diff options
Diffstat (limited to 'arch/arc/include/asm/mmu_context.h')
| -rw-r--r-- | arch/arc/include/asm/mmu_context.h | 61 |
1 files changed, 44 insertions, 17 deletions
diff --git a/arch/arc/include/asm/mmu_context.h b/arch/arc/include/asm/mmu_context.h index 43a1b51bb8cc..1fd467ef658f 100644 --- a/arch/arc/include/asm/mmu_context.h +++ b/arch/arc/include/asm/mmu_context.h @@ -30,13 +30,13 @@ * "Fast Context Switch" i.e. no TLB flush on ctxt-switch * * Linux assigns each task a unique ASID. A simple round-robin allocation - * of H/w ASID is done using software tracker @asid_cache. + * 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. * * 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. - * The 32 bit @asid_cache (and mm->asid) have 8 bits MMU PID and rest 24 bits + * The 32 bit @asid_cpu (and mm->asid) have 8 bits MMU PID and rest 24 bits * serve as cycle/generation indicator and natural 32 bit unsigned math * automagically increments the generation when lower 8 bits rollover. */ @@ -47,9 +47,11 @@ #define MM_CTXT_FIRST_CYCLE (MM_CTXT_ASID_MASK + 1) #define MM_CTXT_NO_ASID 0UL -#define hw_pid(mm) (mm->context.asid & MM_CTXT_ASID_MASK) +#define asid_mm(mm, cpu) mm->context.asid[cpu] +#define hw_pid(mm, cpu) (asid_mm(mm, cpu) & MM_CTXT_ASID_MASK) -extern unsigned int asid_cache; +DECLARE_PER_CPU(unsigned int, asid_cache); +#define asid_cpu(cpu) per_cpu(asid_cache, cpu) /* * Get a new ASID if task doesn't have a valid one (unalloc or from prev cycle) @@ -57,6 +59,7 @@ extern unsigned int asid_cache; */ static inline void get_new_mmu_context(struct mm_struct *mm) { + const unsigned int cpu = smp_processor_id(); unsigned long flags; local_irq_save(flags); @@ -71,28 +74,28 @@ static inline void get_new_mmu_context(struct mm_struct *mm) * first need to destroy the context, setting it to invalid * value. */ - if (!((mm->context.asid ^ asid_cache) & MM_CTXT_CYCLE_MASK)) + if (!((asid_mm(mm, cpu) ^ asid_cpu(cpu)) & MM_CTXT_CYCLE_MASK)) goto set_hw; /* move to new ASID and handle rollover */ - if (unlikely(!(++asid_cache & MM_CTXT_ASID_MASK))) { + if (unlikely(!(++asid_cpu(cpu) & MM_CTXT_ASID_MASK))) { - flush_tlb_all(); + local_flush_tlb_all(); /* * Above checke for rollover of 8 bit ASID in 32 bit container. * If the container itself wrapped around, set it to a non zero * "generation" to distinguish from no context */ - if (!asid_cache) - asid_cache = MM_CTXT_FIRST_CYCLE; + if (!asid_cpu(cpu)) + asid_cpu(cpu) = MM_CTXT_FIRST_CYCLE; } /* Assign new ASID to tsk */ - mm->context.asid = asid_cache; + asid_mm(mm, cpu) = asid_cpu(cpu); set_hw: - write_aux_reg(ARC_REG_PID, hw_pid(mm) | MMU_ENABLE); + write_aux_reg(ARC_REG_PID, hw_pid(mm, cpu) | MMU_ENABLE); local_irq_restore(flags); } @@ -104,16 +107,45 @@ set_hw: static inline int init_new_context(struct task_struct *tsk, struct mm_struct *mm) { - mm->context.asid = MM_CTXT_NO_ASID; + int i; + + for_each_possible_cpu(i) + asid_mm(mm, i) = MM_CTXT_NO_ASID; + return 0; } +static inline void destroy_context(struct mm_struct *mm) +{ + unsigned long flags; + + /* Needed to elide CONFIG_DEBUG_PREEMPT warning */ + local_irq_save(flags); + asid_mm(mm, smp_processor_id()) = MM_CTXT_NO_ASID; + local_irq_restore(flags); +} + /* Prepare the MMU for task: setup PID reg with allocated ASID If task doesn't have an ASID (never alloc or stolen, get a new ASID) */ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk) { + const int cpu = smp_processor_id(); + + /* + * Note that the mm_cpumask is "aggregating" only, we don't clear it + * for the switched-out task, unlike some other arches. + * It is used to enlist cpus for sending TLB flush IPIs and not sending + * it to CPUs where a task once ran-on, could cause stale TLB entry + * re-use, specially for a multi-threaded task. + * e.g. T1 runs on C1, migrates to C3. T2 running on C2 munmaps. + * For a non-aggregating mm_cpumask, IPI not sent C1, and if T1 + * were to re-migrate to C1, it could access the unmapped region + * via any existing stale TLB entries. + */ + cpumask_set_cpu(cpu, mm_cpumask(next)); + #ifndef CONFIG_SMP /* PGD cached in MMU reg to avoid 3 mem lookups: task->mm->pgd */ write_aux_reg(ARC_REG_SCRATCH_DATA0, next->pgd); @@ -131,11 +163,6 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, */ #define activate_mm(prev, next) switch_mm(prev, next, NULL) -static inline void destroy_context(struct mm_struct *mm) -{ - mm->context.asid = MM_CTXT_NO_ASID; -} - /* it seemed that deactivate_mm( ) is a reasonable place to do book-keeping * for retiring-mm. However destroy_context( ) still needs to do that because * between mm_release( ) = >deactive_mm( ) and |