From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Petr Mladek <pmladek@suse.cz>,
"David S. Miller" <davem@davemloft.net>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
Ananth NMavinakayanahalli <ananth@in.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Jiri Kosina <jkosina@suse.cz>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] kprobes/x86: Use 5-byte NOP when the code might be modified by ftrace
Date: Fri, 20 Feb 2015 21:38:18 +0900 [thread overview]
Message-ID: <54E72ABA.8050804@hitachi.com> (raw)
In-Reply-To: <20150220102625.GC25076@gmail.com>
(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
next prev parent reply other threads:[~2015-02-20 12:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-02 17:48 [PATCH v2] kprobes/x86: Use 5-byte NOP when the code might be modified by ftrace Petr Mladek
2015-02-03 7:41 ` Masami Hiramatsu
2015-02-03 11:38 ` Petr Mladek
2015-02-03 11:52 ` Masami Hiramatsu
2015-02-03 12:00 ` Petr Mladek
2015-02-18 21:22 ` Ingo Molnar
2015-02-20 10:16 ` Petr Mladek
2015-02-20 10:16 ` [PATCH 1/2] " Petr Mladek
2015-02-20 10:26 ` Ingo Molnar
2015-02-20 12:38 ` Masami Hiramatsu [this message]
2015-02-20 12:52 ` Ingo Molnar
2015-02-20 13:25 ` Masami Hiramatsu
2015-02-20 13:34 ` Petr Mladek
2015-02-20 10:16 ` [PATCH 2/2] kprobes/x86: Check for invalid ftrace location in __recover_probed_insn() Petr Mladek
2015-02-20 10:19 ` Ingo Molnar
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