• Dave Hansen's avatar
    x86/fpu: Add tracepoints to dump FPU state at key points · d1898b73
    Dave Hansen authored
    I've been carrying this patch around for a bit and it's helped me
    solve at least a couple FPU-related bugs.  In addition to using
    it for debugging, I also drug it out because using AVX (and
    AVX2/AVX-512) can have serious power consequences for a modern
    core.  It's very important to be able to figure out who is using
    it.
    
    It's also insanely useful to go out and see who is using a given
    feature, like MPX or Memory Protection Keys.  If you, for
    instance, want to find all processes using protection keys, you
    can do:
    
    	echo 'xfeatures & 0x200' > filter
    
    Since 0x200 is the protection keys feature bit.
    
    Note that this touches the KVM code.  KVM did a CREATE_TRACE_POINTS
    and then included a bunch of random headers.  If anyone one of
    those included other tracepoints, it would have defined the *OTHER*
    tracepoints.  That's bogus, so move it to the right place.
    Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dave Hansen <dave@sr71.net>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/20160601174220.3CDFB90E@viggo.jf.intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    d1898b73
internal.h 18.2 KB