mirror of https://github.com/acidanthera/audk.git
88 lines
3.3 KiB
ArmAsm
88 lines
3.3 KiB
ArmAsm
#========================================================================================
|
|
# Copyright (c) 2011-2012, ARM Limited. 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.
|
|
#
|
|
#=======================================================================================
|
|
|
|
#start of the code section
|
|
.text
|
|
.align 3
|
|
|
|
GCC_ASM_EXPORT(return_from_exception)
|
|
GCC_ASM_EXPORT(enter_monitor_mode)
|
|
GCC_ASM_EXPORT(copy_cpsr_into_spsr)
|
|
GCC_ASM_EXPORT(set_non_secure_mode)
|
|
|
|
# r0: Monitor World EntryPoint
|
|
# r1: MpId
|
|
# r2: SecBootMode
|
|
# r3: Secure Monitor mode stack
|
|
ASM_PFX(enter_monitor_mode):
|
|
cmp r3, #0 @ If a Secure Monitor stack base has not been defined then use the Secure stack
|
|
moveq r3, sp
|
|
|
|
mrs r4, cpsr @ Save current mode (SVC) in r4
|
|
bic r5, r4, #0x1f @ Clear all mode bits
|
|
orr r5, r5, #0x16 @ Set bits for Monitor mode
|
|
msr cpsr_cxsf, r5 @ We are now in Monitor Mode
|
|
|
|
mov sp, r3 @ Set the stack of the Monitor Mode
|
|
|
|
mov lr, r0 @ Use the pass entrypoint as lr
|
|
|
|
msr spsr_cxsf, r4 @ Use saved mode for the MOVS jump to the kernel
|
|
|
|
mov r4, r0 @ Swap EntryPoint and MpId registers
|
|
mov r0, r1
|
|
mov r1, r2
|
|
mov r2, r3
|
|
|
|
bx r4
|
|
|
|
# We cannot use the instruction 'movs pc, lr' because the caller can be written either in ARM or Thumb2 assembler.
|
|
# When we will jump into this function, we will set the CPSR flag to ARM assembler. By copying directly 'lr' into
|
|
# 'pc'; we will not change the CPSR flag and it will crash.
|
|
# The way to fix this limitation is to do the movs into the ARM assmbler code and then do a 'bx'.
|
|
ASM_PFX(return_from_exception):
|
|
ldr lr, returned_exception
|
|
|
|
#The following instruction breaks the code.
|
|
#movs pc, lr
|
|
mrs r2, cpsr
|
|
bic r2, r2, #0x1f
|
|
orr r2, r2, #0x13
|
|
msr cpsr_c, r2
|
|
|
|
returned_exception: @ We are now in non-secure state
|
|
bx r0
|
|
|
|
# Save the current Program Status Register (PSR) into the Saved PSR
|
|
ASM_PFX(copy_cpsr_into_spsr):
|
|
mrs r0, cpsr
|
|
msr spsr_cxsf, r0
|
|
bx lr
|
|
|
|
# Set the Non Secure Mode
|
|
ASM_PFX(set_non_secure_mode):
|
|
push { r1 }
|
|
and r0, r0, #0x1f @ Keep only the mode bits
|
|
mrs r1, spsr @ Read the spsr
|
|
bic r1, r1, #0x1f @ Clear all mode bits
|
|
orr r1, r1, r0
|
|
msr spsr_cxsf, r1 @ write back spsr (may have caused a mode switch)
|
|
isb
|
|
pop { r1 }
|
|
bx lr @ return (hopefully thumb-safe!)
|
|
|
|
dead:
|
|
b dead
|
|
|
|
ASM_FUNCTION_REMOVE_IF_UNREFERENCED
|