UPSTREAM: arm64: prefetch: don't provide spin_lock_prefetch with LSE
authorWill Deacon <will.deacon@arm.com>
Tue, 2 Feb 2016 12:46:23 +0000 (12:46 +0000)
committerJeff Vander Stoep <jeffv@google.com>
Thu, 22 Sep 2016 20:38:22 +0000 (13:38 -0700)
commit58ffa07081e1aabd092257eb6f2fb718dcd3d486
tree0d4cc1870ed0ae76cd4519151ba4e2216009f0ad
parent0b0254ded773d1f241b1ae7c7fdb137a72f60911
UPSTREAM: arm64: prefetch: don't provide spin_lock_prefetch with LSE

The LSE atomics rely on us not dirtying data at L1 if we can avoid it,
otherwise many of the potential scalability benefits are lost.

This patch replaces spin_lock_prefetch with a nop when the LSE atomics
are in use, so that users don't shoot themselves in the foot by causing
needless coherence traffic at L1.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Tested-by: Andrew Pinski <apinski@cavium.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Bug: 30369029
Patchset: kaslr-arm64-4.4

(cherry picked from commit cd5e10bdf3795d22f10787bb1991c43798c885d5)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: Ib8bc3f38d9306c13e017139ae4f2a7c8d6b61e18
arch/arm64/include/asm/processor.h