| Date | Tue, 20 Sep 2011 18:13:10 +0100 | From | Stefan Hajnoczi <> | Subject | Re: [PATCH v5 3.1.0-rc4-tip 8/26] x86: analyze instruction and determine fixups. |
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On Tue, Sep 20, 2011 at 05:31:27PM +0530, Srikar Dronamraju wrote: > > The instruction analysis is based on x86 instruction decoder and > determines if an instruction can be probed and determines the necessary > fixups after singlestep. Instruction analysis is done at probe > insertion time so that we avoid having to repeat the same analysis every > time a probe is hit. > > Signed-off-by: Jim Keniston <jkenisto@us.ibm.com> > Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> > --- > arch/x86/Kconfig | 3 > arch/x86/include/asm/uprobes.h | 42 ++++ > arch/x86/kernel/Makefile | 1 > arch/x86/kernel/uprobes.c | 385 ++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 431 insertions(+), 0 deletions(-) > create mode 100644 arch/x86/include/asm/uprobes.h > create mode 100644 arch/x86/kernel/uprobes.c
You've probably thought of this but it would be nice to skip XOL for nops. This would be a common case with static probes (e.g. sdt.h) where the probe template includes a nop where we can easily plant int $0x3.
Perhaps a check can be added to the analysis so that after calling the filter/handler we can immediately continue the process instead of executing the (useless) nop out-of-line.
Stefan
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