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Subject[PATCH 11/35] x86/entry/32: Simplify debug entry point
Date
From: Joerg Roedel <jroedel@suse.de>

The common exception entry code now handles the
entry-from-sysenter stack situation and makes sure to leave
with the same stack as it entered the kernel.

So there is no need anymore for the special handling in the
debug entry code.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/entry/entry_32.S | 35 +++--------------------------------
1 file changed, 3 insertions(+), 32 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index b3477ff..71e1cb3 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1231,41 +1231,12 @@ END(common_exception)

ENTRY(debug)
/*
- * #DB can happen at the first instruction of
- * entry_SYSENTER_32 or in Xen's SYSENTER prologue. If this
- * happens, then we will be running on a very small stack. We
- * need to detect this condition and switch to the thread
- * stack before calling any C code at all.
- *
- * If you edit this code, keep in mind that NMIs can happen in here.
+ * Entry from sysenter is now handled in common_exception
*/
ASM_CLAC
pushl $-1 # mark this as an int
-
- SAVE_ALL
- ENCODE_FRAME_POINTER
- xorl %edx, %edx # error code 0
- movl %esp, %eax # pt_regs pointer
-
- /* Are we currently on the SYSENTER stack? */
- movl PER_CPU_VAR(cpu_entry_area), %ecx
- addl $CPU_ENTRY_AREA_entry_stack + SIZEOF_entry_stack, %ecx
- subl %eax, %ecx /* ecx = (end of entry_stack) - esp */
- cmpl $SIZEOF_entry_stack, %ecx
- jb .Ldebug_from_sysenter_stack
-
- TRACE_IRQS_OFF
- call do_debug
- jmp ret_from_exception
-
-.Ldebug_from_sysenter_stack:
- /* We're on the SYSENTER stack. Switch off. */
- movl %esp, %ebx
- movl PER_CPU_VAR(cpu_current_top_of_stack), %esp
- TRACE_IRQS_OFF
- call do_debug
- movl %ebx, %esp
- jmp ret_from_exception
+ pushl $do_debug
+ jmp common_exception
END(debug)

/*
--
2.7.4
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