--- /dev/null
+#------------------------------------------------------------------------------
+#
+# Use ARMv6 instruction to operate on a single stack
+#
+# Copyright (c) 2008-2010 Apple Inc. All rights reserved.
+#
+# All rights reserved. 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.
+#
+#------------------------------------------------------------------------------
+
+/*
+
+This is the stack constructed by the exception handler (low address to high address)
+ # R0 - IFAR is EFI_SYSTEM_CONTEXT for ARM
+ Reg Offset
+ === ======
+ R0 0x00 # stmfd SP!,{R0-R12}
+ R1 0x04
+ R2 0x08
+ R3 0x0c
+ R4 0x10
+ R5 0x14
+ R6 0x18
+ R7 0x1c
+ R8 0x20
+ R9 0x24
+ R10 0x28
+ R11 0x2c
+ R12 0x30
+ SP 0x34 # reserved via adding 0x20 (32) to the SP
+ LR 0x38
+ PC 0x3c
+ CPSR 0x40
+ DFSR 0x44
+ DFAR 0x48
+ IFSR 0x4c
+ IFAR 0x50
+
+ LR 0x54 # SVC Link register (we need to restore it)
+
+ LR 0x58 # pushed by srsfd
+ CPSR 0x5c
+
+ */
+
+
+.globl ASM_PFX(ExceptionHandlersStart)
+.globl ASM_PFX(ExceptionHandlersEnd)
+.globl ASM_PFX(CommonExceptionEntry)
+.globl ASM_PFX(AsmCommonExceptionEntry)
+.globl ASM_PFX(GdbExceptionHandler)
+
+.text
+.align 3
+
+
+//
+// This code gets copied to the ARM vector table
+// ExceptionHandlersStart - ExceptionHandlersEnd gets copied
+//
+ASM_PFX(ExceptionHandlersStart):
+
+ASM_PFX(Reset):
+ b ASM_PFX(Reset)
+
+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(Irq)
+
+ASM_PFX(Fiq):
+ b ASM_PFX(FiqEntry)
+
+
+ASM_PFX(UndefinedInstructionEntry):
+ sub LR, LR, #4 @ Only -2 for Thumb, adjust in CommonExceptionEntry
+ 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 @ ExceptionType
+ ldr R1,ASM_PFX(CommonExceptionEntry)
+ bx R1
+
+ASM_PFX(SoftwareInterruptEntry):
+ sub LR, LR, #4 @ Only -2 for Thumb, adjust in CommonExceptionEntry
+ srsdb #0x13! @ Store return state on SVC stack
+ @ We are already in SVC mode
+ 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 @ ExceptionType
+ 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 @ ExceptionType
+ 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(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
+ @ Since we have already switch to SVC R8_fiq - R12_fiq
+ @ never get used or saved
+ mov R0,#7 @ ExceptionType
+ ldr R1,ASM_PFX(CommonExceptionEntry)
+ bx R1
+
+//
+// This gets patched by the C code that patches in the vector table
+//
+ASM_PFX(CommonExceptionEntry):
+ .byte 0x12
+ .byte 0x34
+ .byte 0x56
+ .byte 0x78
+
+ASM_PFX(ExceptionHandlersEnd):
+
+//
+// This code runs from CpuDxe driver loaded address. It is patched into
+// CommonExceptionEntry.
+//
+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
+
+ add R2, SP, #0x38 @ Make R2 point to EFI_SYSTEM_CONTEXT_ARM.LR
+ and R3, R1, #0x1f @ Check CPSR to see if User or System Mode
+ cmp R3, #0x1f @ if ((CPSR == 0x10) || (CPSR == 0x1df))
+ cmpne R3, #0x10 @
+ stmeqed R2, {lr}^ @ save unbanked lr
+ @ else
+ stmneed R2, {lr} @ save SVC lr
+
+
+ ldr R5, [SP, #0x58] @ PC is the LR pushed by srsfd
+ @ Check to see if we have to adjust for Thumb entry
+ sub r4, r0, #1 @ if (ExceptionType == 1 || ExceptionType ==2)) {
+ cmp r4, #1 @ // UND & SVC have differnt LR adjust for Thumb
+ bhi NoAdjustNeeded
+
+ tst r1, #0x20 @ if ((CPSR & T)) == T) { // Thumb Mode on entry
+ addne R5, R5, #2 @ PC += 2@
+ str R5,[SP,#0x58] @ Update LR value pused by srsfd
+
+NoAdjustNeeded:
+
+ str R5, [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 ExceptionType
+ mov R1,SP @ R1 is SystemContext
+
+/*
+VOID
+EFIAPI
+GdbExceptionHandler (
+ IN EFI_EXCEPTION_TYPE ExceptionType, R0
+ IN OUT EFI_SYSTEM_CONTEXT SystemContext R1
+ )
+
+*/
+ blx ASM_PFX(GdbExceptionHandler) @ Call exception handler
+
+ ldr R1,[SP,#0x3c] @ EFI_SYSTEM_CONTEXT_ARM.PC
+ str R1,[SP,#0x58] @ Store it back to srsfd stack slot so it can be restored
+
+ ldr R1,[SP,#0x40] @ EFI_SYSTEM_CONTEXT_ARM.CPSR
+ str R1,[SP,#0x5c] @ Store it back to srsfd stack slot so it can be restored
+
+ add R3, SP, #0x54 @ Make R3 point to SVC LR saved on entry
+ add R2, SP, #0x38 @ Make R2 point to EFI_SYSTEM_CONTEXT_ARM.LR
+ and R1, R1, #0x1f @ Check to see if User or System Mode
+ cmp R1, #0x1f @ if ((CPSR == 0x10) || (CPSR == 0x1f))
+ cmpne R1, #0x10 @
+ ldmeqed R2, {lr}^ @ restore unbanked lr
+ @ else
+ ldmneed R3, {lr} @ restore SVC lr, via ldmfd SP!, {LR}
+
+ ldmfd SP!,{R0-R12} @ Restore general purpose registers
+ @ Exception handler can not change SP
+
+ 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 srsfd stack slot
+
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