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arm64: prefetch: add alternative pattern for CPUs without a prefetcher

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Most CPUs have a hardware prefetcher which generally performs better
without explicit prefetch instructions issued by software, however
some CPUs (e.g. Cavium ThunderX) rely solely on explicit prefetch
instructions.

This patch adds an alternative pattern (ARM64_HAS_NO_HW_PREFETCH) to
allow our library code to make use of explicit prefetch instructions
during things like copy routines only when the CPU does not have the
capability to perform the prefetching itself.

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>
This commit is contained in:
Will Deacon
2016-02-02 12:46:24 +00:00
committed by Catalin Marinas
parent cd5e10bdf3
commit d5370f7548
4 changed files with 38 additions and 17 deletions
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18
arch/arm64/kernel/cpu_errata.c
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@@ -21,24 +21,12 @@
#include <asm/cputype.h>
#include <asm/cpufeature.h>
#define MIDR_CORTEX_A53 MIDR_CPU_PART(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A53)
#define MIDR_CORTEX_A57 MIDR_CPU_PART(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A57)
#define MIDR_THUNDERX MIDR_CPU_PART(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX)
#define CPU_MODEL_MASK (MIDR_IMPLEMENTOR_MASK | MIDR_PARTNUM_MASK | \
MIDR_ARCHITECTURE_MASK)
static bool __maybe_unused
is_affected_midr_range(const struct arm64_cpu_capabilities *entry)
{
u32 midr = read_cpuid_id();
if ((midr & CPU_MODEL_MASK) != entry->midr_model)
return false;
midr &= MIDR_REVISION_MASK | MIDR_VARIANT_MASK;
return (midr >= entry->midr_range_min && midr <= entry->midr_range_max);
return MIDR_IS_CPU_MODEL_RANGE(read_cpuid_id(), entry->midr_model,
entry->midr_range_min,
entry->midr_range_max);
}
#define MIDR_RANGE(model, min, max) \