diff options
Diffstat (limited to 'arch/arc/include/asm/mmu_context.h')
| -rw-r--r-- | arch/arc/include/asm/mmu_context.h | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/arch/arc/include/asm/mmu_context.h b/arch/arc/include/asm/mmu_context.h index df164066e172..dda471f5f05b 100644 --- a/arch/arc/include/asm/mmu_context.h +++ b/arch/arc/include/asm/mmu_context.h @@ -15,22 +15,23 @@ #ifndef _ASM_ARC_MMU_CONTEXT_H #define _ASM_ARC_MMU_CONTEXT_H -#include <asm/arcregs.h> -#include <asm/tlb.h> #include <linux/sched/mm.h> +#include <asm/tlb.h> #include <asm-generic/mm_hooks.h> -/* ARC700 ASID Management +/* ARC ASID Management + * + * MMU tags TLBs with an 8-bit ASID, avoiding need to flush the TLB on + * context-switch. * - * ARC MMU provides 8-bit ASID (0..255) to TAG TLB entries, allowing entries - * with same vaddr (different tasks) to co-exit. This provides for - * "Fast Context Switch" i.e. no TLB flush on ctxt-switch + * ASID is managed per cpu, so task threads across CPUs can have different + * ASID. Global ASID management is needed if hardware supports TLB shootdown + * and/or shared TLB across cores, which ARC doesn't. * - * Linux assigns each task a unique ASID. A simple round-robin allocation - * of H/w ASID is done using software tracker @asid_cpu. - * When it reaches max 255, the allocation cycle starts afresh by flushing - * the entire TLB and wrapping ASID back to zero. + * Each task is assigned unique ASID, with a simple round-robin allocator + * tracked in @asid_cpu. When 8-bit value rolls over,a new cycle is started + * over from 0, and TLB is flushed * * A new allocation cycle, post rollover, could potentially reassign an ASID * to a different task. Thus the rule is to refresh the ASID in a new cycle. @@ -93,7 +94,7 @@ static inline void get_new_mmu_context(struct mm_struct *mm) asid_mm(mm, cpu) = asid_cpu(cpu); set_hw: - write_aux_reg(ARC_REG_PID, hw_pid(mm, cpu) | MMU_ENABLE); + mmu_setup_asid(mm, hw_pid(mm, cpu)); local_irq_restore(flags); } @@ -146,10 +147,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, */ cpumask_set_cpu(cpu, mm_cpumask(next)); -#ifdef ARC_USE_SCRATCH_REG - /* PGD cached in MMU reg to avoid 3 mem lookups: task->mm->pgd */ - write_aux_reg(ARC_REG_SCRATCH_DATA0, next->pgd); -#endif + mmu_setup_pgd(next, next->pgd); get_new_mmu_context(next); } |