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arm64: Add helper for extracting ASIDBits 

Add a helper to extract ASIDBits on the current cpu

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Suzuki K Poulose 2016-02-23 10:31:44 +00:00 committed by Catalin Marinas
parent fd9c2790cb
commit 038dc9c66a
1 changed files with 23 additions and 13 deletions
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36
arch/arm64/mm/context.c
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@ -40,6 +40,28 @@ static cpumask_t tlb_flush_pending;
#define ASID_FIRST_VERSION (1UL << asid_bits)
#define NUM_USER_ASIDS ASID_FIRST_VERSION
/* Get the ASIDBits supported by the current CPU */
static u32 get_cpu_asid_bits(void)
{
u32 asid;
int fld = cpuid_feature_extract_field(read_cpuid(SYS_ID_AA64MMFR0_EL1),
ID_AA64MMFR0_ASID_SHIFT);
switch (fld) {
default:
pr_warn("CPU%d: Unknown ASID size (%d); assuming 8-bit\n",
smp_processor_id(), fld);
/* Fallthrough */
case 0:
asid = 8;
break;
case 2:
asid = 16;
}
return asid;
}
static void flush_context(unsigned int cpu)
{
int i;
@ -187,19 +209,7 @@ switch_mm_fastpath:
static int asids_init(void)
{
int fld = cpuid_feature_extract_field(read_cpuid(SYS_ID_AA64MMFR0_EL1), 4);
switch (fld) {
default:
pr_warn("Unknown ASID size (%d); assuming 8-bit\n", fld);
/* Fallthrough */
case 0:
asid_bits = 8;
break;
case 2:
asid_bits = 16;
}
asid_bits = get_cpu_asid_bits();
/* If we end up with more CPUs than ASIDs, expect things to crash */
WARN_ON(NUM_USER_ASIDS < num_possible_cpus());
atomic64_set(&asid_generation, ASID_FIRST_VERSION);