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Subject[PATCH v1 2/8] x86/entry/clearregs: Add infrastructure to clear registers
Date
From: Andi Kleen <ak@linux.intel.com>

Add 64bit assembler macros to clear registers on kernel entry.
Used in followon patches.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/entry/calling.h | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index 45a63e00a6af..9444e7623185 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -172,6 +172,34 @@ For 32-bit we have the following conventions - kernel is built with
.byte 0xf1
.endm

+ .macro CLEAR_R11_TO_R15
+ xorq %r15, %r15
+ xorq %r14, %r14
+ xorq %r13, %r13
+ xorq %r12, %r12
+ xorq %r11, %r11
+ .endm
+
+ .macro CLEAR_R8_TO_R15
+ CLEAR_R11_TO_R15
+ xorq %r10, %r10
+ xorq %r9, %r9
+ xorq %r8, %r8
+ .endm
+
+ .macro CLEAR_ALL_REGS
+ CLEAR_R8_TO_R15
+ xorl %eax, %eax
+ xorl %ebx, %ebx
+ xorl %ecx, %ecx
+ xorl %edx, %edx
+ xorl %esi, %esi
+ xorl %edi, %edi
+#ifndef CONFIG_FRAME_POINTER
+ xorl %ebp, %ebp
+#endif
+ .endm
+
/*
* This is a sneaky trick to help the unwinder find pt_regs on the stack. The
* frame pointer is replaced with an encoded pointer to pt_regs. The encoding
--
2.14.3
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