[PATCH]x86_64 debug_stack nested patch (again)

[bibo,mao]

Hi,
In x86_64 platform, INT1 and INT3 trap stack is IST stack called DEBUG_STACK,
when INT1/INT3 trap happens, system will switch to DEBUG_STACK by hardware. 
Current DEBUG_STACK size is 4K, when int1/int3 trap happens, kernel will 
minus current DEBUG_STACK IST value by 4k. But if int3/int1 trap is nested, 
it will destroy other vector's IST stack. This patch modifies this, it sets 
DEBUG_STACK size as 8K and allows two level of nested int1/int3 trap.

Kprobe DEBUG_STACK may be nested, because kprobe hanlder may be probed 
by other kprobes. This patch is against 2.6.17-rc3. Thanks jbeulich for pointing out error in the first patch.

Signed-Off-By: bibo, mao <bibo.mao@xxxxxxxxx>

--- 2.6.17-rc3.org/include/asm-x86_64/page.h	2006-05-10 12:07:18.000000000 +0800
+++ 2.6.17-rc3/include/asm-x86_64/page.h	2006-05-10 12:19:24.000000000 +0800
@@ -20,7 +20,7 @@
 #define EXCEPTION_STACK_ORDER 0
 #define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)
 
-#define DEBUG_STACK_ORDER EXCEPTION_STACK_ORDER
+#define DEBUG_STACK_ORDER (EXCEPTION_STACK_ORDER + 1)
 #define DEBUG_STKSZ (PAGE_SIZE << DEBUG_STACK_ORDER)
 
 #define IRQSTACK_ORDER 2


Thanks
bibo,mao
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