• Steven Rostedt's avatar
    ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine · 08d636b6
    Steven Rostedt authored
    
    
    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: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    08d636b6
ftrace.h 20.1 KB