prom_subr.c revision 7240:c4957ab6a78e
1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26#pragma ident "%Z%%M% %I% %E% SMI" 27 28#include <sys/types.h> 29#include <sys/param.h> 30#include <sys/cmn_err.h> 31#include <sys/mutex.h> 32#include <sys/systm.h> 33#include <sys/sysmacros.h> 34#include <sys/machsystm.h> 35#include <sys/archsystm.h> 36#include <sys/x_call.h> 37#include <sys/promif.h> 38#include <sys/prom_isa.h> 39#include <sys/privregs.h> 40#include <sys/vmem.h> 41#include <sys/atomic.h> 42#include <sys/panic.h> 43#include <sys/rwlock.h> 44#include <sys/reboot.h> 45#include <sys/kdi.h> 46#include <sys/kdi_machimpl.h> 47 48/* 49 * We are called with a pointer to a cell-sized argument array. 50 * The service name (the first element of the argument array) is 51 * the name of the callback being invoked. When called, we are 52 * running on the firmwares trap table as a trusted subroutine 53 * of the firmware. 54 * 55 * We define entry points to allow callback handlers to be dynamically 56 * added and removed, to support obpsym, which is a separate module 57 * and can be dynamically loaded and unloaded and registers its 58 * callback handlers dynamically. 59 * 60 * Note: The actual callback handler we register, is the assembly lang. 61 * glue, callback_handler, which takes care of switching from a 64 62 * bit stack and environment to a 32 bit stack and environment, and 63 * back again, if the callback handler returns. callback_handler calls 64 * vx_handler to process the callback. 65 */ 66 67static kmutex_t vx_cmd_lock; /* protect vx_cmd table */ 68 69#define VX_CMD_MAX 10 70#define ENDADDR(a) &a[sizeof (a) / sizeof (a[0])] 71#define vx_cmd_end ((struct vx_cmd *)(ENDADDR(vx_cmd))) 72 73static struct vx_cmd { 74 char *service; /* Service name */ 75 int take_tba; /* If Non-zero we take over the tba */ 76 void (*func)(cell_t *argument_array); 77} vx_cmd[VX_CMD_MAX+1]; 78 79void 80init_vx_handler(void) 81{ 82 extern int callback_handler(cell_t *arg_array); 83 84 /* 85 * initialize the lock protecting additions and deletions from 86 * the vx_cmd table. At callback time we don't need to grab 87 * this lock. Callback handlers do not need to modify the 88 * callback handler table. 89 */ 90 mutex_init(&vx_cmd_lock, NULL, MUTEX_DEFAULT, NULL); 91 92 /* 93 * Tell OBP about our callback handler. 94 */ 95 (void) prom_set_callback((void *)callback_handler); 96} 97 98/* 99 * Add a kernel callback handler to the kernel's list. 100 * The table is static, so if you add a callback handler, increase 101 * the value of VX_CMD_MAX. Find the first empty slot and use it. 102 */ 103void 104add_vx_handler(char *name, int flag, void (*func)(cell_t *)) 105{ 106 struct vx_cmd *vp; 107 108 mutex_enter(&vx_cmd_lock); 109 for (vp = vx_cmd; vp < vx_cmd_end; vp++) { 110 if (vp->service == NULL) { 111 vp->service = name; 112 vp->take_tba = flag; 113 vp->func = func; 114 mutex_exit(&vx_cmd_lock); 115 return; 116 } 117 } 118 mutex_exit(&vx_cmd_lock); 119 120#ifdef DEBUG 121 122 /* 123 * There must be enough entries to handle all callback entries. 124 * Increase VX_CMD_MAX if this happens. This shouldn't happen. 125 */ 126 cmn_err(CE_PANIC, "add_vx_handler <%s>", name); 127 /* NOTREACHED */ 128 129#else /* DEBUG */ 130 131 cmn_err(CE_WARN, "add_vx_handler: Can't add callback hander <%s>", 132 name); 133 134#endif /* DEBUG */ 135 136} 137 138/* 139 * Remove a vx_handler function -- find the name string in the table, 140 * and clear it. 141 */ 142void 143remove_vx_handler(char *name) 144{ 145 struct vx_cmd *vp; 146 147 mutex_enter(&vx_cmd_lock); 148 for (vp = vx_cmd; vp < vx_cmd_end; vp++) { 149 if (vp->service == NULL) 150 continue; 151 if (strcmp(vp->service, name) != 0) 152 continue; 153 vp->service = 0; 154 vp->take_tba = 0; 155 vp->func = 0; 156 mutex_exit(&vx_cmd_lock); 157 return; 158 } 159 mutex_exit(&vx_cmd_lock); 160 cmn_err(CE_WARN, "remove_vx_handler: <%s> not found", name); 161} 162 163int 164vx_handler(cell_t *argument_array) 165{ 166 char *name; 167 struct vx_cmd *vp; 168 void *old_tba; 169 170 name = p1275_cell2ptr(*argument_array); 171 172 for (vp = vx_cmd; vp < vx_cmd_end; vp++) { 173 if (vp->service == (char *)0) 174 continue; 175 if (strcmp(vp->service, name) != 0) 176 continue; 177 if (vp->take_tba != 0) { 178 reestablish_curthread(); 179 if (tba_taken_over != 0) 180 old_tba = set_tba((void *)&trap_table); 181 } 182 vp->func(argument_array); 183 if ((vp->take_tba != 0) && (tba_taken_over != 0)) 184 (void) set_tba(old_tba); 185 return (0); /* Service name was known */ 186 } 187 188 return (-1); /* Service name unknown */ 189} 190 191/* 192 * PROM Locking Primitives 193 * 194 * These routines are called immediately before and immediately after calling 195 * into the firmware. The firmware is single-threaded and assumes that the 196 * kernel will implement locking to prevent simultaneous service calls. In 197 * addition, some service calls (particularly character rendering) can be 198 * slow, so we would like to sleep if we cannot acquire the lock to allow the 199 * caller's CPU to continue to perform useful work in the interim. Service 200 * routines may also be called early in boot as part of slave CPU startup 201 * when mutexes and cvs are not yet available (i.e. they are still running on 202 * the prom's TLB handlers and cannot touch curthread). Therefore, these 203 * routines must reduce to a simple compare-and-swap spin lock when necessary. 204 * Finally, kernel code may wish to acquire the firmware lock before executing 205 * a block of code that includes service calls, so we also allow the firmware 206 * lock to be acquired recursively by the owning CPU after disabling preemption. 207 * 208 * To meet these constraints, the lock itself is implemented as a compare-and- 209 * swap spin lock on the global prom_cpu pointer. We implement recursion by 210 * atomically incrementing the integer prom_holdcnt after acquiring the lock. 211 * If the current CPU is an "adult" (determined by testing cpu_m.mutex_ready), 212 * we disable preemption before acquiring the lock and leave it disabled once 213 * the lock is held. The kern_postprom() routine then enables preemption if 214 * we drop the lock and prom_holdcnt returns to zero. If the current CPU is 215 * an adult and the lock is held by another adult CPU, we can safely sleep 216 * until the lock is released. To do so, we acquire the adaptive prom_mutex 217 * and then sleep on prom_cv. Therefore, service routines must not be called 218 * from above LOCK_LEVEL on any adult CPU. Finally, if recursive entry is 219 * attempted on an adult CPU, we must also verify that curthread matches the 220 * saved prom_thread (the original owner) to ensure that low-level interrupt 221 * threads do not step on other threads running on the same CPU. 222 */ 223 224static cpu_t *volatile prom_cpu; 225static kthread_t *volatile prom_thread; 226static uint32_t prom_holdcnt; 227static kmutex_t prom_mutex; 228static kcondvar_t prom_cv; 229 230/* 231 * The debugger uses PROM services, and is thus unable to run if any of the 232 * CPUs on the system are executing in the PROM at the time of debugger entry. 233 * If a CPU is determined to be in the PROM when the debugger is entered, 234 * prom_return_enter_debugger will be set, thus triggering a programmed debugger 235 * entry when the given CPU returns from the PROM. That CPU is then released by 236 * the debugger, and is allowed to complete PROM-related work. 237 */ 238int prom_exit_enter_debugger; 239 240void 241kern_preprom(void) 242{ 243 for (;;) { 244 /* 245 * Load the current CPU pointer and examine the mutex_ready bit. 246 * It doesn't matter if we are preempted here because we are 247 * only trying to determine if we are in the *set* of mutex 248 * ready CPUs. We cannot disable preemption until we confirm 249 * that we are running on a CPU in this set, since a call to 250 * kpreempt_disable() requires access to curthread. 251 */ 252 processorid_t cpuid = getprocessorid(); 253 cpu_t *cp = cpu[cpuid]; 254 cpu_t *prcp; 255 256 if (panicstr) 257 return; /* just return if we are currently panicking */ 258 259 if (CPU_IN_SET(cpu_ready_set, cpuid) && cp->cpu_m.mutex_ready) { 260 /* 261 * Disable premption, and reload the current CPU. We 262 * can't move from a mutex_ready cpu to a non-ready cpu 263 * so we don't need to re-check cp->cpu_m.mutex_ready. 264 */ 265 kpreempt_disable(); 266 cp = CPU; 267 ASSERT(cp->cpu_m.mutex_ready); 268 269 /* 270 * Try the lock. If we don't get the lock, re-enable 271 * preemption and see if we should sleep. If we are 272 * already the lock holder, remove the effect of the 273 * previous kpreempt_disable() before returning since 274 * preemption was disabled by an earlier kern_preprom. 275 */ 276 prcp = casptr((void *)&prom_cpu, NULL, cp); 277 if (prcp == NULL || 278 (prcp == cp && prom_thread == curthread)) { 279 if (prcp == cp) 280 kpreempt_enable(); 281 break; 282 } 283 284 kpreempt_enable(); 285 286 /* 287 * We have to be very careful here since both prom_cpu 288 * and prcp->cpu_m.mutex_ready can be changed at any 289 * time by a non mutex_ready cpu holding the lock. 290 * If the owner is mutex_ready, holding prom_mutex 291 * prevents kern_postprom() from completing. If the 292 * owner isn't mutex_ready, we only know it will clear 293 * prom_cpu before changing cpu_m.mutex_ready, so we 294 * issue a membar after checking mutex_ready and then 295 * re-verify that prom_cpu is still held by the same 296 * cpu before actually proceeding to cv_wait(). 297 */ 298 mutex_enter(&prom_mutex); 299 prcp = prom_cpu; 300 if (prcp != NULL && prcp->cpu_m.mutex_ready != 0) { 301 membar_consumer(); 302 if (prcp == prom_cpu) 303 cv_wait(&prom_cv, &prom_mutex); 304 } 305 mutex_exit(&prom_mutex); 306 307 } else { 308 /* 309 * If we are not yet mutex_ready, just attempt to grab 310 * the lock. If we get it or already hold it, break. 311 */ 312 ASSERT(getpil() == PIL_MAX); 313 prcp = casptr((void *)&prom_cpu, NULL, cp); 314 if (prcp == NULL || prcp == cp) 315 break; 316 } 317 } 318 319 /* 320 * We now hold the prom_cpu lock. Increment the hold count by one 321 * and assert our current state before returning to the caller. 322 */ 323 atomic_add_32(&prom_holdcnt, 1); 324 ASSERT(prom_holdcnt >= 1); 325 prom_thread = curthread; 326} 327 328/* 329 * Drop the prom lock if it is held by the current CPU. If the lock is held 330 * recursively, return without clearing prom_cpu. If the hold count is now 331 * zero, clear prom_cpu and cv_signal any waiting CPU. 332 */ 333void 334kern_postprom(void) 335{ 336 processorid_t cpuid = getprocessorid(); 337 cpu_t *cp = cpu[cpuid]; 338 339 if (panicstr) 340 return; /* do not modify lock further if we have panicked */ 341 342 if (prom_cpu != cp) 343 panic("kern_postprom: not owner, cp=%p owner=%p", 344 (void *)cp, (void *)prom_cpu); 345 346 if (prom_holdcnt == 0) 347 panic("kern_postprom: prom_holdcnt == 0, owner=%p", 348 (void *)prom_cpu); 349 350 if (atomic_add_32_nv(&prom_holdcnt, -1) != 0) 351 return; /* prom lock is held recursively by this CPU */ 352 353 if ((boothowto & RB_DEBUG) && prom_exit_enter_debugger) 354 kmdb_enter(); 355 356 prom_thread = NULL; 357 membar_producer(); 358 359 prom_cpu = NULL; 360 membar_producer(); 361 362 if (CPU_IN_SET(cpu_ready_set, cpuid) && cp->cpu_m.mutex_ready) { 363 mutex_enter(&prom_mutex); 364 cv_signal(&prom_cv); 365 mutex_exit(&prom_mutex); 366 kpreempt_enable(); 367 } 368} 369 370/* 371 * If the frame buffer device is busy, briefly capture the other CPUs so that 372 * another CPU executing code to manipulate the device does not execute at the 373 * same time we are rendering characters. Refer to the comments and code in 374 * common/os/console.c for more information on these callbacks. 375 * 376 * Notice that we explicitly acquire the PROM lock using kern_preprom() prior 377 * to idling other CPUs. The idling mechanism will cross-trap the other CPUs 378 * and have them spin at MAX(%pil, XCALL_PIL), so we must be sure that none of 379 * them are holding the PROM lock before we idle them and then call into the 380 * PROM routines that render characters to the frame buffer. 381 */ 382int 383console_enter(int busy) 384{ 385 int s = 0; 386 387 if (busy && panicstr == NULL) { 388 kern_preprom(); 389 s = splhi(); 390 idle_other_cpus(); 391 } 392 393 return (s); 394} 395 396void 397console_exit(int busy, int spl) 398{ 399 if (busy && panicstr == NULL) { 400 resume_other_cpus(); 401 splx(spl); 402 kern_postprom(); 403 } 404} 405 406/* 407 * This routine is a special form of pause_cpus(). It ensures that 408 * prom functions are callable while the cpus are paused. 409 */ 410void 411promsafe_pause_cpus(void) 412{ 413 pause_cpus(NULL); 414 415 /* If some other cpu is entering or is in the prom, spin */ 416 while (prom_cpu || mutex_owner(&prom_mutex)) { 417 418 start_cpus(); 419 mutex_enter(&prom_mutex); 420 421 /* Wait for other cpu to exit prom */ 422 while (prom_cpu) 423 cv_wait(&prom_cv, &prom_mutex); 424 425 mutex_exit(&prom_mutex); 426 pause_cpus(NULL); 427 } 428 429 /* At this point all cpus are paused and none are in the prom */ 430} 431 432/* 433 * This routine is a special form of xc_attention(). It ensures that 434 * prom functions are callable while the cpus are at attention. 435 */ 436void 437promsafe_xc_attention(cpuset_t cpuset) 438{ 439 xc_attention(cpuset); 440 441 /* If some other cpu is entering or is in the prom, spin */ 442 while (prom_cpu || mutex_owner(&prom_mutex)) { 443 444 xc_dismissed(cpuset); 445 mutex_enter(&prom_mutex); 446 447 /* Wait for other cpu to exit prom */ 448 while (prom_cpu) 449 cv_wait(&prom_cv, &prom_mutex); 450 451 mutex_exit(&prom_mutex); 452 xc_attention(cpuset); 453 } 454 455 /* At this point all cpus are paused and none are in the prom */ 456} 457 458 459#if defined(PROM_32BIT_ADDRS) 460 461#include <sys/promimpl.h> 462#include <vm/seg_kmem.h> 463#include <sys/kmem.h> 464#include <sys/bootconf.h> 465 466/* 467 * These routines are only used to workaround "poor feature interaction" 468 * in OBP. See bug 4115680 for details. 469 * 470 * Many of the promif routines need to allocate temporary buffers 471 * with 32-bit addresses to pass in/out of the CIF. The lifetime 472 * of the buffers is extremely short, they are allocated and freed 473 * around the CIF call. We use vmem_alloc() to cache 32-bit memory. 474 * 475 * Note the code in promplat_free() to prevent exhausting the 32 bit 476 * heap during boot. 477 */ 478static void *promplat_last_free = NULL; 479static size_t promplat_last_size; 480static vmem_t *promplat_arena; 481static kmutex_t promplat_lock; /* protect arena, last_free, and last_size */ 482 483void * 484promplat_alloc(size_t size) 485{ 486 487 mutex_enter(&promplat_lock); 488 if (promplat_arena == NULL) { 489 promplat_arena = vmem_create("promplat", NULL, 0, 8, 490 segkmem_alloc, segkmem_free, heap32_arena, 0, VM_SLEEP); 491 } 492 mutex_exit(&promplat_lock); 493 494 return (vmem_alloc(promplat_arena, size, VM_NOSLEEP)); 495} 496 497/* 498 * Delaying the free() of small allocations gets more mileage 499 * from pages during boot, otherwise a cycle of allocate/free 500 * calls could burn through available heap32 space too quickly. 501 */ 502void 503promplat_free(void *p, size_t size) 504{ 505 void *p2 = NULL; 506 size_t s2; 507 508 /* 509 * If VM is initialized, clean up any delayed free(). 510 */ 511 if (kvseg.s_base != 0 && promplat_last_free != NULL) { 512 mutex_enter(&promplat_lock); 513 p2 = promplat_last_free; 514 s2 = promplat_last_size; 515 promplat_last_free = NULL; 516 promplat_last_size = 0; 517 mutex_exit(&promplat_lock); 518 if (p2 != NULL) { 519 vmem_free(promplat_arena, p2, s2); 520 p2 = NULL; 521 } 522 } 523 524 /* 525 * Do the free if VM is initialized or it's a large allocation. 526 */ 527 if (kvseg.s_base != 0 || size >= PAGESIZE) { 528 vmem_free(promplat_arena, p, size); 529 return; 530 } 531 532 /* 533 * Otherwise, do the last free request and delay this one. 534 */ 535 mutex_enter(&promplat_lock); 536 if (promplat_last_free != NULL) { 537 p2 = promplat_last_free; 538 s2 = promplat_last_size; 539 } 540 promplat_last_free = p; 541 promplat_last_size = size; 542 mutex_exit(&promplat_lock); 543 544 if (p2 != NULL) 545 vmem_free(promplat_arena, p2, s2); 546} 547 548void 549promplat_bcopy(const void *src, void *dst, size_t count) 550{ 551 bcopy(src, dst, count); 552} 553 554#endif /* PROM_32BIT_ADDRS */ 555 556static prom_generation_cookie_t prom_tree_gen; 557static krwlock_t prom_tree_lock; 558 559int 560prom_tree_access(int (*callback)(void *arg, int has_changed), void *arg, 561 prom_generation_cookie_t *ckp) 562{ 563 int chg, rv; 564 565 rw_enter(&prom_tree_lock, RW_READER); 566 /* 567 * If the tree has changed since the caller last accessed it 568 * pass 1 as the second argument to the callback function, 569 * otherwise 0. 570 */ 571 if (ckp != NULL && *ckp != prom_tree_gen) { 572 *ckp = prom_tree_gen; 573 chg = 1; 574 } else 575 chg = 0; 576 rv = callback(arg, chg); 577 rw_exit(&prom_tree_lock); 578 return (rv); 579} 580 581int 582prom_tree_update(int (*callback)(void *arg), void *arg) 583{ 584 int rv; 585 586 rw_enter(&prom_tree_lock, RW_WRITER); 587 prom_tree_gen++; 588 rv = callback(arg); 589 rw_exit(&prom_tree_lock); 590 return (rv); 591} 592