| /* |
| * Exception handling for Microblaze |
| * |
| * Rewriten interrupt handling |
| * |
| * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu> |
| * Copyright (C) 2008-2009 PetaLogix |
| * |
| * uClinux customisation (C) 2005 John Williams |
| * |
| * MMU code derived from arch/ppc/kernel/head_4xx.S: |
| * Copyright (C) 1995-1996 Gary Thomas <gdt@linuxppc.org> |
| * Initial PowerPC version. |
| * Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu> |
| * Rewritten for PReP |
| * Copyright (C) 1996 Paul Mackerras <paulus@cs.anu.edu.au> |
| * Low-level exception handers, MMU support, and rewrite. |
| * Copyright (C) 1997 Dan Malek <dmalek@jlc.net> |
| * PowerPC 8xx modifications. |
| * Copyright (C) 1998-1999 TiVo, Inc. |
| * PowerPC 403GCX modifications. |
| * Copyright (C) 1999 Grant Erickson <grant@lcse.umn.edu> |
| * PowerPC 403GCX/405GP modifications. |
| * Copyright 2000 MontaVista Software Inc. |
| * PPC405 modifications |
| * PowerPC 403GCX/405GP modifications. |
| * Author: MontaVista Software, Inc. |
| * frank_rowand@mvista.com or source@mvista.com |
| * debbie_chu@mvista.com |
| * |
| * Original code |
| * Copyright (C) 2004 Xilinx, Inc. |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 as published |
| * by the Free Software Foundation. |
| */ |
| |
| /* |
| * Here are the handlers which don't require enabling translation |
| * and calling other kernel code thus we can keep their design very simple |
| * and do all processing in real mode. All what they need is a valid current |
| * (that is an issue for the CONFIG_REGISTER_TASK_PTR case) |
| * This handlers use r3,r4,r5,r6 and optionally r[current] to work therefore |
| * these registers are saved/restored |
| * The handlers which require translation are in entry.S --KAA |
| * |
| * Microblaze HW Exception Handler |
| * - Non self-modifying exception handler for the following exception conditions |
| * - Unalignment |
| * - Instruction bus error |
| * - Data bus error |
| * - Illegal instruction opcode |
| * - Divide-by-zero |
| * |
| * - Privileged instruction exception (MMU) |
| * - Data storage exception (MMU) |
| * - Instruction storage exception (MMU) |
| * - Data TLB miss exception (MMU) |
| * - Instruction TLB miss exception (MMU) |
| * |
| * Note we disable interrupts during exception handling, otherwise we will |
| * possibly get multiple re-entrancy if interrupt handles themselves cause |
| * exceptions. JW |
| */ |
| |
| #include <asm/exceptions.h> |
| #include <asm/unistd.h> |
| #include <asm/page.h> |
| |
| #include <asm/entry.h> |
| #include <asm/current.h> |
| #include <linux/linkage.h> |
| |
| #include <asm/mmu.h> |
| #include <asm/pgtable.h> |
| #include <asm/signal.h> |
| #include <asm/asm-offsets.h> |
| |
| /* Helpful Macros */ |
| #define NUM_TO_REG(num) r ## num |
| |
| #ifdef CONFIG_MMU |
| #define RESTORE_STATE \ |
| lwi r5, r1, 0; \ |
| mts rmsr, r5; \ |
| nop; \ |
| lwi r3, r1, PT_R3; \ |
| lwi r4, r1, PT_R4; \ |
| lwi r5, r1, PT_R5; \ |
| lwi r6, r1, PT_R6; \ |
| lwi r11, r1, PT_R11; \ |
| lwi r31, r1, PT_R31; \ |
| lwi r1, r0, TOPHYS(r0_ram + 0); |
| #endif /* CONFIG_MMU */ |
| |
| #define LWREG_NOP \ |
| bri ex_handler_unhandled; \ |
| nop; |
| |
| #define SWREG_NOP \ |
| bri ex_handler_unhandled; \ |
| nop; |
| |
| /* FIXME this is weird - for noMMU kernel is not possible to use brid |
| * instruction which can shorten executed time |
| */ |
| |
| /* r3 is the source */ |
| #define R3_TO_LWREG_V(regnum) \ |
| swi r3, r1, 4 * regnum; \ |
| bri ex_handler_done; |
| |
| /* r3 is the source */ |
| #define R3_TO_LWREG(regnum) \ |
| or NUM_TO_REG (regnum), r0, r3; \ |
| bri ex_handler_done; |
| |
| /* r3 is the target */ |
| #define SWREG_TO_R3_V(regnum) \ |
| lwi r3, r1, 4 * regnum; \ |
| bri ex_sw_tail; |
| |
| /* r3 is the target */ |
| #define SWREG_TO_R3(regnum) \ |
| or r3, r0, NUM_TO_REG (regnum); \ |
| bri ex_sw_tail; |
| |
| #ifdef CONFIG_MMU |
| #define R3_TO_LWREG_VM_V(regnum) \ |
| brid ex_lw_end_vm; \ |
| swi r3, r7, 4 * regnum; |
| |
| #define R3_TO_LWREG_VM(regnum) \ |
| brid ex_lw_end_vm; \ |
| or NUM_TO_REG (regnum), r0, r3; |
| |
| #define SWREG_TO_R3_VM_V(regnum) \ |
| brid ex_sw_tail_vm; \ |
| lwi r3, r7, 4 * regnum; |
| |
| #define SWREG_TO_R3_VM(regnum) \ |
| brid ex_sw_tail_vm; \ |
| or r3, r0, NUM_TO_REG (regnum); |
| |
| /* Shift right instruction depending on available configuration */ |
| #if CONFIG_XILINX_MICROBLAZE0_USE_BARREL > 0 |
| #define BSRLI(rD, rA, imm) \ |
| bsrli rD, rA, imm |
| #elif CONFIG_XILINX_MICROBLAZE0_USE_DIV > 0 |
| #define BSRLI(rD, rA, imm) \ |
| ori rD, r0, (1 << imm); \ |
| idivu rD, rD, rA |
| #else |
| #define BSRLI(rD, rA, imm) BSRLI ## imm (rD, rA) |
| /* Only the used shift constants defined here - add more if needed */ |
| #define BSRLI2(rD, rA) \ |
| srl rD, rA; /* << 1 */ \ |
| srl rD, rD; /* << 2 */ |
| #define BSRLI10(rD, rA) \ |
| srl rD, rA; /* << 1 */ \ |
| srl rD, rD; /* << 2 */ \ |
| srl rD, rD; /* << 3 */ \ |
| srl rD, rD; /* << 4 */ \ |
| srl rD, rD; /* << 5 */ \ |
| srl rD, rD; /* << 6 */ \ |
| srl rD, rD; /* << 7 */ \ |
| srl rD, rD; /* << 8 */ \ |
| srl rD, rD; /* << 9 */ \ |
| srl rD, rD /* << 10 */ |
| #define BSRLI20(rD, rA) \ |
| BSRLI10(rD, rA); \ |
| BSRLI10(rD, rD) |
| #endif |
| #endif /* CONFIG_MMU */ |
| |
| .extern other_exception_handler /* Defined in exception.c */ |
| |
| /* |
| * hw_exception_handler - Handler for exceptions |
| * |
| * Exception handler notes: |
| * - Handles all exceptions |
| * - Does not handle unaligned exceptions during load into r17, r1, r0. |
| * - Does not handle unaligned exceptions during store from r17 (cannot be |
| * done) and r1 (slows down common case) |
| * |
| * Relevant register structures |
| * |
| * EAR - |----|----|----|----|----|----|----|----| |
| * - < ## 32 bit faulting address ## > |
| * |
| * ESR - |----|----|----|----|----| - | - |-----|-----| |
| * - W S REG EXC |
| * |
| * |
| * STACK FRAME STRUCTURE (for NO_MMU) |
| * --------------------------------- |
| * |
| * +-------------+ + 0 |
| * | MSR | |
| * +-------------+ + 4 |
| * | r1 | |
| * | . | |
| * | . | |
| * | . | |
| * | . | |
| * | r18 | |
| * +-------------+ + 76 |
| * | . | |
| * | . | |
| * |
| * NO_MMU kernel use the same r0_ram pointed space - look to vmlinux.lds.S |
| * which is used for storing register values - old style was, that value were |
| * stored in stack but in case of failure you lost information about register. |
| * Currently you can see register value in memory in specific place. |
| * In compare to with previous solution the speed should be the same. |
| * |
| * MMU exception handler has different handling compare to no MMU kernel. |
| * Exception handler use jump table for directing of what happen. For MMU kernel |
| * is this approach better because MMU relate exception are handled by asm code |
| * in this file. In compare to with MMU expect of unaligned exception |
| * is everything handled by C code. |
| */ |
| |
| /* |
| * every of these handlers is entered having R3/4/5/6/11/current saved on stack |
| * and clobbered so care should be taken to restore them if someone is going to |
| * return from exception |
| */ |
| |
| /* wrappers to restore state before coming to entry.S */ |
| |
| #ifdef CONFIG_MMU |
| .section .rodata |
| .align 4 |
| _MB_HW_ExceptionVectorTable: |
| /* 0 - Undefined */ |
| .long TOPHYS(ex_handler_unhandled) |
| /* 1 - Unaligned data access exception */ |
| .long TOPHYS(handle_unaligned_ex) |
| /* 2 - Illegal op-code exception */ |
| .long TOPHYS(full_exception_trapw) |
| /* 3 - Instruction bus error exception */ |
| .long TOPHYS(full_exception_trapw) |
| /* 4 - Data bus error exception */ |
| .long TOPHYS(full_exception_trapw) |
| /* 5 - Divide by zero exception */ |
| .long TOPHYS(full_exception_trapw) |
| /* 6 - Floating point unit exception */ |
| .long TOPHYS(full_exception_trapw) |
| /* 7 - Privileged instruction exception */ |
| .long TOPHYS(full_exception_trapw) |
| /* 8 - 15 - Undefined */ |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| /* 16 - Data storage exception */ |
| .long TOPHYS(handle_data_storage_exception) |
| /* 17 - Instruction storage exception */ |
| .long TOPHYS(handle_instruction_storage_exception) |
| /* 18 - Data TLB miss exception */ |
| .long TOPHYS(handle_data_tlb_miss_exception) |
| /* 19 - Instruction TLB miss exception */ |
| .long TOPHYS(handle_instruction_tlb_miss_exception) |
| /* 20 - 31 - Undefined */ |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| .long TOPHYS(ex_handler_unhandled) |
| #endif |
| |
| .global _hw_exception_handler |
| .section .text |
| .align 4 |
| .ent _hw_exception_handler |
| _hw_exception_handler: |
| #ifndef CONFIG_MMU |
| addik r1, r1, -(EX_HANDLER_STACK_SIZ); /* Create stack frame */ |
| #else |
| swi r1, r0, TOPHYS(r0_ram + 0); /* GET_SP */ |
| /* Save date to kernel memory. Here is the problem |
| * when you came from user space */ |
| ori r1, r0, TOPHYS(r0_ram + 28); |
| #endif |
| swi r3, r1, PT_R3 |
| swi r4, r1, PT_R4 |
| swi r5, r1, PT_R5 |
| swi r6, r1, PT_R6 |
| |
| #ifdef CONFIG_MMU |
| swi r11, r1, PT_R11 |
| swi r31, r1, PT_R31 |
| lwi r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE)) /* get saved current */ |
| #endif |
| |
| mfs r5, rmsr; |
| nop |
| swi r5, r1, 0; |
| mfs r4, resr |
| nop |
| mfs r3, rear; |
| nop |
| |
| #ifndef CONFIG_MMU |
| andi r5, r4, 0x1000; /* Check ESR[DS] */ |
| beqi r5, not_in_delay_slot; /* Branch if ESR[DS] not set */ |
| mfs r17, rbtr; /* ESR[DS] set - return address in BTR */ |
| nop |
| not_in_delay_slot: |
| swi r17, r1, PT_R17 |
| #endif |
| |
| andi r5, r4, 0x1F; /* Extract ESR[EXC] */ |
| |
| #ifdef CONFIG_MMU |
| /* Calculate exception vector offset = r5 << 2 */ |
| addk r6, r5, r5; /* << 1 */ |
| addk r6, r6, r6; /* << 2 */ |
| |
| #ifdef DEBUG |
| /* counting which exception happen */ |
| lwi r5, r0, 0x200 + TOPHYS(r0_ram) |
| addi r5, r5, 1 |
| swi r5, r0, 0x200 + TOPHYS(r0_ram) |
| lwi r5, r6, 0x200 + TOPHYS(r0_ram) |
| addi r5, r5, 1 |
| swi r5, r6, 0x200 + TOPHYS(r0_ram) |
| #endif |
| /* end */ |
| /* Load the HW Exception vector */ |
| lwi r6, r6, TOPHYS(_MB_HW_ExceptionVectorTable) |
| bra r6 |
| |
| full_exception_trapw: |
| RESTORE_STATE |
| bri full_exception_trap |
| #else |
| /* Exceptions enabled here. This will allow nested exceptions */ |
| mfs r6, rmsr; |
| nop |
| swi r6, r1, 0; /* RMSR_OFFSET */ |
| ori r6, r6, 0x100; /* Turn ON the EE bit */ |
| andi r6, r6, ~2; /* Disable interrupts */ |
| mts rmsr, r6; |
| nop |
| |
| xori r6, r5, 1; /* 00001 = Unaligned Exception */ |
| /* Jump to unalignment exception handler */ |
| beqi r6, handle_unaligned_ex; |
| |
| handle_other_ex: /* Handle Other exceptions here */ |
| /* Save other volatiles before we make procedure calls below */ |
| swi r7, r1, PT_R7 |
| swi r8, r1, PT_R8 |
| swi r9, r1, PT_R9 |
| swi r10, r1, PT_R10 |
| swi r11, r1, PT_R11 |
| swi r12, r1, PT_R12 |
| swi r14, r1, PT_R14 |
| swi r15, r1, PT_R15 |
| swi r18, r1, PT_R18 |
| |
| or r5, r1, r0 |
| andi r6, r4, 0x1F; /* Load ESR[EC] */ |
| lwi r7, r0, PER_CPU(KM) /* MS: saving current kernel mode to regs */ |
| swi r7, r1, PT_MODE |
| mfs r7, rfsr |
| nop |
| addk r8, r17, r0; /* Load exception address */ |
| bralid r15, full_exception; /* Branch to the handler */ |
| nop; |
| mts rfsr, r0; /* Clear sticky fsr */ |
| nop |
| |
| /* |
| * Trigger execution of the signal handler by enabling |
| * interrupts and calling an invalid syscall. |
| */ |
| mfs r5, rmsr; |
| nop |
| ori r5, r5, 2; |
| mts rmsr, r5; /* enable interrupt */ |
| nop |
| addi r12, r0, __NR_syscalls; |
| brki r14, 0x08; |
| mfs r5, rmsr; /* disable interrupt */ |
| nop |
| andi r5, r5, ~2; |
| mts rmsr, r5; |
| nop |
| |
| lwi r7, r1, PT_R7 |
| lwi r8, r1, PT_R8 |
| lwi r9, r1, PT_R9 |
| lwi r10, r1, PT_R10 |
| lwi r11, r1, PT_R11 |
| lwi r12, r1, PT_R12 |
| lwi r14, r1, PT_R14 |
| lwi r15, r1, PT_R15 |
| lwi r18, r1, PT_R18 |
| |
| bri ex_handler_done; /* Complete exception handling */ |
| #endif |
| |
| /* 0x01 - Unaligned data access exception |
| * This occurs when a word access is not aligned on a word boundary, |
| * or when a 16-bit access is not aligned on a 16-bit boundary. |
| * This handler perform the access, and returns, except for MMU when |
| * the unaligned address is last on a 4k page or the physical address is |
| * not found in the page table, in which case unaligned_data_trap is called. |
| */ |
| handle_unaligned_ex: |
| /* Working registers already saved: R3, R4, R5, R6 |
| * R4 = ESR |
| * R3 = EAR |
| */ |
| #ifdef CONFIG_MMU |
| andi r6, r4, 0x1000 /* Check ESR[DS] */ |
| beqi r6, _no_delayslot /* Branch if ESR[DS] not set */ |
| mfs r17, rbtr; /* ESR[DS] set - return address in BTR */ |
| nop |
| _no_delayslot: |
| /* jump to high level unaligned handler */ |
| RESTORE_STATE; |
| bri unaligned_data_trap |
| #endif |
| andi r6, r4, 0x3E0; /* Mask and extract the register operand */ |
| srl r6, r6; /* r6 >> 5 */ |
| srl r6, r6; |
| srl r6, r6; |
| srl r6, r6; |
| srl r6, r6; |
| /* Store the register operand in a temporary location */ |
| sbi r6, r0, TOPHYS(ex_reg_op); |
| |
| andi r6, r4, 0x400; /* Extract ESR[S] */ |
| bnei r6, ex_sw; |
| ex_lw: |
| andi r6, r4, 0x800; /* Extract ESR[W] */ |
| beqi r6, ex_lhw; |
| lbui r5, r3, 0; /* Exception address in r3 */ |
| /* Load a word, byte-by-byte from destination address |
| and save it in tmp space */ |
| sbi r5, r0, TOPHYS(ex_tmp_data_loc_0); |
| lbui r5, r3, 1; |
| sbi r5, r0, TOPHYS(ex_tmp_data_loc_1); |
| lbui r5, r3, 2; |
| sbi r5, r0, TOPHYS(ex_tmp_data_loc_2); |
| lbui r5, r3, 3; |
| sbi r5, r0, TOPHYS(ex_tmp_data_loc_3); |
| /* Get the destination register value into r4 */ |
| lwi r4, r0, TOPHYS(ex_tmp_data_loc_0); |
| bri ex_lw_tail; |
| ex_lhw: |
| lbui r5, r3, 0; /* Exception address in r3 */ |
| /* Load a half-word, byte-by-byte from destination |
| address and save it in tmp space */ |
| sbi r5, r0, TOPHYS(ex_tmp_data_loc_0); |
| lbui r5, r3, 1; |
| sbi r5, r0, TOPHYS(ex_tmp_data_loc_1); |
| /* Get the destination register value into r4 */ |
| lhui r4, r0, TOPHYS(ex_tmp_data_loc_0); |
| ex_lw_tail: |
| /* Get the destination register number into r5 */ |
| lbui r5, r0, TOPHYS(ex_reg_op); |
| /* Form load_word jump table offset (lw_table + (8 * regnum)) */ |
| la r6, r0, TOPHYS(lw_table); |
| addk r5, r5, r5; |
| addk r5, r5, r5; |
| addk r5, r5, r5; |
| addk r5, r5, r6; |
| bra r5; |
| ex_lw_end: /* Exception handling of load word, ends */ |
| ex_sw: |
| /* Get the destination register number into r5 */ |
| lbui r5, r0, TOPHYS(ex_reg_op); |
| /* Form store_word jump table offset (sw_table + (8 * regnum)) */ |
| la r6, r0, TOPHYS(sw_table); |
| add r5, r5, r5; |
| add r5, r5, r5; |
| add r5, r5, r5; |
| add r5, r5, r6; |
| bra r5; |
| ex_sw_tail: |
| mfs r6, resr; |
| nop |
| andi r6, r6, 0x800; /* Extract ESR[W] */ |
| beqi r6, ex_shw; |
| /* Get the word - delay slot */ |
| swi r4, r0, TOPHYS(ex_tmp_data_loc_0); |
| /* Store the word, byte-by-byte into destination address */ |
| lbui r4, r0, TOPHYS(ex_tmp_data_loc_0); |
| sbi r4, r3, 0; |
| lbui r4, r0, TOPHYS(ex_tmp_data_loc_1); |
| sbi r4, r3, 1; |
| lbui r4, r0, TOPHYS(ex_tmp_data_loc_2); |
| sbi r4, r3, 2; |
| lbui r4, r0, TOPHYS(ex_tmp_data_loc_3); |
| sbi r4, r3, 3; |
| bri ex_handler_done; |
| |
| ex_shw: |
| /* Store the lower half-word, byte-by-byte into destination address */ |
| swi r4, r0, TOPHYS(ex_tmp_data_loc_0); |
| lbui r4, r0, TOPHYS(ex_tmp_data_loc_2); |
| sbi r4, r3, 0; |
| lbui r4, r0, TOPHYS(ex_tmp_data_loc_3); |
| sbi r4, r3, 1; |
| ex_sw_end: /* Exception handling of store word, ends. */ |
| |
| ex_handler_done: |
| #ifndef CONFIG_MMU |
| lwi r5, r1, 0 /* RMSR */ |
| mts rmsr, r5 |
| nop |
| lwi r3, r1, PT_R3 |
| lwi r4, r1, PT_R4 |
| lwi r5, r1, PT_R5 |
| lwi r6, r1, PT_R6 |
| lwi r17, r1, PT_R17 |
| |
| rted r17, 0 |
| addik r1, r1, (EX_HANDLER_STACK_SIZ); /* Restore stack frame */ |
| #else |
| RESTORE_STATE; |
| rted r17, 0 |
| nop |
| #endif |
| |
| #ifdef CONFIG_MMU |
| /* Exception vector entry code. This code runs with address translation |
| * turned off (i.e. using physical addresses). */ |
| |
| /* Exception vectors. */ |
| |
| /* 0x10 - Data Storage Exception |
| * This happens for just a few reasons. U0 set (but we don't do that), |
| * or zone protection fault (user violation, write to protected page). |
| * If this is just an update of modified status, we do that quickly |
| * and exit. Otherwise, we call heavyweight functions to do the work. |
| */ |
| handle_data_storage_exception: |
| /* Working registers already saved: R3, R4, R5, R6 |
| * R3 = ESR |
| */ |
| mfs r11, rpid |
| nop |
| /* If we are faulting a kernel address, we have to use the |
| * kernel page tables. |
| */ |
| ori r5, r0, CONFIG_KERNEL_START |
| cmpu r5, r3, r5 |
| bgti r5, ex3 |
| /* First, check if it was a zone fault (which means a user |
| * tried to access a kernel or read-protected page - always |
| * a SEGV). All other faults here must be stores, so no |
| * need to check ESR_S as well. */ |
| andi r4, r4, 0x800 /* ESR_Z - zone protection */ |
| bnei r4, ex2 |
| |
| ori r4, r0, swapper_pg_dir |
| mts rpid, r0 /* TLB will have 0 TID */ |
| nop |
| bri ex4 |
| |
| /* Get the PGD for the current thread. */ |
| ex3: |
| /* First, check if it was a zone fault (which means a user |
| * tried to access a kernel or read-protected page - always |
| * a SEGV). All other faults here must be stores, so no |
| * need to check ESR_S as well. */ |
| andi r4, r4, 0x800 /* ESR_Z */ |
| bnei r4, ex2 |
| /* get current task address */ |
| addi r4 ,CURRENT_TASK, TOPHYS(0); |
| lwi r4, r4, TASK_THREAD+PGDIR |
| ex4: |
| tophys(r4,r4) |
| BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */ |
| andi r5, r5, 0xffc |
| /* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */ |
| or r4, r4, r5 |
| lwi r4, r4, 0 /* Get L1 entry */ |
| andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */ |
| beqi r5, ex2 /* Bail if no table */ |
| |
| tophys(r5,r5) |
| BSRLI(r6,r3,10) /* Compute PTE address */ |
| andi r6, r6, 0xffc |
| andi r5, r5, 0xfffff003 |
| or r5, r5, r6 |
| lwi r4, r5, 0 /* Get Linux PTE */ |
| |
| andi r6, r4, _PAGE_RW /* Is it writeable? */ |
| beqi r6, ex2 /* Bail if not */ |
| |
| /* Update 'changed' */ |
| ori r4, r4, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE |
| swi r4, r5, 0 /* Update Linux page table */ |
| |
| /* Most of the Linux PTE is ready to load into the TLB LO. |
| * We set ZSEL, where only the LS-bit determines user access. |
| * We set execute, because we don't have the granularity to |
| * properly set this at the page level (Linux problem). |
| * If shared is set, we cause a zero PID->TID load. |
| * Many of these bits are software only. Bits we don't set |
| * here we (properly should) assume have the appropriate value. |
| */ |
| andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */ |
| ori r4, r4, _PAGE_HWEXEC /* make it executable */ |
| |
| /* find the TLB index that caused the fault. It has to be here*/ |
| mts rtlbsx, r3 |
| nop |
| mfs r5, rtlbx /* DEBUG: TBD */ |
| nop |
| mts rtlblo, r4 /* Load TLB LO */ |
| nop |
| /* Will sync shadow TLBs */ |
| |
| /* Done...restore registers and get out of here. */ |
| mts rpid, r11 |
| nop |
| bri 4 |
| |
| RESTORE_STATE; |
| rted r17, 0 |
| nop |
| ex2: |
| /* The bailout. Restore registers to pre-exception conditions |
| * and call the heavyweights to help us out. */ |
| mts rpid, r11 |
| nop |
| bri 4 |
| RESTORE_STATE; |
| bri page_fault_data_trap |
| |
| |
| /* 0x11 - Instruction Storage Exception |
| * This is caused by a fetch from non-execute or guarded pages. */ |
| handle_instruction_storage_exception: |
| /* Working registers already saved: R3, R4, R5, R6 |
| * R3 = ESR |
| */ |
| |
| RESTORE_STATE; |
| bri page_fault_instr_trap |
| |
| /* 0x12 - Data TLB Miss Exception |
| * As the name implies, translation is not in the MMU, so search the |
| * page tables and fix it. The only purpose of this function is to |
| * load TLB entries from the page table if they exist. |
| */ |
| handle_data_tlb_miss_exception: |
| /* Working registers already saved: R3, R4, R5, R6 |
| * R3 = EAR, R4 = ESR |
| */ |
| mfs r11, rpid |
| nop |
| |
| /* If we are faulting a kernel address, we have to use the |
| * kernel page tables. */ |
| ori r6, r0, CONFIG_KERNEL_START |
| cmpu r4, r3, r6 |
| bgti r4, ex5 |
| ori r4, r0, swapper_pg_dir |
| mts rpid, r0 /* TLB will have 0 TID */ |
| nop |
| bri ex6 |
| |
| /* Get the PGD for the current thread. */ |
| ex5: |
| /* get current task address */ |
| addi r4 ,CURRENT_TASK, TOPHYS(0); |
| lwi r4, r4, TASK_THREAD+PGDIR |
| ex6: |
| tophys(r4,r4) |
| BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */ |
| andi r5, r5, 0xffc |
| /* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */ |
| or r4, r4, r5 |
| lwi r4, r4, 0 /* Get L1 entry */ |
| andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */ |
| beqi r5, ex7 /* Bail if no table */ |
| |
| tophys(r5,r5) |
| BSRLI(r6,r3,10) /* Compute PTE address */ |
| andi r6, r6, 0xffc |
| andi r5, r5, 0xfffff003 |
| or r5, r5, r6 |
| lwi r4, r5, 0 /* Get Linux PTE */ |
| |
| andi r6, r4, _PAGE_PRESENT |
| beqi r6, ex7 |
| |
| ori r4, r4, _PAGE_ACCESSED |
| swi r4, r5, 0 |
| |
| /* Most of the Linux PTE is ready to load into the TLB LO. |
| * We set ZSEL, where only the LS-bit determines user access. |
| * We set execute, because we don't have the granularity to |
| * properly set this at the page level (Linux problem). |
| * If shared is set, we cause a zero PID->TID load. |
| * Many of these bits are software only. Bits we don't set |
| * here we (properly should) assume have the appropriate value. |
| */ |
| brid finish_tlb_load |
| andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */ |
| ex7: |
| /* The bailout. Restore registers to pre-exception conditions |
| * and call the heavyweights to help us out. |
| */ |
| mts rpid, r11 |
| nop |
| bri 4 |
| RESTORE_STATE; |
| bri page_fault_data_trap |
| |
| /* 0x13 - Instruction TLB Miss Exception |
| * Nearly the same as above, except we get our information from |
| * different registers and bailout to a different point. |
| */ |
| handle_instruction_tlb_miss_exception: |
| /* Working registers already saved: R3, R4, R5, R6 |
| * R3 = ESR |
| */ |
| mfs r11, rpid |
| nop |
| |
| /* If we are faulting a kernel address, we have to use the |
| * kernel page tables. |
| */ |
| ori r4, r0, CONFIG_KERNEL_START |
| cmpu r4, r3, r4 |
| bgti r4, ex8 |
| ori r4, r0, swapper_pg_dir |
| mts rpid, r0 /* TLB will have 0 TID */ |
| nop |
| bri ex9 |
| |
| /* Get the PGD for the current thread. */ |
| ex8: |
| /* get current task address */ |
| addi r4 ,CURRENT_TASK, TOPHYS(0); |
| lwi r4, r4, TASK_THREAD+PGDIR |
| ex9: |
| tophys(r4,r4) |
| BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */ |
| andi r5, r5, 0xffc |
| /* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */ |
| or r4, r4, r5 |
| lwi r4, r4, 0 /* Get L1 entry */ |
| andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */ |
| beqi r5, ex10 /* Bail if no table */ |
| |
| tophys(r5,r5) |
| BSRLI(r6,r3,10) /* Compute PTE address */ |
| andi r6, r6, 0xffc |
| andi r5, r5, 0xfffff003 |
| or r5, r5, r6 |
| lwi r4, r5, 0 /* Get Linux PTE */ |
| |
| andi r6, r4, _PAGE_PRESENT |
| beqi r6, ex10 |
| |
| ori r4, r4, _PAGE_ACCESSED |
| swi r4, r5, 0 |
| |
| /* Most of the Linux PTE is ready to load into the TLB LO. |
| * We set ZSEL, where only the LS-bit determines user access. |
| * We set execute, because we don't have the granularity to |
| * properly set this at the page level (Linux problem). |
| * If shared is set, we cause a zero PID->TID load. |
| * Many of these bits are software only. Bits we don't set |
| * here we (properly should) assume have the appropriate value. |
| */ |
| brid finish_tlb_load |
| andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */ |
| ex10: |
| /* The bailout. Restore registers to pre-exception conditions |
| * and call the heavyweights to help us out. |
| */ |
| mts rpid, r11 |
| nop |
| bri 4 |
| RESTORE_STATE; |
| bri page_fault_instr_trap |
| |
| /* Both the instruction and data TLB miss get to this point to load the TLB. |
| * r3 - EA of fault |
| * r4 - TLB LO (info from Linux PTE) |
| * r5, r6 - available to use |
| * PID - loaded with proper value when we get here |
| * Upon exit, we reload everything and RFI. |
| * A common place to load the TLB. |
| */ |
| tlb_index: |
| .long 1 /* MS: storing last used tlb index */ |
| finish_tlb_load: |
| /* MS: load the last used TLB index. */ |
| lwi r5, r0, TOPHYS(tlb_index) |
| addik r5, r5, 1 /* MS: inc tlb_index -> use next one */ |
| |
| /* MS: FIXME this is potential fault, because this is mask not count */ |
| andi r5, r5, (MICROBLAZE_TLB_SIZE-1) |
| ori r6, r0, 1 |
| cmp r31, r5, r6 |
| blti r31, ex12 |
| addik r5, r6, 1 |
| ex12: |
| /* MS: save back current TLB index */ |
| swi r5, r0, TOPHYS(tlb_index) |
| |
| ori r4, r4, _PAGE_HWEXEC /* make it executable */ |
| mts rtlbx, r5 /* MS: save current TLB */ |
| nop |
| mts rtlblo, r4 /* MS: save to TLB LO */ |
| nop |
| |
| /* Create EPN. This is the faulting address plus a static |
| * set of bits. These are size, valid, E, U0, and ensure |
| * bits 20 and 21 are zero. |
| */ |
| andi r3, r3, 0xfffff000 |
| ori r3, r3, 0x0c0 |
| mts rtlbhi, r3 /* Load TLB HI */ |
| nop |
| |
| /* Done...restore registers and get out of here. */ |
| mts rpid, r11 |
| nop |
| bri 4 |
| RESTORE_STATE; |
| rted r17, 0 |
| nop |
| |
| /* extern void giveup_fpu(struct task_struct *prev) |
| * |
| * The MicroBlaze processor may have an FPU, so this should not just |
| * return: TBD. |
| */ |
| .globl giveup_fpu; |
| .align 4; |
| giveup_fpu: |
| bralid r15,0 /* TBD */ |
| nop |
| |
| /* At present, this routine just hangs. - extern void abort(void) */ |
| .globl abort; |
| .align 4; |
| abort: |
| br r0 |
| |
| .globl set_context; |
| .align 4; |
| set_context: |
| mts rpid, r5 /* Shadow TLBs are automatically */ |
| nop |
| bri 4 /* flushed by changing PID */ |
| rtsd r15,8 |
| nop |
| |
| #endif |
| .end _hw_exception_handler |
| |
| #ifdef CONFIG_MMU |
| /* Unaligned data access exception last on a 4k page for MMU. |
| * When this is called, we are in virtual mode with exceptions enabled |
| * and registers 1-13,15,17,18 saved. |
| * |
| * R3 = ESR |
| * R4 = EAR |
| * R7 = pointer to saved registers (struct pt_regs *regs) |
| * |
| * This handler perform the access, and returns via ret_from_exc. |
| */ |
| .global _unaligned_data_exception |
| .ent _unaligned_data_exception |
| _unaligned_data_exception: |
| andi r8, r3, 0x3E0; /* Mask and extract the register operand */ |
| BSRLI(r8,r8,2); /* r8 >> 2 = register operand * 8 */ |
| andi r6, r3, 0x400; /* Extract ESR[S] */ |
| bneid r6, ex_sw_vm; |
| andi r6, r3, 0x800; /* Extract ESR[W] - delay slot */ |
| ex_lw_vm: |
| beqid r6, ex_lhw_vm; |
| load1: lbui r5, r4, 0; /* Exception address in r4 - delay slot */ |
| /* Load a word, byte-by-byte from destination address and save it in tmp space*/ |
| la r6, r0, ex_tmp_data_loc_0; |
| sbi r5, r6, 0; |
| load2: lbui r5, r4, 1; |
| sbi r5, r6, 1; |
| load3: lbui r5, r4, 2; |
| sbi r5, r6, 2; |
| load4: lbui r5, r4, 3; |
| sbi r5, r6, 3; |
| brid ex_lw_tail_vm; |
| /* Get the destination register value into r3 - delay slot */ |
| lwi r3, r6, 0; |
| ex_lhw_vm: |
| /* Load a half-word, byte-by-byte from destination address and |
| * save it in tmp space */ |
| la r6, r0, ex_tmp_data_loc_0; |
| sbi r5, r6, 0; |
| load5: lbui r5, r4, 1; |
| sbi r5, r6, 1; |
| lhui r3, r6, 0; /* Get the destination register value into r3 */ |
| ex_lw_tail_vm: |
| /* Form load_word jump table offset (lw_table_vm + (8 * regnum)) */ |
| addik r5, r8, lw_table_vm; |
| bra r5; |
| ex_lw_end_vm: /* Exception handling of load word, ends */ |
| brai ret_from_exc; |
| ex_sw_vm: |
| /* Form store_word jump table offset (sw_table_vm + (8 * regnum)) */ |
| addik r5, r8, sw_table_vm; |
| bra r5; |
| ex_sw_tail_vm: |
| la r5, r0, ex_tmp_data_loc_0; |
| beqid r6, ex_shw_vm; |
| swi r3, r5, 0; /* Get the word - delay slot */ |
| /* Store the word, byte-by-byte into destination address */ |
| lbui r3, r5, 0; |
| store1: sbi r3, r4, 0; |
| lbui r3, r5, 1; |
| store2: sbi r3, r4, 1; |
| lbui r3, r5, 2; |
| store3: sbi r3, r4, 2; |
| lbui r3, r5, 3; |
| brid ret_from_exc; |
| store4: sbi r3, r4, 3; /* Delay slot */ |
| ex_shw_vm: |
| /* Store the lower half-word, byte-by-byte into destination address */ |
| #ifdef __MICROBLAZEEL__ |
| lbui r3, r5, 0; |
| store5: sbi r3, r4, 0; |
| lbui r3, r5, 1; |
| brid ret_from_exc; |
| store6: sbi r3, r4, 1; /* Delay slot */ |
| #else |
| lbui r3, r5, 2; |
| store5: sbi r3, r4, 0; |
| lbui r3, r5, 3; |
| brid ret_from_exc; |
| store6: sbi r3, r4, 1; /* Delay slot */ |
| #endif |
| |
| ex_sw_end_vm: /* Exception handling of store word, ends. */ |
| |
| /* We have to prevent cases that get/put_user macros get unaligned pointer |
| * to bad page area. We have to find out which origin instruction caused it |
| * and called fixup for that origin instruction not instruction in unaligned |
| * handler */ |
| ex_unaligned_fixup: |
| ori r5, r7, 0 /* setup pointer to pt_regs */ |
| lwi r6, r7, PT_PC; /* faulting address is one instruction above */ |
| addik r6, r6, -4 /* for finding proper fixup */ |
| swi r6, r7, PT_PC; /* a save back it to PT_PC */ |
| addik r7, r0, SIGSEGV |
| /* call bad_page_fault for finding aligned fixup, fixup address is saved |
| * in PT_PC which is used as return address from exception */ |
| la r15, r0, ret_from_exc-8 /* setup return address */ |
| brid bad_page_fault |
| nop |
| |
| /* We prevent all load/store because it could failed any attempt to access */ |
| .section __ex_table,"a"; |
| .word load1,ex_unaligned_fixup; |
| .word load2,ex_unaligned_fixup; |
| .word load3,ex_unaligned_fixup; |
| .word load4,ex_unaligned_fixup; |
| .word load5,ex_unaligned_fixup; |
| .word store1,ex_unaligned_fixup; |
| .word store2,ex_unaligned_fixup; |
| .word store3,ex_unaligned_fixup; |
| .word store4,ex_unaligned_fixup; |
| .word store5,ex_unaligned_fixup; |
| .word store6,ex_unaligned_fixup; |
| .previous; |
| .end _unaligned_data_exception |
| #endif /* CONFIG_MMU */ |
| |
| .global ex_handler_unhandled |
| ex_handler_unhandled: |
| /* FIXME add handle function for unhandled exception - dump register */ |
| bri 0 |
| |
| /* |
| * hw_exception_handler Jump Table |
| * - Contains code snippets for each register that caused the unalign exception |
| * - Hence exception handler is NOT self-modifying |
| * - Separate table for load exceptions and store exceptions. |
| * - Each table is of size: (8 * 32) = 256 bytes |
| */ |
| |
| .section .text |
| .align 4 |
| lw_table: |
| lw_r0: R3_TO_LWREG (0); |
| lw_r1: LWREG_NOP; |
| lw_r2: R3_TO_LWREG (2); |
| lw_r3: R3_TO_LWREG_V (3); |
| lw_r4: R3_TO_LWREG_V (4); |
| lw_r5: R3_TO_LWREG_V (5); |
| lw_r6: R3_TO_LWREG_V (6); |
| lw_r7: R3_TO_LWREG (7); |
| lw_r8: R3_TO_LWREG (8); |
| lw_r9: R3_TO_LWREG (9); |
| lw_r10: R3_TO_LWREG (10); |
| lw_r11: R3_TO_LWREG (11); |
| lw_r12: R3_TO_LWREG (12); |
| lw_r13: R3_TO_LWREG (13); |
| lw_r14: R3_TO_LWREG (14); |
| lw_r15: R3_TO_LWREG (15); |
| lw_r16: R3_TO_LWREG (16); |
| lw_r17: LWREG_NOP; |
| lw_r18: R3_TO_LWREG (18); |
| lw_r19: R3_TO_LWREG (19); |
| lw_r20: R3_TO_LWREG (20); |
| lw_r21: R3_TO_LWREG (21); |
| lw_r22: R3_TO_LWREG (22); |
| lw_r23: R3_TO_LWREG (23); |
| lw_r24: R3_TO_LWREG (24); |
| lw_r25: R3_TO_LWREG (25); |
| lw_r26: R3_TO_LWREG (26); |
| lw_r27: R3_TO_LWREG (27); |
| lw_r28: R3_TO_LWREG (28); |
| lw_r29: R3_TO_LWREG (29); |
| lw_r30: R3_TO_LWREG (30); |
| #ifdef CONFIG_MMU |
| lw_r31: R3_TO_LWREG_V (31); |
| #else |
| lw_r31: R3_TO_LWREG (31); |
| #endif |
| |
| sw_table: |
| sw_r0: SWREG_TO_R3 (0); |
| sw_r1: SWREG_NOP; |
| sw_r2: SWREG_TO_R3 (2); |
| sw_r3: SWREG_TO_R3_V (3); |
| sw_r4: SWREG_TO_R3_V (4); |
| sw_r5: SWREG_TO_R3_V (5); |
| sw_r6: SWREG_TO_R3_V (6); |
| sw_r7: SWREG_TO_R3 (7); |
| sw_r8: SWREG_TO_R3 (8); |
| sw_r9: SWREG_TO_R3 (9); |
| sw_r10: SWREG_TO_R3 (10); |
| sw_r11: SWREG_TO_R3 (11); |
| sw_r12: SWREG_TO_R3 (12); |
| sw_r13: SWREG_TO_R3 (13); |
| sw_r14: SWREG_TO_R3 (14); |
| sw_r15: SWREG_TO_R3 (15); |
| sw_r16: SWREG_TO_R3 (16); |
| sw_r17: SWREG_NOP; |
| sw_r18: SWREG_TO_R3 (18); |
| sw_r19: SWREG_TO_R3 (19); |
| sw_r20: SWREG_TO_R3 (20); |
| sw_r21: SWREG_TO_R3 (21); |
| sw_r22: SWREG_TO_R3 (22); |
| sw_r23: SWREG_TO_R3 (23); |
| sw_r24: SWREG_TO_R3 (24); |
| sw_r25: SWREG_TO_R3 (25); |
| sw_r26: SWREG_TO_R3 (26); |
| sw_r27: SWREG_TO_R3 (27); |
| sw_r28: SWREG_TO_R3 (28); |
| sw_r29: SWREG_TO_R3 (29); |
| sw_r30: SWREG_TO_R3 (30); |
| #ifdef CONFIG_MMU |
| sw_r31: SWREG_TO_R3_V (31); |
| #else |
| sw_r31: SWREG_TO_R3 (31); |
| #endif |
| |
| #ifdef CONFIG_MMU |
| lw_table_vm: |
| lw_r0_vm: R3_TO_LWREG_VM (0); |
| lw_r1_vm: R3_TO_LWREG_VM_V (1); |
| lw_r2_vm: R3_TO_LWREG_VM_V (2); |
| lw_r3_vm: R3_TO_LWREG_VM_V (3); |
| lw_r4_vm: R3_TO_LWREG_VM_V (4); |
| lw_r5_vm: R3_TO_LWREG_VM_V (5); |
| lw_r6_vm: R3_TO_LWREG_VM_V (6); |
| lw_r7_vm: R3_TO_LWREG_VM_V (7); |
| lw_r8_vm: R3_TO_LWREG_VM_V (8); |
| lw_r9_vm: R3_TO_LWREG_VM_V (9); |
| lw_r10_vm: R3_TO_LWREG_VM_V (10); |
| lw_r11_vm: R3_TO_LWREG_VM_V (11); |
| lw_r12_vm: R3_TO_LWREG_VM_V (12); |
| lw_r13_vm: R3_TO_LWREG_VM_V (13); |
| lw_r14_vm: R3_TO_LWREG_VM (14); |
| lw_r15_vm: R3_TO_LWREG_VM_V (15); |
| lw_r16_vm: R3_TO_LWREG_VM (16); |
| lw_r17_vm: R3_TO_LWREG_VM_V (17); |
| lw_r18_vm: R3_TO_LWREG_VM_V (18); |
| lw_r19_vm: R3_TO_LWREG_VM (19); |
| lw_r20_vm: R3_TO_LWREG_VM (20); |
| lw_r21_vm: R3_TO_LWREG_VM (21); |
| lw_r22_vm: R3_TO_LWREG_VM (22); |
| lw_r23_vm: R3_TO_LWREG_VM (23); |
| lw_r24_vm: R3_TO_LWREG_VM (24); |
| lw_r25_vm: R3_TO_LWREG_VM (25); |
| lw_r26_vm: R3_TO_LWREG_VM (26); |
| lw_r27_vm: R3_TO_LWREG_VM (27); |
| lw_r28_vm: R3_TO_LWREG_VM (28); |
| lw_r29_vm: R3_TO_LWREG_VM (29); |
| lw_r30_vm: R3_TO_LWREG_VM (30); |
| lw_r31_vm: R3_TO_LWREG_VM_V (31); |
| |
| sw_table_vm: |
| sw_r0_vm: SWREG_TO_R3_VM (0); |
| sw_r1_vm: SWREG_TO_R3_VM_V (1); |
| sw_r2_vm: SWREG_TO_R3_VM_V (2); |
| sw_r3_vm: SWREG_TO_R3_VM_V (3); |
| sw_r4_vm: SWREG_TO_R3_VM_V (4); |
| sw_r5_vm: SWREG_TO_R3_VM_V (5); |
| sw_r6_vm: SWREG_TO_R3_VM_V (6); |
| sw_r7_vm: SWREG_TO_R3_VM_V (7); |
| sw_r8_vm: SWREG_TO_R3_VM_V (8); |
| sw_r9_vm: SWREG_TO_R3_VM_V (9); |
| sw_r10_vm: SWREG_TO_R3_VM_V (10); |
| sw_r11_vm: SWREG_TO_R3_VM_V (11); |
| sw_r12_vm: SWREG_TO_R3_VM_V (12); |
| sw_r13_vm: SWREG_TO_R3_VM_V (13); |
| sw_r14_vm: SWREG_TO_R3_VM (14); |
| sw_r15_vm: SWREG_TO_R3_VM_V (15); |
| sw_r16_vm: SWREG_TO_R3_VM (16); |
| sw_r17_vm: SWREG_TO_R3_VM_V (17); |
| sw_r18_vm: SWREG_TO_R3_VM_V (18); |
| sw_r19_vm: SWREG_TO_R3_VM (19); |
| sw_r20_vm: SWREG_TO_R3_VM (20); |
| sw_r21_vm: SWREG_TO_R3_VM (21); |
| sw_r22_vm: SWREG_TO_R3_VM (22); |
| sw_r23_vm: SWREG_TO_R3_VM (23); |
| sw_r24_vm: SWREG_TO_R3_VM (24); |
| sw_r25_vm: SWREG_TO_R3_VM (25); |
| sw_r26_vm: SWREG_TO_R3_VM (26); |
| sw_r27_vm: SWREG_TO_R3_VM (27); |
| sw_r28_vm: SWREG_TO_R3_VM (28); |
| sw_r29_vm: SWREG_TO_R3_VM (29); |
| sw_r30_vm: SWREG_TO_R3_VM (30); |
| sw_r31_vm: SWREG_TO_R3_VM_V (31); |
| #endif /* CONFIG_MMU */ |
| |
| /* Temporary data structures used in the handler */ |
| .section .data |
| .align 4 |
| ex_tmp_data_loc_0: |
| .byte 0 |
| ex_tmp_data_loc_1: |
| .byte 0 |
| ex_tmp_data_loc_2: |
| .byte 0 |
| ex_tmp_data_loc_3: |
| .byte 0 |
| ex_reg_op: |
| .byte 0 |
