cpuswitch.S revision 1.3.2.21
1 /* $NetBSD: cpuswitch.S,v 1.3.2.21 2002/08/20 15:21:29 thorpej Exp $ */ 2 3 /* 4 * Copyright (c) 1994-1998 Mark Brinicombe. 5 * Copyright (c) 1994 Brini. 6 * All rights reserved. 7 * 8 * This code is derived from software written for Brini by Mark Brinicombe 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by Brini. 21 * 4. The name of the company nor the name of the author may be used to 22 * endorse or promote products derived from this software without specific 23 * prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED 26 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 27 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 29 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 30 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 31 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * RiscBSD kernel project 38 * 39 * cpuswitch.S 40 * 41 * cpu switching functions 42 * 43 * Created : 15/10/94 44 */ 45 46 #include "opt_armfpe.h" 47 48 #include "assym.h" 49 #include <machine/param.h> 50 #include <machine/cpu.h> 51 #include <machine/frame.h> 52 #include <machine/asm.h> 53 54 #undef IRQdisable 55 #undef IRQenable 56 57 /* 58 * New experimental definitions of IRQdisable and IRQenable 59 * These keep FIQ's enabled since FIQ's are special. 60 */ 61 62 #define IRQdisable \ 63 mrs r14, cpsr ; \ 64 orr r14, r14, #(I32_bit) ; \ 65 msr cpsr_c, r14 ; \ 66 67 #define IRQenable \ 68 mrs r14, cpsr ; \ 69 bic r14, r14, #(I32_bit) ; \ 70 msr cpsr_c, r14 ; \ 71 72 /* 73 * setrunqueue() and remrunqueue() 74 * 75 * Functions to add and remove a process for the run queue. 76 */ 77 78 .text 79 80 .Lwhichqs: 81 .word _C_LABEL(sched_whichqs) 82 83 .Lqs: 84 .word _C_LABEL(sched_qs) 85 86 /* 87 * On entry 88 * r0 = lwp 89 */ 90 91 ENTRY(setrunqueue) 92 /* 93 * Local register usage 94 * r0 = process 95 * r1 = queue 96 * r2 = &qs[queue] and temp 97 * r3 = temp 98 * r12 = whichqs 99 */ 100 #ifdef DIAGNOSTIC 101 ldr r1, [r0, #(L_BACK)] 102 teq r1, #0x00000000 103 bne .Lsetrunqueue_erg 104 105 ldr r1, [r0, #(L_WCHAN)] 106 teq r1, #0x00000000 107 bne .Lsetrunqueue_erg 108 #endif 109 110 /* Get the priority of the queue */ 111 ldrb r1, [r0, #(L_PRIORITY)] 112 113 /* Indicate that there is a process on this queue */ 114 ldr r12, .Lwhichqs 115 mov r1, r1, lsr #2 116 ldr r2, [r12] 117 mov r3, #0x00000001 118 mov r3, r3, lsl r1 119 orr r2, r2, r3 120 str r2, [r12] 121 122 /* Get the address of the queue */ 123 ldr r2, .Lqs 124 add r1, r2, r1, lsl # 3 125 126 /* Hook the process in */ 127 str r1, [r0, #(L_FORW)] 128 ldr r2, [r1, #(L_BACK)] 129 130 str r0, [r1, #(L_BACK)] 131 #ifdef DIAGNOSTIC 132 teq r2, #0x00000000 133 beq .Lsetrunqueue_erg 134 #endif 135 str r0, [r2, #(L_FORW)] 136 str r2, [r0, #(L_BACK)] 137 138 mov pc, lr 139 140 #ifdef DIAGNOSTIC 141 .Lsetrunqueue_erg: 142 mov r2, r1 143 mov r1, r0 144 add r0, pc, #Ltext1 - . - 8 145 bl _C_LABEL(printf) 146 147 ldr r2, .Lqs 148 ldr r1, [r2] 149 add r0, pc, #Ltext2 - . - 8 150 b _C_LABEL(panic) 151 152 Ltext1: 153 .asciz "setrunqueue : %08x %08x\n" 154 Ltext2: 155 .asciz "setrunqueue : [qs]=%08x qs=%08x\n" 156 .align 0 157 #endif 158 159 /* 160 * On entry 161 * r0 = lwp 162 */ 163 164 ENTRY(remrunqueue) 165 /* 166 * Local register usage 167 * r0 = oldproc 168 * r1 = queue 169 * r2 = &qs[queue] and scratch 170 * r3 = scratch 171 * r12 = whichqs 172 */ 173 174 /* Get the priority of the queue */ 175 ldrb r1, [r0, #(L_PRIORITY)] 176 mov r1, r1, lsr #2 177 178 /* Unhook the process */ 179 ldr r2, [r0, #(L_FORW)] 180 ldr r3, [r0, #(L_BACK)] 181 182 str r3, [r2, #(L_BACK)] 183 str r2, [r3, #(L_FORW)] 184 185 /* If the queue is now empty clear the queue not empty flag */ 186 teq r2, r3 187 188 /* This could be reworked to avoid the use of r4 */ 189 ldreq r12, .Lwhichqs 190 moveq r3, #0x00000001 191 ldreq r2, [r12] 192 moveq r3, r3, lsl r1 193 biceq r2, r2, r3 194 streq r2, [r12] 195 196 /* Remove the back pointer for the process */ 197 mov r1, #0x00000000 198 str r1, [r0, #(L_BACK)] 199 200 mov pc, lr 201 202 203 /* 204 * cpuswitch() 205 * 206 * preforms a process context switch. 207 * This function has several entry points 208 */ 209 210 .Lcurlwp: 211 .word _C_LABEL(curlwp) 212 213 .Lcurpcb: 214 .word _C_LABEL(curpcb) 215 216 .Lwant_resched: 217 .word _C_LABEL(want_resched) 218 219 .Lcpufuncs: 220 .word _C_LABEL(cpufuncs) 221 222 .data 223 .global _C_LABEL(curpcb) 224 _C_LABEL(curpcb): 225 .word 0x00000000 226 .text 227 228 .Lblock_userspace_access: 229 .word _C_LABEL(block_userspace_access) 230 231 .Lcpu_do_powersave: 232 .word _C_LABEL(cpu_do_powersave) 233 234 /* 235 * Idle loop, exercised while waiting for a process to wake up. 236 * 237 * NOTE: When we jump back to .Lswitch_search, we must have a 238 * pointer to whichqs in r7, which is what it is when we arrive 239 * here. 240 */ 241 /* LINTSTUB: Ignore */ 242 ASENTRY_NP(idle) 243 #if defined(LOCKDEBUG) 244 bl _C_LABEL(sched_unlock_idle) 245 #endif 246 ldr r3, .Lcpu_do_powersave 247 248 /* Enable interrupts */ 249 IRQenable 250 251 /* If we don't want to sleep, use a simpler loop. */ 252 ldr r3, [r3] /* r3 = cpu_do_powersave */ 253 teq r3, #0 254 bne 2f 255 256 /* Non-powersave idle. */ 257 1: /* should maybe do uvm pageidlezero stuff here */ 258 ldr r3, [r7] /* r3 = whichqs */ 259 teq r3, #0x00000000 260 bne .Lswitch_search 261 b 1b 262 263 2: /* Powersave idle. */ 264 ldr r4, .Lcpufuncs 265 3: ldr r3, [r7] /* r3 = whichqs */ 266 teq r3, #0x00000000 267 bne .Lswitch_search 268 269 /* if saving power, don't want to pageidlezero */ 270 mov r0, #0 271 add lr, pc, #3b - . - 8 272 ldr pc, [r4, #(CF_SLEEP)] 273 /* loops back around */ 274 275 276 /* 277 * Find a new lwp to run, save the current context and 278 * load the new context 279 * 280 * Arguments: 281 * r0 'struct lwp *' of the current LWP 282 */ 283 284 ENTRY(cpu_switch) 285 /* 286 * Local register usage. Some of these registers are out of date. 287 * r1 = oldlwp 288 * r2 = spl level 289 * r3 = whichqs 290 * r4 = queue 291 * r5 = &qs[queue] 292 * r6 = newlwp 293 * r7 = scratch 294 */ 295 stmfd sp!, {r4-r7, lr} 296 297 /* 298 * Get the current lwp and indicate that there is no longer 299 * a valid process (curlwp = 0). Zero the current PCB pointer 300 * while we're at it. 301 */ 302 ldr r7, .Lcurlwp 303 ldr r6, .Lcurpcb 304 mov r0, #0x00000000 305 ldr r1, [r7] /* r1 = curproc */ 306 str r0, [r7] /* curproc = NULL */ 307 str r0, [r6] /* curpcb = NULL */ 308 309 /* stash the old proc while we call functions */ 310 mov r5, r1 311 312 #if defined(LOCKDEBUG) 313 /* release the sched_lock before handling interrupts */ 314 bl _C_LABEL(sched_unlock_idle) 315 #endif 316 317 /* Lower the spl level to spl0 and get the current spl level. */ 318 #ifdef __NEWINTR 319 mov r0, #(IPL_NONE) 320 bl _C_LABEL(_spllower) 321 #else /* ! __NEWINTR */ 322 #ifdef spl0 323 mov r0, #(_SPL_0) 324 bl _C_LABEL(splx) 325 #else 326 bl _C_LABEL(spl0) 327 #endif /* spl0 */ 328 #endif /* __NEWINTR */ 329 330 /* Push the old spl level onto the stack */ 331 str r0, [sp, #-0x0004]! 332 333 /* First phase : find a new lwp */ 334 335 ldr r7, .Lwhichqs 336 337 /* rem: r5 = old lwp */ 338 /* rem: r7 = &whichqs */ 339 340 .Lswitch_search: 341 IRQdisable 342 #if defined(LOCKDEBUG) 343 bl _C_LABEL(sched_lock_idle) 344 #endif 345 346 /* Do we have any active queues */ 347 ldr r3, [r7] 348 349 /* If not we must idle until we do. */ 350 teq r3, #0x00000000 351 beq _ASM_LABEL(idle) 352 353 /* put old proc back in r1 */ 354 mov r1, r5 355 356 /* rem: r1 = old lwp */ 357 /* rem: r3 = whichqs */ 358 /* rem: interrupts are disabled */ 359 360 /* 361 * We have found an active queue. Currently we do not know which queue 362 * is active just that one of them is. 363 */ 364 /* this is the ffs algorithm devised by d.seal and posted to 365 * comp.sys.arm on 16 Feb 1994. 366 */ 367 rsb r5, r3, #0 368 ands r0, r3, r5 369 370 adr r5, .Lcpu_switch_ffs_table 371 372 /* X = R0 */ 373 orr r4, r0, r0, lsl #4 /* r4 = X * 0x11 */ 374 orr r4, r4, r4, lsl #6 /* r4 = X * 0x451 */ 375 rsb r4, r4, r4, lsl #16 /* r4 = X * 0x0450fbaf */ 376 377 /* used further down, saves SA stall */ 378 ldr r6, .Lqs 379 380 /* now lookup in table indexed on top 6 bits of a4 */ 381 ldrb r4, [ r5, r4, lsr #26 ] 382 383 /* rem: r0 = bit mask of chosen queue (1 << r4) */ 384 /* rem: r1 = old lwp */ 385 /* rem: r3 = whichqs */ 386 /* rem: r4 = queue number */ 387 /* rem: interrupts are disabled */ 388 389 /* Get the address of the queue (&qs[queue]) */ 390 add r5, r6, r4, lsl #3 391 392 /* 393 * Get the lwp from the queue and place the next process in 394 * the queue at the head. This basically unlinks the lwp at 395 * the head of the queue. 396 */ 397 ldr r6, [r5, #(L_FORW)] 398 399 /* rem: r6 = new lwp */ 400 ldr r7, [r6, #(L_FORW)] 401 str r7, [r5, #(L_FORW)] 402 403 /* 404 * Test to see if the queue is now empty. If the head of the queue 405 * points to the queue itself then there are no more lwps in 406 * the queue. We can therefore clear the queue not empty flag held 407 * in r3. 408 */ 409 410 teq r5, r7 411 biceq r3, r3, r0 412 413 /* rem: r0 = bit mask of chosen queue (1 << r4) - NOT NEEDED AN MORE */ 414 415 /* Fix the back pointer for the lwp now at the head of the queue. */ 416 ldr r0, [r6, #(L_BACK)] 417 str r0, [r7, #(L_BACK)] 418 419 /* Update the RAM copy of the queue not empty flags word. */ 420 ldr r7, .Lwhichqs 421 str r3, [r7] 422 423 /* rem: r1 = old lwp */ 424 /* rem: r3 = whichqs - NOT NEEDED ANY MORE */ 425 /* rem: r4 = queue number - NOT NEEDED ANY MORE */ 426 /* rem: r6 = new lwp */ 427 /* rem: interrupts are disabled */ 428 429 /* Clear the want_resched flag */ 430 ldr r7, .Lwant_resched 431 mov r0, #0x00000000 432 str r0, [r7] 433 434 /* 435 * Clear the back pointer of the lwp we have removed from 436 * the head of the queue. The new lwp is isolated now. 437 */ 438 str r0, [r6, #(L_BACK)] 439 440 #if defined(LOCKDEBUG) 441 /* 442 * unlock the sched_lock, but leave interrupts off, for now. 443 */ 444 mov r7, r1 445 bl _C_LABEL(sched_unlock_idle) 446 mov r1, r7 447 #endif 448 449 .Lswitch_resume: 450 /* l->l_cpu initialized in fork1() for single-processor */ 451 452 /* Process is now on a processor. */ 453 mov r0, #LSONPROC /* l->l_stat = LSONPROC */ 454 str r0, [r6, #(L_STAT)] 455 456 /* We have a new curlwp now so make a note it */ 457 ldr r7, .Lcurlwp 458 str r6, [r7] 459 460 /* Hook in a new pcb */ 461 ldr r7, .Lcurpcb 462 ldr r0, [r6, #(L_ADDR)] 463 str r0, [r7] 464 465 /* At this point we can allow IRQ's again. */ 466 IRQenable 467 468 /* rem: r1 = old lwp */ 469 /* rem: r4 = return value */ 470 /* rem: r6 = new process */ 471 /* rem: interrupts are enabled */ 472 473 /* 474 * If the new process is the same as the process that called 475 * cpu_switch() then we do not need to save and restore any 476 * contexts. This means we can make a quick exit. 477 * The test is simple if curlwp on entry (now in r1) is the 478 * same as the proc removed from the queue we can jump to the exit. 479 */ 480 teq r1, r6 481 moveq r4, #0x00000000 /* default to "didn't switch" */ 482 beq .Lswitch_return 483 484 /* 485 * At this point, we are guaranteed to be switching to 486 * a new lwp. 487 */ 488 mov r4, #0x00000001 489 490 /* Remember the old lwp in r0 */ 491 mov r0, r1 492 493 /* 494 * If the old lwp on entry to cpu_switch was zero then the 495 * process that called it was exiting. This means that we do 496 * not need to save the current context. Instead we can jump 497 * straight to restoring the context for the new process. 498 */ 499 teq r0, #0x00000000 500 beq .Lswitch_exited 501 502 /* rem: r0 = old lwp */ 503 /* rem: r4 = return value */ 504 /* rem: r6 = new process */ 505 /* rem: interrupts are enabled */ 506 507 /* Stage two : Save old context */ 508 509 /* Get the user structure for the old lwp. */ 510 ldr r1, [r0, #(L_ADDR)] 511 512 /* Save all the registers in the old lwp's pcb */ 513 add r7, r1, #(PCB_R8) 514 stmia r7, {r8-r13} 515 516 /* 517 * NOTE: We can now use r8-r13 until it is time to restore 518 * them for the new process. 519 */ 520 521 /* Remember the old PCB. */ 522 mov r8, r1 523 524 /* r1 now free! */ 525 526 /* Get the user structure for the new process in r9 */ 527 ldr r9, [r6, #(L_ADDR)] 528 529 /* 530 * This can be optimised... We know we want to go from SVC32 531 * mode to UND32 mode 532 */ 533 mrs r3, cpsr 534 bic r2, r3, #(PSR_MODE) 535 orr r2, r2, #(PSR_UND32_MODE | I32_bit) 536 msr cpsr_c, r2 537 538 str sp, [r8, #(PCB_UND_SP)] 539 540 msr cpsr_c, r3 /* Restore the old mode */ 541 542 /* rem: r0 = old lwp */ 543 /* rem: r4 = return value */ 544 /* rem: r6 = new process */ 545 /* rem: r8 = old PCB */ 546 /* rem: r9 = new PCB */ 547 /* rem: interrupts are enabled */ 548 549 /* What else needs to be saved Only FPA stuff when that is supported */ 550 551 /* Third phase : restore saved context */ 552 553 /* rem: r0 = old lwp */ 554 /* rem: r4 = return value */ 555 /* rem: r6 = new lwp */ 556 /* rem: r8 = old PCB */ 557 /* rem: r9 = new PCB */ 558 /* rem: interrupts are enabled */ 559 560 /* 561 * Get the new L1 table pointer into r11. If we're switching to 562 * an LWP with the same address space as the outgoing one, we can 563 * skip the cache purge and the TTB load. 564 * 565 * To avoid data dep stalls that would happen anyway, we try 566 * and get some useful work done in the mean time. 567 */ 568 ldr r10, [r8, #(PCB_PAGEDIR)] /* r10 = old L1 */ 569 ldr r11, [r9, #(PCB_PAGEDIR)] /* r11 = new L1 */ 570 571 ldr r3, .Lblock_userspace_access 572 mov r1, #0x00000001 573 mov r2, #0x00000000 574 575 teq r10, r11 /* r10 == r11? */ 576 beq .Lcs_context_switched /* yes! */ 577 578 /* 579 * Don't allow user space access between the purge and the switch. 580 */ 581 ldr r3, .Lblock_userspace_access 582 mov r1, #0x00000001 583 mov r2, #0x00000000 584 str r1, [r3] 585 586 stmfd sp!, {r0-r3} 587 ldr r1, .Lcpufuncs 588 add lr, pc, #.Lcs_cache_purged - . - 8 589 ldr pc, [r1, #CF_IDCACHE_WBINV_ALL] 590 591 .Lcs_cache_purged: 592 ldmfd sp!, {r0-r3} 593 594 .Lcs_cache_purge_skipped: 595 /* At this point we need to kill IRQ's again. */ 596 IRQdisable 597 598 /* rem: r2 = 0 */ 599 /* rem: r3 = &block_userspace_access */ 600 /* rem: r4 = return value */ 601 /* rem: r6 = new lwp */ 602 /* rem: r9 = new PCB */ 603 /* rem: r11 == new L1 */ 604 605 /* 606 * Interrupts are disabled so we can allow user space accesses again 607 * as none will occur until interrupts are re-enabled after the 608 * switch. 609 */ 610 str r2, [r3] 611 612 /* Switch the memory to the new process */ 613 ldr r3, .Lcpufuncs 614 mov r0, r11 615 add lr, pc, #.Lcs_context_switched - . - 8 616 ldr pc, [r3, #CF_CONTEXT_SWITCH] 617 618 .Lcs_context_switched: 619 /* rem: r4 = return value */ 620 /* rem: r6 = new lwp */ 621 /* rem: r9 = new PCB */ 622 623 /* 624 * This can be optimised... We know we want to go from SVC32 625 * mode to UND32 mode 626 */ 627 mrs r3, cpsr 628 bic r2, r3, #(PSR_MODE) 629 orr r2, r2, #(PSR_UND32_MODE) 630 msr cpsr_c, r2 631 632 ldr sp, [r9, #(PCB_UND_SP)] 633 634 msr cpsr_c, r3 /* Restore the old mode */ 635 636 #ifdef ARMFPE 637 add r0, r9, #(USER_SIZE) & 0x00ff 638 add r0, r0, #(USER_SIZE) & 0xff00 639 bl _C_LABEL(arm_fpe_core_changecontext) 640 #endif 641 642 /* Restore all the save registers */ 643 add r7, r9, #PCB_R8 644 ldmia r7, {r8-r13} 645 646 /* 647 * NOTE: We can now no longer use r8-r13. 648 */ 649 650 /* rem: r4 = return value */ 651 /* rem: r6 = new lwp */ 652 653 /* We can enable interrupts again */ 654 IRQenable 655 656 .Lswitch_return: 657 658 /* Get the spl level from the stack and update the current spl level */ 659 ldr r0, [sp], #0x0004 660 bl _C_LABEL(splx) 661 662 /* cpu_switch returns 1 == switched, 0 == didn't switch */ 663 mov r0, r4 664 665 /* 666 * Pull the registers that got pushed when either savectx() or 667 * cpu_switch() was called and return. 668 */ 669 ldmfd sp!, {r4-r7, pc} 670 671 .Lswitch_exited: 672 /* 673 * We skip the cache purge because switch_exit()/switch_lwp_exit() 674 * already did it. Load up registers the way .Lcs_cache_purge_skipped 675 * expects. Userpsace access already blocked by switch_exit()/ 676 * switch_lwp_exit(). 677 */ 678 ldr r9, [r6, #(L_ADDR)] /* r9 = new PCB */ 679 ldr r3, .Lblock_userspace_access 680 mov r2, #0x00000000 681 ldr r11, [r9, #(PCB_PAGEDIR)] /* r11 = new L1 */ 682 b .Lcs_cache_purge_skipped 683 684 /* 685 * cpu_preempt(struct lwp *current, struct lwp *next) 686 * Switch to the specified next LWP 687 * Arguments: 688 * 689 * r0 'struct lwp *' of the current LWP 690 * r1 'struct lwp *' of the LWP to switch to 691 */ 692 ENTRY(cpu_preempt) 693 stmfd sp!, {r4-r7, lr} 694 695 /* Lower the spl level to spl0 and get the current spl level. */ 696 mov r6, r0 /* save old lwp */ 697 mov r5, r1 /* save new lwp */ 698 699 #if defined(LOCKDEBUG) 700 /* release the sched_lock before handling interrupts */ 701 bl _C_LABEL(sched_unlock_idle) 702 #endif 703 704 #ifdef __NEWINTR 705 mov r0, #(IPL_NONE) 706 bl _C_LABEL(_spllower) 707 #else /* ! __NEWINTR */ 708 #ifdef spl0 709 mov r0, #(_SPL_0) 710 bl _C_LABEL(splx) 711 #else 712 bl _C_LABEL(spl0) 713 #endif /* spl0 */ 714 #endif /* __NEWINTR */ 715 716 /* Push the old spl level onto the stack */ 717 str r0, [sp, #-0x0004]! 718 719 IRQdisable 720 #if defined(LOCKDEBUG) 721 bl _C_LABEL(sched_lock_idle) 722 #endif 723 724 /* Do we have any active queues? */ 725 ldr r7, .Lwhichqs 726 ldr r3, [r7] 727 728 /* If none, panic! */ 729 teq r3, #0x00000000 730 beq .Lpreempt_noqueues 731 732 mov r0, r6 /* restore old lwp */ 733 mov r1, r5 /* restore new lwp */ 734 735 /* rem: r0 = old lwp */ 736 /* rem: r1 = new lwp */ 737 /* rem: r3 = whichqs */ 738 /* rem: r7 = &whichqs */ 739 /* rem: interrupts are disabled */ 740 741 /* Compute the queue bit corresponding to the new lwp. */ 742 ldrb r4, [r1, #(L_PRIORITY)] 743 mov r2, #0x00000001 744 mov r4, r4, lsr #2 /* queue number */ 745 mov r2, r2, lsl r4 /* queue bit */ 746 747 /* rem: r0 = old lwp */ 748 /* rem: r1 = new lwp */ 749 /* rem: r2 = queue bit */ 750 /* rem: r3 = whichqs */ 751 /* rem: r4 = queue number */ 752 /* rem: r7 = &whichqs */ 753 754 /* 755 * Unlink the lwp from the queue. 756 */ 757 ldr r5, [r1, #(L_BACK)] /* r5 = l->l_back */ 758 mov r6, #0x00000000 759 str r6, [r1, #(L_BACK)] /* firewall: l->l_back = NULL */ 760 ldr r6, [r1, #(L_FORW)] /* r6 = l->l_forw */ 761 str r5, [r6, #(L_BACK)] /* r6->l_back = r5 */ 762 str r6, [r5, #(L_FORW)] /* r5->l_forw = r6 */ 763 764 teq r5, r6 /* see if queue is empty */ 765 biceq r3, r3, r2 /* clear bit if so */ 766 streq r3, [r7] /* store it back if so */ 767 768 /* rem: r2 (queue bit) now free */ 769 /* rem: r3 (whichqs) now free */ 770 /* rem: r7 (&whichqs) now free */ 771 772 /* 773 * Okay, set up registers the way cpu_switch() wants them, 774 * and jump into the middle of it (where we bring up the 775 * new process). 776 */ 777 mov r6, r1 /* r6 = new lwp */ 778 #if defined(LOCKDEBUG) 779 mov r5, r0 /* preserve old lwp */ 780 bl _C_LABEL(sched_unlock_idle) 781 mov r1, r5 /* r1 = old lwp */ 782 #else 783 mov r1, r0 /* r1 = old lwp */ 784 #endif 785 b .Lswitch_resume 786 787 .Lpreempt_noqueues: 788 add r0, pc, #.Lpreemptpanic - . - 8 789 bl _C_LABEL(panic) 790 791 .Lpreemptpanic: 792 .asciz "cpu_preempt: whichqs empty" 793 .align 0 794 795 /* 796 * void switch_exit(struct lwp *l, struct lwp *l0); 797 * Switch to lwp0's saved context and deallocate the address space and kernel 798 * stack for l. Then jump into cpu_switch(), as if we were in lwp0 all along. 799 */ 800 801 /* LINTSTUB: Func: void switch_exit(struct lwp *l, struct lwp *l0) */ 802 ENTRY(switch_exit) 803 /* 804 * r0 = lwp 805 * r1 = lwp0 806 */ 807 808 mov r3, r0 809 810 /* In case we fault */ 811 ldr r0, .Lcurlwp 812 mov r2, #0x00000000 813 str r2, [r0] 814 815 /* ldr r0, .Lcurpcb 816 str r2, [r0]*/ 817 818 /* 819 * Don't allow user space access between the purge and the switch. 820 */ 821 ldr r0, .Lblock_userspace_access 822 mov r2, #0x00000001 823 str r2, [r0] 824 825 /* Switch to lwp0 context */ 826 827 stmfd sp!, {r0-r3} 828 829 ldr r0, .Lcpufuncs 830 add lr, pc, #.Lse_cache_purged - . - 8 831 ldr pc, [r0, #CF_IDCACHE_WBINV_ALL] 832 833 .Lse_cache_purged: 834 ldmfd sp!, {r0-r3} 835 836 IRQdisable 837 838 ldr r2, [r1, #(L_ADDR)] 839 ldr r0, [r2, #(PCB_PAGEDIR)] 840 841 /* Switch the memory to the new process */ 842 ldr r4, .Lcpufuncs 843 add lr, pc, #.Lse_context_switched - . - 8 844 ldr pc, [r4, #CF_CONTEXT_SWITCH] 845 846 .Lse_context_switched: 847 /* Restore all the save registers */ 848 add r7, r2, #PCB_R8 849 ldmia r7, {r8-r13} 850 851 /* This is not really needed ! */ 852 /* Yes it is for the su and fu routines */ 853 ldr r0, .Lcurpcb 854 str r2, [r0] 855 856 IRQenable 857 858 /* str r3, [sp, #-0x0004]!*/ 859 860 /* 861 * Schedule the vmspace and stack to be freed. 862 */ 863 mov r0, r3 /* exit2(l) */ 864 bl _C_LABEL(exit2) 865 866 /* Paranoia */ 867 mov r0, #0x00000000 868 ldr r1, .Lcurlwp 869 str r0, [r1] 870 871 ldr r7, .Lwhichqs /* r7 = &whichqs */ 872 mov r5, #0x00000000 /* r5 = old lwp = NULL */ 873 b .Lswitch_search 874 875 /* 876 * void switch_lwp_exit(struct lwp *l, struct lwp *l0); 877 * Switch to lwp0's saved context and deallocate the address space and kernel 878 * stack for l. Then jump into cpu_switch(), as if we were in lwp0 all along. 879 */ 880 881 /* LINTSTUB: Func: void switch_exit(struct lwp *l, struct lwp *l0) */ 882 ENTRY(switch_lwp_exit) 883 /* 884 * r0 = lwp 885 * r1 = lwp0 886 */ 887 888 mov r3, r0 889 890 /* In case we fault */ 891 mov r2, #0x00000000 892 ldr r0, .Lcurlwp 893 str r2, [r0] 894 895 /* ldr r0, .Lcurpcb 896 str r2, [r0]*/ 897 898 /* 899 * Don't allow user space access between the purge and the switch. 900 */ 901 ldr r0, .Lblock_userspace_access 902 mov r2, #0x00000001 903 str r2, [r0] 904 905 /* Switch to lwp0 context */ 906 907 stmfd sp!, {r0-r3} 908 909 ldr r0, .Lcpufuncs 910 add lr, pc, #.Lsle_cache_purged - . - 8 911 ldr pc, [r0, #CF_IDCACHE_WBINV_ALL] 912 913 .Lsle_cache_purged: 914 ldmfd sp!, {r0-r3} 915 916 IRQdisable 917 918 ldr r2, [r1, #(L_ADDR)] 919 ldr r0, [r2, #(PCB_PAGEDIR)] 920 921 /* Switch the memory to the new process */ 922 ldr r4, .Lcpufuncs 923 add lr, pc, #.Lsle_context_switched - . - 8 924 ldr pc, [r4, #CF_CONTEXT_SWITCH] 925 926 .Lsle_context_switched: 927 /* Restore all the save registers */ 928 add r7, r2, #PCB_R8 929 ldmia r7, {r8-r13} 930 931 /* This is not really needed ! */ 932 /* Yes it is for the su and fu routines */ 933 ldr r0, .Lcurpcb 934 str r2, [r0] 935 936 IRQenable 937 938 /* str r3, [sp, #-0x0004]!*/ 939 940 /* 941 * Schedule the vmspace and stack to be freed. 942 */ 943 mov r0, r3 /* lwp_exit2(l) */ 944 bl _C_LABEL(lwp_exit2) 945 946 /* Paranoia */ 947 ldr r1, .Lcurlwp 948 mov r0, #0x00000000 949 str r0, [r1] 950 951 ldr r7, .Lwhichqs /* r7 = &whichqs */ 952 mov r5, #0x00000000 /* r5 = old lwp = NULL */ 953 b .Lswitch_search 954 955 /* LINTSTUB: Func: void savectx(struct pcb *pcb) */ 956 ENTRY(savectx) 957 /* 958 * r0 = pcb 959 */ 960 961 /* Push registers.*/ 962 stmfd sp!, {r4-r7, lr} 963 964 /* Store all the registers in the process's pcb */ 965 add r2, r0, #(PCB_R8) 966 stmia r2, {r8-r13} 967 968 /* Pull the regs of the stack */ 969 ldmfd sp!, {r4-r7, pc} 970 971 ENTRY(proc_trampoline) 972 add lr, pc, #(.Ltrampoline_return - . - 8) 973 mov r0, r5 974 mov r1, sp 975 mov pc, r4 976 977 .Ltrampoline_return: 978 /* Kill irq's */ 979 mrs r0, cpsr 980 orr r0, r0, #(I32_bit) 981 msr cpsr_c, r0 982 983 PULLFRAME 984 985 movs pc, lr /* Exit */ 986 987 .type .Lcpu_switch_ffs_table, _ASM_TYPE_OBJECT; 988 .Lcpu_switch_ffs_table: 989 /* same as ffs table but all nums are -1 from that */ 990 /* 0 1 2 3 4 5 6 7 */ 991 .byte 0, 0, 1, 12, 2, 6, 0, 13 /* 0- 7 */ 992 .byte 3, 0, 7, 0, 0, 0, 0, 14 /* 8-15 */ 993 .byte 10, 4, 0, 0, 8, 0, 0, 25 /* 16-23 */ 994 .byte 0, 0, 0, 0, 0, 21, 27, 15 /* 24-31 */ 995 .byte 31, 11, 5, 0, 0, 0, 0, 0 /* 32-39 */ 996 .byte 9, 0, 0, 24, 0, 0, 20, 26 /* 40-47 */ 997 .byte 30, 0, 0, 0, 0, 23, 0, 19 /* 48-55 */ 998 .byte 29, 0, 22, 18, 28, 17, 16, 0 /* 56-63 */ 999
Indexes created Sat Oct 25 16:10:12 GMT 2025