diff options
| -rw-r--r-- | arch/arm/include/asm/mmu.h | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/mmu_context.h | 15 | ||||
| -rw-r--r-- | arch/arm/mm/context.c | 124 |
3 files changed, 126 insertions, 14 deletions
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h index b561584d04a1..68870c776671 100644 --- a/arch/arm/include/asm/mmu.h +++ b/arch/arm/include/asm/mmu.h @@ -6,6 +6,7 @@ typedef struct { #ifdef CONFIG_CPU_HAS_ASID unsigned int id; + spinlock_t id_lock; #endif unsigned int kvm_seq; } mm_context_t; diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h index de6cefb329dd..a0b3cac0547c 100644 --- a/arch/arm/include/asm/mmu_context.h +++ b/arch/arm/include/asm/mmu_context.h @@ -43,12 +43,23 @@ void __check_kvm_seq(struct mm_struct *mm); #define ASID_FIRST_VERSION (1 << ASID_BITS) extern unsigned int cpu_last_asid; +#ifdef CONFIG_SMP +DECLARE_PER_CPU(struct mm_struct *, current_mm); +#endif void __init_new_context(struct task_struct *tsk, struct mm_struct *mm); void __new_context(struct mm_struct *mm); static inline void check_context(struct mm_struct *mm) { + /* + * This code is executed with interrupts enabled. Therefore, + * mm->context.id cannot be updated to the latest ASID version + * on a different CPU (and condition below not triggered) + * without first getting an IPI to reset the context. The + * alternative is to take a read_lock on mm->context.id_lock + * (after changing its type to rwlock_t). + */ if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) __new_context(mm); @@ -108,6 +119,10 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next, __flush_icache_all(); #endif if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) { +#ifdef CONFIG_SMP + struct mm_struct **crt_mm = &per_cpu(current_mm, cpu); + *crt_mm = next; +#endif check_context(next); cpu_switch_mm(next->pgd, next); if (cache_is_vivt()) diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index a9e22e31eaa1..b0ee9ba3cfab 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -10,12 +10,17 @@ #include <linux/init.h> #include <linux/sched.h> #include <linux/mm.h> +#include <linux/smp.h> +#include <linux/percpu.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> static DEFINE_SPINLOCK(cpu_asid_lock); unsigned int cpu_last_asid = ASID_FIRST_VERSION; +#ifdef CONFIG_SMP +DEFINE_PER_CPU(struct mm_struct *, current_mm); +#endif /* * We fork()ed a process, and we need a new context for the child @@ -26,13 +31,109 @@ unsigned int cpu_last_asid = ASID_FIRST_VERSION; void __init_new_context(struct task_struct *tsk, struct mm_struct *mm) { mm->context.id = 0; + spin_lock_init(&mm->context.id_lock); } +static void flush_context(void) +{ + /* set the reserved ASID before flushing the TLB */ + asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (0)); + isb(); + local_flush_tlb_all(); + if (icache_is_vivt_asid_tagged()) { + __flush_icache_all(); + dsb(); + } +} + +#ifdef CONFIG_SMP + +static void set_mm_context(struct mm_struct *mm, unsigned int asid) +{ + unsigned long flags; + + /* + * Locking needed for multi-threaded applications where the + * same mm->context.id could be set from different CPUs during + * the broadcast. This function is also called via IPI so the + * mm->context.id_lock has to be IRQ-safe. + */ + spin_lock_irqsave(&mm->context.id_lock, flags); + if (likely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) { + /* + * Old version of ASID found. Set the new one and + * reset mm_cpumask(mm). + */ + mm->context.id = asid; + cpumask_clear(mm_cpumask(mm)); + } + spin_unlock_irqrestore(&mm->context.id_lock, flags); + + /* + * Set the mm_cpumask(mm) bit for the current CPU. + */ + cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); +} + +/* + * Reset the ASID on the current CPU. This function call is broadcast + * from the CPU handling the ASID rollover and holding cpu_asid_lock. + */ +static void reset_context(void *info) +{ + unsigned int asid; + unsigned int cpu = smp_processor_id(); + struct mm_struct *mm = per_cpu(current_mm, cpu); + + /* + * Check if a current_mm was set on this CPU as it might still + * be in the early booting stages and using the reserved ASID. + */ + if (!mm) + return; + + smp_rmb(); + asid = cpu_last_asid + cpu + 1; + + flush_context(); + set_mm_context(mm, asid); + + /* set the new ASID */ + asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (mm->context.id)); + isb(); +} + +#else + +static inline void set_mm_context(struct mm_struct *mm, unsigned int asid) +{ + mm->context.id = asid; + cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id())); +} + +#endif + void __new_context(struct mm_struct *mm) { unsigned int asid; spin_lock(&cpu_asid_lock); +#ifdef CONFIG_SMP + /* + * Check the ASID again, in case the change was broadcast from + * another CPU before we acquired the lock. + */ + if (unlikely(((mm->context.id ^ cpu_last_asid) >> ASID_BITS) == 0)) { + cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); + spin_unlock(&cpu_asid_lock); + return; + } +#endif + /* + * At this point, it is guaranteed that the current mm (with + * an old ASID) isn't active on any other CPU since the ASIDs + * are changed simultaneously via IPI. + */ asid = ++cpu_last_asid; if (asid == 0) asid = cpu_last_asid = ASID_FIRST_VERSION; @@ -42,20 +143,15 @@ void __new_context(struct mm_struct *mm) * to start a new version and flush the TLB. */ if (unlikely((asid & ~ASID_MASK) == 0)) { - asid = ++cpu_last_asid; - /* set the reserved ASID before flushing the TLB */ - asm("mcr p15, 0, %0, c13, c0, 1 @ set reserved context ID\n" - : - : "r" (0)); - isb(); - flush_tlb_all(); - if (icache_is_vivt_asid_tagged()) { - __flush_icache_all(); - dsb(); - } + asid = cpu_last_asid + smp_processor_id() + 1; + flush_context(); +#ifdef CONFIG_SMP + smp_wmb(); + smp_call_function(reset_context, NULL, 1); +#endif + cpu_last_asid += NR_CPUS; } - spin_unlock(&cpu_asid_lock); - cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id())); - mm->context.id = asid; + set_mm_context(mm, asid); + spin_unlock(&cpu_asid_lock); } |