(2013/11/09 1:56), Will Deacon wrote: > Hi Sandeepa, > > On Thu, Oct 17, 2013 at 12:17:47PM +0100, Sandeepa Prabhu wrote: >> Add support for basic kernel probes(kprobes), jump probes (jprobes) >> for ARM64. > > I think this series will conflict quite heavily with the jump_label series, > since they both introduce some common instruction manipulation code. On the > debug side, there will also be conflicts with the kgdb series, so it might > make sense for us to merge those two first, then you can rebase on a stable > branch from us.
[...] > In fact, how do you avoid a race with hardware breakpoints? E.g., somebody > places a hardware breakpoint on an instruction in the kernel for which > kprobes has patched in a brk. We take the hardware breakpoint, disable the > breakpoint and set up a single step before returning to the brk. The brk > then traps, but we must take care not to disable single-step and/or unmask > debug exceptions, because that will cause the hardware breakpoint code to > re-arm its breakpoint before we've stepped off the brk instruction. Hmm, frankly to say, this kind of race issue is not seriously discussed on x86 too, since kgdb is still a special tool (not used on the production system). I think under such situation kgdb operator must have full control of the system, and he can (and has to) avoid such kind of race. Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
