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Diffstat (limited to 'arch/arc/include/asm/entry-compact.h')
| -rw-r--r-- | arch/arc/include/asm/entry-compact.h | 307 |
1 files changed, 307 insertions, 0 deletions
diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h new file mode 100644 index 000000000..415443c2a --- /dev/null +++ b/arch/arc/include/asm/entry-compact.h @@ -0,0 +1,307 @@ +/* + * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) + * 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_COMPACT_H +#define __ASM_ARC_ENTRY_COMPACT_H + +#include <asm/asm-offsets.h> +#include <asm/irqflags-compact.h> +#include <asm/thread_info.h> /* For THREAD_SIZE */ + +/*-------------------------------------------------------------- + * Switch to Kernel Mode stack if SP points to User Mode stack + * + * Entry : r9 contains pre-IRQ/exception/trap status32 + * Exit : SP set to K mode stack + * SP at the time of entry (K/U) saved @ pt_regs->sp + * 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 + + /*------Intr/Ecxp happened in kernel mode, SP already setup ------ */ + /* save it nevertheless @ pt_regs->sp for uniformity */ + + b.d 66f + st sp, [sp, PT_sp - SZ_PT_REGS] + +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 + + /* save U mode SP @ pt_regs->sp */ + st sp, [r9, PT_sp - SZ_PT_REGS] + + /* final SP switch */ + mov sp, r9 +66: +.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 + + ld r9, [sp, PT_status32] + bic r9, r9, (STATUS_U_MASK|STATUS_DE_MASK) + bset r9, r9, STATUS_L_BIT + sr r9, [erstatus] + mov r9, 55f + sr r9, [eret] + + rtie +55: +.endm + +/*-------------------------------------------------------------- + * For early Exception/ISR 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 PROLOG_FREEUP_REG reg, mem +#ifdef CONFIG_SMP + sr \reg, [ARC_REG_SCRATCH_DATA0] +#else + st \reg, [\mem] +#endif +.endm + +.macro PROLOG_RESTORE_REG reg, mem +#ifdef CONFIG_SMP + lr \reg, [ARC_REG_SCRATCH_DATA0] +#else + ld \reg, [\mem] +#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 */ + PROLOG_FREEUP_REG r9, @ex_saved_reg1 + + /* 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 + +#ifdef CONFIG_ARC_CURR_IN_REG + /* Treat r25 as scratch reg (save on stack) and load with "current" */ + PUSH r25 + GET_CURR_TASK_ON_CPU r25 +#else + sub sp, sp, 4 +#endif + + st.a r0, [sp, -8] /* orig_r0 needed for syscall (skip ECR slot) */ + sub sp, sp, 4 /* skip pt_regs->sp, already saved above */ + + /* Restore r9 used to code the early prologue */ + PROLOG_RESTORE_REG r9, @ex_saved_reg1 + + /* now we are ready to save the regfile */ + 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 + + lr r9, [ecr] + st r9, [sp, PT_event] /* EV_Trap expects r9 to have ECR */ +.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 EXCEPTION_EPILOGUE + 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 + +/* Dummy ECR values for Interrupts */ +#define event_IRQ1 0x0031abcd +#define event_IRQ2 0x0032abcd + +.macro INTERRUPT_PROLOGUE LVL + + /* free up r9 as scratchpad */ + PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg + + /* Which mode (user/kernel) was the system in when intr occured */ + lr r9, [status32_l\LVL\()] + + SWITCH_TO_KERNEL_STK + +#ifdef CONFIG_ARC_CURR_IN_REG + /* Treat r25 as scratch reg (save on stack) and load with "current" */ + PUSH r25 + GET_CURR_TASK_ON_CPU r25 +#else + sub sp, sp, 4 +#endif + + PUSH 0x003\LVL\()abcd /* Dummy ECR */ + sub sp, sp, 8 /* skip orig_r0 (not needed) + skip pt_regs->sp, already saved above */ + + /* Restore r9 used to code the early prologue */ + PROLOG_RESTORE_REG r9, @int\LVL\()_saved_reg + + SAVE_R0_TO_R12 + PUSH gp + PUSH fp + PUSH blink + PUSH ilink\LVL\() + PUSHAX status32_l\LVL\() + PUSH lp_count + PUSHAX lp_end + PUSHAX lp_start + PUSHAX bta_l\LVL\() +.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 INTERRUPT_EPILOGUE LVL + POPAX bta_l\LVL\() + POPAX lp_start + POPAX lp_end + + POP r9 + mov lp_count, r9 ;LD to lp_count is not allowed + + POPAX status32_l\LVL\() + POP ilink\LVL\() + 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 thread_info of "current" tsk */ +.macro GET_CURR_THR_INFO_FROM_SP reg + bic \reg, sp, (THREAD_SIZE - 1) +.endm + +/* Get CPU-ID of this core */ +.macro GET_CPU_ID reg + lr \reg, [identity] + lsr \reg, \reg, 8 + bmsk \reg, \reg, 7 +.endm + +#endif /* __ASM_ARC_ENTRY_COMPACT_H */ |