Messages in this thread | | | Date | Tue, 16 May 2006 17:42:36 +0800 | From | "bibo,mao" <> | Subject | Re: [PATCH]x86_64 debug_stack nested patch (again) |
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Sorry for late reply, interrupt is disabled when int3/int1 trap happens and NMI is not permitted for kprobe in x86_64 platform,nest level of kprobe is 2 at most. So that will work well if DEBUG_STACK is set to 8K when CONFIG_KPROBE option is set.
Thanks bibo,mao
Andi Kleen wrote: > 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 > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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