Re: [RFC][PATCH 0/3] ftrace: Add dynamically allocated trampolines

From: Masami Hiramatsu
Date: Thu Jul 10 2014 - 22:26:46 EST

(2014/07/11 6:44), Jiri Kosina wrote:
> On Thu, 10 Jul 2014, Josh Poimboeuf wrote:
>> I did some testing with kpatch and I found one minor issue. The dynamically
>> allocated trampoline seems to confuse dump_stack() somewhat.
>> I added a dump_stack() call in my ftrace_ops callback function
>> (kpatch_ftrace_handler) which had a filter on meminfo_proc_show().
> Interesting. Are you using dwarf2 unwinder for stack dumping by any
> chance? It seems to get things right here. Will look into it more
> tomorrow.

Hmm, can dwarf2 unwinder work on the trampoline method?
Since the trampoline just a copy of instructions which
will not have CFI(which is stored in dwarf section),
I guess it may not work...
Frame pointer (push bp and save sp to bp on the entry) can
work anyway.

Thank you,

Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at