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#

# 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