ArmPkg/Drivers/CpuDxe/ArmV4/ExceptionSupport.S
#------------------------------------------------------------------------------
#
# Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
#
# This program and the accompanying materials
# are licensed and made available under the terms and conditions of the BSD License
# which accompanies this distribution. The full text of the license may be found at
# http://opensource.org/licenses/bsd-license.php
#
# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#
#------------------------------------------------------------------------------
.text
.align 3
GCC_ASM_EXPORT(ExceptionHandlersStart)
GCC_ASM_EXPORT(ExceptionHandlersEnd)
GCC_ASM_EXPORT(CommonExceptionEntry)
GCC_ASM_EXPORT(AsmCommonExceptionEntry)
GCC_ASM_EXPORT(CommonCExceptionHandler)
ASM_PFX(ExceptionHandlersStart):
ASM_PFX(Reset):
b ASM_PFX(ResetEntry)
ASM_PFX(UndefinedInstruction):
b ASM_PFX(UndefinedInstructionEntry)
ASM_PFX(SoftwareInterrupt):
b ASM_PFX(SoftwareInterruptEntry)
ASM_PFX(PrefetchAbort):
b ASM_PFX(PrefetchAbortEntry)
ASM_PFX(DataAbort):
b ASM_PFX(DataAbortEntry)
ASM_PFX(ReservedException):
b ASM_PFX(ReservedExceptionEntry)
ASM_PFX(Irq):
b ASM_PFX(IrqEntry)
ASM_PFX(Fiq):
b ASM_PFX(FiqEntry)
ASM_PFX(ResetEntry):
srsdb #0x13! @ Store return state on SVC stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov R0,#0
ldr R1,ASM_PFX(CommonExceptionEntry)
bx R1
ASM_PFX(UndefinedInstructionEntry):
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#1
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(SoftwareInterruptEntry):
srsdb #0x13! @ Store return state on SVC stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#2
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(PrefetchAbortEntry):
sub LR,LR,#4
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#3
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(DataAbortEntry):
sub LR,LR,#8
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#4
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(ReservedExceptionEntry):
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#5
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(IrqEntry):
sub LR,LR,#4
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#6
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(FiqEntry):
sub LR,LR,#4
srsdb #0x13! @ Store return state on SVC stack
cps #0x13 @ Switch to SVC for common stack
stmfd SP!,{LR} @ Store the link register for the current mode
sub SP,SP,#0x20 @ Save space for SP, LR, PC, IFAR - CPSR
stmfd SP!,{R0-R12} @ Store the register state
mov r0,#7
ldr r1,ASM_PFX(CommonExceptionEntry)
bx r1
ASM_PFX(CommonExceptionEntry):
.byte 0x12
.byte 0x34
.byte 0x56
.byte 0x78
ASM_PFX(ExceptionHandlersEnd):
ASM_PFX(AsmCommonExceptionEntry):
mrc p15, 0, R1, c6, c0, 2 @ Read IFAR
str R1, [SP, #0x50] @ Store it in EFI_SYSTEM_CONTEXT_ARM.IFAR
mrc p15, 0, R1, c5, c0, 1 @ Read IFSR
str R1, [SP, #0x4c] @ Store it in EFI_SYSTEM_CONTEXT_ARM.IFSR
mrc p15, 0, R1, c6, c0, 0 @ Read DFAR
str R1, [SP, #0x48] @ Store it in EFI_SYSTEM_CONTEXT_ARM.DFAR
mrc p15, 0, R1, c5, c0, 0 @ Read DFSR
str R1, [SP, #0x44] @ Store it in EFI_SYSTEM_CONTEXT_ARM.DFSR
ldr R1, [SP, #0x5c] @ srsdb saved pre-exception CPSR on the stack
str R1, [SP, #0x40] @ Store it in EFI_SYSTEM_CONTEXT_ARM.CPSR
and r1, r1, #0x1f @ Check to see if User or System Mode
cmp r1, #0x1f
cmpne r1, #0x10
add R2, SP, #0x38 @ Store it in EFI_SYSTEM_CONTEXT_ARM.LR
ldmneed r2, {lr}^ @ User or System mode, use unbanked register
ldmneed r2, {lr} @ All other modes used banked register
ldr R1, [SP, #0x58] @ PC is the LR pushed by srsdb
str R1, [SP, #0x3c] @ Store it in EFI_SYSTEM_CONTEXT_ARM.PC
sub R1, SP, #0x60 @ We pused 0x60 bytes on the stack
str R1, [SP, #0x34] @ Store it in EFI_SYSTEM_CONTEXT_ARM.SP
@ R0 is exception type
mov R1,SP @ Prepare System Context pointer as an argument for the exception handler
blx ASM_PFX(CommonCExceptionHandler) @ Call exception handler
ldr R2,[SP,#0x40] @ EFI_SYSTEM_CONTEXT_ARM.CPSR
str R2,[SP,#0x5c] @ Store it back to srsdb stack slot so it can be restored
ldr R2,[SP,#0x3c] @ EFI_SYSTEM_CONTEXT_ARM.PC
str R2,[SP,#0x58] @ Store it back to srsdb stack slot so it can be restored
ldmfd SP!,{R0-R12} @ Restore general purpose registers
@ Exception handler can not change SP or LR as we would blow chunks
add SP,SP,#0x20 @ Clear out the remaining stack space
ldmfd SP!,{LR} @ restore the link register for this context
rfefd SP! @ return from exception via srsdb stack slot