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authorDave Hansen <dave.hansen@linux.intel.com>2016-06-01 19:42:20 +0200
committerIngo Molnar <mingo@kernel.org>2016-06-08 13:33:33 +0200
commitd1898b733619bd46194bd25aa6452d238ff2dc4e (patch)
tree4cc10df3594b68becae9a7dac03e35025aa5c7d1 /arch/x86/kernel/fpu/xstate.c
parentMerge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/vir... (diff)
downloadlinux-d1898b733619bd46194bd25aa6452d238ff2dc4e.tar.xz
linux-d1898b733619bd46194bd25aa6452d238ff2dc4e.zip
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>
Diffstat (limited to 'arch/x86/kernel/fpu/xstate.c')
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