Messages in this thread | | | Date | Fri, 20 Feb 2015 21:38:18 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 1/2] kprobes/x86: Use 5-byte NOP when the code might be modified by ftrace |
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(2015/02/20 19:26), Ingo Molnar wrote: > > * Petr Mladek <pmladek@suse.cz> 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.
Thank you,
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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