linux-kernel - [PATCH 0/4] x86: Fix ftrace recovery when code modification failed

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Date:	Mon, 17 Feb 2014 16:22:49 +0100
From:	Petr Mladek <pmladek@...e.cz>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Jiri Kosina <jkosina@...e.cz>
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org,
	Petr Mladek <pmladek@...e.cz>
Subject: [PATCH 0/4] x86: Fix ftrace recovery when code modification failed

Ftrace modifies function calls using Int3 breakpoints on x86. It patches
all functions in parallel to reduce the number of sync() calls. There is
a code that removes pending Int3 breakpoints when something goes wrong.

The recovery does not work on x86_64. I simulated an error in
ftrace_replace_code() and the system got rebooted.

This patch set fixes the recovery code, improves debugging of this
type of problem, and does some clean up.

BTW: It is an echo from the patch set that tried to use text_poke_bp()
instead of the ftrace-specific Int3 based patching code. Ftrace has
some specific restrictions. I did not find a way how to make the 
universal text_poke_bp effective, safe, and clean to be usable
there.

The patch set is against linux/tip. Last commit is a5b3cca53c43c3ba7
(Merge tag 'v3.14-rc3')

Petr Mladek (4):
  x86: Clean up remove_breakpoint() in ftrace code
  x86: Fix ftrace patching recovery code to work on x86_64
  x86: BUG when ftrace patching recovery fails
  x86: Fix order of warning messages when ftrace modifies code

 arch/x86/kernel/ftrace.c | 67 ++++++++++++++++++++++++------------------------
 1 file changed, 34 insertions(+), 33 deletions(-)

-- 
1.8.4

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