1 files changed, 200 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 000000000..2da0e2eb0
--- /dev/null
+++ b/arch/ia64/include/asm/mmu_context.h
@@ -0,0 +1,200 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#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/mm_types.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) {
+		cpumask_clear(mm_cpumask(mm));
+		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 (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm)))
+			cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
+		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 */