lkml.org 
[lkml]   [2015]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] kprobes/x86: Use 5-byte NOP when the code might be modified by ftrace
(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




\
 
 \ /
  Last update: 2015-02-20 14:01    [W:0.063 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site