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_KERNEL_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_KERNEL_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#ifdef SUPPORT_WINDOWED 230 movi a2, WINDOW_VECTORS_VADDR 231 _bltu a0, a2, .Lfixup 232 addi a2, a2, WINDOW_VECTORS_SIZE 233 _bgeu a0, a2, .Lfixup 234 235 /* Window overflow/underflow exception. Get stack pointer. */ 236 237 l32i a2, a3, EXC_TABLE_KSTK 238 239 /* Check for overflow/underflow exception, jump if overflow. */ 240 241 bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow 242 243 /* 244 * Restart window underflow exception. 245 * Currently: 246 * depc = orig a0, 247 * a0 = orig DEPC, 248 * a2 = new sp based on KSTK from exc_table 249 * a3 = excsave_1 250 * excsave_1 = orig a3 251 * 252 * We return to the instruction in user space that caused the window 253 * underflow exception. Therefore, we change window base to the value 254 * before we entered the window underflow exception and prepare the 255 * registers to return as if we were coming from a regular exception 256 * by changing depc (in a0). 257 * Note: We can trash the current window frame (a0...a3) and depc! 258 */ 259_DoubleExceptionVector_WindowUnderflow: 260 xsr a3, excsave1 261 wsr a2, depc # save stack pointer temporarily 262 rsr a0, ps 263 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 264 wsr a0, windowbase 265 rsync 266 267 /* We are now in the previous window frame. Save registers again. */ 268 269 xsr a2, depc # save a2 and get stack pointer 270 s32i a0, a2, PT_AREG0 271 xsr a3, excsave1 272 rsr a0, exccause 273 s32i a0, a2, PT_DEPC # mark it as a regular exception 274 addx4 a0, a0, a3 275 xsr a3, excsave1 276 l32i a0, a0, EXC_TABLE_FAST_USER 277 jx a0 278 279#else 280 j .Lfixup 281#endif 282 283 /* 284 * We only allow the ITLB miss exception if we are in kernel space. 285 * All other exceptions are unexpected and thus unrecoverable! 286 */ 287 288#ifdef CONFIG_MMU 289 .extern fast_second_level_miss_double_kernel 290 291.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */ 292 293 rsr a3, exccause 294 beqi a3, EXCCAUSE_ITLB_MISS, 1f 295 addi a3, a3, -EXCCAUSE_DTLB_MISS 296 bnez a3, .Lunrecoverable 2971: movi a3, fast_second_level_miss_double_kernel 298 jx a3 299#else 300.equ .Lksp, .Lunrecoverable 301#endif 302 303 /* Critical! We can't handle this situation. PANIC! */ 304 305 .extern unrecoverable_exception 306 307.Lunrecoverable_fixup: 308 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 309 xsr a0, depc 310 311.Lunrecoverable: 312 rsr a3, excsave1 313 wsr a0, excsave1 314 call0 unrecoverable_exception 315 316.Lfixup:/* Check for a fixup handler or if we were in a critical section. */ 317 318 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */ 319 320 /* Enter critical section. */ 321 322 l32i a2, a3, EXC_TABLE_FIXUP 323 s32i a3, a3, EXC_TABLE_FIXUP 324 beq a2, a3, .Lunrecoverable_fixup # critical section 325 beqz a2, .Ldflt # no handler was registered 326 327 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */ 328 329 jx a2 330 331.Ldflt: /* Get stack pointer. */ 332 333 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 334 addi a2, a2, -PT_USER_SIZE 335 336 /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */ 337 338 s32i a0, a2, PT_DEPC 339 l32i a0, a3, EXC_TABLE_DOUBLE_SAVE 340 xsr a0, depc 341 s32i a0, a2, PT_AREG0 342 343 /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */ 344 345 rsr a0, exccause 346 addx4 a0, a0, a3 347 xsr a3, excsave1 348 l32i a0, a0, EXC_TABLE_FAST_USER 349 jx a0 350 351#ifdef SUPPORT_WINDOWED 352 /* 353 * Restart window OVERFLOW exception. 354 * Currently: 355 * depc = orig a0, 356 * a0 = orig DEPC, 357 * a2 = new sp based on KSTK from exc_table 358 * a3 = EXCSAVE_1 359 * excsave_1 = orig a3 360 * 361 * We return to the instruction in user space that caused the window 362 * overflow exception. Therefore, we change window base to the value 363 * before we entered the window overflow exception and prepare the 364 * registers to return as if we were coming from a regular exception 365 * by changing DEPC (in a0). 366 * 367 * NOTE: We CANNOT trash the current window frame (a0...a3), but we 368 * can clobber depc. 369 * 370 * The tricky part here is that overflow8 and overflow12 handlers 371 * save a0, then clobber a0. To restart the handler, we have to restore 372 * a0 if the double exception was past the point where a0 was clobbered. 373 * 374 * To keep things simple, we take advantage of the fact all overflow 375 * handlers save a0 in their very first instruction. If DEPC was past 376 * that instruction, we can safely restore a0 from where it was saved 377 * on the stack. 378 * 379 * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3 380 */ 381_DoubleExceptionVector_WindowOverflow: 382 extui a2, a0, 0, 6 # get offset into 64-byte vector handler 383 beqz a2, 1f # if at start of vector, don't restore 384 385 addi a0, a0, -128 386 bbsi.l a0, 8, 1f # don't restore except for overflow 8 and 12 387 388 /* 389 * This fixup handler is for the extremely unlikely case where the 390 * overflow handler's reference thru a0 gets a hardware TLB refill 391 * that bumps out the (distinct, aliasing) TLB entry that mapped its 392 * prior references thru a9/a13, and where our reference now thru 393 * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill). 394 */ 395 movi a2, window_overflow_restore_a0_fixup 396 s32i a2, a3, EXC_TABLE_FIXUP 397 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 398 xsr a3, excsave1 399 400 bbsi.l a0, 7, 2f 401 402 /* 403 * Restore a0 as saved by _WindowOverflow8(). 404 */ 405 406 l32e a0, a9, -16 407 wsr a0, depc # replace the saved a0 408 j 3f 409 4102: 411 /* 412 * Restore a0 as saved by _WindowOverflow12(). 413 */ 414 415 l32e a0, a13, -16 416 wsr a0, depc # replace the saved a0 4173: 418 xsr a3, excsave1 419 movi a0, 0 420 s32i a0, a3, EXC_TABLE_FIXUP 421 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 4221: 423 /* 424 * Restore WindowBase while leaving all address registers restored. 425 * We have to use ROTW for this, because WSR.WINDOWBASE requires 426 * an address register (which would prevent restore). 427 * 428 * Window Base goes from 0 ... 7 (Module 8) 429 * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s 430 */ 431 432 rsr a0, ps 433 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 434 rsr a2, windowbase 435 sub a0, a2, a0 436 extui a0, a0, 0, 3 437 438 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 439 xsr a3, excsave1 440 beqi a0, 1, .L1pane 441 beqi a0, 3, .L3pane 442 443 rsr a0, depc 444 rotw -2 445 446 /* 447 * We are now in the user code's original window frame. 448 * Process the exception as a user exception as if it was 449 * taken by the user code. 450 * 451 * This is similar to the user exception vector, 452 * except that PT_DEPC isn't set to EXCCAUSE. 453 */ 4541: 455 xsr a3, excsave1 456 wsr a2, depc 457 l32i a2, a3, EXC_TABLE_KSTK 458 s32i a0, a2, PT_AREG0 459 rsr a0, exccause 460 461 s32i a0, a2, PT_DEPC 462 463_DoubleExceptionVector_handle_exception: 464 addi a0, a0, -EXCCAUSE_UNALIGNED 465 beqz a0, 2f 466 addx4 a0, a0, a3 467 l32i a0, a0, EXC_TABLE_FAST_USER + 4 * EXCCAUSE_UNALIGNED 468 xsr a3, excsave1 469 jx a0 4702: 471 movi a0, user_exception 472 xsr a3, excsave1 473 jx a0 474 475.L1pane: 476 rsr a0, depc 477 rotw -1 478 j 1b 479 480.L3pane: 481 rsr a0, depc 482 rotw -3 483 j 1b 484#endif 485 486ENDPROC(_DoubleExceptionVector) 487 488#ifdef SUPPORT_WINDOWED 489 490/* 491 * Fixup handler for TLB miss in double exception handler for window owerflow. 492 * We get here with windowbase set to the window that was being spilled and 493 * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12 494 * (bit set) window. 495 * 496 * We do the following here: 497 * - go to the original window retaining a0 value; 498 * - set up exception stack to return back to appropriate a0 restore code 499 * (we'll need to rotate window back and there's no place to save this 500 * information, use different return address for that); 501 * - handle the exception; 502 * - go to the window that was being spilled; 503 * - set up window_overflow_restore_a0_fixup as a fixup routine; 504 * - reload a0; 505 * - restore the original window; 506 * - reset the default fixup routine; 507 * - return to user. By the time we get to this fixup handler all information 508 * about the conditions of the original double exception that happened in 509 * the window overflow handler is lost, so we just return to userspace to 510 * retry overflow from start. 511 * 512 * a0: value of depc, original value in depc 513 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE 514 * a3: exctable, original value in excsave1 515 */ 516 517 __XTENSA_HANDLER 518 .literal_position 519 520ENTRY(window_overflow_restore_a0_fixup) 521 522 rsr a0, ps 523 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH 524 rsr a2, windowbase 525 sub a0, a2, a0 526 extui a0, a0, 0, 3 527 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 528 xsr a3, excsave1 529 530 _beqi a0, 1, .Lhandle_1 531 _beqi a0, 3, .Lhandle_3 532 533 .macro overflow_fixup_handle_exception_pane n 534 535 rsr a0, depc 536 rotw -\n 537 538 xsr a3, excsave1 539 wsr a2, depc 540 l32i a2, a3, EXC_TABLE_KSTK 541 s32i a0, a2, PT_AREG0 542 543 movi a0, .Lrestore_\n 544 s32i a0, a2, PT_DEPC 545 rsr a0, exccause 546 j _DoubleExceptionVector_handle_exception 547 548 .endm 549 550 overflow_fixup_handle_exception_pane 2 551.Lhandle_1: 552 overflow_fixup_handle_exception_pane 1 553.Lhandle_3: 554 overflow_fixup_handle_exception_pane 3 555 556 .macro overflow_fixup_restore_a0_pane n 557 558 rotw \n 559 /* Need to preserve a0 value here to be able to handle exception 560 * that may occur on a0 reload from stack. It may occur because 561 * TLB miss handler may not be atomic and pointer to page table 562 * may be lost before we get here. There are no free registers, 563 * so we need to use EXC_TABLE_DOUBLE_SAVE area. 564 */ 565 xsr a3, excsave1 566 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 567 movi a2, window_overflow_restore_a0_fixup 568 s32i a2, a3, EXC_TABLE_FIXUP 569 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 570 xsr a3, excsave1 571 bbsi.l a0, 7, 1f 572 l32e a0, a9, -16 573 j 2f 5741: 575 l32e a0, a13, -16 5762: 577 rotw -\n 578 579 .endm 580 581.Lrestore_2: 582 overflow_fixup_restore_a0_pane 2 583 584.Lset_default_fixup: 585 xsr a3, excsave1 586 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE 587 movi a2, 0 588 s32i a2, a3, EXC_TABLE_FIXUP 589 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE 590 xsr a3, excsave1 591 rfe 592 593.Lrestore_1: 594 overflow_fixup_restore_a0_pane 1 595 j .Lset_default_fixup 596.Lrestore_3: 597 overflow_fixup_restore_a0_pane 3 598 j .Lset_default_fixup 599 600ENDPROC(window_overflow_restore_a0_fixup) 601 602#endif 603 604/* 605 * Debug interrupt vector 606 * 607 * There is not much space here, so simply jump to another handler. 608 * EXCSAVE[DEBUGLEVEL] has been set to that handler. 609 */ 610 611 .section .DebugInterruptVector.text, "ax" 612 613ENTRY(_DebugInterruptVector) 614 615 xsr a3, SREG_EXCSAVE + XCHAL_DEBUGLEVEL 616 s32i a0, a3, DT_DEBUG_SAVE 617 l32i a0, a3, DT_DEBUG_EXCEPTION 618 jx a0 619 620ENDPROC(_DebugInterruptVector) 621 622 623 624/* 625 * Medium priority level interrupt vectors 626 * 627 * Each takes less than 16 (0x10) bytes, no literals, by placing 628 * the extra 8 bytes that would otherwise be required in the window 629 * vectors area where there is space. With relocatable vectors, 630 * all vectors are within ~ 4 kB range of each other, so we can 631 * simply jump (J) to another vector without having to use JX. 632 * 633 * common_exception code gets current IRQ level in PS.INTLEVEL 634 * and preserves it for the IRQ handling time. 635 */ 636 637 .macro irq_entry_level level 638 639 .if XCHAL_EXCM_LEVEL >= \level 640 .section .Level\level\()InterruptVector.text, "ax" 641ENTRY(_Level\level\()InterruptVector) 642 wsr a0, excsave2 643 rsr a0, epc\level 644 wsr a0, epc1 645 .if \level <= LOCKLEVEL 646 movi a0, EXCCAUSE_LEVEL1_INTERRUPT 647 .else 648 movi a0, EXCCAUSE_MAPPED_NMI 649 .endif 650 wsr a0, exccause 651 rsr a0, eps\level 652 # branch to user or kernel vector 653 j _SimulateUserKernelVectorException 654 .endif 655 656 .endm 657 658 irq_entry_level 2 659 irq_entry_level 3 660 irq_entry_level 4 661 irq_entry_level 5 662 irq_entry_level 6 663 664#if XCHAL_EXCM_LEVEL >= 2 665 /* 666 * Continuation of medium priority interrupt dispatch code. 667 * On entry here, a0 contains PS, and EPC2 contains saved a0: 668 */ 669 __XTENSA_HANDLER 670 .align 4 671_SimulateUserKernelVectorException: 672 addi a0, a0, (1 << PS_EXCM_BIT) 673#if !XTENSA_FAKE_NMI 674 wsr a0, ps 675#endif 676 bbsi.l a0, PS_UM_BIT, 1f # branch if user mode 677 xsr a0, excsave2 # restore a0 678 j _KernelExceptionVector # simulate kernel vector exception 6791: xsr a0, excsave2 # restore a0 680 j _UserExceptionVector # simulate user vector exception 681#endif 682 683 684/* Window overflow and underflow handlers. 685 * The handlers must be 64 bytes apart, first starting with the underflow 686 * handlers underflow-4 to underflow-12, then the overflow handlers 687 * overflow-4 to overflow-12. 688 * 689 * Note: We rerun the underflow handlers if we hit an exception, so 690 * we try to access any page that would cause a page fault early. 691 */ 692 693#define ENTRY_ALIGN64(name) \ 694 .globl name; \ 695 .align 64; \ 696 name: 697 698 .section .WindowVectors.text, "ax" 699 700 701#ifdef SUPPORT_WINDOWED 702 703/* 4-Register Window Overflow Vector (Handler) */ 704 705ENTRY_ALIGN64(_WindowOverflow4) 706 707 s32e a0, a5, -16 708 s32e a1, a5, -12 709 s32e a2, a5, -8 710 s32e a3, a5, -4 711 rfwo 712 713ENDPROC(_WindowOverflow4) 714 715/* 4-Register Window Underflow Vector (Handler) */ 716 717ENTRY_ALIGN64(_WindowUnderflow4) 718 719 l32e a0, a5, -16 720 l32e a1, a5, -12 721 l32e a2, a5, -8 722 l32e a3, a5, -4 723 rfwu 724 725ENDPROC(_WindowUnderflow4) 726 727/* 8-Register Window Overflow Vector (Handler) */ 728 729ENTRY_ALIGN64(_WindowOverflow8) 730 731 s32e a0, a9, -16 732 l32e a0, a1, -12 733 s32e a2, a9, -8 734 s32e a1, a9, -12 735 s32e a3, a9, -4 736 s32e a4, a0, -32 737 s32e a5, a0, -28 738 s32e a6, a0, -24 739 s32e a7, a0, -20 740 rfwo 741 742ENDPROC(_WindowOverflow8) 743 744/* 8-Register Window Underflow Vector (Handler) */ 745 746ENTRY_ALIGN64(_WindowUnderflow8) 747 748 l32e a1, a9, -12 749 l32e a0, a9, -16 750 l32e a7, a1, -12 751 l32e a2, a9, -8 752 l32e a4, a7, -32 753 l32e a3, a9, -4 754 l32e a5, a7, -28 755 l32e a6, a7, -24 756 l32e a7, a7, -20 757 rfwu 758 759ENDPROC(_WindowUnderflow8) 760 761/* 12-Register Window Overflow Vector (Handler) */ 762 763ENTRY_ALIGN64(_WindowOverflow12) 764 765 s32e a0, a13, -16 766 l32e a0, a1, -12 767 s32e a1, a13, -12 768 s32e a2, a13, -8 769 s32e a3, a13, -4 770 s32e a4, a0, -48 771 s32e a5, a0, -44 772 s32e a6, a0, -40 773 s32e a7, a0, -36 774 s32e a8, a0, -32 775 s32e a9, a0, -28 776 s32e a10, a0, -24 777 s32e a11, a0, -20 778 rfwo 779 780ENDPROC(_WindowOverflow12) 781 782/* 12-Register Window Underflow Vector (Handler) */ 783 784ENTRY_ALIGN64(_WindowUnderflow12) 785 786 l32e a1, a13, -12 787 l32e a0, a13, -16 788 l32e a11, a1, -12 789 l32e a2, a13, -8 790 l32e a4, a11, -48 791 l32e a8, a11, -32 792 l32e a3, a13, -4 793 l32e a5, a11, -44 794 l32e a6, a11, -40 795 l32e a7, a11, -36 796 l32e a9, a11, -28 797 l32e a10, a11, -24 798 l32e a11, a11, -20 799 rfwu 800 801ENDPROC(_WindowUnderflow12) 802 803#endif 804 805 .text 806
