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Diffstat (limited to 'kernel/arch/arc/include/asm/entry.h')
| -rw-r--r-- | kernel/arch/arc/include/asm/entry.h | 648 |
1 files changed, 648 insertions, 0 deletions
diff --git a/kernel/arch/arc/include/asm/entry.h b/kernel/arch/arc/include/asm/entry.h new file mode 100644 index 000000000..884081099 --- /dev/null +++ b/kernel/arch/arc/include/asm/entry.h @@ -0,0 +1,648 @@ +/* + * 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: March 2009 (Supporting 2 levels of Interrupts) + * Stack switching code can no longer reliably rely on the fact that + * if we are NOT in user mode, stack is switched to kernel mode. + * e.g. L2 IRQ interrupted a L1 ISR which had not yet completed + * it's prologue including stack switching from user mode + * + * 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 + * -Modified CALLEE_REG save/restore macros to handle the fact that + * r25 contains the kernel current task ptr + * - 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/processor.h> /* For VMALLOC_START */ +#include <asm/thread_info.h> /* For THREAD_SIZE */ +#include <asm/mmu.h> + +/* 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] + */ + +.macro PUSH reg + st.a \reg, [sp, -4] +.endm + +.macro PUSHAX aux + lr r9, [\aux] + PUSH r9 +.endm + +.macro POP reg + ld.ab \reg, [sp, 4] +.endm + +.macro POPAX aux + POP r9 + sr r9, [\aux] +.endm + +/*-------------------------------------------------------------- + * Helpers to save/restore Scratch Regs: + * used by Interrupt/Exception Prologue/Epilogue + *-------------------------------------------------------------*/ +.macro SAVE_R0_TO_R12 + PUSH r0 + PUSH r1 + PUSH r2 + PUSH r3 + PUSH r4 + PUSH r5 + PUSH r6 + PUSH r7 + PUSH r8 + PUSH r9 + PUSH r10 + PUSH r11 + PUSH r12 +.endm + +.macro RESTORE_R12_TO_R0 + POP r12 + POP r11 + POP r10 + POP r9 + POP r8 + POP r7 + POP r6 + POP r5 + POP r4 + POP r3 + POP r2 + POP r1 + POP r0 + +#ifdef CONFIG_ARC_CURR_IN_REG + ld r25, [sp, 12] +#endif +.endm + +/*-------------------------------------------------------------- + * Helpers to save/restore callee-saved regs: + * used by several macros below + *-------------------------------------------------------------*/ +.macro SAVE_R13_TO_R24 + PUSH r13 + PUSH r14 + PUSH r15 + PUSH r16 + PUSH r17 + PUSH r18 + PUSH r19 + PUSH r20 + PUSH r21 + PUSH r22 + PUSH r23 + PUSH r24 +.endm + +.macro RESTORE_R24_TO_R13 + POP r24 + POP r23 + POP r22 + POP r21 + POP r20 + POP r19 + POP r18 + POP r17 + POP r16 + POP r15 + POP r14 + POP r13 +.endm + +#define OFF_USER_R25_FROM_R24 (SZ_CALLEE_REGS + SZ_PT_REGS - 8)/4 + +/*-------------------------------------------------------------- + * Collect User Mode callee regs as struct callee_regs - needed by + * fork/do_signal/unaligned-access-emulation. + * (By default only scratch regs are saved on entry to kernel) + * + * Special handling for r25 if used for caching Task Pointer. + * It would have been saved in task->thread.user_r25 already, but to keep + * the interface same it is copied into regular r25 placeholder in + * struct callee_regs. + *-------------------------------------------------------------*/ +.macro SAVE_CALLEE_SAVED_USER + + SAVE_R13_TO_R24 + +#ifdef CONFIG_ARC_CURR_IN_REG + ; Retrieve orig r25 and save it on stack + ld.as r12, [sp, OFF_USER_R25_FROM_R24] + st.a r12, [sp, -4] +#else + PUSH r25 +#endif + +.endm + +/*-------------------------------------------------------------- + * Save kernel Mode callee regs at the time of Contect Switch. + * + * Special handling for r25 if used for caching Task Pointer. + * Kernel simply skips saving it since it will be loaded with + * incoming task pointer anyways + *-------------------------------------------------------------*/ +.macro SAVE_CALLEE_SAVED_KERNEL + + SAVE_R13_TO_R24 + +#ifdef CONFIG_ARC_CURR_IN_REG + sub sp, sp, 4 +#else + PUSH r25 +#endif +.endm + +/*-------------------------------------------------------------- + * Opposite of SAVE_CALLEE_SAVED_KERNEL + *-------------------------------------------------------------*/ +.macro RESTORE_CALLEE_SAVED_KERNEL + +#ifdef CONFIG_ARC_CURR_IN_REG + add sp, sp, 4 /* skip usual r25 placeholder */ +#else + POP r25 +#endif + RESTORE_R24_TO_R13 +.endm + +/*-------------------------------------------------------------- + * Opposite of SAVE_CALLEE_SAVED_USER + * + * ptrace tracer or unaligned-access fixup might have changed a user mode + * callee reg which is saved back to usual r25 storage location + *-------------------------------------------------------------*/ +.macro RESTORE_CALLEE_SAVED_USER + +#ifdef CONFIG_ARC_CURR_IN_REG + ld.ab r12, [sp, 4] + st.as r12, [sp, OFF_USER_R25_FROM_R24] +#else + POP r25 +#endif + RESTORE_R24_TO_R13 +.endm + +/*-------------------------------------------------------------- + * Super FAST Restore callee saved regs by simply re-adjusting SP + *-------------------------------------------------------------*/ +.macro DISCARD_CALLEE_SAVED_USER + add sp, sp, SZ_CALLEE_REGS +.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 + +.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 + * If CURR_IN_REG, r25 set to "current" task 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 + */ + +#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS + /* However.... + * If Level 2 Interrupts enabled, we may end up with a corner case: + * 1. User Task executing + * 2. L1 IRQ taken, ISR starts (CPU auto-switched to KERNEL mode) + * 3. But before it could switch SP from USER to KERNEL stack + * a L2 IRQ "Interrupts" L1 + * Thay way although L2 IRQ happened in Kernel mode, stack is still + * not switched. + * To handle this, we may need to switch stack even if in kernel mode + * provided SP has values in range of USER mode stack ( < 0x7000_0000 ) + */ + brlo sp, VMALLOC_START, 88f + + /* TODO: vineetg: + * We need to be a bit more cautious here. What if a kernel bug in + * L1 ISR, caused SP to go whaco (some small value which looks like + * USER stk) and then we take L2 ISR. + * Above brlo alone would treat it as a valid L1-L2 sceanrio + * instead of shouting alound + * The only feasible way is to make sure this L2 happened in + * L1 prelogue ONLY i.e. ilink2 is less than a pre-set marker in + * L1 ISR before it switches stack + */ + +#endif + + /* 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 66f + mov r9, sp + +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 + +66: +#ifdef CONFIG_ARC_CURR_IN_REG + /* + * Treat r25 as scratch reg, save it on stack first + * Load it with current task pointer + */ + st r25, [r9, -4] + GET_CURR_TASK_ON_CPU r25 +#endif + + /* Save Pre Intr/Exception User SP on kernel stack */ + st.a sp, [r9, -16] ; Make room for orig_r0, ECR, user_r25 + + /* 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 + + /* ----- 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 + bic \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 pt_regs. + *-------------------------------------------------------------*/ +.macro EXCPN_PROLOG_FREEUP_REG reg +#ifdef CONFIG_SMP + sr \reg, [ARC_REG_SCRATCH_DATA0] +#else + st \reg, [@ex_saved_reg1] +#endif +.endm + +.macro EXCPN_PROLOG_RESTORE_REG reg +#ifdef CONFIG_SMP + lr \reg, [ARC_REG_SCRATCH_DATA0] +#else + ld \reg, [@ex_saved_reg1] +#endif +.endm + +/*-------------------------------------------------------------- + * Exception Entry prologue + * -Switches stack to K mode (if not already) + * -Saves the register file + * + * After this it is safe to call the "C" handlers + *-------------------------------------------------------------*/ +.macro EXCEPTION_PROLOGUE + + /* Need at least 1 reg to code the early exception prologue */ + EXCPN_PROLOG_FREEUP_REG r9 + + /* U/K mode at time of exception (stack not switched if already K) */ + lr r9, [erstatus] + + /* ARC700 doesn't provide auto-stack switching */ + SWITCH_TO_KERNEL_STK + + /* save the regfile */ + SAVE_ALL_SYS +.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_SYS + + lr r9, [ecr] + st r9, [sp, 8] /* ECR */ + st r0, [sp, 4] /* orig_r0, needed only for sys calls */ + + /* Restore r9 used to code the early prologue */ + EXCPN_PROLOG_RESTORE_REG r9 + + SAVE_R0_TO_R12 + PUSH gp + PUSH fp + PUSH blink + PUSHAX eret + PUSHAX erstatus + PUSH lp_count + PUSHAX lp_end + PUSHAX lp_start + PUSHAX erbta +.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 + POPAX erbta + POPAX lp_start + POPAX lp_end + + POP r9 + mov lp_count, r9 ;LD to lp_count is not allowed + + POPAX erstatus + POPAX eret + POP blink + POP fp + POP gp + RESTORE_R12_TO_R0 + + ld sp, [sp] /* restore original sp */ + /* orig_r0, ECR, user_r25 skipped automatically */ +.endm + + +/*-------------------------------------------------------------- + * Save all registers used by interrupt handlers. + *-------------------------------------------------------------*/ +.macro SAVE_ALL_INT1 + + /* restore original r9 to be saved as part of reg-file */ +#ifdef CONFIG_SMP + lr r9, [ARC_REG_SCRATCH_DATA0] +#else + ld r9, [@int1_saved_reg] +#endif + + /* now we are ready to save the remaining context :) */ + st event_IRQ1, [sp, 8] /* Dummy ECR */ + st 0, [sp, 4] /* orig_r0 , N/A for IRQ */ + + SAVE_R0_TO_R12 + PUSH gp + PUSH fp + PUSH blink + PUSH ilink1 + PUSHAX status32_l1 + PUSH lp_count + PUSHAX lp_end + PUSHAX lp_start + PUSHAX bta_l1 +.endm + +.macro SAVE_ALL_INT2 + + /* TODO-vineetg: SMP we can't use global nor can we use + * SCRATCH0 as we do for int1 because while int1 is using + * it, int2 can come + */ + /* retsore original r9 , saved in sys_saved_r9 */ + ld r9, [@int2_saved_reg] + + /* now we are ready to save the remaining context :) */ + st event_IRQ2, [sp, 8] /* Dummy ECR */ + st 0, [sp, 4] /* orig_r0 , N/A for IRQ */ + + SAVE_R0_TO_R12 + PUSH gp + PUSH fp + PUSH blink + PUSH ilink2 + PUSHAX status32_l2 + PUSH lp_count + PUSHAX lp_end + PUSHAX lp_start + PUSHAX bta_l2 +.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 + POPAX bta_l1 + POPAX lp_start + POPAX lp_end + + POP r9 + mov lp_count, r9 ;LD to lp_count is not allowed + + POPAX status32_l1 + POP ilink1 + POP blink + POP fp + POP gp + RESTORE_R12_TO_R0 + + ld sp, [sp] /* restore original sp */ + /* orig_r0, ECR, user_r25 skipped automatically */ +.endm + +.macro RESTORE_ALL_INT2 + POPAX bta_l2 + POPAX lp_start + POPAX lp_end + + POP r9 + mov lp_count, r9 ;LD to lp_count is not allowed + + POPAX status32_l2 + POP ilink2 + POP blink + POP fp + POP gp + RESTORE_R12_TO_R0 + + ld sp, [sp] /* restore original sp */ + /* orig_r0, ECR, user_r25 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 + +#ifdef CONFIG_SMP + +/*------------------------------------------------- + * Retrieve the current running task on this CPU + * 1. Determine curr CPU id. + * 2. Use it to index into _current_task[ ] + */ +.macro GET_CURR_TASK_ON_CPU reg + GET_CPU_ID \reg + ld.as \reg, [@_current_task, \reg] +.endm + +/*------------------------------------------------- + * Save a new task as the "current" task on this CPU + * 1. Determine curr CPU id. + * 2. Use it to index into _current_task[ ] + * + * Coded differently than GET_CURR_TASK_ON_CPU (which uses LD.AS) + * because ST r0, [r1, offset] can ONLY have s9 @offset + * while LD can take s9 (4 byte insn) or LIMM (8 byte insn) + */ + +.macro SET_CURR_TASK_ON_CPU tsk, tmp + GET_CPU_ID \tmp + add2 \tmp, @_current_task, \tmp + st \tsk, [\tmp] +#ifdef CONFIG_ARC_CURR_IN_REG + mov r25, \tsk +#endif + +.endm + + +#else /* Uniprocessor implementation of macros */ + +.macro GET_CURR_TASK_ON_CPU reg + ld \reg, [@_current_task] +.endm + +.macro SET_CURR_TASK_ON_CPU tsk, tmp + st \tsk, [@_current_task] +#ifdef CONFIG_ARC_CURR_IN_REG + mov r25, \tsk +#endif +.endm + +#endif /* SMP / UNI */ + +/* ------------------------------------------------------------------ + * Get the ptr to some field of Current Task at @off in task struct + * -Uses r25 for Current task ptr if that is enabled + */ + +#ifdef CONFIG_ARC_CURR_IN_REG + +.macro GET_CURR_TASK_FIELD_PTR off, reg + add \reg, r25, \off +.endm + +#else + +.macro GET_CURR_TASK_FIELD_PTR off, reg + GET_CURR_TASK_ON_CPU \reg + add \reg, \reg, \off +.endm + +#endif /* CONFIG_ARC_CURR_IN_REG */ + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_ARC_ENTRY_H */ |