Subversion Repositories HelenOS

#
# Copyright (c) 2009 Vineeth Pillai
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

.text   

.global irq_exception_entry
.global fiq_exception_entry
.global data_abort_exception_entry
.global prefetch_abort_exception_entry
.global undef_instr_exception_entry
.global swi_exception_entry
.global reset_exception_entry


# Switches to kernel stack and saves all registers there.
#
#  The stack frame created by the function looks like:
#
#              |_________________|
#              |                 |
#              |     SPSR        |
#              |                 |
#              |_________________|
#              | Stack Pointer   |
#              |      of         |
#              | Previous Mode   |
#              |_________________|
#              | Return address  |
#              |      of         |
#              | Previous Mode   |
#              |_________________|
#              |   R0  - R12     |
#              |      of         |
#              | Previous Mode   |
#              |_________________|
#              | Return address  |
#              |     from        |
#              |Exception Handler|
#              |_________________|
#              |                 |
#
#

.macro SAVE_REGS_TO_STACK
    stmfd r13!, {r0-r3}
    mov r3, sp
    add sp, sp, #16
    mrs r1, cpsr
    bic r1, r1, #0x1f
    mrs r2, spsr
    and r0, r2, #0x1f
    cmp r0, #0x10
    bne 1f

    # prev mode was usermode
    mov r0, lr

    # Switch to supervisor mode
    orr r1, r1, #0x13
    msr cpsr_c, r1

    # Load sp with [supervisor_sp]
    ldr r13, =supervisor_sp
    ldr r13, [r13]

    # Populate the stack frame
    msr spsr, r2
    mov lr, r0
    stmfd r13!, {lr}
    stmfd r13!, {r4-r12}
    ldmfd r3!, {r4-r7}
    stmfd r13!, {r4-r7}
    stmfd r13!, {r13, lr}^
    stmfd r13!, {r2}
    b 2f

    # mode was not usermode
1:
    # Switch to previous mode which is undoubtedly the supervisor mode
    orr r1, r1, r0
    mov r0, lr
    msr cpsr_c, r1

    # Populate the stack frame
    mov r1, sp
    stmfd r13!, {r0}
    stmfd r13!, {r4-r12}

    # Store r0-r3 in r4-r7 and then push it on to stack
    ldmfd r3!, {r4-r7}
    stmfd r13!, {r4-r7}

    # Push return address and stack pointer on to stack
    stmfd r13!, {lr}
    stmfd r13!, {r1}
    mov lr, r0
    msr spsr, r2
    stmfd r13!, {r2}
2:
.endm

.macro LOAD_REGS_FROM_STACK
    ldmfd r13!, {r0}
    msr spsr, r0
    and r0, r0, #0x1f
    cmp r0, #0x10
    bne 1f

    # return to user mode
    ldmfd r13!, {r13, lr}^
    b 2f

    # return to non-user mode
1:
    ldmfd r13!, {r1, lr}

2:
    ldmfd r13!, {r0-r12, pc}^
.endm

reset_exception_entry:
    SAVE_REGS_TO_STACK
    mov r0, #0
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK

irq_exception_entry:
    sub lr, lr, #4
    SAVE_REGS_TO_STACK
    mov r0, #5
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK

fiq_exception_entry:
    sub lr, lr, #4
    SAVE_REGS_TO_STACK
    mov r0, #6
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK

undef_instr_exception_entry:
    SAVE_REGS_TO_STACK
    mov r0, #1
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK

prefetch_abort_exception_entry:
    sub lr, lr, #4
    SAVE_REGS_TO_STACK
    mov r0, #3
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK

data_abort_exception_entry:
    sub lr, lr, #8
    SAVE_REGS_TO_STACK
    mov r0, #4
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK

swi_exception_entry:
    ldr r13, =exc_stack
    SAVE_REGS_TO_STACK
    mov r0, #2
    mov r1, r13
    bl exc_dispatch
    LOAD_REGS_FROM_STACK