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author | andrewfish <andrewfish@6f19259b-4bc3-4df7-8a09-765794883524> | 2011-02-01 05:41:42 +0000 |
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committer | andrewfish <andrewfish@6f19259b-4bc3-4df7-8a09-765794883524> | 2011-02-01 05:41:42 +0000 |
commit | 1d5d0ae92d95410f20bc6daab7a47e129fb2547a (patch) | |
tree | 8679c57c5f85cadad47d4604450c1c3702276cf1 /ArmPlatformPkg/Sec/Helper.S | |
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.S')
-rw-r--r-- | ArmPlatformPkg/Sec/Helper.S | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/ArmPlatformPkg/Sec/Helper.S b/ArmPlatformPkg/Sec/Helper.S new file mode 100644 index 0000000000..94bd68f8bc --- /dev/null +++ b/ArmPlatformPkg/Sec/Helper.S @@ -0,0 +1,74 @@ +#========================================================================================
+# 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.
+#
+#=======================================================================================
+
+#start of the code section
+.text
+.align 3
+
+GCC_ASM_EXPORT(monitor_vector_table)
+GCC_ASM_EXPORT(return_from_exception)
+GCC_ASM_EXPORT(enter_monitor_mode)
+GCC_ASM_EXPORT(copy_cpsr_into_spsr)
+
+ASM_PFX(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
+ASM_PFX(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'.
+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
+
+dead:
+ B dead
+
+.end
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