Enlarge debug stack for nested kprobes From: "bibo,mao" 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 handler may be probed by other kprobes. Thanks jbeulich for pointing out error in the first patch. [AK: nested kprobes are pretty dubious. Hopefully one nest will be enough. This will cost 8K per CPU (4K more than before)] Signed-Off-By: bibo, mao Signed-off-by: Andi Kleen --- include/asm-x86_64/page.h | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) Index: linux/include/asm-x86_64/page.h =================================================================== --- linux.orig/include/asm-x86_64/page.h +++ linux/include/asm-x86_64/page.h @@ -19,7 +19,7 @@ #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