diff options
Diffstat (limited to 'arch/xtensa/kernel/entry.S')
| -rw-r--r-- | arch/xtensa/kernel/entry.S | 387 |
1 files changed, 123 insertions, 264 deletions
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 9298742f0fd0..de1dfa18d0a1 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -31,8 +31,6 @@ /* Unimplemented features. */ #undef KERNEL_STACK_OVERFLOW_CHECK -#undef PREEMPTIBLE_KERNEL -#undef ALLOCA_EXCEPTION_IN_IRAM /* Not well tested. * @@ -92,9 +90,9 @@ * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original value in depc - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave1: a3 + * excsave1: dispatch table * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception @@ -110,9 +108,8 @@ ENTRY(user_exception) - /* Save a2, a3, and depc, restore excsave_1 and set SP. */ + /* Save a1, a2, a3, and set SP. */ - xsr a3, excsave1 rsr a0, depc s32i a1, a2, PT_AREG1 s32i a0, a2, PT_AREG2 @@ -238,9 +235,9 @@ ENDPROC(user_exception) * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception @@ -256,9 +253,8 @@ ENDPROC(user_exception) ENTRY(kernel_exception) - /* Save a0, a2, a3, DEPC and set SP. */ + /* Save a1, a2, a3, and set SP. */ - xsr a3, excsave1 # restore a3, excsave_1 rsr a0, depc # get a2 s32i a1, a2, PT_AREG1 s32i a0, a2, PT_AREG2 @@ -409,7 +405,7 @@ common_exception: * exception handler and call the exception handler. */ - movi a4, exc_table + rsr a4, excsave1 mov a6, a1 # pass stack frame mov a7, a0 # pass EXCCAUSE addx4 a4, a0, a4 @@ -423,28 +419,15 @@ common_exception: .global common_exception_return common_exception_return: -#ifdef CONFIG_TRACE_IRQFLAGS - l32i a4, a1, PT_DEPC - /* Double exception means we came here with an exception - * while PS.EXCM was set, i.e. interrupts disabled. - */ - bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f - l32i a4, a1, PT_EXCCAUSE - bnei a4, EXCCAUSE_LEVEL1_INTERRUPT, 1f - /* We came here with an interrupt means interrupts were enabled - * and we'll reenable them on return. - */ - movi a4, trace_hardirqs_on - callx4 a4 1: -#endif + rsil a2, LOCKLEVEL /* Jump if we are returning from kernel exceptions. */ -1: l32i a3, a1, PT_PS - _bbci.l a3, PS_UM_BIT, 4f - - rsil a2, 0 + l32i a3, a1, PT_PS + GET_THREAD_INFO(a2, a1) + l32i a4, a2, TI_FLAGS + _bbci.l a3, PS_UM_BIT, 6f /* Specific to a user exception exit: * We need to check some flags for signal handling and rescheduling, @@ -453,9 +436,6 @@ common_exception_return: * Note that we don't disable interrupts here. */ - GET_THREAD_INFO(a2,a1) - l32i a4, a2, TI_FLAGS - _bbsi.l a4, TIF_NEED_RESCHED, 3f _bbsi.l a4, TIF_NOTIFY_RESUME, 2f _bbci.l a4, TIF_SIGPENDING, 5f @@ -465,6 +445,7 @@ common_exception_return: /* Call do_signal() */ + rsil a2, 0 movi a4, do_notify_resume # int do_notify_resume(struct pt_regs*) mov a6, a1 callx4 a4 @@ -472,10 +453,24 @@ common_exception_return: 3: /* Reschedule */ + rsil a2, 0 movi a4, schedule # void schedule (void) callx4 a4 j 1b +#ifdef CONFIG_PREEMPT +6: + _bbci.l a4, TIF_NEED_RESCHED, 4f + + /* Check current_thread_info->preempt_count */ + + l32i a4, a2, TI_PRE_COUNT + bnez a4, 4f + movi a4, preempt_schedule_irq + callx4 a4 + j 1b +#endif + 5: #ifdef CONFIG_DEBUG_TLB_SANITY l32i a4, a1, PT_DEPC @@ -483,7 +478,24 @@ common_exception_return: movi a4, check_tlb_sanity callx4 a4 #endif -4: /* Restore optional registers. */ +6: +4: +#ifdef CONFIG_TRACE_IRQFLAGS + l32i a4, a1, PT_DEPC + /* Double exception means we came here with an exception + * while PS.EXCM was set, i.e. interrupts disabled. + */ + bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f + l32i a4, a1, PT_EXCCAUSE + bnei a4, EXCCAUSE_LEVEL1_INTERRUPT, 1f + /* We came here with an interrupt means interrupts were enabled + * and we'll reenable them on return. + */ + movi a4, trace_hardirqs_on + callx4 a4 +1: +#endif + /* Restore optional registers. */ load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT @@ -570,29 +582,6 @@ user_exception_exit: kernel_exception_exit: -#ifdef PREEMPTIBLE_KERNEL - -#ifdef CONFIG_PREEMPT - - /* - * Note: We've just returned from a call4, so we have - * at least 4 addt'l regs. - */ - - /* Check current_thread_info->preempt_count */ - - GET_THREAD_INFO(a2) - l32i a3, a2, TI_PREEMPT - bnez a3, 1f - - l32i a2, a2, TI_FLAGS - -1: - -#endif - -#endif - /* Check if we have to do a movsp. * * We only have to do a movsp if the previous window-frame has @@ -829,176 +818,63 @@ ENDPROC(unrecoverable_exception) * * The ALLOCA handler is entered when user code executes the MOVSP * instruction and the caller's frame is not in the register file. - * In this case, the caller frame's a0..a3 are on the stack just - * below sp (a1), and this handler moves them. * - * For "MOVSP <ar>,<as>" without destination register a1, this routine - * simply moves the value from <as> to <ar> without moving the save area. + * This algorithm was taken from the Ross Morley's RTOS Porting Layer: + * + * /home/ross/rtos/porting/XtensaRTOS-PortingLayer-20090507/xtensa_vectors.S + * + * It leverages the existing window spill/fill routines and their support for + * double exceptions. The 'movsp' instruction will only cause an exception if + * the next window needs to be loaded. In fact this ALLOCA exception may be + * replaced at some point by changing the hardware to do a underflow exception + * of the proper size instead. + * + * This algorithm simply backs out the register changes started by the user + * excpetion handler, makes it appear that we have started a window underflow + * by rotating the window back and then setting the old window base (OWB) in + * the 'ps' register with the rolled back window base. The 'movsp' instruction + * will be re-executed and this time since the next window frames is in the + * active AR registers it won't cause an exception. + * + * If the WindowUnderflow code gets a TLB miss the page will get mapped + * the the partial windeowUnderflow will be handeled in the double exception + * handler. * * Entry condition: * * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception */ -#if XCHAL_HAVE_BE -#define _EXTUI_MOVSP_SRC(ar) extui ar, ar, 4, 4 -#define _EXTUI_MOVSP_DST(ar) extui ar, ar, 0, 4 -#else -#define _EXTUI_MOVSP_SRC(ar) extui ar, ar, 0, 4 -#define _EXTUI_MOVSP_DST(ar) extui ar, ar, 4, 4 -#endif - ENTRY(fast_alloca) + rsr a0, windowbase + rotw -1 + rsr a2, ps + extui a3, a2, PS_OWB_SHIFT, PS_OWB_WIDTH + xor a3, a3, a4 + l32i a4, a6, PT_AREG0 + l32i a1, a6, PT_DEPC + rsr a6, depc + wsr a1, depc + slli a3, a3, PS_OWB_SHIFT + xor a2, a2, a3 + wsr a2, ps + rsync - /* We shouldn't be in a double exception. */ - - l32i a0, a2, PT_DEPC - _bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lunhandled_double - - rsr a0, depc # get a2 - s32i a4, a2, PT_AREG4 # save a4 and - s32i a0, a2, PT_AREG2 # a2 to stack - - /* Exit critical section. */ - - movi a0, 0 - s32i a0, a3, EXC_TABLE_FIXUP - - /* Restore a3, excsave_1 */ - - xsr a3, excsave1 # make sure excsave_1 is valid for dbl. - rsr a4, epc1 # get exception address - s32i a3, a2, PT_AREG3 # save a3 to stack - -#ifdef ALLOCA_EXCEPTION_IN_IRAM -#error iram not supported -#else - /* Note: l8ui not allowed in IRAM/IROM!! */ - l8ui a0, a4, 1 # read as(src) from MOVSP instruction -#endif - movi a3, .Lmovsp_src - _EXTUI_MOVSP_SRC(a0) # extract source register number - addx8 a3, a0, a3 - jx a3 - -.Lunhandled_double: - wsr a0, excsave1 - movi a0, unrecoverable_exception - callx0 a0 - - .align 8 -.Lmovsp_src: - l32i a3, a2, PT_AREG0; _j 1f; .align 8 - mov a3, a1; _j 1f; .align 8 - l32i a3, a2, PT_AREG2; _j 1f; .align 8 - l32i a3, a2, PT_AREG3; _j 1f; .align 8 - l32i a3, a2, PT_AREG4; _j 1f; .align 8 - mov a3, a5; _j 1f; .align 8 - mov a3, a6; _j 1f; .align 8 - mov a3, a7; _j 1f; .align 8 - mov a3, a8; _j 1f; .align 8 - mov a3, a9; _j 1f; .align 8 - mov a3, a10; _j 1f; .align 8 - mov a3, a11; _j 1f; .align 8 - mov a3, a12; _j 1f; .align 8 - mov a3, a13; _j 1f; .align 8 - mov a3, a14; _j 1f; .align 8 - mov a3, a15; _j 1f; .align 8 - -1: - -#ifdef ALLOCA_EXCEPTION_IN_IRAM -#error iram not supported -#else - l8ui a0, a4, 0 # read ar(dst) from MOVSP instruction -#endif - addi a4, a4, 3 # step over movsp - _EXTUI_MOVSP_DST(a0) # extract destination register - wsr a4, epc1 # save new epc_1 - - _bnei a0, 1, 1f # no 'movsp a1, ax': jump - - /* Move the save area. This implies the use of the L32E - * and S32E instructions, because this move must be done with - * the user's PS.RING privilege levels, not with ring 0 - * (kernel's) privileges currently active with PS.EXCM - * set. Note that we have stil registered a fixup routine with the - * double exception vector in case a double exception occurs. - */ - - /* a0,a4:avail a1:old user stack a2:exc. stack a3:new user stack. */ - - l32e a0, a1, -16 - l32e a4, a1, -12 - s32e a0, a3, -16 - s32e a4, a3, -12 - l32e a0, a1, -8 - l32e a4, a1, -4 - s32e a0, a3, -8 - s32e a4, a3, -4 - - /* Restore stack-pointer and all the other saved registers. */ - - mov a1, a3 - - l32i a4, a2, PT_AREG4 - l32i a3, a2, PT_AREG3 - l32i a0, a2, PT_AREG0 - l32i a2, a2, PT_AREG2 - rfe - - /* MOVSP <at>,<as> was invoked with <at> != a1. - * Because the stack pointer is not being modified, - * we should be able to just modify the pointer - * without moving any save area. - * The processor only traps these occurrences if the - * caller window isn't live, so unfortunately we can't - * use this as an alternate trap mechanism. - * So we just do the move. This requires that we - * resolve the destination register, not just the source, - * so there's some extra work. - * (PERHAPS NOT REALLY NEEDED, BUT CLEANER...) - */ - - /* a0 dst-reg, a1 user-stack, a2 stack, a3 value of src reg. */ - -1: movi a4, .Lmovsp_dst - addx8 a4, a0, a4 - jx a4 - - .align 8 -.Lmovsp_dst: - s32i a3, a2, PT_AREG0; _j 1f; .align 8 - mov a1, a3; _j 1f; .align 8 - s32i a3, a2, PT_AREG2; _j 1f; .align 8 - s32i a3, a2, PT_AREG3; _j 1f; .align 8 - s32i a3, a2, PT_AREG4; _j 1f; .align 8 - mov a5, a3; _j 1f; .align 8 - mov a6, a3; _j 1f; .align 8 - mov a7, a3; _j 1f; .align 8 - mov a8, a3; _j 1f; .align 8 - mov a9, a3; _j 1f; .align 8 - mov a10, a3; _j 1f; .align 8 - mov a11, a3; _j 1f; .align 8 - mov a12, a3; _j 1f; .align 8 - mov a13, a3; _j 1f; .align 8 - mov a14, a3; _j 1f; .align 8 - mov a15, a3; _j 1f; .align 8 - -1: l32i a4, a2, PT_AREG4 - l32i a3, a2, PT_AREG3 - l32i a0, a2, PT_AREG0 - l32i a2, a2, PT_AREG2 - rfe - + _bbci.l a4, 31, 4f + rotw -1 + _bbci.l a8, 30, 8f + rotw -1 + j _WindowUnderflow12 +8: j _WindowUnderflow8 +4: j _WindowUnderflow4 ENDPROC(fast_alloca) /* @@ -1015,9 +891,9 @@ ENDPROC(fast_alloca) * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table */ ENTRY(fast_syscall_kernel) @@ -1064,7 +940,6 @@ ENTRY(fast_syscall_unrecoverable) l32i a0, a2, PT_AREG0 # restore a0 xsr a2, depc # restore a2, depc - rsr a3, excsave1 wsr a0, excsave1 movi a0, unrecoverable_exception @@ -1086,10 +961,10 @@ ENDPROC(fast_syscall_unrecoverable) * a0: a2 (syscall-nr), original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in a0 and DEPC - * a3: dispatch table, original in excsave_1 + * a3: a3 * a4..a15: unchanged * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception @@ -1122,8 +997,6 @@ ENDPROC(fast_syscall_unrecoverable) ENTRY(fast_syscall_xtensa) - xsr a3, excsave1 # restore a3, excsave1 - s32i a7, a2, PT_AREG7 # we need an additional register movi a7, 4 # sizeof(unsigned int) access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp @@ -1186,9 +1059,9 @@ ENDPROC(fast_syscall_xtensa) * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table * * Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler. */ @@ -1197,15 +1070,16 @@ ENTRY(fast_syscall_spill_registers) /* Register a FIXUP handler (pass current wb as a parameter) */ + xsr a3, excsave1 movi a0, fast_syscall_spill_registers_fixup s32i a0, a3, EXC_TABLE_FIXUP rsr a0, windowbase s32i a0, a3, EXC_TABLE_PARAM + xsr a3, excsave1 # restore a3 and excsave_1 - /* Save a3 and SAR on stack. */ + /* Save a3, a4 and SAR on stack. */ rsr a0, sar - xsr a3, excsave1 # restore a3 and excsave_1 s32i a3, a2, PT_AREG3 s32i a4, a2, PT_AREG4 s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5 @@ -1259,14 +1133,14 @@ fast_syscall_spill_registers_fixup: * in WS, so that the exception handlers save them to the task stack. */ - rsr a3, excsave1 # get spill-mask + xsr a3, excsave1 # get spill-mask slli a2, a3, 1 # shift left by one slli a3, a2, 32-WSBITS src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy...... wsr a2, windowstart # set corrected windowstart - movi a3, exc_table + rsr a3, excsave1 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2 l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task) @@ -1303,7 +1177,7 @@ fast_syscall_spill_registers_fixup: /* Jump to the exception handler. */ - movi a3, exc_table + rsr a3, excsave1 rsr a0, exccause addx4 a0, a0, a3 # find entry in table l32i a0, a0, EXC_TABLE_FAST_USER # load handler @@ -1320,6 +1194,7 @@ fast_syscall_spill_registers_fixup_return: xsr a3, excsave1 movi a2, fast_syscall_spill_registers_fixup s32i a2, a3, EXC_TABLE_FIXUP + s32i a0, a3, EXC_TABLE_DOUBLE_SAVE rsr a2, windowbase s32i a2, a3, EXC_TABLE_PARAM l32i a2, a3, EXC_TABLE_KSTK @@ -1331,11 +1206,6 @@ fast_syscall_spill_registers_fixup_return: wsr a3, windowbase rsync - /* Restore a3 and return. */ - - movi a3, exc_table - xsr a3, excsave1 - rfde @@ -1522,9 +1392,8 @@ ENTRY(_spill_registers) movi a0, 0 - movi a3, exc_table + rsr a3, excsave1 l32i a1, a3, EXC_TABLE_KSTK - wsr a3, excsave1 movi a4, (1 << PS_WOE_BIT) | LOCKLEVEL wsr a4, ps @@ -1568,9 +1437,9 @@ ENDPROC(fast_second_level_miss_double_kernel) * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception @@ -1578,9 +1447,10 @@ ENDPROC(fast_second_level_miss_double_kernel) ENTRY(fast_second_level_miss) - /* Save a1. Note: we don't expect a double exception. */ + /* Save a1 and a3. Note: we don't expect a double exception. */ s32i a1, a2, PT_AREG1 + s32i a3, a2, PT_AREG3 /* We need to map the page of PTEs for the user task. Find * the pointer to that page. Also, it's possible for tsk->mm @@ -1602,9 +1472,6 @@ ENTRY(fast_second_level_miss) l32i a0, a1, TASK_MM # tsk->mm beqz a0, 9f - - /* We deliberately destroy a3 that holds the exception table. */ - 8: rsr a3, excvaddr # fault address _PGD_OFFSET(a0, a3, a1) l32i a0, a0, 0 # read pmdval @@ -1655,7 +1522,7 @@ ENTRY(fast_second_level_miss) /* Exit critical section. */ -4: movi a3, exc_table # restore a3 +4: rsr a3, excsave1 movi a0, 0 s32i a0, a3, EXC_TABLE_FIXUP @@ -1663,8 +1530,8 @@ ENTRY(fast_second_level_miss) l32i a0, a2, PT_AREG0 l32i a1, a2, PT_AREG1 + l32i a3, a2, PT_AREG3 l32i a2, a2, PT_DEPC - xsr a3, excsave1 bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f @@ -1751,11 +1618,8 @@ ENTRY(fast_second_level_miss) 2: /* Invalid PGD, default exception handling */ - movi a3, exc_table rsr a1, depc - xsr a3, excsave1 s32i a1, a2, PT_AREG2 - s32i a3, a2, PT_AREG3 mov a1, a2 rsr a2, ps @@ -1775,9 +1639,9 @@ ENDPROC(fast_second_level_miss) * a0: trashed, original value saved on stack (PT_AREG0) * a1: a1 * a2: new stack pointer, original in DEPC - * a3: dispatch table + * a3: a3 * depc: a2, original value saved on stack (PT_DEPC) - * excsave_1: a3 + * excsave_1: dispatch table * * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception @@ -1785,17 +1649,17 @@ ENDPROC(fast_second_level_miss) ENTRY(fast_store_prohibited) - /* Save a1 and a4. */ + /* Save a1 and a3. */ s32i a1, a2, PT_AREG1 - s32i a4, a2, PT_AREG4 + s32i a3, a2, PT_AREG3 GET_CURRENT(a1,a2) l32i a0, a1, TASK_MM # tsk->mm beqz a0, 9f 8: rsr a1, excvaddr # fault address - _PGD_OFFSET(a0, a1, a4) + _PGD_OFFSET(a0, a1, a3) l32i a0, a0, 0 beqz a0, 2f @@ -1804,39 +1668,37 @@ ENTRY(fast_store_prohibited) * and is not PAGE_NONE. See pgtable.h for possible PTE layouts. */ - _PTE_OFFSET(a0, a1, a4) - l32i a4, a0, 0 # read pteval + _PTE_OFFSET(a0, a1, a3) + l32i a3, a0, 0 # read pteval movi a1, _PAGE_CA_INVALID - ball a4, a1, 2f - bbci.l a4, _PAGE_WRITABLE_BIT, 2f + ball a3, a1, 2f + bbci.l a3, _PAGE_WRITABLE_BIT, 2f movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE - or a4, a4, a1 + or a3, a3, a1 rsr a1, excvaddr - s32i a4, a0, 0 + s32i a3, a0, 0 /* We need to flush the cache if we have page coloring. */ #if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK dhwb a0, 0 #endif pdtlb a0, a1 - wdtlb a4, a0 + wdtlb a3, a0 /* Exit critical section. */ movi a0, 0 + rsr a3, excsave1 s32i a0, a3, EXC_TABLE_FIXUP /* Restore the working registers, and return. */ - l32i a4, a2, PT_AREG4 + l32i a3, a2, PT_AREG3 l32i a1, a2, PT_AREG1 l32i a0, a2, PT_AREG0 l32i a2, a2, PT_DEPC - /* Restore excsave1 and a3. */ - - xsr a3, excsave1 bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f rsr a2, depc @@ -1853,11 +1715,8 @@ ENTRY(fast_store_prohibited) 2: /* If there was a problem, handle fault in C */ - rsr a4, depc # still holds a2 - xsr a3, excsave1 - s32i a4, a2, PT_AREG2 - s32i a3, a2, PT_AREG3 - l32i a4, a2, PT_AREG4 + rsr a3, depc # still holds a2 + s32i a3, a2, PT_AREG2 mov a1, a2 rsr a2, ps |