Date: Fri, 20 Feb 2015 11:26:25 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Petr Mladek <pmladek@suse.cz>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        "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
Message-ID: <20150220102625.GC25076@gmail.com>
References: <20150218212205.GA26334@gmail.com>
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* 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)

Thanks,

	Ingo
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