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+/*
+ * 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 */