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 <linux/pgtable.h> 47#include <asm/asmmacro.h> 48#include <asm/ptrace.h> 49#include <asm/current.h> 50#include <asm/asm-offsets.h> 51#include <asm/processor.h> 52#include <asm/page.h> 53#include <asm/thread_info.h> 54#include <asm/vectors.h> 55 56#define WINDOW_VECTORS_SIZE 0x180 57 58 59/* 60 * User exception vector. (Exceptions with PS.UM == 1, PS.EXCM == 0) 61 * 62 * We get here when an exception occurred while we were in userland. 63 * We switch to the kernel stack and jump to the first level handler 64 * associated to the exception cause. 65 * 66 * Note: the saved kernel stack pointer (EXC_TABLE_KSTK) is already 67 * decremented by PT_USER_SIZE. 68 */ 69 70 .section .UserExceptionVector.text, "ax" 71 72ENTRY(_UserExceptionVector) 73 74 xsr a3, excsave1 # save a3 and get dispatch table 75 wsr a2, depc # save a2 76 l32i a2, a3, EXC_TABLE_KSTK # load kernel stack to a2 77 s32i a0, a2, PT_AREG0 # save a0 to ESF 78 rsr a0, exccause # retrieve exception cause 79 s32i a0, a2, PT_DEPC # mark it as a regular exception 80 addx4 a0, a0, a3 # find entry in table 81 l32i a0, a0, EXC_TABLE_FAST_USER # load handler 82 xsr a3, excsave1 # restore a3 and dispatch table 83 jx a0 84 85ENDPROC(_UserExceptionVector) 86 87/* 88 * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0) 89 * 90 * We get this exception when we were already in kernel space. 91 * We decrement the current stack pointer (kernel) by PT_SIZE and 92 * jump to the first-level handler associated with the exception cause. 93 * 94 * Note: we need to preserve space for the spill region. 95 */ 96 97 .section .KernelExceptionVector.text, "ax" 98 99ENTRY(_KernelExceptionVector) 100 101 xsr a3, excsave1 # save a3, and get dispatch table 102 wsr a2, depc # save a2 103 addi a2, a1, -16-PT_SIZE # adjust stack pointer 104 s32i a0, a2, PT_AREG0 # save a0 to ESF 105 rsr a0, exccause # retrieve exception cause 106 s32i a0, a2, PT_DEPC # mark it as a regular exception 107 addx4 a0, a0, a3 # find entry in table 108 l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address 109 xsr a3, excsave1 # restore a3 and dispatch table 110 jx a0 111 112ENDPROC(_KernelExceptionVector) 113 114/* 115 * Double exception vector (Exceptions with PS.EXCM == 1) 116 * We get this exception when another exception occurs while were are 117 * already in an exception, such as window overflow/underflow exception, 118 * or 'expected' exceptions, for example memory exception when we were trying 119 * to read data from an invalid address in user space. 120 * 121 * Note that this vector is never invoked for level-1 interrupts, because such 122 * interrupts are disabled (masked) when PS.EXCM is set. 123 * 124 * We decode the exception and take the appropriate action. However, the 125 * double exception vector is much more careful, because a lot more error 126 * cases go through the double exception vector than through the user and 127 * kernel exception vectors. 128 * 129 * Occasionally, the kernel expects a double exception to occur. This usually 130 * happens when accessing user-space memory with the user's permissions 131 * (l32e/s32e instructions). The kernel state, though, is not always suitable 132 * for immediate transfer of control to handle_double, where "normal" exception 133 * processing occurs. Also in kernel mode, TLB misses can occur if accessing 134 * vmalloc memory, possibly requiring repair in a double exception handler. 135 * 136 * The variable at TABLE_FIXUP offset from the pointer in EXCSAVE_1 doubles as 137 * a boolean variable and a pointer to a fixup routine. If the variable 138 * EXC_TABLE_FIXUP is non-zero, this handler jumps to that address. A value of 139 * zero indicates to use the default kernel/user exception handler. 140 * There is only one exception, when the value is identical to the exc_table 141 * label, the kernel is in trouble. This mechanism is used to protect critical 142 * sections, mainly when the handler writes to the stack to assert the stack 143 * pointer is valid. Once the fixup/default handler leaves that area, the 144 * EXC_TABLE_FIXUP variable is reset to the fixup handler or zero. 145 * 146 * Procedures wishing to use this mechanism should set EXC_TABLE_FIXUP to the 147 * nonzero address of a fixup routine before it could cause a double exception 148 * and reset it before it returns. 149 * 150 * Some other things to take care of when a fast exception handler doesn't 151 * specify a particular fixup handler but wants to use the default handlers: 152 * 153 * - The original stack pointer (in a1) must not be modified. The fast 154 * exception handler should only use a2 as the stack pointer. 155 * 156 * - If the fast handler manipulates the stack pointer (in a2), it has to 157 * register a valid fixup handler and cannot use the default handlers. 158 * 159 * - The handler can use any other generic register from a3 to a15, but it 160 * must save the content of these registers to stack (PT_AREG3...PT_AREGx) 161 * 162 * - These registers must be saved before a double exception can occur. 163 * 164 * - If we ever implement handling signals while in double exceptions, the 165 * number of registers a fast handler has saved (excluding a0 and a1) must 166 * be written to PT_AREG1. (1 if only a3 is used, 2 for a3 and a4, etc. ) 167 * 168 * The fixup handlers are special handlers: 169 * 170 * - Fixup entry conditions differ from regular exceptions: 171 * 172 * a0: DEPC 173 * a1: a1 174 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE 175 * a3: exctable 176 * depc: a0 177 * excsave_1: a3 178 * 179 * - When the kernel enters the fixup handler, it still assumes it is in a 180 * critical section, so EXC_TABLE_FIXUP variable is set to exc_table. 181 * The fixup handler, therefore, has to re-register itself as the fixup 182 * handler before it returns from the double exception. 183 * 184 * - Fixup handler can share the same exception frame with the fast handler. 185 * The kernel stack pointer is not changed when entering the fixup handler. 186 * 187 * - Fixup handlers can jump to the default kernel and user exception 188 * handlers. Before it jumps, though, it has to setup a exception frame 189 * on stack. Because the default handler resets the register fixup handler 190 * the fixup handler must make sure that the default handler returns to 191 * it instead of the exception address, so it can re-register itself as 192 * the fixup handler. 193 * 194 * In case of a critical condition where the kernel cannot recover, we jump 195 * to unrecoverable_exception with the following entry conditions. 196 * All registers a0...a15 are unchanged from the last exception, except: 197 * 198 * a0: last address before we jumped to the unrecoverable_exception. 199 * excsave_1: a0 200 * 201 * 202 * See the handle_alloca_user and spill_registers routines for example clients. 203 * 204 * FIXME: Note: we currently don't allow signal handling coming from a double 205 * exception, so the item markt with (*) is not required. 206 */ 207 208 .section .DoubleExceptionVector.text, "ax" 209 210ENTRY(_DoubleExceptionVector) 211 212 xsr a3, excsave1 213 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 214 215 /* Check for kernel double exception (usually fatal). */ 216 217 rsr a2, ps 218 _bbsi.l a2, PS_UM_BIT, 1f 219 j .Lksp 220 221 .align 4 222 .literal_position 2231: 224 /* Check if we are currently handling a window exception. */ 225 /* Note: We don't need to indicate that we enter a critical section. */ 226 227 xsr a0, depc # get DEPC, save a0 228 229 movi a2, WINDOW_VECTORS_VADDR 230 _bltu a0, a2, .Lfixup 231 addi a2, a2, WINDOW_VECTORS_SIZE 232 _bgeu a0, a2, .Lfixup 233 234 /* Window overflow/underflow exception. Get stack pointer. */ 235 236 l32i a2, a3, EXC_TABLE_KSTK 237 238 /* Check for overflow/underflow exception, jump if overflow. */ 239 240 bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow 241 242 /* 243 * Restart window underflow exception. 244 * Currently: 245 * depc = orig a0, 246 * a0 = orig DEPC, 247 * a2 = new sp based on KSTK from exc_table 248 * a3 = excsave_1 249 * excsave_1 = orig a3 250 * 251 * We return to the instruction in user space that caused the window 252 * underflow exception. Therefore, we change window base to the value 253 * before we entered the window underflow exception and prepare the 254 * registers to return as if we were coming from a regular exception 255 * by changing depc (in a0). 256 * Note: We can trash the current window frame (a0...a3) and depc! 257 */ 258_DoubleExceptionVector_WindowUnderflow: 259 xsr a3, excsave1 260 wsr a2, depc # save stack pointer temporarily 261 rsr a0, ps 262 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 263 wsr a0, windowbase 264 rsync 265 266 /* We are now in the previous window frame. Save registers again. */ 267 268 xsr a2, depc # save a2 and get stack pointer 269 s32i a0, a2, PT_AREG0 270 xsr a3, excsave1 271 rsr a0, exccause 272 s32i a0, a2, PT_DEPC # mark it as a regular exception 273 addx4 a0, a0, a3 274 xsr a3, excsave1 275 l32i a0, a0, EXC_TABLE_FAST_USER 276 jx a0 277 278 /* 279 * We only allow the ITLB miss exception if we are in kernel space. 280 * All other exceptions are unexpected and thus unrecoverable! 281 */ 282 283#ifdef CONFIG_MMU 284 .extern fast_second_level_miss_double_kernel 285 286.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */ 287 288 rsr a3, exccause 289 beqi a3, EXCCAUSE_ITLB_MISS, 1f 290 addi a3, a3, -EXCCAUSE_DTLB_MISS 291 bnez a3, .Lunrecoverable 2921: movi a3, fast_second_level_miss_double_kernel 293 jx a3 294#else 295.equ .Lksp, .Lunrecoverable 296#endif 297 298 /* Critical! We can't handle this situation. PANIC! */ 299 300 .extern unrecoverable_exception 301 302.Lunrecoverable_fixup: 303 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 304 xsr a0, depc 305 306.Lunrecoverable: 307 rsr a3, excsave1 308 wsr a0, excsave1 309 call0 unrecoverable_exception 310 311.Lfixup:/* Check for a fixup handler or if we were in a critical section. */ 312 313 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */ 314 315 /* Enter critical section. */ 316 317 l32i a2, a3, EXC_TABLE_FIXUP 318 s32i a3, a3, EXC_TABLE_FIXUP 319 beq a2, a3, .Lunrecoverable_fixup # critical section 320 beqz a2, .Ldflt # no handler was registered 321 322 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */ 323 324 jx a2 325 326.Ldflt: /* Get stack pointer. */ 327 328 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 329 addi a2, a2, -PT_USER_SIZE 330 331 /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */ 332 333 s32i a0, a2, PT_DEPC 334 l32i a0, a3, EXC_TABLE_DOUBLE_SAVE 335 xsr a0, depc 336 s32i a0, a2, PT_AREG0 337 338 /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */ 339 340 rsr a0, exccause 341 addx4 a0, a0, a3 342 xsr a3, excsave1 343 l32i a0, a0, EXC_TABLE_FAST_USER 344 jx a0 345 346 /* 347 * Restart window OVERFLOW exception. 348 * Currently: 349 * depc = orig a0, 350 * a0 = orig DEPC, 351 * a2 = new sp based on KSTK from exc_table 352 * a3 = EXCSAVE_1 353 * excsave_1 = orig a3 354 * 355 * We return to the instruction in user space that caused the window 356 * overflow exception. Therefore, we change window base to the value 357 * before we entered the window overflow exception and prepare the 358 * registers to return as if we were coming from a regular exception 359 * by changing DEPC (in a0). 360 * 361 * NOTE: We CANNOT trash the current window frame (a0...a3), but we 362 * can clobber depc. 363 * 364 * The tricky part here is that overflow8 and overflow12 handlers 365 * save a0, then clobber a0. To restart the handler, we have to restore 366 * a0 if the double exception was past the point where a0 was clobbered. 367 * 368 * To keep things simple, we take advantage of the fact all overflow 369 * handlers save a0 in their very first instruction. If DEPC was past 370 * that instruction, we can safely restore a0 from where it was saved 371 * on the stack. 372 * 373 * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3 374 */ 375_DoubleExceptionVector_WindowOverflow: 376 extui a2, a0, 0, 6 # get offset into 64-byte vector handler 377 beqz a2, 1f # if at start of vector, don't restore 378 379 addi a0, a0, -128 380 bbsi.l a0, 8, 1f # don't restore except for overflow 8 and 12 381 382 /* 383 * This fixup handler is for the extremely unlikely case where the 384 * overflow handler's reference thru a0 gets a hardware TLB refill 385 * that bumps out the (distinct, aliasing) TLB entry that mapped its 386 * prior references thru a9/a13, and where our reference now thru 387 * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill). 388 */ 389 movi a2, window_overflow_restore_a0_fixup 390 s32i a2, a3, EXC_TABLE_FIXUP 391 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 392 xsr a3, excsave1 393 394 bbsi.l a0, 7, 2f 395 396 /* 397 * Restore a0 as saved by _WindowOverflow8(). 398 */ 399 400 l32e a0, a9, -16 401 wsr a0, depc # replace the saved a0 402 j 3f 403 4042: 405 /* 406 * Restore a0 as saved by _WindowOverflow12(). 407 */ 408 409 l32e a0, a13, -16 410 wsr a0, depc # replace the saved a0 4113: 412 xsr a3, excsave1 413 movi a0, 0 414 s32i a0, a3, EXC_TABLE_FIXUP 415 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 4161: 417 /* 418 * Restore WindowBase while leaving all address registers restored. 419 * We have to use ROTW for this, because WSR.WINDOWBASE requires 420 * an address register (which would prevent restore). 421 * 422 * Window Base goes from 0 ... 7 (Module 8) 423 * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s 424 */ 425 426 rsr a0, ps 427 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 428 rsr a2, windowbase 429 sub a0, a2, a0 430 extui a0, a0, 0, 3 431 432 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 433 xsr a3, excsave1 434 beqi a0, 1, .L1pane 435 beqi a0, 3, .L3pane 436 437 rsr a0, depc 438 rotw -2 439 440 /* 441 * We are now in the user code's original window frame. 442 * Process the exception as a user exception as if it was 443 * taken by the user code. 444 * 445 * This is similar to the user exception vector, 446 * except that PT_DEPC isn't set to EXCCAUSE. 447 */ 4481: 449 xsr a3, excsave1 450 wsr a2, depc 451 l32i a2, a3, EXC_TABLE_KSTK 452 s32i a0, a2, PT_AREG0 453 rsr a0, exccause 454 455 s32i a0, a2, PT_DEPC 456 457_DoubleExceptionVector_handle_exception: 458 addi a0, a0, -EXCCAUSE_UNALIGNED 459 beqz a0, 2f 460 addx4 a0, a0, a3 461 l32i a0, a0, EXC_TABLE_FAST_USER + 4 * EXCCAUSE_UNALIGNED 462 xsr a3, excsave1 463 jx a0 4642: 465 movi a0, user_exception 466 xsr a3, excsave1 467 jx a0 468 469.L1pane: 470 rsr a0, depc 471 rotw -1 472 j 1b 473 474.L3pane: 475 rsr a0, depc 476 rotw -3 477 j 1b 478 479ENDPROC(_DoubleExceptionVector) 480 481/* 482 * Fixup handler for TLB miss in double exception handler for window owerflow. 483 * We get here with windowbase set to the window that was being spilled and 484 * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12 485 * (bit set) window. 486 * 487 * We do the following here: 488 * - go to the original window retaining a0 value; 489 * - set up exception stack to return back to appropriate a0 restore code 490 * (we'll need to rotate window back and there's no place to save this 491 * information, use different return address for that); 492 * - handle the exception; 493 * - go to the window that was being spilled; 494 * - set up window_overflow_restore_a0_fixup as a fixup routine; 495 * - reload a0; 496 * - restore the original window; 497 * - reset the default fixup routine; 498 * - return to user. By the time we get to this fixup handler all information 499 * about the conditions of the original double exception that happened in 500 * the window overflow handler is lost, so we just return to userspace to 501 * retry overflow from start. 502 * 503 * a0: value of depc, original value in depc 504 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE 505 * a3: exctable, original value in excsave1 506 */ 507 508 __XTENSA_HANDLER 509 .literal_position 510 511ENTRY(window_overflow_restore_a0_fixup) 512 513 rsr a0, ps 514 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 515 rsr a2, windowbase 516 sub a0, a2, a0 517 extui a0, a0, 0, 3 518 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 519 xsr a3, excsave1 520 521 _beqi a0, 1, .Lhandle_1 522 _beqi a0, 3, .Lhandle_3 523 524 .macro overflow_fixup_handle_exception_pane n 525 526 rsr a0, depc 527 rotw -\n 528 529 xsr a3, excsave1 530 wsr a2, depc 531 l32i a2, a3, EXC_TABLE_KSTK 532 s32i a0, a2, PT_AREG0 533 534 movi a0, .Lrestore_\n 535 s32i a0, a2, PT_DEPC 536 rsr a0, exccause 537 j _DoubleExceptionVector_handle_exception 538 539 .endm 540 541 overflow_fixup_handle_exception_pane 2 542.Lhandle_1: 543 overflow_fixup_handle_exception_pane 1 544.Lhandle_3: 545 overflow_fixup_handle_exception_pane 3 546 547 .macro overflow_fixup_restore_a0_pane n 548 549 rotw \n 550 /* Need to preserve a0 value here to be able to handle exception 551 * that may occur on a0 reload from stack. It may occur because 552 * TLB miss handler may not be atomic and pointer to page table 553 * may be lost before we get here. There are no free registers, 554 * so we need to use EXC_TABLE_DOUBLE_SAVE area. 555 */ 556 xsr a3, excsave1 557 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 558 movi a2, window_overflow_restore_a0_fixup 559 s32i a2, a3, EXC_TABLE_FIXUP 560 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 561 xsr a3, excsave1 562 bbsi.l a0, 7, 1f 563 l32e a0, a9, -16 564 j 2f 5651: 566 l32e a0, a13, -16 5672: 568 rotw -\n 569 570 .endm 571 572.Lrestore_2: 573 overflow_fixup_restore_a0_pane 2 574 575.Lset_default_fixup: 576 xsr a3, excsave1 577 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 578 movi a2, 0 579 s32i a2, a3, EXC_TABLE_FIXUP 580 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 581 xsr a3, excsave1 582 rfe 583 584.Lrestore_1: 585 overflow_fixup_restore_a0_pane 1 586 j .Lset_default_fixup 587.Lrestore_3: 588 overflow_fixup_restore_a0_pane 3 589 j .Lset_default_fixup 590 591ENDPROC(window_overflow_restore_a0_fixup) 592 593/* 594 * Debug interrupt vector 595 * 596 * There is not much space here, so simply jump to another handler. 597 * EXCSAVE[DEBUGLEVEL] has been set to that handler. 598 */ 599 600 .section .DebugInterruptVector.text, "ax" 601 602ENTRY(_DebugInterruptVector) 603 604 xsr a3, SREG_EXCSAVE + XCHAL_DEBUGLEVEL 605 s32i a0, a3, DT_DEBUG_SAVE 606 l32i a0, a3, DT_DEBUG_EXCEPTION 607 jx a0 608 609ENDPROC(_DebugInterruptVector) 610 611 612 613/* 614 * Medium priority level interrupt vectors 615 * 616 * Each takes less than 16 (0x10) bytes, no literals, by placing 617 * the extra 8 bytes that would otherwise be required in the window 618 * vectors area where there is space. With relocatable vectors, 619 * all vectors are within ~ 4 kB range of each other, so we can 620 * simply jump (J) to another vector without having to use JX. 621 * 622 * common_exception code gets current IRQ level in PS.INTLEVEL 623 * and preserves it for the IRQ handling time. 624 */ 625 626 .macro irq_entry_level level 627 628 .if XCHAL_EXCM_LEVEL >= \level 629 .section .Level\level\()InterruptVector.text, "ax" 630ENTRY(_Level\level\()InterruptVector) 631 wsr a0, excsave2 632 rsr a0, epc\level 633 wsr a0, epc1 634 .if \level <= LOCKLEVEL 635 movi a0, EXCCAUSE_LEVEL1_INTERRUPT 636 .else 637 movi a0, EXCCAUSE_MAPPED_NMI 638 .endif 639 wsr a0, exccause 640 rsr a0, eps\level 641 # branch to user or kernel vector 642 j _SimulateUserKernelVectorException 643 .endif 644 645 .endm 646 647 irq_entry_level 2 648 irq_entry_level 3 649 irq_entry_level 4 650 irq_entry_level 5 651 irq_entry_level 6 652 653 654/* Window overflow and underflow handlers. 655 * The handlers must be 64 bytes apart, first starting with the underflow 656 * handlers underflow-4 to underflow-12, then the overflow handlers 657 * overflow-4 to overflow-12. 658 * 659 * Note: We rerun the underflow handlers if we hit an exception, so 660 * we try to access any page that would cause a page fault early. 661 */ 662 663#define ENTRY_ALIGN64(name) \ 664 .globl name; \ 665 .align 64; \ 666 name: 667 668 .section .WindowVectors.text, "ax" 669 670 671/* 4-Register Window Overflow Vector (Handler) */ 672 673ENTRY_ALIGN64(_WindowOverflow4) 674 675 s32e a0, a5, -16 676 s32e a1, a5, -12 677 s32e a2, a5, -8 678 s32e a3, a5, -4 679 rfwo 680 681ENDPROC(_WindowOverflow4) 682 683 684#if XCHAL_EXCM_LEVEL >= 2 685 /* Not a window vector - but a convenient location 686 * (where we know there's space) for continuation of 687 * medium priority interrupt dispatch code. 688 * On entry here, a0 contains PS, and EPC2 contains saved a0: 689 */ 690 .align 4 691_SimulateUserKernelVectorException: 692 addi a0, a0, (1 << PS_EXCM_BIT) 693#if !XTENSA_FAKE_NMI 694 wsr a0, ps 695#endif 696 bbsi.l a0, PS_UM_BIT, 1f # branch if user mode 697 xsr a0, excsave2 # restore a0 698 j _KernelExceptionVector # simulate kernel vector exception 6991: xsr a0, excsave2 # restore a0 700 j _UserExceptionVector # simulate user vector exception 701#endif 702 703 704/* 4-Register Window Underflow Vector (Handler) */ 705 706ENTRY_ALIGN64(_WindowUnderflow4) 707 708 l32e a0, a5, -16 709 l32e a1, a5, -12 710 l32e a2, a5, -8 711 l32e a3, a5, -4 712 rfwu 713 714ENDPROC(_WindowUnderflow4) 715 716/* 8-Register Window Overflow Vector (Handler) */ 717 718ENTRY_ALIGN64(_WindowOverflow8) 719 720 s32e a0, a9, -16 721 l32e a0, a1, -12 722 s32e a2, a9, -8 723 s32e a1, a9, -12 724 s32e a3, a9, -4 725 s32e a4, a0, -32 726 s32e a5, a0, -28 727 s32e a6, a0, -24 728 s32e a7, a0, -20 729 rfwo 730 731ENDPROC(_WindowOverflow8) 732 733/* 8-Register Window Underflow Vector (Handler) */ 734 735ENTRY_ALIGN64(_WindowUnderflow8) 736 737 l32e a1, a9, -12 738 l32e a0, a9, -16 739 l32e a7, a1, -12 740 l32e a2, a9, -8 741 l32e a4, a7, -32 742 l32e a3, a9, -4 743 l32e a5, a7, -28 744 l32e a6, a7, -24 745 l32e a7, a7, -20 746 rfwu 747 748ENDPROC(_WindowUnderflow8) 749 750/* 12-Register Window Overflow Vector (Handler) */ 751 752ENTRY_ALIGN64(_WindowOverflow12) 753 754 s32e a0, a13, -16 755 l32e a0, a1, -12 756 s32e a1, a13, -12 757 s32e a2, a13, -8 758 s32e a3, a13, -4 759 s32e a4, a0, -48 760 s32e a5, a0, -44 761 s32e a6, a0, -40 762 s32e a7, a0, -36 763 s32e a8, a0, -32 764 s32e a9, a0, -28 765 s32e a10, a0, -24 766 s32e a11, a0, -20 767 rfwo 768 769ENDPROC(_WindowOverflow12) 770 771/* 12-Register Window Underflow Vector (Handler) */ 772 773ENTRY_ALIGN64(_WindowUnderflow12) 774 775 l32e a1, a13, -12 776 l32e a0, a13, -16 777 l32e a11, a1, -12 778 l32e a2, a13, -8 779 l32e a4, a11, -48 780 l32e a8, a11, -32 781 l32e a3, a13, -4 782 l32e a5, a11, -44 783 l32e a6, a11, -40 784 l32e a7, a11, -36 785 l32e a9, a11, -28 786 l32e a10, a11, -24 787 l32e a11, a11, -20 788 rfwu 789 790ENDPROC(_WindowUnderflow12) 791 792 .text 793