diff options
Diffstat (limited to 'arch/arc')
| -rw-r--r-- | arch/arc/include/asm/entry.h | 495 | ||||
| -rw-r--r-- | arch/arc/kernel/entry.S | 571 |
2 files changed, 1066 insertions, 0 deletions
diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h new file mode 100644 index 0000000..63705b1 --- /dev/null +++ b/arch/arc/include/asm/entry.h @@ -0,0 +1,495 @@ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * 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. + * + * Vineetg: Aug 28th 2008: Bug #94984 + * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap + * Normally CPU does this automatically, however when doing FAKE rtie, + * we also need to explicitly do this. The problem in macros + * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit + * was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context + * + * Vineetg: May 5th 2008 + * - Defined Stack Switching Macro to be reused in all intr/excp hdlrs + * - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the + * address Write back load ld.ab instead of seperate ld/add instn + * + * Amit Bhor, Sameer Dhavale: Codito Technologies 2004 + */ + +#ifndef __ASM_ARC_ENTRY_H +#define __ASM_ARC_ENTRY_H + +#ifdef __ASSEMBLY__ +#include <asm/unistd.h> /* For NR_syscalls defination */ +#include <asm/asm-offsets.h> +#include <asm/arcregs.h> +#include <asm/ptrace.h> +#include <asm/thread_info.h> /* For THREAD_SIZE */ + +/* Note on the LD/ST addr modes with addr reg wback + * + * LD.a same as LD.aw + * + * LD.a reg1, [reg2, x] => Pre Incr + * Eff Addr for load = [reg2 + x] + * + * LD.ab reg1, [reg2, x] => Post Incr + * Eff Addr for load = [reg2] + */ + +/*-------------------------------------------------------------- + * Save caller saved registers (scratch registers) ( r0 - r12 ) + * Registers are pushed / popped in the order defined in struct ptregs + * in asm/ptrace.h + *-------------------------------------------------------------*/ +.macro SAVE_CALLER_SAVED + st.a r0, [sp, -4] + st.a r1, [sp, -4] + st.a r2, [sp, -4] + st.a r3, [sp, -4] + st.a r4, [sp, -4] + st.a r5, [sp, -4] + st.a r6, [sp, -4] + st.a r7, [sp, -4] + st.a r8, [sp, -4] + st.a r9, [sp, -4] + st.a r10, [sp, -4] + st.a r11, [sp, -4] + st.a r12, [sp, -4] +.endm + +/*-------------------------------------------------------------- + * Restore caller saved registers (scratch registers) + *-------------------------------------------------------------*/ +.macro RESTORE_CALLER_SAVED + ld.ab r12, [sp, 4] + ld.ab r11, [sp, 4] + ld.ab r10, [sp, 4] + ld.ab r9, [sp, 4] + ld.ab r8, [sp, 4] + ld.ab r7, [sp, 4] + ld.ab r6, [sp, 4] + ld.ab r5, [sp, 4] + ld.ab r4, [sp, 4] + ld.ab r3, [sp, 4] + ld.ab r2, [sp, 4] + ld.ab r1, [sp, 4] + ld.ab r0, [sp, 4] +.endm + + +/*-------------------------------------------------------------- + * Save callee saved registers (non scratch registers) ( r13 - r25 ) + * on kernel stack. + * User mode callee regs need to be saved in case of + * -fork and friends for replicating from parent to child + * -before going into do_signal( ) for ptrace/core-dump + * Special case handling is required for r25 in case it is used by kernel + * for caching task ptr. Low level exception/ISR save user mode r25 + * into task->thread.user_r25. So it needs to be retrieved from there and + * saved into kernel stack with rest of callee reg-file + *-------------------------------------------------------------*/ +.macro SAVE_CALLEE_SAVED_USER + st.a r13, [sp, -4] + st.a r14, [sp, -4] + st.a r15, [sp, -4] + st.a r16, [sp, -4] + st.a r17, [sp, -4] + st.a r18, [sp, -4] + st.a r19, [sp, -4] + st.a r20, [sp, -4] + st.a r21, [sp, -4] + st.a r22, [sp, -4] + st.a r23, [sp, -4] + st.a r24, [sp, -4] + st.a r25, [sp, -4] + + /* move up by 1 word to "create" callee_regs->"stack_place_holder" */ + sub sp, sp, 4 +.endm + +/*-------------------------------------------------------------- + * Save callee saved registers (non scratch registers) ( r13 - r25 ) + * kernel mode callee regs needed to be saved in case of context switch + * If r25 is used for caching task pointer then that need not be saved + * as it can be re-created from current task global + *-------------------------------------------------------------*/ +.macro SAVE_CALLEE_SAVED_KERNEL + st.a r13, [sp, -4] + st.a r14, [sp, -4] + st.a r15, [sp, -4] + st.a r16, [sp, -4] + st.a r17, [sp, -4] + st.a r18, [sp, -4] + st.a r19, [sp, -4] + st.a r20, [sp, -4] + st.a r21, [sp, -4] + st.a r22, [sp, -4] + st.a r23, [sp, -4] + st.a r24, [sp, -4] + st.a r25, [sp, -4] + sub sp, sp, 4 +.endm + +/*-------------------------------------------------------------- + * RESTORE_CALLEE_SAVED_KERNEL: + * Loads callee (non scratch) Reg File by popping from Kernel mode stack. + * This is reverse of SAVE_CALLEE_SAVED, + * + * NOTE: + * Ideally this shd only be called in switch_to for loading + * switched-IN task's CALLEE Reg File. + * For all other cases RESTORE_CALLEE_SAVED_FAST must be used + * which simply pops the stack w/o touching regs. + *-------------------------------------------------------------*/ +.macro RESTORE_CALLEE_SAVED_KERNEL + + add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */ + ld.ab r25, [sp, 4] + ld.ab r24, [sp, 4] + ld.ab r23, [sp, 4] + ld.ab r22, [sp, 4] + ld.ab r21, [sp, 4] + ld.ab r20, [sp, 4] + ld.ab r19, [sp, 4] + ld.ab r18, [sp, 4] + ld.ab r17, [sp, 4] + ld.ab r16, [sp, 4] + ld.ab r15, [sp, 4] + ld.ab r14, [sp, 4] + ld.ab r13, [sp, 4] + +.endm + +/*-------------------------------------------------------------- + * Super FAST Restore callee saved regs by simply re-adjusting SP + *-------------------------------------------------------------*/ +.macro DISCARD_CALLEE_SAVED_USER + add sp, sp, 14 * 4 +.endm + +/*-------------------------------------------------------------- + * Restore User mode r25 saved in task_struct->thread.user_r25 + *-------------------------------------------------------------*/ +.macro RESTORE_USER_R25 + ld r25, [r25, TASK_THREAD + THREAD_USER_R25] +.endm + +/*------------------------------------------------------------- + * given a tsk struct, get to the base of it's kernel mode stack + * tsk->thread_info is really a PAGE, whose bottom hoists stack + * which grows upwards towards thread_info + *------------------------------------------------------------*/ + +.macro GET_TSK_STACK_BASE tsk, out + + /* Get task->thread_info (this is essentially start of a PAGE) */ + ld \out, [\tsk, TASK_THREAD_INFO] + + /* Go to end of page where stack begins (grows upwards) */ + add2 \out, \out, (THREAD_SIZE - 4)/4 /* one word GUTTER */ + +.endm + +/*-------------------------------------------------------------- + * Switch to Kernel Mode stack if SP points to User Mode stack + * + * Entry : r9 contains pre-IRQ/exception/trap status32 + * Exit : SP is set to kernel mode stack pointer + * Clobbers: r9 + *-------------------------------------------------------------*/ + +.macro SWITCH_TO_KERNEL_STK + + /* User Mode when this happened ? Yes: Proceed to switch stack */ + bbit1 r9, STATUS_U_BIT, 88f + + /* OK we were already in kernel mode when this event happened, thus can + * assume SP is kernel mode SP. _NO_ need to do any stack switching + */ + + /* Save Pre Intr/Exception KERNEL MODE SP on kernel stack + * safe-keeping not really needed, but it keeps the epilogue code + * (SP restore) simpler/uniform. + */ + b.d 77f + + st.a sp, [sp, -12] ; Make room for orig_r0 and orig_r8 + +88: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */ + + GET_CURR_TASK_ON_CPU r9 + + /* With current tsk in r9, get it's kernel mode stack base */ + GET_TSK_STACK_BASE r9, r9 + +#ifdef PT_REGS_CANARY + st 0xabcdabcd, [r9, 0] +#endif + + /* Save Pre Intr/Exception User SP on kernel stack */ + st.a sp, [r9, -12] ; Make room for orig_r0 and orig_r8 + + /* CAUTION: + * SP should be set at the very end when we are done with everything + * In case of 2 levels of interrupt we depend on value of SP to assume + * that everything else is done (loading r25 etc) + */ + + /* set SP to point to kernel mode stack */ + mov sp, r9 + +77: /* ----- Stack Switched to kernel Mode, Now save REG FILE ----- */ + +.endm + +/*------------------------------------------------------------ + * "FAKE" a rtie to return from CPU Exception context + * This is to re-enable Exceptions within exception + * Look at EV_ProtV to see how this is actually used + *-------------------------------------------------------------*/ + +.macro FAKE_RET_FROM_EXCPN reg + + ld \reg, [sp, PT_status32] + bic \reg, \reg, (STATUS_U_MASK|STATUS_DE_MASK) + bset \reg, \reg, STATUS_L_BIT + sr \reg, [erstatus] + mov \reg, 55f + sr \reg, [eret] + + rtie +55: +.endm + +/* + * @reg [OUT] &thread_info of "current" + */ +.macro GET_CURR_THR_INFO_FROM_SP reg + and \reg, sp, ~(THREAD_SIZE - 1) +.endm + +/* + * @reg [OUT] thread_info->flags of "current" + */ +.macro GET_CURR_THR_INFO_FLAGS reg + GET_CURR_THR_INFO_FROM_SP \reg + ld \reg, [\reg, THREAD_INFO_FLAGS] +.endm + +/*-------------------------------------------------------------- + * For early Exception Prologue, a core reg is temporarily needed to + * code the rest of prolog (stack switching). This is done by stashing + * it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP). + * + * Before saving the full regfile - this reg is restored back, only + * to be saved again on kernel mode stack, as part of ptregs. + *-------------------------------------------------------------*/ +.macro EXCPN_PROLOG_FREEUP_REG reg + st \reg, [@ex_saved_reg1] +.endm + +.macro EXCPN_PROLOG_RESTORE_REG reg + ld \reg, [@ex_saved_reg1] +.endm + +/*-------------------------------------------------------------- + * Save all registers used by Exceptions (TLB Miss, Prot-V, Mem err etc) + * Requires SP to be already switched to kernel mode Stack + * sp points to the next free element on the stack at exit of this macro. + * Registers are pushed / popped in the order defined in struct ptregs + * in asm/ptrace.h + * Note that syscalls are implemented via TRAP which is also a exception + * from CPU's point of view + *-------------------------------------------------------------*/ +.macro SAVE_ALL_EXCEPTION marker + + /* Restore r9 used to code the early prologue */ + EXCPN_PROLOG_RESTORE_REG r9 + + /* Save the complete regfile now */ + + /* orig_r8 marker: + * syscalls -> 1 to NR_SYSCALLS + * Exceptions -> NR_SYSCALLS + 1 + * Break-point-> NR_SYSCALLS + 2 + */ + st \marker, [sp, 8] + st r0, [sp, 4] /* orig_r0, needed only for sys calls */ + SAVE_CALLER_SAVED + st.a r26, [sp, -4] /* gp */ + st.a fp, [sp, -4] + st.a blink, [sp, -4] + lr r9, [eret] + st.a r9, [sp, -4] + lr r9, [erstatus] + st.a r9, [sp, -4] + st.a lp_count, [sp, -4] + lr r9, [lp_end] + st.a r9, [sp, -4] + lr r9, [lp_start] + st.a r9, [sp, -4] + lr r9, [erbta] + st.a r9, [sp, -4] + +#ifdef PT_REGS_CANARY + mov r9, 0xdeadbeef + st r9, [sp, -4] +#endif + + /* move up by 1 word to "create" pt_regs->"stack_place_holder" */ + sub sp, sp, 4 +.endm + +/*-------------------------------------------------------------- + * Save scratch regs for exceptions + *-------------------------------------------------------------*/ +.macro SAVE_ALL_SYS + SAVE_ALL_EXCEPTION (NR_syscalls + 1) +.endm + +/*-------------------------------------------------------------- + * Save scratch regs for sys calls + *-------------------------------------------------------------*/ +.macro SAVE_ALL_TRAP + SAVE_ALL_EXCEPTION r8 +.endm + +/*-------------------------------------------------------------- + * Restore all registers used by system call or Exceptions + * SP should always be pointing to the next free stack element + * when entering this macro. + * + * NOTE: + * + * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg + * for memory load operations. If used in that way interrupts are deffered + * by hardware and that is not good. + *-------------------------------------------------------------*/ +.macro RESTORE_ALL_SYS + + add sp, sp, 4 /* hop over unused "pt_regs->stack_place_holder" */ + + ld.ab r9, [sp, 4] + sr r9, [erbta] + ld.ab r9, [sp, 4] + sr r9, [lp_start] + ld.ab r9, [sp, 4] + sr r9, [lp_end] + ld.ab r9, [sp, 4] + mov lp_count, r9 + ld.ab r9, [sp, 4] + sr r9, [erstatus] + ld.ab r9, [sp, 4] + sr r9, [eret] + ld.ab blink, [sp, 4] + ld.ab fp, [sp, 4] + ld.ab r26, [sp, 4] /* gp */ + RESTORE_CALLER_SAVED + + ld sp, [sp] /* restore original sp */ + /* orig_r0 and orig_r8 skipped automatically */ +.endm + + +/*-------------------------------------------------------------- + * Save all registers used by interrupt handlers. + *-------------------------------------------------------------*/ +.macro SAVE_ALL_INT1 + + /* restore original r9 , saved in int1_saved_reg + * It will be saved on stack in macro: SAVE_CALLER_SAVED + */ + ld r9, [@int1_saved_reg] + + /* now we are ready to save the remaining context :) */ + st -1, [sp, 8] /* orig_r8, -1 for interuppt level one */ + st 0, [sp, 4] /* orig_r0 , N/A for IRQ */ + SAVE_CALLER_SAVED + st.a r26, [sp, -4] /* gp */ + st.a fp, [sp, -4] + st.a blink, [sp, -4] + st.a ilink1, [sp, -4] + lr r9, [status32_l1] + st.a r9, [sp, -4] + st.a lp_count, [sp, -4] + lr r9, [lp_end] + st.a r9, [sp, -4] + lr r9, [lp_start] + st.a r9, [sp, -4] + lr r9, [bta_l1] + st.a r9, [sp, -4] + +#ifdef PT_REGS_CANARY + mov r9, 0xdeadbee1 + st r9, [sp, -4] +#endif + /* move up by 1 word to "create" pt_regs->"stack_place_holder" */ + sub sp, sp, 4 +.endm + +/*-------------------------------------------------------------- + * Restore all registers used by interrupt handlers. + * + * NOTE: + * + * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg + * for memory load operations. If used in that way interrupts are deffered + * by hardware and that is not good. + *-------------------------------------------------------------*/ + +.macro RESTORE_ALL_INT1 + add sp, sp, 4 /* hop over unused "pt_regs->stack_place_holder" */ + + ld.ab r9, [sp, 4] /* Actual reg file */ + sr r9, [bta_l1] + ld.ab r9, [sp, 4] + sr r9, [lp_start] + ld.ab r9, [sp, 4] + sr r9, [lp_end] + ld.ab r9, [sp, 4] + mov lp_count, r9 + ld.ab r9, [sp, 4] + sr r9, [status32_l1] + ld.ab r9, [sp, 4] + mov ilink1, r9 + ld.ab blink, [sp, 4] + ld.ab fp, [sp, 4] + ld.ab r26, [sp, 4] /* gp */ + RESTORE_CALLER_SAVED + + ld sp, [sp] /* restore original sp */ + /* orig_r0 and orig_r8 skipped automatically */ +.endm + +/* Get CPU-ID of this core */ +.macro GET_CPU_ID reg + lr \reg, [identity] + lsr \reg, \reg, 8 + bmsk \reg, \reg, 7 +.endm + +.macro GET_CURR_TASK_ON_CPU reg + ld \reg, [@_current_task] +.endm + +.macro SET_CURR_TASK_ON_CPU tsk, tmp + st \tsk, [@_current_task] +.endm + +/* ------------------------------------------------------------------ + * Get the ptr to some field of Current Task at @off in task struct + */ + +.macro GET_CURR_TASK_FIELD_PTR off, reg + GET_CURR_TASK_ON_CPU \reg + add \reg, \reg, \off +.endm + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_ARC_ENTRY_H */ diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S new file mode 100644 index 0000000..a4acc9e --- /dev/null +++ b/arch/arc/kernel/entry.S @@ -0,0 +1,571 @@ +/* + * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * 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. + * + * vineetg: Nov 2010: + * -Vector table jumps (@8 bytes) converted into branches (@4 bytes) + * -To maintain the slot size of 8 bytes/vector, added nop, which is + * not executed at runtime. + * + * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) + * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well + * -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't + * need ptregs anymore + * + * Vineetg: Oct 2009 + * -In a rare scenario, Process gets a Priv-V exception and gets scheduled + * out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains + * active (AE bit enabled). This causes a double fault for a subseq valid + * exception. Thus FAKE RTIE needed in low level Priv-Violation handler. + * Instr Error could also cause similar scenario, so same there as well. + * + * Vineetg: Aug 28th 2008: Bug #94984 + * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap + * Normally CPU does this automatically, however when doing FAKE rtie, + * we need to explicitly do this. The problem in macros + * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit + * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit, + * setting it and not clearing it clears ZOL context + * + * Vineetg: Dec 22, 2007 + * Minor Surgery of Low Level ISR to make it SMP safe + * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR + * - _current_task is made an array of NR_CPUS + * - Access of _current_task wrapped inside a macro so that if hardware + * team agrees for a dedicated reg, no other code is touched + * + * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004 + */ + +/*------------------------------------------------------------------ + * Function ABI + *------------------------------------------------------------------ + * + * Arguments r0 - r7 + * Caller Saved Registers r0 - r12 + * Callee Saved Registers r13- r25 + * Global Pointer (gp) r26 + * Frame Pointer (fp) r27 + * Stack Pointer (sp) r28 + * Interrupt link register (ilink1) r29 + * Interrupt link register (ilink2) r30 + * Branch link register (blink) r31 + *------------------------------------------------------------------ + */ + + .cpu A7 + +;############################ Vector Table ################################# + +.macro VECTOR lbl +#if 1 /* Just in case, build breaks */ + j \lbl +#else + b \lbl + nop +#endif +.endm + + .section .vector, "ax",@progbits + .align 4 + +/* Each entry in the vector table must occupy 2 words. Since it is a jump + * across sections (.vector to .text) we are gauranteed that 'j somewhere' + * will use the 'j limm' form of the intrsuction as long as somewhere is in + * a section other than .vector. + */ + +; ********* Critical System Events ********************** +VECTOR res_service ; 0x0, Restart Vector (0x0) +VECTOR mem_service ; 0x8, Mem exception (0x1) +VECTOR instr_service ; 0x10, Instrn Error (0x2) + +; ******************** Device ISRs ********************** +VECTOR handle_interrupt_level1 + +VECTOR handle_interrupt_level1 + +VECTOR handle_interrupt_level1 + +VECTOR handle_interrupt_level1 + +.rept 25 +VECTOR handle_interrupt_level1 ; Other devices +.endr + +/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */ + +; ******************** Exceptions ********************** +VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20) +VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21) +VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22) +VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23) + ; or Misaligned Access +VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24) +VECTOR EV_Trap ; 0x128, Trap exception (0x25) +VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26) + +.rept 24 +VECTOR reserved ; Reserved Exceptions +.endr + +#include <linux/linkage.h> /* ARC_{EXTRY,EXIT} */ +#include <asm/entry.h> /* SAVE_ALL_{INT1,INT2,TRAP...} */ +#include <asm/errno.h> +#include <asm/arcregs.h> +#include <asm/irqflags.h> + +;##################### Scratch Mem for IRQ stack switching ############# + + .section .data ; NOT .global + .align 32 + .type int1_saved_reg, @object + .size int1_saved_reg, 4 +int1_saved_reg: + .zero 4 + +; --------------------------------------------- + .section .text, "ax",@progbits + +res_service: ; processor restart + flag 0x1 ; not implemented + nop + nop + +reserved: ; processor restart + rtie ; jump to processor initializations + +;##################### Interrupt Handling ############################## + +; --------------------------------------------- +; Level 1 ISR +; --------------------------------------------- +ARC_ENTRY handle_interrupt_level1 + + /* free up r9 as scratchpad */ + st r9, [@int1_saved_reg] + + ;Which mode (user/kernel) was the system in when intr occured + lr r9, [status32_l1] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_INT1 + + lr r0, [icause1] + and r0, r0, 0x1f + + bl.d @arch_do_IRQ + mov r1, sp + + mov r8,0x1 + sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg + + b ret_from_exception +ARC_EXIT handle_interrupt_level1 + +;################### Non TLB Exception Handling ############################# + +; --------------------------------------------- +; Instruction Error Exception Handler +; --------------------------------------------- + +ARC_ENTRY instr_service + + EXCPN_PROLOG_FREEUP_REG r9 + + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_SYS + + lr r0, [ecr] + lr r1, [efa] + + mov r2, sp + + FAKE_RET_FROM_EXCPN r9 + + bl do_insterror_or_kprobe + b ret_from_exception +ARC_EXIT instr_service + +; --------------------------------------------- +; Memory Error Exception Handler +; --------------------------------------------- + +ARC_ENTRY mem_service + + EXCPN_PROLOG_FREEUP_REG r9 + + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_SYS + + lr r0, [ecr] + lr r1, [efa] + mov r2, sp + bl do_memory_error + b ret_from_exception +ARC_EXIT mem_service + +; --------------------------------------------- +; Machine Check Exception Handler +; --------------------------------------------- + +ARC_ENTRY EV_MachineCheck + + EXCPN_PROLOG_FREEUP_REG r9 + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_SYS + + lr r0, [ecr] + lr r1, [efa] + mov r2, sp + + brne r0, 0x200100, 1f + bl do_tlb_overlap_fault + b ret_from_exception + +1: + ; DEAD END: can't do much, display Regs and HALT + SAVE_CALLEE_SAVED_USER + + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 + st sp, [r10, THREAD_CALLEE_REG] + + j do_machine_check_fault + +ARC_EXIT EV_MachineCheck + +; --------------------------------------------- +; Protection Violation Exception Handler +; --------------------------------------------- + +ARC_ENTRY EV_TLBProtV + + EXCPN_PROLOG_FREEUP_REG r9 + + ;Which mode (user/kernel) was the system in when Exception occured + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_SYS + + ;---------(3) Save some more regs----------------- + ; vineetg: Mar 6th: Random Seg Fault issue #1 + ; ecr and efa were not saved in case an Intr sneaks in + ; after fake rtie + ; + lr r3, [ecr] + lr r4, [efa] + + ; --------(4) Return from CPU Exception Mode --------- + ; Fake a rtie, but rtie to next label + ; That way, subsequently, do_page_fault ( ) executes in pure kernel + ; mode with further Exceptions enabled + + FAKE_RET_FROM_EXCPN r9 + + ;------ (5) Type of Protection Violation? ---------- + ; + ; ProtV Hardware Exception is triggered for Access Faults of 2 types + ; -Access Violaton (WRITE to READ ONLY Page) - for linux COW + ; -Unaligned Access (READ/WRITE on odd boundary) + ; + cmp r3, 0x230400 ; Misaligned data access ? + beq 4f + + ;========= (6a) Access Violation Processing ======== + cmp r3, 0x230100 + mov r1, 0x0 ; if LD exception ? write = 0 + mov.ne r1, 0x1 ; else write = 1 + + mov r2, r4 ; faulting address + mov r0, sp ; pt_regs + bl do_page_fault + b ret_from_exception + + ;========== (6b) Non aligned access ============ +4: + mov r0, r3 ; cause code + mov r1, r4 ; faulting address + mov r2, sp ; pt_regs + + bl do_misaligned_access + b ret_from_exception + +ARC_EXIT EV_TLBProtV + +; --------------------------------------------- +; Privilege Violation Exception Handler +; --------------------------------------------- +ARC_ENTRY EV_PrivilegeV + + EXCPN_PROLOG_FREEUP_REG r9 + + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_SYS + + lr r0, [ecr] + lr r1, [efa] + mov r2, sp + + FAKE_RET_FROM_EXCPN r9 + + bl do_privilege_fault + b ret_from_exception +ARC_EXIT EV_PrivilegeV + +; --------------------------------------------- +; Extension Instruction Exception Handler +; --------------------------------------------- +ARC_ENTRY EV_Extension + + EXCPN_PROLOG_FREEUP_REG r9 + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_SYS + + lr r0, [ecr] + lr r1, [efa] + mov r2, sp + bl do_extension_fault + b ret_from_exception +ARC_EXIT EV_Extension + +;################### Break Point TRAP ########################## + + ; ======= (5b) Trap is due to Break-Point ========= + +trap_with_param: + + ;make sure orig_r8 is a positive value + st NR_syscalls + 2, [sp, PT_orig_r8] + + mov r0, r12 + lr r1, [efa] + mov r2, sp + + ; Now that we have read EFA, its safe to do "fake" rtie + ; and get out of CPU exception mode + FAKE_RET_FROM_EXCPN r11 + + ; Save callee regs in case gdb wants to have a look + ; SP will grow up by size of CALLEE Reg-File + ; NOTE: clobbers r12 + SAVE_CALLEE_SAVED_USER + + ; save location of saved Callee Regs @ thread_struct->pc + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 + st sp, [r10, THREAD_CALLEE_REG] + + ; Call the trap handler + bl do_non_swi_trap + + ; unwind stack to discard Callee saved Regs + DISCARD_CALLEE_SAVED_USER + + b ret_from_exception + +;##################### Trap Handling ############################## +; +; EV_Trap caused by TRAP_S and TRAP0 instructions. +;------------------------------------------------------------------ +; (1) System Calls +; :parameters in r0-r7. +; :r8 has the system call number +; (2) Break Points +;------------------------------------------------------------------ + +ARC_ENTRY EV_Trap + + ; Need at least 1 reg to code the early exception prolog + EXCPN_PROLOG_FREEUP_REG r9 + + ;Which mode (user/kernel) was the system in when intr occured + lr r9, [erstatus] + + SWITCH_TO_KERNEL_STK + SAVE_ALL_TRAP + + ;------- (4) What caused the Trap -------------- + lr r12, [ecr] + and.f 0, r12, ECR_PARAM_MASK + bnz trap_with_param + + ; ======= (5a) Trap is due to System Call ======== + + ; Before doing anything, return from CPU Exception Mode + FAKE_RET_FROM_EXCPN r11 + + ;============ This is normal System Call case ========== + ; Sys-call num shd not exceed the total system calls avail + cmp r8, NR_syscalls + mov.hi r0, -ENOSYS + bhi ret_from_system_call + + ; Offset into the syscall_table and call handler + ld.as r9,[sys_call_table, r8] + jl [r9] ; Entry into Sys Call Handler + + ; fall through to ret_from_system_call +ARC_EXIT EV_Trap + +ARC_ENTRY ret_from_system_call + + st r0, [sp, PT_r0] ; sys call return value in pt_regs + + ; fall through yet again to ret_from_exception + +;############# Return from Intr/Excp/Trap (Linux Specifics) ############## +; +; If ret to user mode do we need to handle signals, schedule() et al. + +ARC_ENTRY ret_from_exception + + ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 + ld r8, [sp, PT_status32] ; returning to User/Kernel Mode + +#ifdef CONFIG_PREEMPT + bbit0 r8, STATUS_U_BIT, resume_kernel_mode +#else + bbit0 r8, STATUS_U_BIT, restore_regs +#endif + + ; Before returning to User mode check-for-and-complete any pending work + ; such as rescheduling/signal-delivery etc. +resume_user_mode_begin: + + ; Disable IRQs to ensures that chk for pending work itself is atomic + ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an + ; interim IRQ). + IRQ_DISABLE r10 + + ; Fast Path return to user mode if no pending work + GET_CURR_THR_INFO_FLAGS r9 + and.f 0, r9, _TIF_WORK_MASK + bz restore_regs + + ; --- (Slow Path #1) task preemption --- + bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals + mov blink, resume_user_mode_begin ; tail-call to U mode ret chks + b @schedule ; BTST+Bnz causes relo error in link + +.Lchk_pend_signals: + IRQ_ENABLE r10 + + ; --- (Slow Path #2) pending signal --- + mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() + + bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume + + ; save CALLEE Regs. + ; (i) If this signal causes coredump - full regfile needed + ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus + ; tracer might call PEEKUSR(CALLEE reg) + ; + ; NOTE: SP will grow up by size of CALLEE Reg-File + SAVE_CALLEE_SAVED_USER ; clobbers r12 + + ; save location of saved Callee Regs @ thread_struct->callee + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 + st sp, [r10, THREAD_CALLEE_REG] + + bl @do_signal + + ; unwind SP for cheap discard of Callee saved Regs + DISCARD_CALLEE_SAVED_USER + + b resume_user_mode_begin ; loop back to start of U mode ret + + ; --- (Slow Path #3) notify_resume --- +.Lchk_notify_resume: + btst r9, TIF_NOTIFY_RESUME + blnz @do_notify_resume + b resume_user_mode_begin ; unconditionally back to U mode ret chks + ; for single exit point from this block + +#ifdef CONFIG_PREEMPT + +resume_kernel_mode: + + ; Can't preempt if preemption disabled + GET_CURR_THR_INFO_FROM_SP r10 + ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] + brne r8, 0, restore_regs + + ; check if this task's NEED_RESCHED flag set + ld r9, [r10, THREAD_INFO_FLAGS] + bbit0 r9, TIF_NEED_RESCHED, restore_regs + + IRQ_DISABLE r9 + + ; Invoke PREEMPTION + bl preempt_schedule_irq + + ; preempt_schedule_irq() always returns with IRQ disabled +#endif + + ; fall through + +;############# Return from Intr/Excp/Trap (ARC Specifics) ############## +; +; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap) +; IRQ shd definitely not happen between now and rtie + +restore_regs : + + ; Disable Interrupts while restoring reg-file back + ; XXX can this be optimised out + IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy + + ; Restore REG File. In case multiple Events outstanding, + ; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None + ; Note that we use realtime STATUS32 (not pt_regs->status32) to + ; decide that. + + ; if Returning from Exception + bbit0 r10, STATUS_AE_BIT, not_exception + RESTORE_ALL_SYS + rtie + + ; Not Exception so maybe Interrupts (Level 1 or 2) + +not_exception: + + bbit0 r10, STATUS_A1_BIT, not_level1_interrupt + + ;return from level 1 + + RESTORE_ALL_INT1 +debug_marker_l1: + rtie + +not_level1_interrupt: + + ;this case is for syscalls or Exceptions (with fake rtie) + + RESTORE_ALL_SYS +debug_marker_syscall: + rtie + +ARC_EXIT ret_from_exception + +ARC_ENTRY ret_from_fork + ; when the forked child comes here from the __switch_to function + ; r0 has the last task pointer. + ; put last task in scheduler queue + bl @schedule_tail + b @ret_from_exception +ARC_EXIT ret_from_fork |