vectors.S 22 KB

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  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. * We use a two-level table approach. The user and kernel exception vectors
  20. * use a first-level dispatch table to dispatch the exception to a registered
  21. * fast handler or the default handler, if no fast handler was registered.
  22. * The default handler sets up a C-stack and dispatches the exception to a
  23. * registerd C handler in the second-level dispatch table.
  24. *
  25. * Fast handler entry condition:
  26. *
  27. * a0: trashed, original value saved on stack (PT_AREG0)
  28. * a1: a1
  29. * a2: new stack pointer, original value in depc
  30. * a3: dispatch table
  31. * depc: a2, original value saved on stack (PT_DEPC)
  32. * excsave_1: a3
  33. *
  34. * The value for PT_DEPC saved to stack also functions as a boolean to
  35. * indicate that the exception is either a double or a regular exception:
  36. *
  37. * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception
  38. * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
  39. *
  40. * Note: Neither the kernel nor the user exception handler generate literals.
  41. *
  42. */
  43. #include <linux/linkage.h>
  44. #include <linux/pgtable.h>
  45. #include <asm/asmmacro.h>
  46. #include <asm/ptrace.h>
  47. #include <asm/current.h>
  48. #include <asm/asm-offsets.h>
  49. #include <asm/processor.h>
  50. #include <asm/page.h>
  51. #include <asm/thread_info.h>
  52. #include <asm/vectors.h>
  53. #define WINDOW_VECTORS_SIZE 0x180
  54. /*
  55. * User exception vector. (Exceptions with PS.UM == 1, PS.EXCM == 0)
  56. *
  57. * We get here when an exception occurred while we were in userland.
  58. * We switch to the kernel stack and jump to the first level handler
  59. * associated to the exception cause.
  60. *
  61. * Note: the saved kernel stack pointer (EXC_TABLE_KSTK) is already
  62. * decremented by PT_USER_SIZE.
  63. */
  64. .section .UserExceptionVector.text, "ax"
  65. ENTRY(_UserExceptionVector)
  66. xsr a3, excsave1 # save a3 and get dispatch table
  67. wsr a2, depc # save a2
  68. l32i a2, a3, EXC_TABLE_KSTK # load kernel stack to a2
  69. s32i a0, a2, PT_AREG0 # save a0 to ESF
  70. rsr a0, exccause # retrieve exception cause
  71. s32i a0, a2, PT_DEPC # mark it as a regular exception
  72. addx4 a0, a0, a3 # find entry in table
  73. l32i a0, a0, EXC_TABLE_FAST_USER # load handler
  74. xsr a3, excsave1 # restore a3 and dispatch table
  75. jx a0
  76. ENDPROC(_UserExceptionVector)
  77. /*
  78. * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0)
  79. *
  80. * We get this exception when we were already in kernel space.
  81. * We decrement the current stack pointer (kernel) by PT_SIZE and
  82. * jump to the first-level handler associated with the exception cause.
  83. *
  84. * Note: we need to preserve space for the spill region.
  85. */
  86. .section .KernelExceptionVector.text, "ax"
  87. ENTRY(_KernelExceptionVector)
  88. xsr a3, excsave1 # save a3, and get dispatch table
  89. wsr a2, depc # save a2
  90. addi a2, a1, -16-PT_SIZE # adjust stack pointer
  91. s32i a0, a2, PT_AREG0 # save a0 to ESF
  92. rsr a0, exccause # retrieve exception cause
  93. s32i a0, a2, PT_DEPC # mark it as a regular exception
  94. addx4 a0, a0, a3 # find entry in table
  95. l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address
  96. xsr a3, excsave1 # restore a3 and dispatch table
  97. jx a0
  98. ENDPROC(_KernelExceptionVector)
  99. /*
  100. * Double exception vector (Exceptions with PS.EXCM == 1)
  101. * We get this exception when another exception occurs while were are
  102. * already in an exception, such as window overflow/underflow exception,
  103. * or 'expected' exceptions, for example memory exception when we were trying
  104. * to read data from an invalid address in user space.
  105. *
  106. * Note that this vector is never invoked for level-1 interrupts, because such
  107. * interrupts are disabled (masked) when PS.EXCM is set.
  108. *
  109. * We decode the exception and take the appropriate action. However, the
  110. * double exception vector is much more careful, because a lot more error
  111. * cases go through the double exception vector than through the user and
  112. * kernel exception vectors.
  113. *
  114. * Occasionally, the kernel expects a double exception to occur. This usually
  115. * happens when accessing user-space memory with the user's permissions
  116. * (l32e/s32e instructions). The kernel state, though, is not always suitable
  117. * for immediate transfer of control to handle_double, where "normal" exception
  118. * processing occurs. Also in kernel mode, TLB misses can occur if accessing
  119. * vmalloc memory, possibly requiring repair in a double exception handler.
  120. *
  121. * The variable at TABLE_FIXUP offset from the pointer in EXCSAVE_1 doubles as
  122. * a boolean variable and a pointer to a fixup routine. If the variable
  123. * EXC_TABLE_FIXUP is non-zero, this handler jumps to that address. A value of
  124. * zero indicates to use the default kernel/user exception handler.
  125. * There is only one exception, when the value is identical to the exc_table
  126. * label, the kernel is in trouble. This mechanism is used to protect critical
  127. * sections, mainly when the handler writes to the stack to assert the stack
  128. * pointer is valid. Once the fixup/default handler leaves that area, the
  129. * EXC_TABLE_FIXUP variable is reset to the fixup handler or zero.
  130. *
  131. * Procedures wishing to use this mechanism should set EXC_TABLE_FIXUP to the
  132. * nonzero address of a fixup routine before it could cause a double exception
  133. * and reset it before it returns.
  134. *
  135. * Some other things to take care of when a fast exception handler doesn't
  136. * specify a particular fixup handler but wants to use the default handlers:
  137. *
  138. * - The original stack pointer (in a1) must not be modified. The fast
  139. * exception handler should only use a2 as the stack pointer.
  140. *
  141. * - If the fast handler manipulates the stack pointer (in a2), it has to
  142. * register a valid fixup handler and cannot use the default handlers.
  143. *
  144. * - The handler can use any other generic register from a3 to a15, but it
  145. * must save the content of these registers to stack (PT_AREG3...PT_AREGx)
  146. *
  147. * - These registers must be saved before a double exception can occur.
  148. *
  149. * - If we ever implement handling signals while in double exceptions, the
  150. * number of registers a fast handler has saved (excluding a0 and a1) must
  151. * be written to PT_AREG1. (1 if only a3 is used, 2 for a3 and a4, etc. )
  152. *
  153. * The fixup handlers are special handlers:
  154. *
  155. * - Fixup entry conditions differ from regular exceptions:
  156. *
  157. * a0: DEPC
  158. * a1: a1
  159. * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
  160. * a3: exctable
  161. * depc: a0
  162. * excsave_1: a3
  163. *
  164. * - When the kernel enters the fixup handler, it still assumes it is in a
  165. * critical section, so EXC_TABLE_FIXUP variable is set to exc_table.
  166. * The fixup handler, therefore, has to re-register itself as the fixup
  167. * handler before it returns from the double exception.
  168. *
  169. * - Fixup handler can share the same exception frame with the fast handler.
  170. * The kernel stack pointer is not changed when entering the fixup handler.
  171. *
  172. * - Fixup handlers can jump to the default kernel and user exception
  173. * handlers. Before it jumps, though, it has to setup a exception frame
  174. * on stack. Because the default handler resets the register fixup handler
  175. * the fixup handler must make sure that the default handler returns to
  176. * it instead of the exception address, so it can re-register itself as
  177. * the fixup handler.
  178. *
  179. * In case of a critical condition where the kernel cannot recover, we jump
  180. * to unrecoverable_exception with the following entry conditions.
  181. * All registers a0...a15 are unchanged from the last exception, except:
  182. *
  183. * a0: last address before we jumped to the unrecoverable_exception.
  184. * excsave_1: a0
  185. *
  186. *
  187. * See the handle_alloca_user and spill_registers routines for example clients.
  188. *
  189. * FIXME: Note: we currently don't allow signal handling coming from a double
  190. * exception, so the item markt with (*) is not required.
  191. */
  192. .section .DoubleExceptionVector.text, "ax"
  193. ENTRY(_DoubleExceptionVector)
  194. xsr a3, excsave1
  195. s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  196. /* Check for kernel double exception (usually fatal). */
  197. rsr a2, ps
  198. _bbsi.l a2, PS_UM_BIT, 1f
  199. j .Lksp
  200. .align 4
  201. .literal_position
  202. 1:
  203. /* Check if we are currently handling a window exception. */
  204. /* Note: We don't need to indicate that we enter a critical section. */
  205. xsr a0, depc # get DEPC, save a0
  206. movi a2, WINDOW_VECTORS_VADDR
  207. _bltu a0, a2, .Lfixup
  208. addi a2, a2, WINDOW_VECTORS_SIZE
  209. _bgeu a0, a2, .Lfixup
  210. /* Window overflow/underflow exception. Get stack pointer. */
  211. l32i a2, a3, EXC_TABLE_KSTK
  212. /* Check for overflow/underflow exception, jump if overflow. */
  213. bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
  214. /*
  215. * Restart window underflow exception.
  216. * Currently:
  217. * depc = orig a0,
  218. * a0 = orig DEPC,
  219. * a2 = new sp based on KSTK from exc_table
  220. * a3 = excsave_1
  221. * excsave_1 = orig a3
  222. *
  223. * We return to the instruction in user space that caused the window
  224. * underflow exception. Therefore, we change window base to the value
  225. * before we entered the window underflow exception and prepare the
  226. * registers to return as if we were coming from a regular exception
  227. * by changing depc (in a0).
  228. * Note: We can trash the current window frame (a0...a3) and depc!
  229. */
  230. _DoubleExceptionVector_WindowUnderflow:
  231. xsr a3, excsave1
  232. wsr a2, depc # save stack pointer temporarily
  233. rsr a0, ps
  234. extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
  235. wsr a0, windowbase
  236. rsync
  237. /* We are now in the previous window frame. Save registers again. */
  238. xsr a2, depc # save a2 and get stack pointer
  239. s32i a0, a2, PT_AREG0
  240. xsr a3, excsave1
  241. rsr a0, exccause
  242. s32i a0, a2, PT_DEPC # mark it as a regular exception
  243. addx4 a0, a0, a3
  244. xsr a3, excsave1
  245. l32i a0, a0, EXC_TABLE_FAST_USER
  246. jx a0
  247. /*
  248. * We only allow the ITLB miss exception if we are in kernel space.
  249. * All other exceptions are unexpected and thus unrecoverable!
  250. */
  251. #ifdef CONFIG_MMU
  252. .extern fast_second_level_miss_double_kernel
  253. .Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */
  254. rsr a3, exccause
  255. beqi a3, EXCCAUSE_ITLB_MISS, 1f
  256. addi a3, a3, -EXCCAUSE_DTLB_MISS
  257. bnez a3, .Lunrecoverable
  258. 1: movi a3, fast_second_level_miss_double_kernel
  259. jx a3
  260. #else
  261. .equ .Lksp, .Lunrecoverable
  262. #endif
  263. /* Critical! We can't handle this situation. PANIC! */
  264. .extern unrecoverable_exception
  265. .Lunrecoverable_fixup:
  266. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  267. xsr a0, depc
  268. .Lunrecoverable:
  269. rsr a3, excsave1
  270. wsr a0, excsave1
  271. call0 unrecoverable_exception
  272. .Lfixup:/* Check for a fixup handler or if we were in a critical section. */
  273. /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */
  274. /* Enter critical section. */
  275. l32i a2, a3, EXC_TABLE_FIXUP
  276. s32i a3, a3, EXC_TABLE_FIXUP
  277. beq a2, a3, .Lunrecoverable_fixup # critical section
  278. beqz a2, .Ldflt # no handler was registered
  279. /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
  280. jx a2
  281. .Ldflt: /* Get stack pointer. */
  282. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  283. addi a2, a2, -PT_USER_SIZE
  284. /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */
  285. s32i a0, a2, PT_DEPC
  286. l32i a0, a3, EXC_TABLE_DOUBLE_SAVE
  287. xsr a0, depc
  288. s32i a0, a2, PT_AREG0
  289. /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */
  290. rsr a0, exccause
  291. addx4 a0, a0, a3
  292. xsr a3, excsave1
  293. l32i a0, a0, EXC_TABLE_FAST_USER
  294. jx a0
  295. /*
  296. * Restart window OVERFLOW exception.
  297. * Currently:
  298. * depc = orig a0,
  299. * a0 = orig DEPC,
  300. * a2 = new sp based on KSTK from exc_table
  301. * a3 = EXCSAVE_1
  302. * excsave_1 = orig a3
  303. *
  304. * We return to the instruction in user space that caused the window
  305. * overflow exception. Therefore, we change window base to the value
  306. * before we entered the window overflow exception and prepare the
  307. * registers to return as if we were coming from a regular exception
  308. * by changing DEPC (in a0).
  309. *
  310. * NOTE: We CANNOT trash the current window frame (a0...a3), but we
  311. * can clobber depc.
  312. *
  313. * The tricky part here is that overflow8 and overflow12 handlers
  314. * save a0, then clobber a0. To restart the handler, we have to restore
  315. * a0 if the double exception was past the point where a0 was clobbered.
  316. *
  317. * To keep things simple, we take advantage of the fact all overflow
  318. * handlers save a0 in their very first instruction. If DEPC was past
  319. * that instruction, we can safely restore a0 from where it was saved
  320. * on the stack.
  321. *
  322. * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3
  323. */
  324. _DoubleExceptionVector_WindowOverflow:
  325. extui a2, a0, 0, 6 # get offset into 64-byte vector handler
  326. beqz a2, 1f # if at start of vector, don't restore
  327. addi a0, a0, -128
  328. bbsi.l a0, 8, 1f # don't restore except for overflow 8 and 12
  329. /*
  330. * This fixup handler is for the extremely unlikely case where the
  331. * overflow handler's reference thru a0 gets a hardware TLB refill
  332. * that bumps out the (distinct, aliasing) TLB entry that mapped its
  333. * prior references thru a9/a13, and where our reference now thru
  334. * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill).
  335. */
  336. movi a2, window_overflow_restore_a0_fixup
  337. s32i a2, a3, EXC_TABLE_FIXUP
  338. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  339. xsr a3, excsave1
  340. bbsi.l a0, 7, 2f
  341. /*
  342. * Restore a0 as saved by _WindowOverflow8().
  343. */
  344. l32e a0, a9, -16
  345. wsr a0, depc # replace the saved a0
  346. j 3f
  347. 2:
  348. /*
  349. * Restore a0 as saved by _WindowOverflow12().
  350. */
  351. l32e a0, a13, -16
  352. wsr a0, depc # replace the saved a0
  353. 3:
  354. xsr a3, excsave1
  355. movi a0, 0
  356. s32i a0, a3, EXC_TABLE_FIXUP
  357. s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  358. 1:
  359. /*
  360. * Restore WindowBase while leaving all address registers restored.
  361. * We have to use ROTW for this, because WSR.WINDOWBASE requires
  362. * an address register (which would prevent restore).
  363. *
  364. * Window Base goes from 0 ... 7 (Module 8)
  365. * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s
  366. */
  367. rsr a0, ps
  368. extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
  369. rsr a2, windowbase
  370. sub a0, a2, a0
  371. extui a0, a0, 0, 3
  372. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  373. xsr a3, excsave1
  374. beqi a0, 1, .L1pane
  375. beqi a0, 3, .L3pane
  376. rsr a0, depc
  377. rotw -2
  378. /*
  379. * We are now in the user code's original window frame.
  380. * Process the exception as a user exception as if it was
  381. * taken by the user code.
  382. *
  383. * This is similar to the user exception vector,
  384. * except that PT_DEPC isn't set to EXCCAUSE.
  385. */
  386. 1:
  387. xsr a3, excsave1
  388. wsr a2, depc
  389. l32i a2, a3, EXC_TABLE_KSTK
  390. s32i a0, a2, PT_AREG0
  391. rsr a0, exccause
  392. s32i a0, a2, PT_DEPC
  393. _DoubleExceptionVector_handle_exception:
  394. addi a0, a0, -EXCCAUSE_UNALIGNED
  395. beqz a0, 2f
  396. addx4 a0, a0, a3
  397. l32i a0, a0, EXC_TABLE_FAST_USER + 4 * EXCCAUSE_UNALIGNED
  398. xsr a3, excsave1
  399. jx a0
  400. 2:
  401. movi a0, user_exception
  402. xsr a3, excsave1
  403. jx a0
  404. .L1pane:
  405. rsr a0, depc
  406. rotw -1
  407. j 1b
  408. .L3pane:
  409. rsr a0, depc
  410. rotw -3
  411. j 1b
  412. ENDPROC(_DoubleExceptionVector)
  413. /*
  414. * Fixup handler for TLB miss in double exception handler for window owerflow.
  415. * We get here with windowbase set to the window that was being spilled and
  416. * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12
  417. * (bit set) window.
  418. *
  419. * We do the following here:
  420. * - go to the original window retaining a0 value;
  421. * - set up exception stack to return back to appropriate a0 restore code
  422. * (we'll need to rotate window back and there's no place to save this
  423. * information, use different return address for that);
  424. * - handle the exception;
  425. * - go to the window that was being spilled;
  426. * - set up window_overflow_restore_a0_fixup as a fixup routine;
  427. * - reload a0;
  428. * - restore the original window;
  429. * - reset the default fixup routine;
  430. * - return to user. By the time we get to this fixup handler all information
  431. * about the conditions of the original double exception that happened in
  432. * the window overflow handler is lost, so we just return to userspace to
  433. * retry overflow from start.
  434. *
  435. * a0: value of depc, original value in depc
  436. * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
  437. * a3: exctable, original value in excsave1
  438. */
  439. __XTENSA_HANDLER
  440. .literal_position
  441. ENTRY(window_overflow_restore_a0_fixup)
  442. rsr a0, ps
  443. extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
  444. rsr a2, windowbase
  445. sub a0, a2, a0
  446. extui a0, a0, 0, 3
  447. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  448. xsr a3, excsave1
  449. _beqi a0, 1, .Lhandle_1
  450. _beqi a0, 3, .Lhandle_3
  451. .macro overflow_fixup_handle_exception_pane n
  452. rsr a0, depc
  453. rotw -\n
  454. xsr a3, excsave1
  455. wsr a2, depc
  456. l32i a2, a3, EXC_TABLE_KSTK
  457. s32i a0, a2, PT_AREG0
  458. movi a0, .Lrestore_\n
  459. s32i a0, a2, PT_DEPC
  460. rsr a0, exccause
  461. j _DoubleExceptionVector_handle_exception
  462. .endm
  463. overflow_fixup_handle_exception_pane 2
  464. .Lhandle_1:
  465. overflow_fixup_handle_exception_pane 1
  466. .Lhandle_3:
  467. overflow_fixup_handle_exception_pane 3
  468. .macro overflow_fixup_restore_a0_pane n
  469. rotw \n
  470. /* Need to preserve a0 value here to be able to handle exception
  471. * that may occur on a0 reload from stack. It may occur because
  472. * TLB miss handler may not be atomic and pointer to page table
  473. * may be lost before we get here. There are no free registers,
  474. * so we need to use EXC_TABLE_DOUBLE_SAVE area.
  475. */
  476. xsr a3, excsave1
  477. s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  478. movi a2, window_overflow_restore_a0_fixup
  479. s32i a2, a3, EXC_TABLE_FIXUP
  480. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  481. xsr a3, excsave1
  482. bbsi.l a0, 7, 1f
  483. l32e a0, a9, -16
  484. j 2f
  485. 1:
  486. l32e a0, a13, -16
  487. 2:
  488. rotw -\n
  489. .endm
  490. .Lrestore_2:
  491. overflow_fixup_restore_a0_pane 2
  492. .Lset_default_fixup:
  493. xsr a3, excsave1
  494. s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  495. movi a2, 0
  496. s32i a2, a3, EXC_TABLE_FIXUP
  497. l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
  498. xsr a3, excsave1
  499. rfe
  500. .Lrestore_1:
  501. overflow_fixup_restore_a0_pane 1
  502. j .Lset_default_fixup
  503. .Lrestore_3:
  504. overflow_fixup_restore_a0_pane 3
  505. j .Lset_default_fixup
  506. ENDPROC(window_overflow_restore_a0_fixup)
  507. /*
  508. * Debug interrupt vector
  509. *
  510. * There is not much space here, so simply jump to another handler.
  511. * EXCSAVE[DEBUGLEVEL] has been set to that handler.
  512. */
  513. .section .DebugInterruptVector.text, "ax"
  514. ENTRY(_DebugInterruptVector)
  515. xsr a3, SREG_EXCSAVE + XCHAL_DEBUGLEVEL
  516. s32i a0, a3, DT_DEBUG_SAVE
  517. l32i a0, a3, DT_DEBUG_EXCEPTION
  518. jx a0
  519. ENDPROC(_DebugInterruptVector)
  520. /*
  521. * Medium priority level interrupt vectors
  522. *
  523. * Each takes less than 16 (0x10) bytes, no literals, by placing
  524. * the extra 8 bytes that would otherwise be required in the window
  525. * vectors area where there is space. With relocatable vectors,
  526. * all vectors are within ~ 4 kB range of each other, so we can
  527. * simply jump (J) to another vector without having to use JX.
  528. *
  529. * common_exception code gets current IRQ level in PS.INTLEVEL
  530. * and preserves it for the IRQ handling time.
  531. */
  532. .macro irq_entry_level level
  533. .if XCHAL_EXCM_LEVEL >= \level
  534. .section .Level\level\()InterruptVector.text, "ax"
  535. ENTRY(_Level\level\()InterruptVector)
  536. wsr a0, excsave2
  537. rsr a0, epc\level
  538. wsr a0, epc1
  539. .if \level <= LOCKLEVEL
  540. movi a0, EXCCAUSE_LEVEL1_INTERRUPT
  541. .else
  542. movi a0, EXCCAUSE_MAPPED_NMI
  543. .endif
  544. wsr a0, exccause
  545. rsr a0, eps\level
  546. # branch to user or kernel vector
  547. j _SimulateUserKernelVectorException
  548. .endif
  549. .endm
  550. irq_entry_level 2
  551. irq_entry_level 3
  552. irq_entry_level 4
  553. irq_entry_level 5
  554. irq_entry_level 6
  555. /* Window overflow and underflow handlers.
  556. * The handlers must be 64 bytes apart, first starting with the underflow
  557. * handlers underflow-4 to underflow-12, then the overflow handlers
  558. * overflow-4 to overflow-12.
  559. *
  560. * Note: We rerun the underflow handlers if we hit an exception, so
  561. * we try to access any page that would cause a page fault early.
  562. */
  563. #define ENTRY_ALIGN64(name) \
  564. .globl name; \
  565. .align 64; \
  566. name:
  567. .section .WindowVectors.text, "ax"
  568. /* 4-Register Window Overflow Vector (Handler) */
  569. ENTRY_ALIGN64(_WindowOverflow4)
  570. s32e a0, a5, -16
  571. s32e a1, a5, -12
  572. s32e a2, a5, -8
  573. s32e a3, a5, -4
  574. rfwo
  575. ENDPROC(_WindowOverflow4)
  576. #if XCHAL_EXCM_LEVEL >= 2
  577. /* Not a window vector - but a convenient location
  578. * (where we know there's space) for continuation of
  579. * medium priority interrupt dispatch code.
  580. * On entry here, a0 contains PS, and EPC2 contains saved a0:
  581. */
  582. .align 4
  583. _SimulateUserKernelVectorException:
  584. addi a0, a0, (1 << PS_EXCM_BIT)
  585. #if !XTENSA_FAKE_NMI
  586. wsr a0, ps
  587. #endif
  588. bbsi.l a0, PS_UM_BIT, 1f # branch if user mode
  589. xsr a0, excsave2 # restore a0
  590. j _KernelExceptionVector # simulate kernel vector exception
  591. 1: xsr a0, excsave2 # restore a0
  592. j _UserExceptionVector # simulate user vector exception
  593. #endif
  594. /* 4-Register Window Underflow Vector (Handler) */
  595. ENTRY_ALIGN64(_WindowUnderflow4)
  596. l32e a0, a5, -16
  597. l32e a1, a5, -12
  598. l32e a2, a5, -8
  599. l32e a3, a5, -4
  600. rfwu
  601. ENDPROC(_WindowUnderflow4)
  602. /* 8-Register Window Overflow Vector (Handler) */
  603. ENTRY_ALIGN64(_WindowOverflow8)
  604. s32e a0, a9, -16
  605. l32e a0, a1, -12
  606. s32e a2, a9, -8
  607. s32e a1, a9, -12
  608. s32e a3, a9, -4
  609. s32e a4, a0, -32
  610. s32e a5, a0, -28
  611. s32e a6, a0, -24
  612. s32e a7, a0, -20
  613. rfwo
  614. ENDPROC(_WindowOverflow8)
  615. /* 8-Register Window Underflow Vector (Handler) */
  616. ENTRY_ALIGN64(_WindowUnderflow8)
  617. l32e a1, a9, -12
  618. l32e a0, a9, -16
  619. l32e a7, a1, -12
  620. l32e a2, a9, -8
  621. l32e a4, a7, -32
  622. l32e a3, a9, -4
  623. l32e a5, a7, -28
  624. l32e a6, a7, -24
  625. l32e a7, a7, -20
  626. rfwu
  627. ENDPROC(_WindowUnderflow8)
  628. /* 12-Register Window Overflow Vector (Handler) */
  629. ENTRY_ALIGN64(_WindowOverflow12)
  630. s32e a0, a13, -16
  631. l32e a0, a1, -12
  632. s32e a1, a13, -12
  633. s32e a2, a13, -8
  634. s32e a3, a13, -4
  635. s32e a4, a0, -48
  636. s32e a5, a0, -44
  637. s32e a6, a0, -40
  638. s32e a7, a0, -36
  639. s32e a8, a0, -32
  640. s32e a9, a0, -28
  641. s32e a10, a0, -24
  642. s32e a11, a0, -20
  643. rfwo
  644. ENDPROC(_WindowOverflow12)
  645. /* 12-Register Window Underflow Vector (Handler) */
  646. ENTRY_ALIGN64(_WindowUnderflow12)
  647. l32e a1, a13, -12
  648. l32e a0, a13, -16
  649. l32e a11, a1, -12
  650. l32e a2, a13, -8
  651. l32e a4, a11, -48
  652. l32e a8, a11, -32
  653. l32e a3, a13, -4
  654. l32e a5, a11, -44
  655. l32e a6, a11, -40
  656. l32e a7, a11, -36
  657. l32e a9, a11, -28
  658. l32e a10, a11, -24
  659. l32e a11, a11, -20
  660. rfwu
  661. ENDPROC(_WindowUnderflow12)
  662. .text