diff options
| author | andrewfish <andrewfish@6f19259b-4bc3-4df7-8a09-765794883524> | 2011-02-01 05:41:42 +0000 |
|---|---|---|
| committer | andrewfish <andrewfish@6f19259b-4bc3-4df7-8a09-765794883524> | 2011-02-01 05:41:42 +0000 |
| commit | 1d5d0ae92d95410f20bc6daab7a47e129fb2547a (patch) | |
| tree | 8679c57c5f85cadad47d4604450c1c3702276cf1 /ArmPlatformPkg/Sec/Helper.asm | |
| parent | fb334ef6c543b1babc9d8a613ad5d1ce6fe536e1 (diff) | |
| download | edk2-platforms-1d5d0ae92d95410f20bc6daab7a47e129fb2547a.tar.xz | |
Add ArmPlatformPkg from ARM Ltd. patch.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11291 6f19259b-4bc3-4df7-8a09-765794883524
Diffstat (limited to 'ArmPlatformPkg/Sec/Helper.asm')
| -rw-r--r-- | ArmPlatformPkg/Sec/Helper.asm | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/ArmPlatformPkg/Sec/Helper.asm b/ArmPlatformPkg/Sec/Helper.asm new file mode 100644 index 0000000000..43a0749138 --- /dev/null +++ b/ArmPlatformPkg/Sec/Helper.asm @@ -0,0 +1,66 @@ +//
+// 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
+
+ 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
+
+dead
+ B dead
+
+ END
|