From 58ffa07081e1aabd092257eb6f2fb718dcd3d486 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 2 Feb 2016 12:46:23 +0000 Subject: [PATCH] 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 Tested-by: Andrew Pinski Signed-off-by: Catalin Marinas Bug: 30369029 Patchset: kaslr-arm64-4.4 (cherry picked from commit cd5e10bdf3795d22f10787bb1991c43798c885d5) Signed-off-by: Jeff Vander Stoep Change-Id: Ib8bc3f38d9306c13e017139ae4f2a7c8d6b61e18 --- arch/arm64/include/asm/processor.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 4acb7ca94fcd..31b76fce4477 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -29,6 +29,7 @@ #include +#include #include #include #include @@ -177,9 +178,11 @@ static inline void prefetchw(const void *ptr) } #define ARCH_HAS_SPINLOCK_PREFETCH -static inline void spin_lock_prefetch(const void *x) +static inline void spin_lock_prefetch(const void *ptr) { - prefetchw(x); + asm volatile(ARM64_LSE_ATOMIC_INSN( + "prfm pstl1strm, %a0", + "nop") : : "p" (ptr)); } #define HAVE_ARCH_PICK_MMAP_LAYOUT -- 2.20.1