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entry-compact.h
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/* * 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 lr r9, [status32] bclr r9, r9, STATUS_AE_BIT or r9, r9, (STATUS_E1_MASK|STATUS_E2_MASK) 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 */