diff options
Diffstat (limited to 'arch/xtensa/kernel/vectors.S')
| -rw-r--r-- | arch/xtensa/kernel/vectors.S | 500 |
1 files changed, 404 insertions, 96 deletions
diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S index 70066e3582d..8453e6e3989 100644 --- a/arch/xtensa/kernel/vectors.S +++ b/arch/xtensa/kernel/vectors.S @@ -10,7 +10,7 @@ * Public License. See the file "COPYING" in the main directory of * this archive for more details. * - * Copyright (C) 2005 Tensilica, Inc. + * Copyright (C) 2005 - 2008 Tensilica, Inc. * * Chris Zankel <chris@zankel.net> * @@ -50,6 +50,7 @@ #include <asm/processor.h> #include <asm/page.h> #include <asm/thread_info.h> +#include <asm/vectors.h> #define WINDOW_VECTORS_SIZE 0x180 @@ -69,16 +70,19 @@ ENTRY(_UserExceptionVector) - xsr a3, EXCSAVE_1 # save a3 and get dispatch table - wsr a2, DEPC # save a2 + xsr a3, excsave1 # save a3 and get dispatch table + wsr a2, depc # save a2 l32i a2, a3, EXC_TABLE_KSTK # load kernel stack to a2 s32i a0, a2, PT_AREG0 # save a0 to ESF - rsr a0, EXCCAUSE # retrieve exception cause + rsr a0, exccause # retrieve exception cause s32i a0, a2, PT_DEPC # mark it as a regular exception addx4 a0, a0, a3 # find entry in table l32i a0, a0, EXC_TABLE_FAST_USER # load handler + xsr a3, excsave1 # restore a3 and dispatch table jx a0 +ENDPROC(_UserExceptionVector) + /* * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0) * @@ -93,16 +97,18 @@ ENTRY(_UserExceptionVector) ENTRY(_KernelExceptionVector) - xsr a3, EXCSAVE_1 # save a3, and get dispatch table - wsr a2, DEPC # save a2 + xsr a3, excsave1 # save a3, and get dispatch table + wsr a2, depc # save a2 addi a2, a1, -16-PT_SIZE # adjust stack pointer s32i a0, a2, PT_AREG0 # save a0 to ESF - rsr a0, EXCCAUSE # retrieve exception cause + rsr a0, exccause # retrieve exception cause s32i a0, a2, PT_DEPC # mark it as a regular exception addx4 a0, a0, a3 # find entry in table l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address + xsr a3, excsave1 # restore a3 and dispatch table jx a0 +ENDPROC(_KernelExceptionVector) /* * Double exception vector (Exceptions with PS.EXCM == 1) @@ -164,7 +170,7 @@ ENTRY(_KernelExceptionVector) * * a0: DEPC * a1: a1 - * a2: trashed, original value in EXC_TABLE_DOUBLE_A2 + * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE * a3: exctable * depc: a0 * excsave_1: a3 @@ -200,41 +206,46 @@ ENTRY(_KernelExceptionVector) .section .DoubleExceptionVector.text, "ax" .begin literal_prefix .DoubleExceptionVector + .globl _DoubleExceptionVector_WindowUnderflow + .globl _DoubleExceptionVector_WindowOverflow ENTRY(_DoubleExceptionVector) - /* Deliberately destroy excsave (don't assume it's value was valid). */ - - wsr a3, EXCSAVE_1 # save a3 + xsr a3, excsave1 + s32i a2, a3, EXC_TABLE_DOUBLE_SAVE /* Check for kernel double exception (usually fatal). */ - rsr a3, PS - _bbci.l a3, PS_UM_BIT, .Lksp + rsr a2, ps + _bbci.l a2, PS_UM_BIT, .Lksp /* Check if we are currently handling a window exception. */ /* Note: We don't need to indicate that we enter a critical section. */ - xsr a0, DEPC # get DEPC, save a0 + xsr a0, depc # get DEPC, save a0 - movi a3, XCHAL_WINDOW_VECTORS_VADDR - _bltu a0, a3, .Lfixup - addi a3, a3, WINDOW_VECTORS_SIZE - _bgeu a0, a3, .Lfixup + movi a2, WINDOW_VECTORS_VADDR + _bltu a0, a2, .Lfixup + addi a2, a2, WINDOW_VECTORS_SIZE + _bgeu a0, a2, .Lfixup /* Window overflow/underflow exception. Get stack pointer. */ - mov a3, a2 - movi a2, exc_table - l32i a2, a2, EXC_TABLE_KSTK + l32i a2, a3, EXC_TABLE_KSTK /* Check for overflow/underflow exception, jump if overflow. */ - _bbci.l a0, 6, .Lovfl - - /* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */ + bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow - /* Restart window underflow exception. + /* + * Restart window underflow exception. + * Currently: + * depc = orig a0, + * a0 = orig DEPC, + * a2 = new sp based on KSTK from exc_table + * a3 = excsave_1 + * excsave_1 = orig a3 + * * We return to the instruction in user space that caused the window * underflow exception. Therefore, we change window base to the value * before we entered the window underflow exception and prepare the @@ -242,39 +253,69 @@ ENTRY(_DoubleExceptionVector) * by changing depc (in a0). * Note: We can trash the current window frame (a0...a3) and depc! */ - - wsr a2, DEPC # save stack pointer temporarily - rsr a0, PS - extui a0, a0, PS_OWB_SHIFT, 4 - wsr a0, WINDOWBASE +_DoubleExceptionVector_WindowUnderflow: + xsr a3, excsave1 + wsr a2, depc # save stack pointer temporarily + rsr a0, ps + extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH + wsr a0, windowbase rsync /* We are now in the previous window frame. Save registers again. */ - xsr a2, DEPC # save a2 and get stack pointer + xsr a2, depc # save a2 and get stack pointer s32i a0, a2, PT_AREG0 - - wsr a3, EXCSAVE_1 # save a3 - movi a3, exc_table - - rsr a0, EXCCAUSE + xsr a3, excsave1 + rsr a0, exccause s32i a0, a2, PT_DEPC # mark it as a regular exception addx4 a0, a0, a3 + xsr a3, excsave1 l32i a0, a0, EXC_TABLE_FAST_USER jx a0 -.Lfixup:/* Check for a fixup handler or if we were in a critical section. */ + /* + * We only allow the ITLB miss exception if we are in kernel space. + * All other exceptions are unexpected and thus unrecoverable! + */ + +#ifdef CONFIG_MMU + .extern fast_second_level_miss_double_kernel + +.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */ + + rsr a3, exccause + beqi a3, EXCCAUSE_ITLB_MISS, 1f + addi a3, a3, -EXCCAUSE_DTLB_MISS + bnez a3, .Lunrecoverable +1: movi a3, fast_second_level_miss_double_kernel + jx a3 +#else +.equ .Lksp, .Lunrecoverable +#endif + + /* Critical! We can't handle this situation. PANIC! */ - /* a0: depc, a1: a1, a2: a2, a3: trashed, depc: a0, excsave1: a3 */ + .extern unrecoverable_exception - movi a3, exc_table - s32i a2, a3, EXC_TABLE_DOUBLE_SAVE # temporary variable +.Lunrecoverable_fixup: + l32i a2, a3, EXC_TABLE_DOUBLE_SAVE + xsr a0, depc + +.Lunrecoverable: + rsr a3, excsave1 + wsr a0, excsave1 + movi a0, unrecoverable_exception + callx0 a0 + +.Lfixup:/* Check for a fixup handler or if we were in a critical section. */ + + /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */ /* Enter critical section. */ l32i a2, a3, EXC_TABLE_FIXUP s32i a3, a3, EXC_TABLE_FIXUP - beq a2, a3, .Lunrecoverable_fixup # critical! + beq a2, a3, .Lunrecoverable_fixup # critical section beqz a2, .Ldflt # no handler was registered /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */ @@ -283,62 +324,264 @@ ENTRY(_DoubleExceptionVector) .Ldflt: /* Get stack pointer. */ - l32i a3, a3, EXC_TABLE_DOUBLE_SAVE - addi a2, a3, -PT_USER_SIZE - -.Lovfl: /* Jump to default handlers. */ + l32i a2, a3, EXC_TABLE_DOUBLE_SAVE + addi a2, a2, -PT_USER_SIZE - /* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */ + /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */ - xsr a3, DEPC s32i a0, a2, PT_DEPC - s32i a3, a2, PT_AREG0 + l32i a0, a3, EXC_TABLE_DOUBLE_SAVE + xsr a0, depc + s32i a0, a2, PT_AREG0 - /* a0: avail, a1: a1, a2: kstk, a3: avail, depc: a2, excsave: a3 */ + /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */ - movi a3, exc_table - rsr a0, EXCCAUSE + rsr a0, exccause addx4 a0, a0, a3 + xsr a3, excsave1 l32i a0, a0, EXC_TABLE_FAST_USER jx a0 /* - * We only allow the ITLB miss exception if we are in kernel space. - * All other exceptions are unexpected and thus unrecoverable! + * Restart window OVERFLOW exception. + * Currently: + * depc = orig a0, + * a0 = orig DEPC, + * a2 = new sp based on KSTK from exc_table + * a3 = EXCSAVE_1 + * excsave_1 = orig a3 + * + * We return to the instruction in user space that caused the window + * overflow exception. Therefore, we change window base to the value + * before we entered the window overflow exception and prepare the + * registers to return as if we were coming from a regular exception + * by changing DEPC (in a0). + * + * NOTE: We CANNOT trash the current window frame (a0...a3), but we + * can clobber depc. + * + * The tricky part here is that overflow8 and overflow12 handlers + * save a0, then clobber a0. To restart the handler, we have to restore + * a0 if the double exception was past the point where a0 was clobbered. + * + * To keep things simple, we take advantage of the fact all overflow + * handlers save a0 in their very first instruction. If DEPC was past + * that instruction, we can safely restore a0 from where it was saved + * on the stack. + * + * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3 */ +_DoubleExceptionVector_WindowOverflow: + extui a2, a0, 0, 6 # get offset into 64-byte vector handler + beqz a2, 1f # if at start of vector, don't restore -#ifdef CONFIG_MMU - .extern fast_second_level_miss_double_kernel + addi a0, a0, -128 + bbsi.l a0, 8, 1f # don't restore except for overflow 8 and 12 -.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */ + /* + * This fixup handler is for the extremely unlikely case where the + * overflow handler's reference thru a0 gets a hardware TLB refill + * that bumps out the (distinct, aliasing) TLB entry that mapped its + * prior references thru a9/a13, and where our reference now thru + * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill). + */ + movi a2, window_overflow_restore_a0_fixup + s32i a2, a3, EXC_TABLE_FIXUP + l32i a2, a3, EXC_TABLE_DOUBLE_SAVE + xsr a3, excsave1 - rsr a3, EXCCAUSE - beqi a3, EXCCAUSE_ITLB_MISS, 1f - addi a3, a3, -EXCCAUSE_DTLB_MISS - bnez a3, .Lunrecoverable -1: movi a3, fast_second_level_miss_double_kernel - jx a3 -#else -.equ .Lksp, .Lunrecoverable -#endif + bbsi.l a0, 7, 2f - /* Critical! We can't handle this situation. PANIC! */ + /* + * Restore a0 as saved by _WindowOverflow8(). + */ - .extern unrecoverable_exception + l32e a0, a9, -16 + wsr a0, depc # replace the saved a0 + j 3f + +2: + /* + * Restore a0 as saved by _WindowOverflow12(). + */ + + l32e a0, a13, -16 + wsr a0, depc # replace the saved a0 +3: + xsr a3, excsave1 + movi a0, 0 + s32i a0, a3, EXC_TABLE_FIXUP + s32i a2, a3, EXC_TABLE_DOUBLE_SAVE +1: + /* + * Restore WindowBase while leaving all address registers restored. + * We have to use ROTW for this, because WSR.WINDOWBASE requires + * an address register (which would prevent restore). + * + * Window Base goes from 0 ... 7 (Module 8) + * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s + */ + + rsr a0, ps + extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH + rsr a2, windowbase + sub a0, a2, a0 + extui a0, a0, 0, 3 -.Lunrecoverable_fixup: l32i a2, a3, EXC_TABLE_DOUBLE_SAVE - xsr a0, DEPC + xsr a3, excsave1 + beqi a0, 1, .L1pane + beqi a0, 3, .L3pane -.Lunrecoverable: - rsr a3, EXCSAVE_1 - wsr a0, EXCSAVE_1 - movi a0, unrecoverable_exception - callx0 a0 + rsr a0, depc + rotw -2 - .end literal_prefix + /* + * We are now in the user code's original window frame. + * Process the exception as a user exception as if it was + * taken by the user code. + * + * This is similar to the user exception vector, + * except that PT_DEPC isn't set to EXCCAUSE. + */ +1: + xsr a3, excsave1 + wsr a2, depc + l32i a2, a3, EXC_TABLE_KSTK + s32i a0, a2, PT_AREG0 + rsr a0, exccause + + s32i a0, a2, PT_DEPC + +_DoubleExceptionVector_handle_exception: + addx4 a0, a0, a3 + l32i a0, a0, EXC_TABLE_FAST_USER + xsr a3, excsave1 + jx a0 + +.L1pane: + rsr a0, depc + rotw -1 + j 1b + +.L3pane: + rsr a0, depc + rotw -3 + j 1b + + +ENDPROC(_DoubleExceptionVector) + +/* + * Fixup handler for TLB miss in double exception handler for window owerflow. + * We get here with windowbase set to the window that was being spilled and + * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12 + * (bit set) window. + * + * We do the following here: + * - go to the original window retaining a0 value; + * - set up exception stack to return back to appropriate a0 restore code + * (we'll need to rotate window back and there's no place to save this + * information, use different return address for that); + * - handle the exception; + * - go to the window that was being spilled; + * - set up window_overflow_restore_a0_fixup as a fixup routine; + * - reload a0; + * - restore the original window; + * - reset the default fixup routine; + * - return to user. By the time we get to this fixup handler all information + * about the conditions of the original double exception that happened in + * the window overflow handler is lost, so we just return to userspace to + * retry overflow from start. + * + * a0: value of depc, original value in depc + * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE + * a3: exctable, original value in excsave1 + */ + +ENTRY(window_overflow_restore_a0_fixup) + + rsr a0, ps + extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH + rsr a2, windowbase + sub a0, a2, a0 + extui a0, a0, 0, 3 + l32i a2, a3, EXC_TABLE_DOUBLE_SAVE + xsr a3, excsave1 + + _beqi a0, 1, .Lhandle_1 + _beqi a0, 3, .Lhandle_3 + + .macro overflow_fixup_handle_exception_pane n + + rsr a0, depc + rotw -\n + + xsr a3, excsave1 + wsr a2, depc + l32i a2, a3, EXC_TABLE_KSTK + s32i a0, a2, PT_AREG0 + + movi a0, .Lrestore_\n + s32i a0, a2, PT_DEPC + rsr a0, exccause + j _DoubleExceptionVector_handle_exception + + .endm + + overflow_fixup_handle_exception_pane 2 +.Lhandle_1: + overflow_fixup_handle_exception_pane 1 +.Lhandle_3: + overflow_fixup_handle_exception_pane 3 + + .macro overflow_fixup_restore_a0_pane n + + rotw \n + /* Need to preserve a0 value here to be able to handle exception + * that may occur on a0 reload from stack. It may occur because + * TLB miss handler may not be atomic and pointer to page table + * may be lost before we get here. There are no free registers, + * so we need to use EXC_TABLE_DOUBLE_SAVE area. + */ + xsr a3, excsave1 + s32i a2, a3, EXC_TABLE_DOUBLE_SAVE + movi a2, window_overflow_restore_a0_fixup + s32i a2, a3, EXC_TABLE_FIXUP + l32i a2, a3, EXC_TABLE_DOUBLE_SAVE + xsr a3, excsave1 + bbsi.l a0, 7, 1f + l32e a0, a9, -16 + j 2f +1: + l32e a0, a13, -16 +2: + rotw -\n + + .endm + +.Lrestore_2: + overflow_fixup_restore_a0_pane 2 + +.Lset_default_fixup: + xsr a3, excsave1 + s32i a2, a3, EXC_TABLE_DOUBLE_SAVE + movi a2, 0 + s32i a2, a3, EXC_TABLE_FIXUP + l32i a2, a3, EXC_TABLE_DOUBLE_SAVE + xsr a3, excsave1 + rfe + +.Lrestore_1: + overflow_fixup_restore_a0_pane 1 + j .Lset_default_fixup +.Lrestore_3: + overflow_fixup_restore_a0_pane 3 + j .Lset_default_fixup +ENDPROC(window_overflow_restore_a0_fixup) + .end literal_prefix /* * Debug interrupt vector * @@ -349,9 +592,49 @@ ENTRY(_DoubleExceptionVector) .section .DebugInterruptVector.text, "ax" ENTRY(_DebugInterruptVector) - xsr a0, EXCSAVE + XCHAL_DEBUGLEVEL + + xsr a0, SREG_EXCSAVE + XCHAL_DEBUGLEVEL jx a0 +ENDPROC(_DebugInterruptVector) + + + +/* + * Medium priority level interrupt vectors + * + * Each takes less than 16 (0x10) bytes, no literals, by placing + * the extra 8 bytes that would otherwise be required in the window + * vectors area where there is space. With relocatable vectors, + * all vectors are within ~ 4 kB range of each other, so we can + * simply jump (J) to another vector without having to use JX. + * + * common_exception code gets current IRQ level in PS.INTLEVEL + * and preserves it for the IRQ handling time. + */ + + .macro irq_entry_level level + + .if XCHAL_EXCM_LEVEL >= \level + .section .Level\level\()InterruptVector.text, "ax" +ENTRY(_Level\level\()InterruptVector) + wsr a0, excsave2 + rsr a0, epc\level + wsr a0, epc1 + movi a0, EXCCAUSE_LEVEL1_INTERRUPT + wsr a0, exccause + rsr a0, eps\level + # branch to user or kernel vector + j _SimulateUserKernelVectorException + .endif + + .endm + + irq_entry_level 2 + irq_entry_level 3 + irq_entry_level 4 + irq_entry_level 5 + irq_entry_level 6 /* Window overflow and underflow handlers. @@ -363,38 +646,61 @@ ENTRY(_DebugInterruptVector) * we try to access any page that would cause a page fault early. */ +#define ENTRY_ALIGN64(name) \ + .globl name; \ + .align 64; \ + name: + .section .WindowVectors.text, "ax" /* 4-Register Window Overflow Vector (Handler) */ - .align 64 -.global _WindowOverflow4 -_WindowOverflow4: +ENTRY_ALIGN64(_WindowOverflow4) + s32e a0, a5, -16 s32e a1, a5, -12 s32e a2, a5, -8 s32e a3, a5, -4 rfwo +ENDPROC(_WindowOverflow4) + + +#if XCHAL_EXCM_LEVEL >= 2 + /* Not a window vector - but a convenient location + * (where we know there's space) for continuation of + * medium priority interrupt dispatch code. + * On entry here, a0 contains PS, and EPC2 contains saved a0: + */ + .align 4 +_SimulateUserKernelVectorException: + addi a0, a0, (1 << PS_EXCM_BIT) + wsr a0, ps + bbsi.l a0, PS_UM_BIT, 1f # branch if user mode + rsr a0, excsave2 # restore a0 + j _KernelExceptionVector # simulate kernel vector exception +1: rsr a0, excsave2 # restore a0 + j _UserExceptionVector # simulate user vector exception +#endif + /* 4-Register Window Underflow Vector (Handler) */ - .align 64 -.global _WindowUnderflow4 -_WindowUnderflow4: +ENTRY_ALIGN64(_WindowUnderflow4) + l32e a0, a5, -16 l32e a1, a5, -12 l32e a2, a5, -8 l32e a3, a5, -4 rfwu +ENDPROC(_WindowUnderflow4) /* 8-Register Window Overflow Vector (Handler) */ - .align 64 -.global _WindowOverflow8 -_WindowOverflow8: +ENTRY_ALIGN64(_WindowOverflow8) + s32e a0, a9, -16 l32e a0, a1, -12 s32e a2, a9, -8 @@ -406,11 +712,12 @@ _WindowOverflow8: s32e a7, a0, -20 rfwo +ENDPROC(_WindowOverflow8) + /* 8-Register Window Underflow Vector (Handler) */ - .align 64 -.global _WindowUnderflow8 -_WindowUnderflow8: +ENTRY_ALIGN64(_WindowUnderflow8) + l32e a1, a9, -12 l32e a0, a9, -16 l32e a7, a1, -12 @@ -422,12 +729,12 @@ _WindowUnderflow8: l32e a7, a7, -20 rfwu +ENDPROC(_WindowUnderflow8) /* 12-Register Window Overflow Vector (Handler) */ - .align 64 -.global _WindowOverflow12 -_WindowOverflow12: +ENTRY_ALIGN64(_WindowOverflow12) + s32e a0, a13, -16 l32e a0, a1, -12 s32e a1, a13, -12 @@ -443,11 +750,12 @@ _WindowOverflow12: s32e a11, a0, -20 rfwo +ENDPROC(_WindowOverflow12) + /* 12-Register Window Underflow Vector (Handler) */ - .align 64 -.global _WindowUnderflow12 -_WindowUnderflow12: +ENTRY_ALIGN64(_WindowUnderflow12) + l32e a1, a13, -12 l32e a0, a13, -16 l32e a11, a1, -12 @@ -463,6 +771,6 @@ _WindowUnderflow12: l32e a11, a11, -20 rfwu - .text - +ENDPROC(_WindowUnderflow12) + .text |