Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH]x86_64 debug_stack nested patch (again) | Date | Thu, 11 May 2006 13:28:44 +0200 |
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On Thursday 11 May 2006 13:17, Andrew Morton wrote: > "bibo,mao" <bibo.mao@intel.com> wrote: > > > > 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@intel.com> > > > > --- 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 > > So.... why not do it this way?
Last time we discussed this I was told it could nest upto 3 or 4 times So that still wouldn't work.
If anything they should decrease the int3/debug stack to 2K, then 8K might be enough.
Or even better would be to fix kprobes to not do that.
I think paranoidentry would need to be fixed for that too.
-Andi
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