i387: Uninline the generic FP helpers that we expose to kernel modules

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Instead of exporting the very low-level internals of the FPU state
save/restore code (ie things like 'fpu_owner_task'), we should export
the higher-level interfaces.

Inlining these things is pointless anyway: sure, sometimes the end
result is small, but while 'stts()' can result in just three x86
instructions, those are not cheap instructions (writing %cr0 is a
serializing instruction and a very slow one at that).

So the overhead of a function call is not noticeable, and we really
don't want random modules mucking about with our internal state save
logic anyway.

So this unexports 'fpu_owner_task', and instead uninlines and exports
the actual functions that modules can use: fpu_kernel_begin/end() and
unlazy_fpu().

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211339590.5354@i5.linux-foundation.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

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This commit is contained in:

Linus Torvalds 2012-02-21 10:25:45 -08:00 • committed by H. Peter Anvin

parent 27e74da980

commit 8546c00892

3 changed files with 84 additions and 76 deletions

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78

arch/x86/include/asm/i387.h

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2

arch/x86/kernel/cpu/common.c

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80

arch/x86/kernel/i387.c

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