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linux/arch/arc/include/asm/entry.h
Vineet Gupta 37f3ac498c ARC: Exception Handlers Code consolidation 
After the recent cleanups, all the exception handlers now have same
boilerplate prologue code. Move that into common macro.

This reduces readability but helps greatly with sharing / duplicating
entry code with ARCv2 ISA where the handlers are pretty much the same,
just the entry prologue is different (due to hardware assist).

Also while at it, add the missing FAKE_RET_FROM_EXCPN calls in couple of
places to drop down to pure kernel mode (from exception mode) before
jumping off into "C" code.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-08-26 09:40:25 +05:30

649 lines
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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 */
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