--- /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
+
+ */
+
+
+ EXPORT ExceptionHandlersStart
+ EXPORT ExceptionHandlersEnd
+ EXPORT CommonExceptionEntry
+ EXPORT AsmCommonExceptionEntry
+ IMPORT GdbExceptionHandler
+
+ PRESERVE8
+ AREA DxeExceptionHandlers, CODE, READONLY
+
+//
+// This code gets copied to the ARM vector table
+// ExceptionHandlersStart - ExceptionHandlersEnd gets copied
+//
+ExceptionHandlersStart
+
+Reset
+ b Reset
+
+UndefinedInstruction
+ b UndefinedInstructionEntry
+
+SoftwareInterrupt
+ b SoftwareInterruptEntry
+
+PrefetchAbort
+ b PrefetchAbortEntry
+
+DataAbort
+ b DataAbortEntry
+
+ReservedException
+ b ReservedExceptionEntry
+
+Irq
+ b Irq
+
+Fiq
+ b FiqEntry
+
+
+UndefinedInstructionEntry
+ sub LR, LR, #4 ; Only -2 for Thumb, adjust in CommonExceptionEntry
+ srsfd #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,CommonExceptionEntry;
+ bx R1
+
+SoftwareInterruptEntry
+ sub LR, LR, #4 ; Only -2 for Thumb, adjust in CommonExceptionEntry
+ srsfd #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,CommonExceptionEntry
+ bx R1
+
+PrefetchAbortEntry
+ sub LR,LR,#4
+ srsfd #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,CommonExceptionEntry
+ bx R1
+
+DataAbortEntry
+ sub LR,LR,#8
+ srsfd #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 ; ExceptionType
+ ldr R1,CommonExceptionEntry
+ bx R1
+
+ReservedExceptionEntry
+ srsfd #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 ; ExceptionType
+ ldr R1,CommonExceptionEntry
+ bx R1
+
+FiqEntry
+ sub LR,LR,#4
+ srsfd #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,CommonExceptionEntry
+ bx R1
+
+//
+// This gets patched by the C code that patches in the vector table
+//
+CommonExceptionEntry
+ dcd 0x12345678
+
+ExceptionHandlersEnd
+
+//
+// This code runs from CpuDxe driver loaded address. It is patched into
+// CommonExceptionEntry.
+//
+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] ; srsfd 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 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
+
+ END
+
+
projects / mirror_edk2.git / blobdiff