| // | |
| // Copyright (c) 2011, 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. | |
| // | |
| // | |
| EXPORT monitor_vector_table | |
| EXPORT return_from_exception | |
| EXPORT enter_monitor_mode | |
| EXPORT copy_cpsr_into_spsr | |
| EXPORT set_non_secure_mode | |
| AREA Helper, CODE, READONLY | |
| ALIGN 32 | |
| monitor_vector_table | |
| ldr pc, dead | |
| ldr pc, dead | |
| ldr pc, dead | |
| ldr pc, dead | |
| ldr pc, dead | |
| ldr pc, dead | |
| ldr pc, dead | |
| ldr pc, dead | |
| // arg0: Secure Monitor mode stack | |
| enter_monitor_mode | |
| mov r2, lr // Save current lr | |
| mrs r1, cpsr // Save current mode (SVC) in r1 | |
| bic r3, r1, #0x1f // Clear all mode bits | |
| orr r3, r3, #0x16 // Set bits for Monitor mode | |
| msr cpsr_cxsf, r3 // We are now in Monitor Mode | |
| mov sp, r0 // Use the passed sp | |
| mov lr, r2 // Use the same lr as before | |
| msr spsr_cxsf, r1 // Use saved mode for the MOVS jump to the kernel | |
| bx lr | |
| // 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'. | |
| return_from_exception | |
| adr lr, returned_exception | |
| movs pc, lr | |
| returned_exception // We are now in non-secure state | |
| bx r0 | |
| // Save the current Program Status Register (PSR) into the Saved PSR | |
| copy_cpsr_into_spsr | |
| mrs r0, cpsr | |
| msr spsr_cxsf, r0 | |
| bx lr | |
| // Set the Non Secure Mode | |
| 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 | |
| END |