1 #ifndef _ASM_IA64_MMU_CONTEXT_H
2 #define _ASM_IA64_MMU_CONTEXT_H
5 * Copyright (C) 1998-2002 Hewlett-Packard Co
6 * David Mosberger-Tang <davidm@hpl.hp.com>
10 * Routines to manage the allocation of task context numbers. Task context numbers are
11 * used to reduce or eliminate the need to perform TLB flushes due to context switches.
12 * Context numbers are implemented using ia-64 region ids. Since the IA-64 TLB does not
13 * consider the region number when performing a TLB lookup, we need to assign a unique
14 * region id to each region in a process. We use the least significant three bits in a
15 * region id for this purpose.
18 #define IA64_REGION_ID_KERNEL 0 /* the kernel's region id (tlb.c depends on this being 0) */
20 #define ia64_rid(ctx,addr) (((ctx) << 3) | (addr >> 61))
22 # include <asm/page.h>
25 #include <linux/compiler.h>
26 #include <linux/percpu.h>
27 #include <linux/sched.h>
28 #include <linux/spinlock.h>
30 #include <asm/processor.h>
34 unsigned int next; /* next context number to use */
35 unsigned int limit; /* next >= limit => must call wrap_mmu_context() */
36 unsigned int max_ctx; /* max. context value supported by all CPUs */
39 extern struct ia64_ctx ia64_ctx;
40 DECLARE_PER_CPU(u8, ia64_need_tlb_flush);
42 extern void wrap_mmu_context (struct mm_struct *mm);
45 enter_lazy_tlb (struct mm_struct *mm, struct task_struct *tsk)
50 * When the context counter wraps around all TLBs need to be flushed because an old
51 * context number might have been reused. This is signalled by the ia64_need_tlb_flush
52 * per-CPU variable, which is checked in the routine below. Called by activate_mm().
56 delayed_tlb_flush (void)
58 extern void local_flush_tlb_all (void);
60 if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) {
61 local_flush_tlb_all();
62 __ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
66 static inline mm_context_t
67 get_mmu_context (struct mm_struct *mm)
70 mm_context_t context = mm->context;
75 spin_lock_irqsave(&ia64_ctx.lock, flags);
77 /* re-check, now that we've got the lock: */
78 context = mm->context;
80 cpus_clear(mm->cpu_vm_mask);
81 if (ia64_ctx.next >= ia64_ctx.limit)
83 mm->context = context = ia64_ctx.next++;
86 spin_unlock_irqrestore(&ia64_ctx.lock, flags);
91 * Initialize context number to some sane value. MM is guaranteed to be a brand-new
92 * address-space, so no TLB flushing is needed, ever.
95 init_new_context (struct task_struct *p, struct mm_struct *mm)
102 destroy_context (struct mm_struct *mm)
108 reload_context (mm_context_t context)
111 unsigned long rid_incr = 0;
112 unsigned long rr0, rr1, rr2, rr3, rr4, old_rr4;
114 old_rr4 = ia64_get_rr(RGN_BASE(RGN_HPAGE));
115 rid = context << 3; /* make space for encoding the region number */
118 /* encode the region id, preferred page size, and VHPT enable bit: */
119 rr0 = (rid << 8) | (PAGE_SHIFT << 2) | 1;
120 rr1 = rr0 + 1*rid_incr;
121 rr2 = rr0 + 2*rid_incr;
122 rr3 = rr0 + 3*rid_incr;
123 rr4 = rr0 + 4*rid_incr;
124 #ifdef CONFIG_HUGETLB_PAGE
125 rr4 = (rr4 & (~(0xfcUL))) | (old_rr4 & 0xfc);
128 # error "reload_context assumes RGN_HPAGE is 4"
132 ia64_set_rr(0x0000000000000000UL, rr0);
133 ia64_set_rr(0x2000000000000000UL, rr1);
134 ia64_set_rr(0x4000000000000000UL, rr2);
135 ia64_set_rr(0x6000000000000000UL, rr3);
136 ia64_set_rr(0x8000000000000000UL, rr4);
137 ia64_srlz_i(); /* srlz.i implies srlz.d */
141 * Must be called with preemption off
144 activate_context (struct mm_struct *mm)
146 mm_context_t context;
149 context = get_mmu_context(mm);
150 if (!cpu_isset(smp_processor_id(), mm->cpu_vm_mask))
151 cpu_set(smp_processor_id(), mm->cpu_vm_mask);
152 reload_context(context);
153 /* in the unlikely event of a TLB-flush by another thread, redo the load: */
154 } while (unlikely(context != mm->context));
157 #define deactivate_mm(tsk,mm) do { } while (0)
160 * Switch from address space PREV to address space NEXT.
163 activate_mm (struct mm_struct *prev, struct mm_struct *next)
168 * We may get interrupts here, but that's OK because interrupt handlers cannot
171 ia64_set_kr(IA64_KR_PT_BASE, __pa(next->pgd));
172 activate_context(next);
175 #define switch_mm(prev_mm,next_mm,next_task) activate_mm(prev_mm, next_mm)
177 # endif /* ! __ASSEMBLY__ */
178 #endif /* _ASM_IA64_MMU_CONTEXT_H */