1/* 2 * arch/xtensa/kernel/vectors.S 3 * 4 * This file contains all exception vectors (user, kernel, and double), 5 * as well as the window vectors (overflow and underflow), and the debug 6 * vector. These are the primary vectors executed by the processor if an 7 * exception occurs. 8 * 9 * This file is subject to the terms and conditions of the GNU General 10 * Public License. See the file "COPYING" in the main directory of 11 * this archive for more details. 12 * 13 * Copyright (C) 2005 - 2008 Tensilica, Inc. 14 * 15 * Chris Zankel <chris@zankel.net> 16 * 17 */ 18 19/* 20 * We use a two-level table approach. The user and kernel exception vectors 21 * use a first-level dispatch table to dispatch the exception to a registered 22 * fast handler or the default handler, if no fast handler was registered. 23 * The default handler sets up a C-stack and dispatches the exception to a 24 * registerd C handler in the second-level dispatch table. 25 * 26 * Fast handler entry condition: 27 * 28 * a0: trashed, original value saved on stack (PT_AREG0) 29 * a1: a1 30 * a2: new stack pointer, original value in depc 31 * a3: dispatch table 32 * depc: a2, original value saved on stack (PT_DEPC) 33 * excsave_1: a3 34 * 35 * The value for PT_DEPC saved to stack also functions as a boolean to 36 * indicate that the exception is either a double or a regular exception: 37 * 38 * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception 39 * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception 40 * 41 * Note: Neither the kernel nor the user exception handler generate literals. 42 * 43 */ 44 45#include <linux/linkage.h> 46#include <asm/ptrace.h> 47#include <asm/current.h> 48#include <asm/asm-offsets.h> 49#include <asm/pgtable.h> 50#include <asm/processor.h> 51#include <asm/page.h> 52#include <asm/thread_info.h> 53#include <asm/vectors.h> 54 55#define WINDOW_VECTORS_SIZE 0x180 56 57 58/* 59 * User exception vector. (Exceptions with PS.UM == 1, PS.EXCM == 0) 60 * 61 * We get here when an exception occurred while we were in userland. 62 * We switch to the kernel stack and jump to the first level handler 63 * associated to the exception cause. 64 * 65 * Note: the saved kernel stack pointer (EXC_TABLE_KSTK) is already 66 * decremented by PT_USER_SIZE. 67 */ 68 69 .section .UserExceptionVector.text, "ax" 70 71ENTRY(_UserExceptionVector) 72 73 xsr a3, excsave1 # save a3 and get dispatch table 74 wsr a2, depc # save a2 75 l32i a2, a3, EXC_TABLE_KSTK # load kernel stack to a2 76 s32i a0, a2, PT_AREG0 # save a0 to ESF 77 rsr a0, exccause # retrieve exception cause 78 s32i a0, a2, PT_DEPC # mark it as a regular exception 79 addx4 a0, a0, a3 # find entry in table 80 l32i a0, a0, EXC_TABLE_FAST_USER # load handler 81 xsr a3, excsave1 # restore a3 and dispatch table 82 jx a0 83 84ENDPROC(_UserExceptionVector) 85 86/* 87 * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0) 88 * 89 * We get this exception when we were already in kernel space. 90 * We decrement the current stack pointer (kernel) by PT_SIZE and 91 * jump to the first-level handler associated with the exception cause. 92 * 93 * Note: we need to preserve space for the spill region. 94 */ 95 96 .section .KernelExceptionVector.text, "ax" 97 98ENTRY(_KernelExceptionVector) 99 100 xsr a3, excsave1 # save a3, and get dispatch table 101 wsr a2, depc # save a2 102 addi a2, a1, -16-PT_SIZE # adjust stack pointer 103 s32i a0, a2, PT_AREG0 # save a0 to ESF 104 rsr a0, exccause # retrieve exception cause 105 s32i a0, a2, PT_DEPC # mark it as a regular exception 106 addx4 a0, a0, a3 # find entry in table 107 l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address 108 xsr a3, excsave1 # restore a3 and dispatch table 109 jx a0 110 111ENDPROC(_KernelExceptionVector) 112 113/* 114 * Double exception vector (Exceptions with PS.EXCM == 1) 115 * We get this exception when another exception occurs while were are 116 * already in an exception, such as window overflow/underflow exception, 117 * or 'expected' exceptions, for example memory exception when we were trying 118 * to read data from an invalid address in user space. 119 * 120 * Note that this vector is never invoked for level-1 interrupts, because such 121 * interrupts are disabled (masked) when PS.EXCM is set. 122 * 123 * We decode the exception and take the appropriate action. However, the 124 * double exception vector is much more careful, because a lot more error 125 * cases go through the double exception vector than through the user and 126 * kernel exception vectors. 127 * 128 * Occasionally, the kernel expects a double exception to occur. This usually 129 * happens when accessing user-space memory with the user's permissions 130 * (l32e/s32e instructions). The kernel state, though, is not always suitable 131 * for immediate transfer of control to handle_double, where "normal" exception 132 * processing occurs. Also in kernel mode, TLB misses can occur if accessing 133 * vmalloc memory, possibly requiring repair in a double exception handler. 134 * 135 * The variable at TABLE_FIXUP offset from the pointer in EXCSAVE_1 doubles as 136 * a boolean variable and a pointer to a fixup routine. If the variable 137 * EXC_TABLE_FIXUP is non-zero, this handler jumps to that address. A value of 138 * zero indicates to use the default kernel/user exception handler. 139 * There is only one exception, when the value is identical to the exc_table 140 * label, the kernel is in trouble. This mechanism is used to protect critical 141 * sections, mainly when the handler writes to the stack to assert the stack 142 * pointer is valid. Once the fixup/default handler leaves that area, the 143 * EXC_TABLE_FIXUP variable is reset to the fixup handler or zero. 144 * 145 * Procedures wishing to use this mechanism should set EXC_TABLE_FIXUP to the 146 * nonzero address of a fixup routine before it could cause a double exception 147 * and reset it before it returns. 148 * 149 * Some other things to take care of when a fast exception handler doesn't 150 * specify a particular fixup handler but wants to use the default handlers: 151 * 152 * - The original stack pointer (in a1) must not be modified. The fast 153 * exception handler should only use a2 as the stack pointer. 154 * 155 * - If the fast handler manipulates the stack pointer (in a2), it has to 156 * register a valid fixup handler and cannot use the default handlers. 157 * 158 * - The handler can use any other generic register from a3 to a15, but it 159 * must save the content of these registers to stack (PT_AREG3...PT_AREGx) 160 * 161 * - These registers must be saved before a double exception can occur. 162 * 163 * - If we ever implement handling signals while in double exceptions, the 164 * number of registers a fast handler has saved (excluding a0 and a1) must 165 * be written to PT_AREG1. (1 if only a3 is used, 2 for a3 and a4, etc. ) 166 * 167 * The fixup handlers are special handlers: 168 * 169 * - Fixup entry conditions differ from regular exceptions: 170 * 171 * a0: DEPC 172 * a1: a1 173 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE 174 * a3: exctable 175 * depc: a0 176 * excsave_1: a3 177 * 178 * - When the kernel enters the fixup handler, it still assumes it is in a 179 * critical section, so EXC_TABLE_FIXUP variable is set to exc_table. 180 * The fixup handler, therefore, has to re-register itself as the fixup 181 * handler before it returns from the double exception. 182 * 183 * - Fixup handler can share the same exception frame with the fast handler. 184 * The kernel stack pointer is not changed when entering the fixup handler. 185 * 186 * - Fixup handlers can jump to the default kernel and user exception 187 * handlers. Before it jumps, though, it has to setup a exception frame 188 * on stack. Because the default handler resets the register fixup handler 189 * the fixup handler must make sure that the default handler returns to 190 * it instead of the exception address, so it can re-register itself as 191 * the fixup handler. 192 * 193 * In case of a critical condition where the kernel cannot recover, we jump 194 * to unrecoverable_exception with the following entry conditions. 195 * All registers a0...a15 are unchanged from the last exception, except: 196 * 197 * a0: last address before we jumped to the unrecoverable_exception. 198 * excsave_1: a0 199 * 200 * 201 * See the handle_alloca_user and spill_registers routines for example clients. 202 * 203 * FIXME: Note: we currently don't allow signal handling coming from a double 204 * exception, so the item markt with (*) is not required. 205 */ 206 207 .section .DoubleExceptionVector.text, "ax" 208 .begin literal_prefix .DoubleExceptionVector 209 .globl _DoubleExceptionVector_WindowUnderflow 210 .globl _DoubleExceptionVector_WindowOverflow 211 212ENTRY(_DoubleExceptionVector) 213 214 xsr a3, excsave1 215 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 216 217 /* Check for kernel double exception (usually fatal). */ 218 219 rsr a2, ps 220 _bbci.l a2, PS_UM_BIT, .Lksp 221 222 /* Check if we are currently handling a window exception. */ 223 /* Note: We don't need to indicate that we enter a critical section. */ 224 225 xsr a0, depc # get DEPC, save a0 226 227 movi a2, WINDOW_VECTORS_VADDR 228 _bltu a0, a2, .Lfixup 229 addi a2, a2, WINDOW_VECTORS_SIZE 230 _bgeu a0, a2, .Lfixup 231 232 /* Window overflow/underflow exception. Get stack pointer. */ 233 234 l32i a2, a3, EXC_TABLE_KSTK 235 236 /* Check for overflow/underflow exception, jump if overflow. */ 237 238 bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow 239 240 /* 241 * Restart window underflow exception. 242 * Currently: 243 * depc = orig a0, 244 * a0 = orig DEPC, 245 * a2 = new sp based on KSTK from exc_table 246 * a3 = excsave_1 247 * excsave_1 = orig a3 248 * 249 * We return to the instruction in user space that caused the window 250 * underflow exception. Therefore, we change window base to the value 251 * before we entered the window underflow exception and prepare the 252 * registers to return as if we were coming from a regular exception 253 * by changing depc (in a0). 254 * Note: We can trash the current window frame (a0...a3) and depc! 255 */ 256_DoubleExceptionVector_WindowUnderflow: 257 xsr a3, excsave1 258 wsr a2, depc # save stack pointer temporarily 259 rsr a0, ps 260 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 261 wsr a0, windowbase 262 rsync 263 264 /* We are now in the previous window frame. Save registers again. */ 265 266 xsr a2, depc # save a2 and get stack pointer 267 s32i a0, a2, PT_AREG0 268 xsr a3, excsave1 269 rsr a0, exccause 270 s32i a0, a2, PT_DEPC # mark it as a regular exception 271 addx4 a0, a0, a3 272 xsr a3, excsave1 273 l32i a0, a0, EXC_TABLE_FAST_USER 274 jx a0 275 276 /* 277 * We only allow the ITLB miss exception if we are in kernel space. 278 * All other exceptions are unexpected and thus unrecoverable! 279 */ 280 281#ifdef CONFIG_MMU 282 .extern fast_second_level_miss_double_kernel 283 284.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */ 285 286 rsr a3, exccause 287 beqi a3, EXCCAUSE_ITLB_MISS, 1f 288 addi a3, a3, -EXCCAUSE_DTLB_MISS 289 bnez a3, .Lunrecoverable 2901: movi a3, fast_second_level_miss_double_kernel 291 jx a3 292#else 293.equ .Lksp, .Lunrecoverable 294#endif 295 296 /* Critical! We can't handle this situation. PANIC! */ 297 298 .extern unrecoverable_exception 299 300.Lunrecoverable_fixup: 301 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 302 xsr a0, depc 303 304.Lunrecoverable: 305 rsr a3, excsave1 306 wsr a0, excsave1 307 movi a0, unrecoverable_exception 308 callx0 a0 309 310.Lfixup:/* Check for a fixup handler or if we were in a critical section. */ 311 312 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */ 313 314 /* Enter critical section. */ 315 316 l32i a2, a3, EXC_TABLE_FIXUP 317 s32i a3, a3, EXC_TABLE_FIXUP 318 beq a2, a3, .Lunrecoverable_fixup # critical section 319 beqz a2, .Ldflt # no handler was registered 320 321 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */ 322 323 jx a2 324 325.Ldflt: /* Get stack pointer. */ 326 327 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 328 addi a2, a2, -PT_USER_SIZE 329 330 /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */ 331 332 s32i a0, a2, PT_DEPC 333 l32i a0, a3, EXC_TABLE_DOUBLE_SAVE 334 xsr a0, depc 335 s32i a0, a2, PT_AREG0 336 337 /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */ 338 339 rsr a0, exccause 340 addx4 a0, a0, a3 341 xsr a3, excsave1 342 l32i a0, a0, EXC_TABLE_FAST_USER 343 jx a0 344 345 /* 346 * Restart window OVERFLOW exception. 347 * Currently: 348 * depc = orig a0, 349 * a0 = orig DEPC, 350 * a2 = new sp based on KSTK from exc_table 351 * a3 = EXCSAVE_1 352 * excsave_1 = orig a3 353 * 354 * We return to the instruction in user space that caused the window 355 * overflow exception. Therefore, we change window base to the value 356 * before we entered the window overflow exception and prepare the 357 * registers to return as if we were coming from a regular exception 358 * by changing DEPC (in a0). 359 * 360 * NOTE: We CANNOT trash the current window frame (a0...a3), but we 361 * can clobber depc. 362 * 363 * The tricky part here is that overflow8 and overflow12 handlers 364 * save a0, then clobber a0. To restart the handler, we have to restore 365 * a0 if the double exception was past the point where a0 was clobbered. 366 * 367 * To keep things simple, we take advantage of the fact all overflow 368 * handlers save a0 in their very first instruction. If DEPC was past 369 * that instruction, we can safely restore a0 from where it was saved 370 * on the stack. 371 * 372 * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3 373 */ 374_DoubleExceptionVector_WindowOverflow: 375 extui a2, a0, 0, 6 # get offset into 64-byte vector handler 376 beqz a2, 1f # if at start of vector, don't restore 377 378 addi a0, a0, -128 379 bbsi.l a0, 8, 1f # don't restore except for overflow 8 and 12 380 381 /* 382 * This fixup handler is for the extremely unlikely case where the 383 * overflow handler's reference thru a0 gets a hardware TLB refill 384 * that bumps out the (distinct, aliasing) TLB entry that mapped its 385 * prior references thru a9/a13, and where our reference now thru 386 * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill). 387 */ 388 movi a2, window_overflow_restore_a0_fixup 389 s32i a2, a3, EXC_TABLE_FIXUP 390 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 391 xsr a3, excsave1 392 393 bbsi.l a0, 7, 2f 394 395 /* 396 * Restore a0 as saved by _WindowOverflow8(). 397 */ 398 399 l32e a0, a9, -16 400 wsr a0, depc # replace the saved a0 401 j 3f 402 4032: 404 /* 405 * Restore a0 as saved by _WindowOverflow12(). 406 */ 407 408 l32e a0, a13, -16 409 wsr a0, depc # replace the saved a0 4103: 411 xsr a3, excsave1 412 movi a0, 0 413 s32i a0, a3, EXC_TABLE_FIXUP 414 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 4151: 416 /* 417 * Restore WindowBase while leaving all address registers restored. 418 * We have to use ROTW for this, because WSR.WINDOWBASE requires 419 * an address register (which would prevent restore). 420 * 421 * Window Base goes from 0 ... 7 (Module 8) 422 * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s 423 */ 424 425 rsr a0, ps 426 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 427 rsr a2, windowbase 428 sub a0, a2, a0 429 extui a0, a0, 0, 3 430 431 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 432 xsr a3, excsave1 433 beqi a0, 1, .L1pane 434 beqi a0, 3, .L3pane 435 436 rsr a0, depc 437 rotw -2 438 439 /* 440 * We are now in the user code's original window frame. 441 * Process the exception as a user exception as if it was 442 * taken by the user code. 443 * 444 * This is similar to the user exception vector, 445 * except that PT_DEPC isn't set to EXCCAUSE. 446 */ 4471: 448 xsr a3, excsave1 449 wsr a2, depc 450 l32i a2, a3, EXC_TABLE_KSTK 451 s32i a0, a2, PT_AREG0 452 rsr a0, exccause 453 454 s32i a0, a2, PT_DEPC 455 456_DoubleExceptionVector_handle_exception: 457 addx4 a0, a0, a3 458 l32i a0, a0, EXC_TABLE_FAST_USER 459 xsr a3, excsave1 460 jx a0 461 462.L1pane: 463 rsr a0, depc 464 rotw -1 465 j 1b 466 467.L3pane: 468 rsr a0, depc 469 rotw -3 470 j 1b 471 472 473ENDPROC(_DoubleExceptionVector) 474 475/* 476 * Fixup handler for TLB miss in double exception handler for window owerflow. 477 * We get here with windowbase set to the window that was being spilled and 478 * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12 479 * (bit set) window. 480 * 481 * We do the following here: 482 * - go to the original window retaining a0 value; 483 * - set up exception stack to return back to appropriate a0 restore code 484 * (we'll need to rotate window back and there's no place to save this 485 * information, use different return address for that); 486 * - handle the exception; 487 * - go to the window that was being spilled; 488 * - set up window_overflow_restore_a0_fixup as a fixup routine; 489 * - reload a0; 490 * - restore the original window; 491 * - reset the default fixup routine; 492 * - return to user. By the time we get to this fixup handler all information 493 * about the conditions of the original double exception that happened in 494 * the window overflow handler is lost, so we just return to userspace to 495 * retry overflow from start. 496 * 497 * a0: value of depc, original value in depc 498 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE 499 * a3: exctable, original value in excsave1 500 */ 501 502ENTRY(window_overflow_restore_a0_fixup) 503 504 rsr a0, ps 505 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 506 rsr a2, windowbase 507 sub a0, a2, a0 508 extui a0, a0, 0, 3 509 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 510 xsr a3, excsave1 511 512 _beqi a0, 1, .Lhandle_1 513 _beqi a0, 3, .Lhandle_3 514 515 .macro overflow_fixup_handle_exception_pane n 516 517 rsr a0, depc 518 rotw -\n 519 520 xsr a3, excsave1 521 wsr a2, depc 522 l32i a2, a3, EXC_TABLE_KSTK 523 s32i a0, a2, PT_AREG0 524 525 movi a0, .Lrestore_\n 526 s32i a0, a2, PT_DEPC 527 rsr a0, exccause 528 j _DoubleExceptionVector_handle_exception 529 530 .endm 531 532 overflow_fixup_handle_exception_pane 2 533.Lhandle_1: 534 overflow_fixup_handle_exception_pane 1 535.Lhandle_3: 536 overflow_fixup_handle_exception_pane 3 537 538 .macro overflow_fixup_restore_a0_pane n 539 540 rotw \n 541 /* Need to preserve a0 value here to be able to handle exception 542 * that may occur on a0 reload from stack. It may occur because 543 * TLB miss handler may not be atomic and pointer to page table 544 * may be lost before we get here. There are no free registers, 545 * so we need to use EXC_TABLE_DOUBLE_SAVE area. 546 */ 547 xsr a3, excsave1 548 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 549 movi a2, window_overflow_restore_a0_fixup 550 s32i a2, a3, EXC_TABLE_FIXUP 551 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 552 xsr a3, excsave1 553 bbsi.l a0, 7, 1f 554 l32e a0, a9, -16 555 j 2f 5561: 557 l32e a0, a13, -16 5582: 559 rotw -\n 560 561 .endm 562 563.Lrestore_2: 564 overflow_fixup_restore_a0_pane 2 565 566.Lset_default_fixup: 567 xsr a3, excsave1 568 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 569 movi a2, 0 570 s32i a2, a3, EXC_TABLE_FIXUP 571 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 572 xsr a3, excsave1 573 rfe 574 575.Lrestore_1: 576 overflow_fixup_restore_a0_pane 1 577 j .Lset_default_fixup 578.Lrestore_3: 579 overflow_fixup_restore_a0_pane 3 580 j .Lset_default_fixup 581 582ENDPROC(window_overflow_restore_a0_fixup) 583 584 .end literal_prefix 585/* 586 * Debug interrupt vector 587 * 588 * There is not much space here, so simply jump to another handler. 589 * EXCSAVE[DEBUGLEVEL] has been set to that handler. 590 */ 591 592 .section .DebugInterruptVector.text, "ax" 593 594ENTRY(_DebugInterruptVector) 595 596 xsr a0, SREG_EXCSAVE + XCHAL_DEBUGLEVEL 597 jx a0 598 599ENDPROC(_DebugInterruptVector) 600 601 602 603/* 604 * Medium priority level interrupt vectors 605 * 606 * Each takes less than 16 (0x10) bytes, no literals, by placing 607 * the extra 8 bytes that would otherwise be required in the window 608 * vectors area where there is space. With relocatable vectors, 609 * all vectors are within ~ 4 kB range of each other, so we can 610 * simply jump (J) to another vector without having to use JX. 611 * 612 * common_exception code gets current IRQ level in PS.INTLEVEL 613 * and preserves it for the IRQ handling time. 614 */ 615 616 .macro irq_entry_level level 617 618 .if XCHAL_EXCM_LEVEL >= \level 619 .section .Level\level\()InterruptVector.text, "ax" 620ENTRY(_Level\level\()InterruptVector) 621 wsr a0, excsave2 622 rsr a0, epc\level 623 wsr a0, epc1 624 movi a0, EXCCAUSE_LEVEL1_INTERRUPT 625 wsr a0, exccause 626 rsr a0, eps\level 627 # branch to user or kernel vector 628 j _SimulateUserKernelVectorException 629 .endif 630 631 .endm 632 633 irq_entry_level 2 634 irq_entry_level 3 635 irq_entry_level 4 636 irq_entry_level 5 637 irq_entry_level 6 638 639 640/* Window overflow and underflow handlers. 641 * The handlers must be 64 bytes apart, first starting with the underflow 642 * handlers underflow-4 to underflow-12, then the overflow handlers 643 * overflow-4 to overflow-12. 644 * 645 * Note: We rerun the underflow handlers if we hit an exception, so 646 * we try to access any page that would cause a page fault early. 647 */ 648 649#define ENTRY_ALIGN64(name) \ 650 .globl name; \ 651 .align 64; \ 652 name: 653 654 .section .WindowVectors.text, "ax" 655 656 657/* 4-Register Window Overflow Vector (Handler) */ 658 659ENTRY_ALIGN64(_WindowOverflow4) 660 661 s32e a0, a5, -16 662 s32e a1, a5, -12 663 s32e a2, a5, -8 664 s32e a3, a5, -4 665 rfwo 666 667ENDPROC(_WindowOverflow4) 668 669 670#if XCHAL_EXCM_LEVEL >= 2 671 /* Not a window vector - but a convenient location 672 * (where we know there's space) for continuation of 673 * medium priority interrupt dispatch code. 674 * On entry here, a0 contains PS, and EPC2 contains saved a0: 675 */ 676 .align 4 677_SimulateUserKernelVectorException: 678 addi a0, a0, (1 << PS_EXCM_BIT) 679 wsr a0, ps 680 bbsi.l a0, PS_UM_BIT, 1f # branch if user mode 681 rsr a0, excsave2 # restore a0 682 j _KernelExceptionVector # simulate kernel vector exception 6831: rsr a0, excsave2 # restore a0 684 j _UserExceptionVector # simulate user vector exception 685#endif 686 687 688/* 4-Register Window Underflow Vector (Handler) */ 689 690ENTRY_ALIGN64(_WindowUnderflow4) 691 692 l32e a0, a5, -16 693 l32e a1, a5, -12 694 l32e a2, a5, -8 695 l32e a3, a5, -4 696 rfwu 697 698ENDPROC(_WindowUnderflow4) 699 700/* 8-Register Window Overflow Vector (Handler) */ 701 702ENTRY_ALIGN64(_WindowOverflow8) 703 704 s32e a0, a9, -16 705 l32e a0, a1, -12 706 s32e a2, a9, -8 707 s32e a1, a9, -12 708 s32e a3, a9, -4 709 s32e a4, a0, -32 710 s32e a5, a0, -28 711 s32e a6, a0, -24 712 s32e a7, a0, -20 713 rfwo 714 715ENDPROC(_WindowOverflow8) 716 717/* 8-Register Window Underflow Vector (Handler) */ 718 719ENTRY_ALIGN64(_WindowUnderflow8) 720 721 l32e a1, a9, -12 722 l32e a0, a9, -16 723 l32e a7, a1, -12 724 l32e a2, a9, -8 725 l32e a4, a7, -32 726 l32e a3, a9, -4 727 l32e a5, a7, -28 728 l32e a6, a7, -24 729 l32e a7, a7, -20 730 rfwu 731 732ENDPROC(_WindowUnderflow8) 733 734/* 12-Register Window Overflow Vector (Handler) */ 735 736ENTRY_ALIGN64(_WindowOverflow12) 737 738 s32e a0, a13, -16 739 l32e a0, a1, -12 740 s32e a1, a13, -12 741 s32e a2, a13, -8 742 s32e a3, a13, -4 743 s32e a4, a0, -48 744 s32e a5, a0, -44 745 s32e a6, a0, -40 746 s32e a7, a0, -36 747 s32e a8, a0, -32 748 s32e a9, a0, -28 749 s32e a10, a0, -24 750 s32e a11, a0, -20 751 rfwo 752 753ENDPROC(_WindowOverflow12) 754 755/* 12-Register Window Underflow Vector (Handler) */ 756 757ENTRY_ALIGN64(_WindowUnderflow12) 758 759 l32e a1, a13, -12 760 l32e a0, a13, -16 761 l32e a11, a1, -12 762 l32e a2, a13, -8 763 l32e a4, a11, -48 764 l32e a8, a11, -32 765 l32e a3, a13, -4 766 l32e a5, a11, -44 767 l32e a6, a11, -40 768 l32e a7, a11, -36 769 l32e a9, a11, -28 770 l32e a10, a11, -24 771 l32e a11, a11, -20 772 rfwu 773 774ENDPROC(_WindowUnderflow12) 775 776 .text 777