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Diffstat (limited to 'include/asm-ia64/mmu_context.h')
| -rw-r--r-- | include/asm-ia64/mmu_context.h | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/include/asm-ia64/mmu_context.h b/include/asm-ia64/mmu_context.h new file mode 100644 index 000000000000..0096e7e05012 --- /dev/null +++ b/include/asm-ia64/mmu_context.h @@ -0,0 +1,170 @@ +#ifndef _ASM_IA64_MMU_CONTEXT_H +#define _ASM_IA64_MMU_CONTEXT_H + +/* + * Copyright (C) 1998-2002 Hewlett-Packard Co + * David Mosberger-Tang <davidm@hpl.hp.com> + */ + +/* + * Routines to manage the allocation of task context numbers. Task context numbers are + * used to reduce or eliminate the need to perform TLB flushes due to context switches. + * Context numbers are implemented using ia-64 region ids. Since the IA-64 TLB does not + * consider the region number when performing a TLB lookup, we need to assign a unique + * region id to each region in a process. We use the least significant three bits in a + * region id for this purpose. + */ + +#define IA64_REGION_ID_KERNEL 0 /* the kernel's region id (tlb.c depends on this being 0) */ + +#define ia64_rid(ctx,addr) (((ctx) << 3) | (addr >> 61)) + +# ifndef __ASSEMBLY__ + +#include <linux/compiler.h> +#include <linux/percpu.h> +#include <linux/sched.h> +#include <linux/spinlock.h> + +#include <asm/processor.h> + +struct ia64_ctx { + spinlock_t lock; + unsigned int next; /* next context number to use */ + unsigned int limit; /* next >= limit => must call wrap_mmu_context() */ + unsigned int max_ctx; /* max. context value supported by all CPUs */ +}; + +extern struct ia64_ctx ia64_ctx; +DECLARE_PER_CPU(u8, ia64_need_tlb_flush); + +extern void wrap_mmu_context (struct mm_struct *mm); + +static inline void +enter_lazy_tlb (struct mm_struct *mm, struct task_struct *tsk) +{ +} + +/* + * When the context counter wraps around all TLBs need to be flushed because an old + * context number might have been reused. This is signalled by the ia64_need_tlb_flush + * per-CPU variable, which is checked in the routine below. Called by activate_mm(). + * <efocht@ess.nec.de> + */ +static inline void +delayed_tlb_flush (void) +{ + extern void local_flush_tlb_all (void); + + if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) { + local_flush_tlb_all(); + __ia64_per_cpu_var(ia64_need_tlb_flush) = 0; + } +} + +static inline mm_context_t +get_mmu_context (struct mm_struct *mm) +{ + unsigned long flags; + mm_context_t context = mm->context; + + if (context) + return context; + + spin_lock_irqsave(&ia64_ctx.lock, flags); + { + /* re-check, now that we've got the lock: */ + context = mm->context; + if (context == 0) { + cpus_clear(mm->cpu_vm_mask); + if (ia64_ctx.next >= ia64_ctx.limit) + wrap_mmu_context(mm); + mm->context = context = ia64_ctx.next++; + } + } + spin_unlock_irqrestore(&ia64_ctx.lock, flags); + return context; +} + +/* + * Initialize context number to some sane value. MM is guaranteed to be a brand-new + * address-space, so no TLB flushing is needed, ever. + */ +static inline int +init_new_context (struct task_struct *p, struct mm_struct *mm) +{ + mm->context = 0; + return 0; +} + +static inline void +destroy_context (struct mm_struct *mm) +{ + /* Nothing to do. */ +} + +static inline void +reload_context (mm_context_t context) +{ + unsigned long rid; + unsigned long rid_incr = 0; + unsigned long rr0, rr1, rr2, rr3, rr4, old_rr4; + + old_rr4 = ia64_get_rr(0x8000000000000000UL); + rid = context << 3; /* make space for encoding the region number */ + rid_incr = 1 << 8; + + /* encode the region id, preferred page size, and VHPT enable bit: */ + rr0 = (rid << 8) | (PAGE_SHIFT << 2) | 1; + rr1 = rr0 + 1*rid_incr; + rr2 = rr0 + 2*rid_incr; + rr3 = rr0 + 3*rid_incr; + rr4 = rr0 + 4*rid_incr; +#ifdef CONFIG_HUGETLB_PAGE + rr4 = (rr4 & (~(0xfcUL))) | (old_rr4 & 0xfc); +#endif + + ia64_set_rr(0x0000000000000000UL, rr0); + ia64_set_rr(0x2000000000000000UL, rr1); + ia64_set_rr(0x4000000000000000UL, rr2); + ia64_set_rr(0x6000000000000000UL, rr3); + ia64_set_rr(0x8000000000000000UL, rr4); + ia64_srlz_i(); /* srlz.i implies srlz.d */ +} + +static inline void +activate_context (struct mm_struct *mm) +{ + mm_context_t context; + + do { + context = get_mmu_context(mm); + if (!cpu_isset(smp_processor_id(), mm->cpu_vm_mask)) + cpu_set(smp_processor_id(), mm->cpu_vm_mask); + reload_context(context); + /* in the unlikely event of a TLB-flush by another thread, redo the load: */ + } while (unlikely(context != mm->context)); +} + +#define deactivate_mm(tsk,mm) do { } while (0) + +/* + * Switch from address space PREV to address space NEXT. + */ +static inline void +activate_mm (struct mm_struct *prev, struct mm_struct *next) +{ + delayed_tlb_flush(); + + /* + * We may get interrupts here, but that's OK because interrupt handlers cannot + * touch user-space. + */ + ia64_set_kr(IA64_KR_PT_BASE, __pa(next->pgd)); + activate_context(next); +} + +#define switch_mm(prev_mm,next_mm,next_task) activate_mm(prev_mm, next_mm) + +# endif /* ! __ASSEMBLY__ */ +#endif /* _ASM_IA64_MMU_CONTEXT_H */ |