linux/arch/x86/kernel/fpu
Dave Hansen d1898b7336 x86/fpu: Add tracepoints to dump FPU state at key points
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: Dave 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.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-08 13:33:33 +02:00
..
bugs.c x86/fpu: Remove check_fpu() indirection 2016-04-13 11:37:43 +02:00
core.c x86/fpu: Add tracepoints to dump FPU state at key points 2016-06-08 13:33:33 +02:00
init.c x86/cpufeature: Replace cpu_has_fxsr with boot_cpu_has() usage 2016-04-13 11:37:41 +02:00
Makefile x86/fpu: Factor out the FPU regset code into fpu/regset.c 2015-05-19 15:48:09 +02:00
regset.c x86/fpu/regset: Replace static_cpu_has() usage with boot_cpu_has() 2016-04-13 11:37:42 +02:00
signal.c x86/fpu: Add tracepoints to dump FPU state at key points 2016-06-08 13:33:33 +02:00
xstate.c x86/cpufeature: Replace cpu_has_xsaves with boot_cpu_has() usage 2016-04-13 11:37:42 +02:00