x86: A fast way to check capabilities of the current cpu

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Add this_cpu_has() which determines if the current cpu has a certain
ability using a segment prefix and a bit test operation.

For that we need to add bit operations to x86s percpu.h.

Many uses of cpu_has use a pointer passed to a function to determine
the current flags. That is no longer necessary after this patch.

However, this patch only converts the straightforward cases where
cpu_has is used with this_cpu_ptr. The rest is work for later.

-tj: Rolled up patch to add x86_ prefix and use percpu_read() instead
     of percpu_read_stable().

Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

...

This commit is contained in:

Christoph Lameter 2011-03-12 12:50:10 +01:00 • committed by Tejun Heo

parent 89078d572e

commit 349c004e3d

5 changed files with 41 additions and 9 deletions

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13

arch/x86/include/asm/cpufeature.h

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27

arch/x86/include/asm/percpu.h

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2

arch/x86/kernel/apic/apic.c

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4

arch/x86/kernel/process.c

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4

arch/x86/kernel/smpboot.c

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