ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine

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This method changes x86 to add a breakpoint to the mcount locations
instead of calling stop machine.

Now that iret can be handled by NMIs, we perform the following to
update code:

1) Add a breakpoint to all locations that will be modified

2) Sync all cores

3) Update all locations to be either a nop or call (except breakpoint
   op)

4) Sync all cores

5) Remove the breakpoint with the new code.

6) Sync all cores

[
  Added updates that Masami suggested:
   Use unlikely(modifying_ftrace_code) in int3 trap to keep kprobes efficient.
   Don't use NOTIFY_* in ftrace handler in int3 as it is not a notifier.
]

Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

...

This commit is contained in:

Steven Rostedt 2011-08-16 09:57:10 -04:00 • committed by Steven Rostedt

parent 438ced1720

commit 08d636b6d4

4 changed files with 358 additions and 1 deletions

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3

arch/x86/include/asm/ftrace.h

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342

arch/x86/kernel/ftrace.c

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8

arch/x86/kernel/traps.c

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6

include/linux/ftrace.h

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