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

[Petr Mladek]

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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