From a9d7090fc217dad23330ddc54cad4d4987cab65a Mon Sep 17 00:00:00 2001
From: oliviermartin <oliviermartin@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Tue, 12 Mar 2013 00:54:02 +0000
Subject: ArmPlatformPkg: Moved ARMv7 specific files to a 'Arm' subdirectory

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14182 6f19259b-4bc3-4df7-8a09-765794883524
---
 ArmPlatformPkg/Sec/Arm/Helper.asm | 79 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 ArmPlatformPkg/Sec/Arm/Helper.asm

(limited to 'ArmPlatformPkg/Sec/Arm/Helper.asm')

diff --git a/ArmPlatformPkg/Sec/Arm/Helper.asm b/ArmPlatformPkg/Sec/Arm/Helper.asm
new file mode 100644
index 0000000000..b31cc31a97
--- /dev/null
+++ b/ArmPlatformPkg/Sec/Arm/Helper.asm
@@ -0,0 +1,79 @@
+//
+//  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.             
+//
+//
+
+    EXPORT  return_from_exception
+    EXPORT  enter_monitor_mode
+    EXPORT  copy_cpsr_into_spsr
+    EXPORT  set_non_secure_mode
+    
+    AREA   Helper, CODE, READONLY
+
+// r0: Monitor World EntryPoint
+// r1: MpId
+// r2: SecBootMode
+// r3: Secure Monitor mode stack
+enter_monitor_mode FUNCTION
+    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
+    ENDFUNC
+
+// 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
-- 
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