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ARC: Low level IRQ/Trap/Exception Handling 

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
This commit is contained in:
Vineet Gupta 2013-01-18 15:12:18 +05:30
parent 5210d1e688
commit 9d42c84f91
2 changed files with 1066 additions and 0 deletions
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495
arch/arc/include/asm/entry.h Normal file
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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: 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
* - 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/thread_info.h> /* For THREAD_SIZE */
/* 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]
*/
/*--------------------------------------------------------------
* Save caller saved registers (scratch registers) ( r0 - r12 )
* Registers are pushed / popped in the order defined in struct ptregs
* in asm/ptrace.h
*-------------------------------------------------------------*/
.macro SAVE_CALLER_SAVED
st.a r0, [sp, -4]
st.a r1, [sp, -4]
st.a r2, [sp, -4]
st.a r3, [sp, -4]
st.a r4, [sp, -4]
st.a r5, [sp, -4]
st.a r6, [sp, -4]
st.a r7, [sp, -4]
st.a r8, [sp, -4]
st.a r9, [sp, -4]
st.a r10, [sp, -4]
st.a r11, [sp, -4]
st.a r12, [sp, -4]
.endm
/*--------------------------------------------------------------
* Restore caller saved registers (scratch registers)
*-------------------------------------------------------------*/
.macro RESTORE_CALLER_SAVED
ld.ab r12, [sp, 4]
ld.ab r11, [sp, 4]
ld.ab r10, [sp, 4]
ld.ab r9, [sp, 4]
ld.ab r8, [sp, 4]
ld.ab r7, [sp, 4]
ld.ab r6, [sp, 4]
ld.ab r5, [sp, 4]
ld.ab r4, [sp, 4]
ld.ab r3, [sp, 4]
ld.ab r2, [sp, 4]
ld.ab r1, [sp, 4]
ld.ab r0, [sp, 4]
.endm
/*--------------------------------------------------------------
* Save callee saved registers (non scratch registers) ( r13 - r25 )
* on kernel stack.
* User mode callee regs need to be saved in case of
* -fork and friends for replicating from parent to child
* -before going into do_signal( ) for ptrace/core-dump
* Special case handling is required for r25 in case it is used by kernel
* for caching task ptr. Low level exception/ISR save user mode r25
* into task->thread.user_r25. So it needs to be retrieved from there and
* saved into kernel stack with rest of callee reg-file
*-------------------------------------------------------------*/
.macro SAVE_CALLEE_SAVED_USER
st.a r13, [sp, -4]
st.a r14, [sp, -4]
st.a r15, [sp, -4]
st.a r16, [sp, -4]
st.a r17, [sp, -4]
st.a r18, [sp, -4]
st.a r19, [sp, -4]
st.a r20, [sp, -4]
st.a r21, [sp, -4]
st.a r22, [sp, -4]
st.a r23, [sp, -4]
st.a r24, [sp, -4]
st.a r25, [sp, -4]
/* move up by 1 word to "create" callee_regs->"stack_place_holder" */
sub sp, sp, 4
.endm
/*--------------------------------------------------------------
* Save callee saved registers (non scratch registers) ( r13 - r25 )
* kernel mode callee regs needed to be saved in case of context switch
* If r25 is used for caching task pointer then that need not be saved
* as it can be re-created from current task global
*-------------------------------------------------------------*/
.macro SAVE_CALLEE_SAVED_KERNEL
st.a r13, [sp, -4]
st.a r14, [sp, -4]
st.a r15, [sp, -4]
st.a r16, [sp, -4]
st.a r17, [sp, -4]
st.a r18, [sp, -4]
st.a r19, [sp, -4]
st.a r20, [sp, -4]
st.a r21, [sp, -4]
st.a r22, [sp, -4]
st.a r23, [sp, -4]
st.a r24, [sp, -4]
st.a r25, [sp, -4]
sub sp, sp, 4
.endm
/*--------------------------------------------------------------
* RESTORE_CALLEE_SAVED_KERNEL:
* Loads callee (non scratch) Reg File by popping from Kernel mode stack.
* This is reverse of SAVE_CALLEE_SAVED,
*
* NOTE:
* Ideally this shd only be called in switch_to for loading
* switched-IN task's CALLEE Reg File.
* For all other cases RESTORE_CALLEE_SAVED_FAST must be used
* which simply pops the stack w/o touching regs.
*-------------------------------------------------------------*/
.macro RESTORE_CALLEE_SAVED_KERNEL
add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */
ld.ab r25, [sp, 4]
ld.ab r24, [sp, 4]
ld.ab r23, [sp, 4]
ld.ab r22, [sp, 4]
ld.ab r21, [sp, 4]
ld.ab r20, [sp, 4]
ld.ab r19, [sp, 4]
ld.ab r18, [sp, 4]
ld.ab r17, [sp, 4]
ld.ab r16, [sp, 4]
ld.ab r15, [sp, 4]
ld.ab r14, [sp, 4]
ld.ab r13, [sp, 4]
.endm
/*--------------------------------------------------------------
* Super FAST Restore callee saved regs by simply re-adjusting SP
*-------------------------------------------------------------*/
.macro DISCARD_CALLEE_SAVED_USER
add sp, sp, 14 * 4
.endm
/*--------------------------------------------------------------
* Restore User mode r25 saved in task_struct->thread.user_r25
*-------------------------------------------------------------*/
.macro RESTORE_USER_R25
ld r25, [r25, TASK_THREAD + THREAD_USER_R25]
.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)/4 /* one word GUTTER */
.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
* 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
*/
/* 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 77f
st.a sp, [sp, -12] ; Make room for orig_r0 and orig_r8
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
#ifdef PT_REGS_CANARY
st 0xabcdabcd, [r9, 0]
#endif
/* Save Pre Intr/Exception User SP on kernel stack */
st.a sp, [r9, -12] ; Make room for orig_r0 and orig_r8
/* 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
77: /* ----- 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
and \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 ptregs.
*-------------------------------------------------------------*/
.macro EXCPN_PROLOG_FREEUP_REG reg
st \reg, [@ex_saved_reg1]
.endm
.macro EXCPN_PROLOG_RESTORE_REG reg
ld \reg, [@ex_saved_reg1]
.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_EXCEPTION marker
/* Restore r9 used to code the early prologue */
EXCPN_PROLOG_RESTORE_REG r9
/* Save the complete regfile now */
/* orig_r8 marker:
* syscalls -> 1 to NR_SYSCALLS
* Exceptions -> NR_SYSCALLS + 1
* Break-point-> NR_SYSCALLS + 2
*/
st \marker, [sp, 8]
st r0, [sp, 4] /* orig_r0, needed only for sys calls */
SAVE_CALLER_SAVED
st.a r26, [sp, -4] /* gp */
st.a fp, [sp, -4]
st.a blink, [sp, -4]
lr r9, [eret]
st.a r9, [sp, -4]
lr r9, [erstatus]
st.a r9, [sp, -4]
st.a lp_count, [sp, -4]
lr r9, [lp_end]
st.a r9, [sp, -4]
lr r9, [lp_start]
st.a r9, [sp, -4]
lr r9, [erbta]
st.a r9, [sp, -4]
#ifdef PT_REGS_CANARY
mov r9, 0xdeadbeef
st r9, [sp, -4]
#endif
/* move up by 1 word to "create" pt_regs->"stack_place_holder" */
sub sp, sp, 4
.endm
/*--------------------------------------------------------------
* Save scratch regs for exceptions
*-------------------------------------------------------------*/
.macro SAVE_ALL_SYS
SAVE_ALL_EXCEPTION (NR_syscalls + 1)
.endm
/*--------------------------------------------------------------
* Save scratch regs for sys calls
*-------------------------------------------------------------*/
.macro SAVE_ALL_TRAP
SAVE_ALL_EXCEPTION r8
.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
add sp, sp, 4 /* hop over unused "pt_regs->stack_place_holder" */
ld.ab r9, [sp, 4]
sr r9, [erbta]
ld.ab r9, [sp, 4]
sr r9, [lp_start]
ld.ab r9, [sp, 4]
sr r9, [lp_end]
ld.ab r9, [sp, 4]
mov lp_count, r9
ld.ab r9, [sp, 4]
sr r9, [erstatus]
ld.ab r9, [sp, 4]
sr r9, [eret]
ld.ab blink, [sp, 4]
ld.ab fp, [sp, 4]
ld.ab r26, [sp, 4] /* gp */
RESTORE_CALLER_SAVED
ld sp, [sp] /* restore original sp */
/* orig_r0 and orig_r8 skipped automatically */
.endm
/*--------------------------------------------------------------
* Save all registers used by interrupt handlers.
*-------------------------------------------------------------*/
.macro SAVE_ALL_INT1
/* restore original r9 , saved in int1_saved_reg
* It will be saved on stack in macro: SAVE_CALLER_SAVED
*/
ld r9, [@int1_saved_reg]
/* now we are ready to save the remaining context :) */
st -1, [sp, 8] /* orig_r8, -1 for interuppt level one */
st 0, [sp, 4] /* orig_r0 , N/A for IRQ */
SAVE_CALLER_SAVED
st.a r26, [sp, -4] /* gp */
st.a fp, [sp, -4]
st.a blink, [sp, -4]
st.a ilink1, [sp, -4]
lr r9, [status32_l1]
st.a r9, [sp, -4]
st.a lp_count, [sp, -4]
lr r9, [lp_end]
st.a r9, [sp, -4]
lr r9, [lp_start]
st.a r9, [sp, -4]
lr r9, [bta_l1]
st.a r9, [sp, -4]
#ifdef PT_REGS_CANARY
mov r9, 0xdeadbee1
st r9, [sp, -4]
#endif
/* move up by 1 word to "create" pt_regs->"stack_place_holder" */
sub sp, sp, 4
.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
add sp, sp, 4 /* hop over unused "pt_regs->stack_place_holder" */
ld.ab r9, [sp, 4] /* Actual reg file */
sr r9, [bta_l1]
ld.ab r9, [sp, 4]
sr r9, [lp_start]
ld.ab r9, [sp, 4]
sr r9, [lp_end]
ld.ab r9, [sp, 4]
mov lp_count, r9
ld.ab r9, [sp, 4]
sr r9, [status32_l1]
ld.ab r9, [sp, 4]
mov ilink1, r9
ld.ab blink, [sp, 4]
ld.ab fp, [sp, 4]
ld.ab r26, [sp, 4] /* gp */
RESTORE_CALLER_SAVED
ld sp, [sp] /* restore original sp */
/* orig_r0 and orig_r8 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
.macro GET_CURR_TASK_ON_CPU reg
ld \reg, [@_current_task]
.endm
.macro SET_CURR_TASK_ON_CPU tsk, tmp
st \tsk, [@_current_task]
.endm
/* ------------------------------------------------------------------
* Get the ptr to some field of Current Task at @off in task struct
*/
.macro GET_CURR_TASK_FIELD_PTR off, reg
GET_CURR_TASK_ON_CPU \reg
add \reg, \reg, \off
.endm
#endif /* __ASSEMBLY__ */
#endif /* __ASM_ARC_ENTRY_H */

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arch/arc/kernel/entry.S Normal file
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/*
* Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC
*
* 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: Nov 2010:
* -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
* -To maintain the slot size of 8 bytes/vector, added nop, which is
* not executed at runtime.
*
* vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
* -do_signal()invoked upon TIF_RESTORE_SIGMASK as well
* -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't
* need ptregs anymore
*
* Vineetg: Oct 2009
* -In a rare scenario, Process gets a Priv-V exception and gets scheduled
* out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains
* active (AE bit enabled). This causes a double fault for a subseq valid
* exception. Thus FAKE RTIE needed in low level Priv-Violation handler.
* Instr Error could also cause similar scenario, so same there as well.
*
* 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 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". Since it is Loop INHIBIT Bit,
* setting it and not clearing it clears ZOL context
*
* Vineetg: Dec 22, 2007
* Minor Surgery of Low Level ISR to make it SMP safe
* - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
* - _current_task is made an array of NR_CPUS
* - Access of _current_task wrapped inside a macro so that if hardware
* team agrees for a dedicated reg, no other code is touched
*
* Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004
*/
/*------------------------------------------------------------------
* Function ABI
*------------------------------------------------------------------
*
* Arguments r0 - r7
* Caller Saved Registers r0 - r12
* Callee Saved Registers r13- r25
* Global Pointer (gp) r26
* Frame Pointer (fp) r27
* Stack Pointer (sp) r28
* Interrupt link register (ilink1) r29
* Interrupt link register (ilink2) r30
* Branch link register (blink) r31
*------------------------------------------------------------------
*/
.cpu A7
;############################ Vector Table #################################
.macro VECTOR lbl
#if 1 /* Just in case, build breaks */
j \lbl
#else
b \lbl
nop
#endif
.endm
.section .vector, "ax",@progbits
.align 4
/* Each entry in the vector table must occupy 2 words. Since it is a jump
* across sections (.vector to .text) we are gauranteed that 'j somewhere'
* will use the 'j limm' form of the intrsuction as long as somewhere is in
* a section other than .vector.
*/
; ********* Critical System Events **********************
VECTOR res_service ; 0x0, Restart Vector (0x0)
VECTOR mem_service ; 0x8, Mem exception (0x1)
VECTOR instr_service ; 0x10, Instrn Error (0x2)
; ******************** Device ISRs **********************
VECTOR handle_interrupt_level1
VECTOR handle_interrupt_level1
VECTOR handle_interrupt_level1
VECTOR handle_interrupt_level1
.rept 25
VECTOR handle_interrupt_level1 ; Other devices
.endr
/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */
; ******************** Exceptions **********************
VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20)
VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21)
VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22)
VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23)
; or Misaligned Access
VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24)
VECTOR EV_Trap ; 0x128, Trap exception (0x25)
VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26)
.rept 24
VECTOR reserved ; Reserved Exceptions
.endr
#include <linux/linkage.h> /* ARC_{EXTRY,EXIT} */
#include <asm/entry.h> /* SAVE_ALL_{INT1,INT2,TRAP...} */
#include <asm/errno.h>
#include <asm/arcregs.h>
#include <asm/irqflags.h>
;##################### Scratch Mem for IRQ stack switching #############
.section .data ; NOT .global
.align 32
.type int1_saved_reg, @object
.size int1_saved_reg, 4
int1_saved_reg:
.zero 4
; ---------------------------------------------
.section .text, "ax",@progbits
res_service: ; processor restart
flag 0x1 ; not implemented
nop
nop
reserved: ; processor restart
rtie ; jump to processor initializations
;##################### Interrupt Handling ##############################
; ---------------------------------------------
; Level 1 ISR
; ---------------------------------------------
ARC_ENTRY handle_interrupt_level1
/* free up r9 as scratchpad */
st r9, [@int1_saved_reg]
;Which mode (user/kernel) was the system in when intr occured
lr r9, [status32_l1]
SWITCH_TO_KERNEL_STK
SAVE_ALL_INT1
lr r0, [icause1]
and r0, r0, 0x1f
bl.d @arch_do_IRQ
mov r1, sp
mov r8,0x1
sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
b ret_from_exception
ARC_EXIT handle_interrupt_level1
;################### Non TLB Exception Handling #############################
; ---------------------------------------------
; Instruction Error Exception Handler
; ---------------------------------------------
ARC_ENTRY instr_service
EXCPN_PROLOG_FREEUP_REG r9
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_SYS
lr r0, [ecr]
lr r1, [efa]
mov r2, sp
FAKE_RET_FROM_EXCPN r9
bl do_insterror_or_kprobe
b ret_from_exception
ARC_EXIT instr_service
; ---------------------------------------------
; Memory Error Exception Handler
; ---------------------------------------------
ARC_ENTRY mem_service
EXCPN_PROLOG_FREEUP_REG r9
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_SYS
lr r0, [ecr]
lr r1, [efa]
mov r2, sp
bl do_memory_error
b ret_from_exception
ARC_EXIT mem_service
; ---------------------------------------------
; Machine Check Exception Handler
; ---------------------------------------------
ARC_ENTRY EV_MachineCheck
EXCPN_PROLOG_FREEUP_REG r9
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_SYS
lr r0, [ecr]
lr r1, [efa]
mov r2, sp
brne r0, 0x200100, 1f
bl do_tlb_overlap_fault
b ret_from_exception
1:
; DEAD END: can't do much, display Regs and HALT
SAVE_CALLEE_SAVED_USER
GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
st sp, [r10, THREAD_CALLEE_REG]
j do_machine_check_fault
ARC_EXIT EV_MachineCheck
; ---------------------------------------------
; Protection Violation Exception Handler
; ---------------------------------------------
ARC_ENTRY EV_TLBProtV
EXCPN_PROLOG_FREEUP_REG r9
;Which mode (user/kernel) was the system in when Exception occured
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_SYS
;---------(3) Save some more regs-----------------
; vineetg: Mar 6th: Random Seg Fault issue #1
; ecr and efa were not saved in case an Intr sneaks in
; after fake rtie
;
lr r3, [ecr]
lr r4, [efa]
; --------(4) Return from CPU Exception Mode ---------
; Fake a rtie, but rtie to next label
; That way, subsequently, do_page_fault ( ) executes in pure kernel
; mode with further Exceptions enabled
FAKE_RET_FROM_EXCPN r9
;------ (5) Type of Protection Violation? ----------
;
; ProtV Hardware Exception is triggered for Access Faults of 2 types
; -Access Violaton (WRITE to READ ONLY Page) - for linux COW
; -Unaligned Access (READ/WRITE on odd boundary)
;
cmp r3, 0x230400 ; Misaligned data access ?
beq 4f
;========= (6a) Access Violation Processing ========
cmp r3, 0x230100
mov r1, 0x0 ; if LD exception ? write = 0
mov.ne r1, 0x1 ; else write = 1
mov r2, r4 ; faulting address
mov r0, sp ; pt_regs
bl do_page_fault
b ret_from_exception
;========== (6b) Non aligned access ============
4:
mov r0, r3 ; cause code
mov r1, r4 ; faulting address
mov r2, sp ; pt_regs
bl do_misaligned_access
b ret_from_exception
ARC_EXIT EV_TLBProtV
; ---------------------------------------------
; Privilege Violation Exception Handler
; ---------------------------------------------
ARC_ENTRY EV_PrivilegeV
EXCPN_PROLOG_FREEUP_REG r9
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_SYS
lr r0, [ecr]
lr r1, [efa]
mov r2, sp
FAKE_RET_FROM_EXCPN r9
bl do_privilege_fault
b ret_from_exception
ARC_EXIT EV_PrivilegeV
; ---------------------------------------------
; Extension Instruction Exception Handler
; ---------------------------------------------
ARC_ENTRY EV_Extension
EXCPN_PROLOG_FREEUP_REG r9
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_SYS
lr r0, [ecr]
lr r1, [efa]
mov r2, sp
bl do_extension_fault
b ret_from_exception
ARC_EXIT EV_Extension
;################### Break Point TRAP ##########################
; ======= (5b) Trap is due to Break-Point =========
trap_with_param:
;make sure orig_r8 is a positive value
st NR_syscalls + 2, [sp, PT_orig_r8]
mov r0, r12
lr r1, [efa]
mov r2, sp
; Now that we have read EFA, its safe to do "fake" rtie
; and get out of CPU exception mode
FAKE_RET_FROM_EXCPN r11
; Save callee regs in case gdb wants to have a look
; SP will grow up by size of CALLEE Reg-File
; NOTE: clobbers r12
SAVE_CALLEE_SAVED_USER
; save location of saved Callee Regs @ thread_struct->pc
GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
st sp, [r10, THREAD_CALLEE_REG]
; Call the trap handler
bl do_non_swi_trap
; unwind stack to discard Callee saved Regs
DISCARD_CALLEE_SAVED_USER
b ret_from_exception
;##################### Trap Handling ##############################
;
; EV_Trap caused by TRAP_S and TRAP0 instructions.
;------------------------------------------------------------------
; (1) System Calls
; :parameters in r0-r7.
; :r8 has the system call number
; (2) Break Points
;------------------------------------------------------------------
ARC_ENTRY EV_Trap
; Need at least 1 reg to code the early exception prolog
EXCPN_PROLOG_FREEUP_REG r9
;Which mode (user/kernel) was the system in when intr occured
lr r9, [erstatus]
SWITCH_TO_KERNEL_STK
SAVE_ALL_TRAP
;------- (4) What caused the Trap --------------
lr r12, [ecr]
and.f 0, r12, ECR_PARAM_MASK
bnz trap_with_param
; ======= (5a) Trap is due to System Call ========
; Before doing anything, return from CPU Exception Mode
FAKE_RET_FROM_EXCPN r11
;============ This is normal System Call case ==========
; Sys-call num shd not exceed the total system calls avail
cmp r8, NR_syscalls
mov.hi r0, -ENOSYS
bhi ret_from_system_call
; Offset into the syscall_table and call handler
ld.as r9,[sys_call_table, r8]
jl [r9] ; Entry into Sys Call Handler
; fall through to ret_from_system_call
ARC_EXIT EV_Trap
ARC_ENTRY ret_from_system_call
st r0, [sp, PT_r0] ; sys call return value in pt_regs
; fall through yet again to ret_from_exception
;############# Return from Intr/Excp/Trap (Linux Specifics) ##############
;
; If ret to user mode do we need to handle signals, schedule() et al.
ARC_ENTRY ret_from_exception
; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32
ld r8, [sp, PT_status32] ; returning to User/Kernel Mode
#ifdef CONFIG_PREEMPT
bbit0 r8, STATUS_U_BIT, resume_kernel_mode
#else
bbit0 r8, STATUS_U_BIT, restore_regs
#endif
; Before returning to User mode check-for-and-complete any pending work
; such as rescheduling/signal-delivery etc.
resume_user_mode_begin:
; Disable IRQs to ensures that chk for pending work itself is atomic
; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an
; interim IRQ).
IRQ_DISABLE r10
; Fast Path return to user mode if no pending work
GET_CURR_THR_INFO_FLAGS r9
and.f 0, r9, _TIF_WORK_MASK
bz restore_regs
; --- (Slow Path #1) task preemption ---
bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals
mov blink, resume_user_mode_begin ; tail-call to U mode ret chks
b @schedule ; BTST+Bnz causes relo error in link
.Lchk_pend_signals:
IRQ_ENABLE r10
; --- (Slow Path #2) pending signal ---
mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume()
bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume
; save CALLEE Regs.
; (i) If this signal causes coredump - full regfile needed
; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus
; tracer might call PEEKUSR(CALLEE reg)
;
; NOTE: SP will grow up by size of CALLEE Reg-File
SAVE_CALLEE_SAVED_USER ; clobbers r12
; save location of saved Callee Regs @ thread_struct->callee
GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
st sp, [r10, THREAD_CALLEE_REG]
bl @do_signal
; unwind SP for cheap discard of Callee saved Regs
DISCARD_CALLEE_SAVED_USER
b resume_user_mode_begin ; loop back to start of U mode ret
; --- (Slow Path #3) notify_resume ---
.Lchk_notify_resume:
btst r9, TIF_NOTIFY_RESUME
blnz @do_notify_resume
b resume_user_mode_begin ; unconditionally back to U mode ret chks
; for single exit point from this block
#ifdef CONFIG_PREEMPT
resume_kernel_mode:
; Can't preempt if preemption disabled
GET_CURR_THR_INFO_FROM_SP r10
ld r8, [r10, THREAD_INFO_PREEMPT_COUNT]
brne r8, 0, restore_regs
; check if this task's NEED_RESCHED flag set
ld r9, [r10, THREAD_INFO_FLAGS]
bbit0 r9, TIF_NEED_RESCHED, restore_regs
IRQ_DISABLE r9
; Invoke PREEMPTION
bl preempt_schedule_irq
; preempt_schedule_irq() always returns with IRQ disabled
#endif
; fall through
;############# Return from Intr/Excp/Trap (ARC Specifics) ##############
;
; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap)
; IRQ shd definitely not happen between now and rtie
restore_regs :
; Disable Interrupts while restoring reg-file back
; XXX can this be optimised out
IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
; Restore REG File. In case multiple Events outstanding,
; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
; Note that we use realtime STATUS32 (not pt_regs->status32) to
; decide that.
; if Returning from Exception
bbit0 r10, STATUS_AE_BIT, not_exception
RESTORE_ALL_SYS
rtie
; Not Exception so maybe Interrupts (Level 1 or 2)
not_exception:
bbit0 r10, STATUS_A1_BIT, not_level1_interrupt
;return from level 1
RESTORE_ALL_INT1
debug_marker_l1:
rtie
not_level1_interrupt:
;this case is for syscalls or Exceptions (with fake rtie)
RESTORE_ALL_SYS
debug_marker_syscall:
rtie
ARC_EXIT ret_from_exception
ARC_ENTRY ret_from_fork
; when the forked child comes here from the __switch_to function
; r0 has the last task pointer.
; put last task in scheduler queue
bl @schedule_tail
b @ret_from_exception
ARC_EXIT ret_from_fork