[RFC v2 0/8] x86, xsave: rework of extended state handling, LWP support

From: Hans Rosenfeld
Date: Wed Mar 23 2011 - 11:28:57 EST

Changes since last patch set:
* fixed race in signal return path that could lead to xstate corruptions
* avoid LWP state inconsitency after signal return by disabling LWP
when entering a signal handler

This patch set is a general cleanup and rework of the code related to
handling of FPU and other extended states.

All handling of extended states, including the FPU state, is now handled
by xsave/xrstor wrappers that fall back to fxsave/fxrstor, or even
fsave/frstor, if hardware support for those features is lacking.

Non-lazy xstates, which cannot be restored lazily, can now be easily
supported with almost no processing overhead. This makes adding basic
support for AMDs LWP almost trivial.

Since non-lazy xstates are inherently incompatible with lazy allocation
of the xstate area, the complete removal of lazy allocation to further
reduce code complexity should be considered. Since SSE-optimized library
functions are widely used today, most processes will have an xstate area
anyway, so the memory overhead wouldn't be big enough to be much of an

Hans Rosenfeld (8):
x86, xsave: cleanup fpu/xsave support
x86, xsave: rework fpu/xsave support
x86, xsave: cleanup fpu/xsave signal frame setup
x86, xsave: remove unused code
x86, xsave: more cleanups
x86, xsave: add support for non-lazy xstates
x86, xsave: add kernel support for AMDs Lightweight Profiling (LWP)
x86, xsave: remove lazy allocation of xstate area

arch/x86/ia32/ia32_signal.c | 4 +-
arch/x86/include/asm/i387.h | 243 ++++++++--------------------
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/include/asm/processor.h | 12 ++
arch/x86/include/asm/sigcontext.h | 12 ++
arch/x86/include/asm/thread_info.h | 4 +-
arch/x86/include/asm/xsave.h | 100 +++----------
arch/x86/kernel/i387.c | 310 ++++--------------------------------
arch/x86/kernel/process_32.c | 29 ++---
arch/x86/kernel/process_64.c | 28 +---
arch/x86/kernel/signal.c | 4 +-
arch/x86/kernel/traps.c | 47 +-----
arch/x86/kernel/xsave.c | 311 +++++++++++++++++++++++-------------
arch/x86/kvm/vmx.c | 2 +-
arch/x86/kvm/x86.c | 11 +-
arch/x86/math-emu/fpu_entry.c | 8 +-
drivers/lguest/x86/core.c | 2 +-
17 files changed, 380 insertions(+), 748 deletions(-)

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