Dave Hansen 1f96b1efba x86/fpu: Add placeholder for 'Processor Trace' XSAVE state ... There is an XSAVE state component for Intel Processor Trace (PT). But, we do not currently use it. We add a placeholder in the code for it so it is not a mystery and also so we do not need an explicit enum initialization for Protection Keys in a moment. Why don't we use it? We might end up using this at _some_ point in the future. But, this is a "system" state which requires using the currently unsupported XSAVES feature. Unlike all the other XSAVE states, PT state is also not directly tied to a thread. You might context-switch between threads, but not want to change any of the PT state. Or, you might switch between threads, and *do* want to change PT state, all depending on what is being traced. We currently just manually set some MSRs to do this PT context switching, and it is unclear whether replacing our direct MSR use with XSAVE will be a net win or loss, both in code complexity and performance. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> 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: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: fenghua.yu@intel.com Cc: linux-mm@kvack.org Cc: yu-cheng.yu@intel.com Link: http://lkml.kernel.org/r/20160212210158.5E4BCAE2@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2016-02-16 10:11:13 +01:00
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asm	x86/fpu: Add placeholder for 'Processor Trace' XSAVE state	2016-02-16 10:11:13 +01:00
uapi/asm	* s390: Support for runtime instrumentation within guests,	2016-01-12 13:22:12 -08:00