1 files changed, 198 insertions, 0 deletions

diff --git a/arch/ia64/include/asm/mmu_context.h b/arch/ia64/include/asm/mmu_context.h
new file mode 100644
index 000000000000..040bc87db930
--- /dev/null
+++ b/arch/ia64/include/asm/mmu_context.h
@@ -0,0 +1,198 @@
+#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 aregion
+ * 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))
+
+# include <asm/page.h>
+# ifndef __ASSEMBLY__
+
+#include <linux/compiler.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#include <asm/processor.h>
+#include <asm-generic/mm_hooks.h>
+
+struct ia64_ctx {
+        spinlock_t lock;
+        unsigned int next;      /* next context number to use */
+        unsigned int limit;     /* available free range */
+        unsigned int max_ctx;   /* max. context value supported by all CPUs */
+                                /* call wrap_mmu_context when next >= max */
+        unsigned long *bitmap;  /* bitmap size is max_ctx+1 */
+        unsigned long *flushmap;/* pending rid to be flushed */
+};
+
+extern struct ia64_ctx ia64_ctx;
+DECLARE_PER_CPU(u8, ia64_need_tlb_flush);
+
+extern void mmu_context_init (void);
+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);
+        unsigned long flags;
+
+        if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) {
+                spin_lock_irqsave(&ia64_ctx.lock, flags);
+                if (__ia64_per_cpu_var(ia64_need_tlb_flush)) {
+                        local_flush_tlb_all();
+                        __ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
+                }
+                spin_unlock_irqrestore(&ia64_ctx.lock, flags);
+        }
+}
+
+static inline nv_mm_context_t
+get_mmu_context (struct mm_struct *mm)
+{
+        unsigned long flags;
+        nv_mm_context_t context = mm->context;
+
+        if (likely(context))
+                goto out;
+
+        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) {
+                        ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
+                                        ia64_ctx.max_ctx, ia64_ctx.next);
+                        ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
+                                        ia64_ctx.max_ctx, ia64_ctx.next);
+                        if (ia64_ctx.next >= ia64_ctx.max_ctx)
+                                wrap_mmu_context(mm);
+                }
+                mm->context = context = ia64_ctx.next++;
+                __set_bit(context, ia64_ctx.bitmap);
+        }
+        spin_unlock_irqrestore(&ia64_ctx.lock, flags);
+out:
+        /*
+         * Ensure we're not starting to use "context" before any old
+         * uses of it are gone from our TLB.
+         */
+        delayed_tlb_flush();
+
+        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 (nv_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(RGN_BASE(RGN_HPAGE));
+        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);
+
+#  if RGN_HPAGE != 4
+#    error "reload_context assumes RGN_HPAGE is 4"
+#  endif
+#endif
+
+        ia64_set_rr0_to_rr4(rr0, rr1, rr2, rr3, rr4);
+        ia64_srlz_i();                  /* srlz.i implies srlz.d */
+}
+
+/*
+ * Must be called with preemption off
+ */
+static inline void
+activate_context (struct mm_struct *mm)
+{
+        nv_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)
+{
+        /*
+         * 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 */