(2015/02/20 21:52), Ingo Molnar wrote: > > * Masami Hiramatsu <[email protected]> wrote: > >> (2015/02/20 19:26), Ingo Molnar wrote: >>> >>> * Petr Mladek <[email protected]> wrote: >>> >>>> can_probe() checks if the given address points to the >>>> beginning of an instruction. It analyzes all the >>>> instructions from the beginning of the function until the >>>> given address. The code might be modified by another >>>> Kprobe. In this case, the current code is read into a >>>> buffer, int3 breakpoint is replaced by the saved opcode >>>> in the buffer, and can_probe() analyzes the buffer >>>> instead. >>>> >>>> [...] >>> >>> Had to drop this patch due to build failures on 32-bit x86: >>> >>> arch/x86/kernel/kprobes/core.c:258:40: error: ‘MCOUNT_INSN_SIZE’ undeclared >>> (first use in this function) >> >> Oops, MCOUNT_INSN_SIZE actually depends on >> CONFIG_FUNCTION_TRACER... I think we can use 5 instead of >> that since we are copying NOP_ATOMIC5. > > Or just make the define more widely available? It's not > like the size changes from disabling the function tracer.
Yeah, it could be. Actually, to tell the truth, if CONFIG_FUNCTION_TRACER=n, ftrace_location() always returns 0, so the 2nd memcpy never be executed (it should be disappeared by optimization). Thus *this* issue is very local one, and I thought we'd better fix this locally. :) Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
