Re: [PATCH] uprobes tracer: Add stack/memory/retval access support

[Hyeoncheol Lee]

2012/10/16 Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>:
> (2012/10/16 18:02), Hyeoncheol Lee wrote:
>> Event arguments except @SYM are supported. They are @ADDR,
>> $stack, $stackN, $retval, and offs(arguments).
>>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
>> Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Hyeoncheol Lee <hyc.lee@xxxxxxxxx>
>> ---
>
> [...]
>>  #define DEFINE_FETCH_stack(type)                                     \
>>  static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\
>> -                                       void *offset, void *dest)     \
>> +                                       void *offset, void *dest,     \
>> +                                       bool kprobe)                  \
>>  {                                                                    \
>> -     *(type *)dest = (type)regs_get_kernel_stack_nth(regs,           \
>> +     if (kprobe)                                                     \
>> +             *(type *)dest = (type)regs_get_kernel_stack_nth(regs,   \
>>                               (unsigned int)((unsigned long)offset)); \
>> +     else                                                            \
>> +             *(type *)dest = (type)regs_get_user_stack_nth(regs,     \
>> +                             (unsigned int)((unsigned long)offset)); \
>>  }
>
>
> Hmm, I don't think this is a good way to do that.
> If fetching user space objects is different from the kernel one,
> we'd better introduce new fetch handlers for it, instead of checking
> a bool flag every time, because it will be done on every events.
>
> Thank you,
>
>
> --
> Masami HIRAMATSU
> IT Management Research Dept. Linux Technology Center
> Hitachi, Ltd., Yokohama Research Laboratory
> E-mail: masami.hiramatsu.pt@xxxxxxxxxxx
>
>

Yes
Thank you for your comment
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