipiq(send_pasv, func, arg1, arg2, gd, target); 263 #ifdef INVARIANTS 264 if (gd->gd_intr_nesting_level > 20) 265 panic("lwkt_send_ipiq: TOO HEAVILY NESTED!"); 266 #endif 267 KKASSERT(curthread->td_critcount); 268 ++ipiq_count; 269 ++ipiq_passive; 270 ip = &gd->gd_ipiq[target->gd_cpuid]; 271 272 /* 273 * Do not allow the FIFO to become full. Interrupts must be physically 274 * enabled while we liveloop to avoid deadlocking the APIC. 275 */ 276 if (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 2) { 277 #if defined(__i386__) 278 unsigned int eflags = read_eflags(); 279 #elif defined(__x86_64__) 280 unsigned long rflags = read_rflags(); 281 #endif 282 283 cpu_enable_intr(); 284 ++ipiq_fifofull; 285 DEBUG_PUSH_INFO("send_ipiq3_passive"); 286 while (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 4) { 287 if (atomic_poll_acquire_int(&ip->ip_npoll) || ipiq_optimized == 0) { 288 logipiq(cpu_send, func, arg1, arg2, gd, target); 289 cpu_send_ipiq(target->gd_cpuid); 290 } 291 KKASSERT(ip->ip_windex - ip->ip_rindex != MAXCPUFIFO - 1); 292 lwkt_process_ipiq(); 293 cpu_pause(); 294 } 295 DEBUG_POP_INFO(); 296 #if defined(__i386__) 297 write_eflags(eflags); 298 #elif defined(__x86_64__) 299 write_rflags(rflags); 300 #endif 301 } 302 303 /* 304 * Queue the new message 305 */ 306 windex = ip->ip_windex & MAXCPUFIFO_MASK; 307 ip->ip_func[windex] = func; 308 ip->ip_arg1[windex] = arg1; 309 ip->ip_arg2[windex] = arg2; 310 cpu_sfence(); 311 ++ip->ip_windex; 312 --gd->gd_intr_nesting_level; 313 314 /* 315 * Do not signal the target cpu, it will pick up the IPI when it next 316 * polls (typically on the next tick). 317 */ 318 crit_exit(); 319 logipiq(send_end, func, arg1, arg2, gd, target); 320 321 return(ip->ip_windex); 322 } 323 324 /* 325 * Send an IPI request without blocking, return 0 on success, ENOENT on 326 * failure. The actual queueing of the hardware IPI may still force us 327 * to spin and process incoming IPIs but that will eventually go away 328 * when we've gotten rid of the other general IPIs. 329 */ 330 int 331 lwkt_send_ipiq3_nowait(globaldata_t target, ipifunc3_t func, 332 void *arg1, int arg2) 333 { 334 lwkt_ipiq_t ip; 335 int windex; 336 struct globaldata *gd = mycpu; 337 338 logipiq(send_nbio, func, arg1, arg2, gd, target); 339 KKASSERT(curthread->td_critcount); 340 if (target == gd) { 341 func(arg1, arg2, NULL); 342 logipiq(send_end, func, arg1, arg2, gd, target); 343 return(0); 344 } 345 crit_enter(); 346 ++gd->gd_intr_nesting_level; 347 ++ipiq_count; 348 ip = &gd->gd_ipiq[target->gd_cpuid]; 349 350 if (ip->ip_windex - ip->ip_rindex >= MAXCPUFIFO * 2 / 3) { 351 logipiq(send_fail, func, arg1, arg2, gd, target); 352 --gd->gd_intr_nesting_level; 353 crit_exit(); 354 return(ENOENT); 355 } 356 windex = ip->ip_windex & MAXCPUFIFO_MASK; 357 ip->ip_func[windex] = func; 358 ip->ip_arg1[windex] = arg1; 359 ip->ip_arg2[windex] = arg2; 360 cpu_sfence(); 361 ++ip->ip_windex; 362 363 /* 364 * This isn't a passive IPI, we still have to signal the target cpu. 365 */ 366 if (atomic_poll_acquire_int(&ip->ip_npoll) || ipiq_optimized == 0) { 367 logipiq(cpu_send, func, arg1, arg2, gd, target); 368 cpu_send_ipiq(target->gd_cpuid); 369 } else { 370 ++ipiq_avoided; 371 } 372 --gd->gd_intr_nesting_level; 373 crit_exit(); 374 375 logipiq(send_end, func, arg1, arg2, gd, target); 376 return(0); 377 } 378 379 /* 380 * deprecated, used only by fast int forwarding. 381 */ 382 int 383 lwkt_send_ipiq3_bycpu(int dcpu, ipifunc3_t func, void *arg1, int arg2) 384 { 385 return(lwkt_send_ipiq3(globaldata_find(dcpu), func, arg1, arg2)); 386 } 387 388 /* 389 * Send a message to several target cpus. Typically used for scheduling. 390 * The message will not be sent to stopped cpus. 391 */ 392 int 393 lwkt_send_ipiq3_mask(cpumask_t mask, ipifunc3_t func, void *arg1, int arg2) 394 { 395 int cpuid; 396 int count = 0; 397 398 mask &= ~stopped_cpus; 399 while (mask) { 400 cpuid = BSFCPUMASK(mask); 401 lwkt_send_ipiq3(globaldata_find(cpuid), func, arg1, arg2); 402 mask &= ~CPUMASK(cpuid); 403 ++count; 404 } 405 return(count); 406 } 407 408 /* 409 * Wait for the remote cpu to finish processing a function. 410 * 411 * YYY we have to enable interrupts and process the IPIQ while waiting 412 * for it to empty or we may deadlock with another cpu. Create a CPU_*() 413 * function to do this! YYY we really should 'block' here. 414 * 415 * MUST be called from a critical section. This routine may be called 416 * from an interrupt (for example, if an interrupt wakes a foreign thread 417 * up). 418 */ 419 void 420 lwkt_wait_ipiq(globaldata_t target, int seq) 421 { 422 lwkt_ipiq_t ip; 423 int maxc = 100000000; 424 425 if (target != mycpu) { 426 ip = &mycpu->gd_ipiq[target->gd_cpuid]; 427 if ((int)(ip->ip_xindex - seq) < 0) { 428 #if defined(__i386__) 429 unsigned int eflags = read_eflags(); 430 #elif defined(__x86_64__) 431 unsigned long rflags = read_rflags(); 432 #endif 433 cpu_enable_intr(); 434 DEBUG_PUSH_INFO("wait_ipiq"); 435 while ((int)(ip->ip_xindex - seq) < 0) { 436 crit_enter(); 437 lwkt_process_ipiq(); 438 crit_exit(); 439 if (--maxc == 0) 440 kprintf("LWKT_WAIT_IPIQ WARNING! %d wait %d (%d)\n", mycpu->gd_cpuid, target->gd_cpuid, ip->ip_xindex - seq); 441 if (maxc < -1000000) 442 panic("LWKT_WAIT_IPIQ"); 443 /* 444 * xindex may be modified by another cpu, use a load fence 445 * to ensure that the loop does not use a speculative value 446 * (which may improve performance). 447 */ 448 cpu_lfence(); 449 } 450 DEBUG_POP_INFO(); 451 #if defined(__i386__) 452 write_eflags(eflags); 453 #elif defined(__x86_64__) 454 write_rflags(rflags); 455 #endif 456 } 457 } 458 } 459 460 int 461 lwkt_seq_ipiq(globaldata_t target) 462 { 463 lwkt_ipiq_t ip; 464 465 ip = &mycpu->gd_ipiq[target->gd_cpuid]; 466 return(ip->ip_windex); 467 } 468 469 /* 470 * Called from IPI interrupt (like a fast interrupt), which has placed 471 * us in a critical section. The MP lock may or may not be held. 472 * May also be called from doreti or splz, or be reentrantly called 473 * indirectly through the ip_func[] we run. 474 * 475 * There are two versions, one where no interrupt frame is available (when 476 * called from the send code and from splz, and one where an interrupt 477 * frame is available. 478 * 479 * When the current cpu is mastering a cpusync we do NOT internally loop 480 * on the cpusyncq poll. We also do not re-flag a pending ipi due to 481 * the cpusyncq poll because this can cause doreti/splz to loop internally. 482 * The cpusync master's own loop must be allowed to run to avoid a deadlock. 483 */ 484 void 485 lwkt_process_ipiq(void) 486 { 487 globaldata_t gd = mycpu; 488 globaldata_t sgd; 489 lwkt_ipiq_t ip; 490 int n; 491 492 ++gd->gd_processing_ipiq; 493 again: 494 for (n = 0; n < ncpus; ++n) { 495 if (n != gd->gd_cpuid) { 496 sgd = globaldata_find(n); 497 ip = sgd->gd_ipiq; 498 if (ip != NULL) { 499 while (lwkt_process_ipiq_core(sgd, &ip[gd->gd_cpuid], NULL)) 500 ; 501 } 502 } 503 } 504 if (lwkt_process_ipiq_core(gd, &gd->gd_cpusyncq, NULL)) { 505 if (gd->gd_curthread->td_cscount == 0) 506 goto again; 507 /* need_ipiq(); do not reflag */ 508 } 509 --gd->gd_processing_ipiq; 510 } 511 512 void 513 lwkt_process_ipiq_frame(struct intrframe *frame) 514 { 515 globaldata_t gd = mycpu; 516 globaldata_t sgd; 517 lwkt_ipiq_t ip; 518 int n; 519 520 again: 521 for (n = 0; n < ncpus; ++n) { 522 if (n != gd->gd_cpuid) { 523 sgd = globaldata_find(n); 524 ip = sgd->gd_ipiq; 525 if (ip != NULL) { 526 while (lwkt_process_ipiq_core(sgd, &ip[gd->gd_cpuid], frame)) 527 ; 528 } 529 } 530 } 531 if (gd->gd_cpusyncq.ip_rindex != gd->gd_cpusyncq.ip_windex) { 532 if (lwkt_process_ipiq_core(gd, &gd->gd_cpusyncq, frame)) { 533 if (gd->gd_curthread->td_cscount == 0) 534 goto again; 535 /* need_ipiq(); do not reflag */ 536 } 537 } 538 } 539 540 #if 0 541 static int iqticks[SMP_MAXCPU]; 542 static int iqcount[SMP_MAXCPU]; 543 #endif 544 #if 0 545 static int iqterm[SMP_MAXCPU]; 546 #endif 547 548 static int 549 lwkt_process_ipiq_core(globaldata_t sgd, lwkt_ipiq_t ip, 550 struct intrframe *frame) 551 { 552 globaldata_t mygd = mycpu; 553 int ri; 554 int wi; 555 ipifunc3_t copy_func; 556 void *copy_arg1; 557 int copy_arg2; 558 559 #if 0 560 if (iqticks[mygd->gd_cpuid] != ticks) { 561 iqticks[mygd->gd_cpuid] = ticks; 562 iqcount[mygd->gd_cpuid] = 0; 563 } 564 if (++iqcount[mygd->gd_cpuid] > 3000000) { 565 kprintf("cpu %d ipiq maxed cscount %d spin %d\n", 566 mygd->gd_cpuid, 567 mygd->gd_curthread->td_cscount, 568 mygd->gd_spinlocks_wr); 569 iqcount[mygd->gd_cpuid] = 0; 570 #if 0 571 if (++iqterm[mygd->gd_cpuid] > 10) 572 panic("cpu %d ipiq maxed", mygd->gd_cpuid); 573 #endif 574 int i; 575 for (i = 0; i < ncpus; ++i) { 576 if (globaldata_find(i)->gd_infomsg) 577 kprintf(" %s", globaldata_find(i)->gd_infomsg); 578 } 579 kprintf("\n"); 580 } 581 #endif 582 583 /* 584 * Obtain the current write index, which is modified by a remote cpu. 585 * Issue a load fence to prevent speculative reads of e.g. data written 586 * by the other cpu prior to it updating the index. 587 */ 588 KKASSERT(curthread->td_critcount); 589 wi = ip->ip_windex; 590 cpu_lfence(); 591 ++mygd->gd_intr_nesting_level; 592 593 /* 594 * NOTE: xindex is only updated after we are sure the function has 595 * finished execution. Beware lwkt_process_ipiq() reentrancy! 596 * The function may send an IPI which may block/drain. 597 * 598 * NOTE: Due to additional IPI operations that the callback function 599 * may make, it is possible for both rindex and windex to advance and 600 * thus for rindex to advance passed our cached windex. 601 * 602 * NOTE: A load fence is required to prevent speculative loads prior 603 * to the loading of ip_rindex. Even though stores might be 604 * ordered, loads are probably not. A memory fence is required 605 * to prevent reordering of the loads after the ip_rindex update. 606 */ 607 while (wi - (ri = ip->ip_rindex) > 0) { 608 ri &= MAXCPUFIFO_MASK; 609 cpu_lfence(); 610 copy_func = ip->ip_func[ri]; 611 copy_arg1 = ip->ip_arg1[ri]; 612 copy_arg2 = ip->ip_arg2[ri]; 613 cpu_mfence(); 614 ++ip->ip_rindex; 615 KKASSERT((ip->ip_rindex & MAXCPUFIFO_MASK) == 616 ((ri + 1) & MAXCPUFIFO_MASK)); 617 logipiq(receive, copy_func, copy_arg1, copy_arg2, sgd, mycpu); 618 #ifdef INVARIANTS 619 if (ipiq_debug && (ip->ip_rindex & 0xFFFFFF) == 0) { 620 kprintf("cpu %d ipifunc %p %p %d (frame %p)\n", 621 mycpu->gd_cpuid, 622 copy_func, copy_arg1, copy_arg2, 623 #if defined(__i386__) 624 (frame ? (void *)frame->if_eip : NULL)); 625 #elif defined(__amd64__) 626 (frame ? (void *)frame->if_rip : NULL)); 627 #else 628 NULL); 629 #endif 630 } 631 #endif 632 copy_func(copy_arg1, copy_arg2, frame); 633 cpu_sfence(); 634 ip->ip_xindex = ip->ip_rindex; 635 636 #ifdef PANIC_DEBUG 637 /* 638 * Simulate panics during the processing of an IPI 639 */ 640 if (mycpu->gd_cpuid == panic_ipiq_cpu && panic_ipiq_count) { 641 if (--panic_ipiq_count == 0) { 642 #ifdef DDB 643 Debugger("PANIC_DEBUG"); 644 #else 645 panic("PANIC_DEBUG"); 646 #endif 647 } 648 } 649 #endif 650 } 651 --mygd->gd_intr_nesting_level; 652 653 /* 654 * If the queue is empty release ip_npoll to enable the other cpu to 655 * send us an IPI interrupt again. 656 * 657 * Return non-zero if there is still more in the queue. Note that we 658 * must re-check the indexes after potentially releasing ip_npoll. The 659 * caller must loop or otherwise ensure that a loop will occur prior to 660 * blocking. 661 */ 662 if (ip->ip_rindex == ip->ip_windex); 663 atomic_poll_release_int(&ip->ip_npoll); 664 cpu_lfence(); 665 return (ip->ip_rindex != ip->ip_windex); 666 } 667 668 static void 669 lwkt_sync_ipiq(void *arg) 670 { 671 volatile cpumask_t *cpumask = arg; 672 673 atomic_clear_cpumask(cpumask, mycpu->gd_cpumask); 674 if (*cpumask == 0) 675 wakeup(cpumask); 676 } 677 678 void 679 lwkt_synchronize_ipiqs(const char *wmesg) 680 { 681 volatile cpumask_t other_cpumask; 682 683 other_cpumask = mycpu->gd_other_cpus & smp_active_mask; 684 lwkt_send_ipiq_mask(other_cpumask, lwkt_sync_ipiq, 685 __DEVOLATILE(void *, &other_cpumask)); 686 687 while (other_cpumask != 0) { 688 tsleep_interlock(&other_cpumask, 0); 689 if (other_cpumask != 0) 690 tsleep(&other_cpumask, PINTERLOCKED, wmesg, 0); 691 } 692 } 693 694 #endif 695 696 /* 697 * CPU Synchronization Support 698 * 699 * lwkt_cpusync_interlock() - Place specified cpus in a quiescent state. 700 * The current cpu is placed in a hard critical 701 * section. 702 * 703 * lwkt_cpusync_deinterlock() - Execute cs_func on specified cpus, including 704 * current cpu if specified, then return. 705 */ 706 void 707 lwkt_cpusync_simple(cpumask_t mask, cpusync_func_t func, void *arg) 708 { 709 struct lwkt_cpusync cs; 710 711 lwkt_cpusync_init(&cs, mask, func, arg); 712 lwkt_cpusync_interlock(&cs); 713 lwkt_cpusync_deinterlock(&cs); 714 } 715 716 717 void 718 lwkt_cpusync_interlock(lwkt_cpusync_t cs) 719 { 720 #ifdef SMP 721 globaldata_t gd = mycpu; 722 cpumask_t mask; 723 724 /* 725 * mask acknowledge (cs_mack): 0->mask for stage 1 726 * 727 * mack does not include the current cpu. 728 */ 729 mask = cs->cs_mask & gd->gd_other_cpus & smp_active_mask; 730 cs->cs_mack = 0; 731 crit_enter_id("cpusync"); 732 if (mask) { 733 DEBUG_PUSH_INFO("cpusync_interlock"); 734 ++ipiq_cscount; 735 ++gd->gd_curthread->td_cscount; 736 lwkt_send_ipiq_mask(mask, (ipifunc1_t)lwkt_cpusync_remote1, cs); 737 logipiq2(sync_start, mask); 738 while (cs->cs_mack != mask) { 739 lwkt_process_ipiq(); 740 cpu_pause(); 741 } 742 DEBUG_POP_INFO(); 743 } 744 #else 745 cs->cs_mack = 0; 746 #endif 747 } 748 749 /* 750 * Interlocked cpus have executed remote1 and are polling in remote2. 751 * To deinterlock we clear cs_mack and wait for the cpus to execute 752 * the func and set their bit in cs_mack again. 753 * 754 */ 755 void 756 lwkt_cpusync_deinterlock(lwkt_cpusync_t cs) 757 { 758 globaldata_t gd = mycpu; 759 #ifdef SMP 760 cpumask_t mask; 761 762 /* 763 * mask acknowledge (cs_mack): mack->0->mack for stage 2 764 * 765 * Clearing cpu bits for polling cpus in cs_mack will cause them to 766 * execute stage 2, which executes the cs_func(cs_data) and then sets 767 * their bit in cs_mack again. 768 * 769 * mack does not include the current cpu. 770 */ 771 mask = cs->cs_mack; 772 cpu_ccfence(); 773 cs->cs_mack = 0; 774 if (cs->cs_func && (cs->cs_mask & gd->gd_cpumask)) 775 cs->cs_func(cs->cs_data); 776 if (mask) { 777 DEBUG_PUSH_INFO("cpusync_deinterlock"); 778 while (cs->cs_mack != mask) { 779 lwkt_process_ipiq(); 780 cpu_pause(); 781 } 782 DEBUG_POP_INFO(); 783 /* 784 * cpusyncq ipis may be left queued without the RQF flag set due to 785 * a non-zero td_cscount, so be sure to process any laggards after 786 * decrementing td_cscount. 787 */ 788 --gd->gd_curthread->td_cscount; 789 lwkt_process_ipiq(); 790 logipiq2(sync_end, mask); 791 } 792 crit_exit_id("cpusync"); 793 #else 794 if (cs->cs_func && (cs->cs_mask & gd->gd_cpumask)) 795 cs->cs_func(cs->cs_data); 796 #endif 797 } 798 799 #ifdef SMP 800 801 /* 802 * helper IPI remote messaging function. 803 * 804 * Called on remote cpu when a new cpu synchronization request has been 805 * sent to us. Execute the run function and adjust cs_count, then requeue 806 * the request so we spin on it. 807 */ 808 static void 809 lwkt_cpusync_remote1(lwkt_cpusync_t cs) 810 { 811 globaldata_t gd = mycpu; 812 813 atomic_set_cpumask(&cs->cs_mack, gd->gd_cpumask); 814 lwkt_cpusync_remote2(cs); 815 } 816 817 /* 818 * helper IPI remote messaging function. 819 * 820 * Poll for the originator telling us to finish. If it hasn't, requeue 821 * our request so we spin on it. 822 */ 823 static void 824 lwkt_cpusync_remote2(lwkt_cpusync_t cs) 825 { 826 globaldata_t gd = mycpu; 827 828 if ((cs->cs_mack & gd->gd_cpumask) == 0) { 829 if (cs->cs_func) 830 cs->cs_func(cs->cs_data); 831 atomic_set_cpumask(&cs->cs_mack, gd->gd_cpumask); 832 } else { 833 lwkt_ipiq_t ip; 834 int wi; 835 836 ip = &gd->gd_cpusyncq; 837 wi = ip->ip_windex & MAXCPUFIFO_MASK; 838 ip->ip_func[wi] = (ipifunc3_t)(ipifunc1_t)lwkt_cpusync_remote2; 839 ip->ip_arg1[wi] = cs; 840 ip->ip_arg2[wi] = 0; 841 cpu_sfence(); 842 ++ip->ip_windex; 843 if (ipiq_debug && (ip->ip_windex & 0xFFFFFF) == 0) { 844 kprintf("cpu %d cm=%016jx %016jx f=%p\n", 845 gd->gd_cpuid, 846 (intmax_t)cs->cs_mask, (intmax_t)cs->cs_mack, 847 cs->cs_func); 848 } 849 } 850 } 851 852 #endif 853