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powerpc/64s: Add support for ori barrier_nospec patching

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Based on the RFI patching. This is required to be able to disable the
speculation barrier.

Only one barrier type is supported and it does nothing when the
firmware does not enable it. Also re-patching modules is not supported
So the only meaningful thing that can be done is patching out the
speculation barrier at boot when the user says it is not wanted.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Michal Suchanek
2018-04-24 14:15:55 +10:00
committed by Michael Ellerman
parent a6b3964ad7
commit 2eea7f067f
6 changed files with 54 additions and 1 deletions
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2
arch/powerpc/include/asm/barrier.h
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@@ -81,7 +81,7 @@ do { \
* Prevent execution of subsequent instructions until preceding branches have
* been fully resolved and are no longer executing speculatively.
*/
#define barrier_nospec_asm ori 31,31,0
#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; nop
// This also acts as a compiler barrier due to the memory clobber.
#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")