patch-2.3.43 linux/include/asm-ia64/mmu_context.h

• Lines: 144
• Date: Sun Feb 6 18:42:40 2000
• Orig file: v2.3.42/linux/include/asm-ia64/mmu_context.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.42/linux/include/asm-ia64/mmu_context.h linux/include/asm-ia64/mmu_context.h
@@ -0,0 +1,143 @@
+#ifndef _ASM_IA64_MMU_CONTEXT_H
+#define _ASM_IA64_MMU_CONTEXT_H
+
+/*
+ * Copyright (C) 1998, 1999 Hewlett-Packard Co
+ * Copyright (C) 1998, 1999 David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+
+#include <linux/config.h>
+#include <linux/sched.h>
+
+#include <asm/processor.h>
+
+/*
+ * 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 ia-64 TLBs do not
+ * guarantee that the region number is checked 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.  On processors where the region number is checked
+ * in TLB lookups, we can get back those two bits by defining
+ * CONFIG_IA64_TLB_CHECKS_REGION_NUMBER.  The macro
+ * IA64_REGION_ID_BITS gives the number of bits in a region id.  The
+ * architecture manual guarantees this number to be in the range
+ * 18-24.
+ *
+ * A context number has the following format:
+ *
+ *  +--------------------+---------------------+
+ *  |  generation number |    region id        |
+ *  +--------------------+---------------------+
+ *
+ * A context number of 0 is considered "invalid".
+ *
+ * The generation number is incremented whenever we end up having used
+ * up all available region ids.  At that point with flush the entire
+ * TLB and reuse the first region id.  The new generation number
+ * ensures that when we context switch back to an old process, we do
+ * not inadvertently end up using its possibly reused region id.
+ * Instead, we simply allocate a new region id for that process.
+ *
+ * Copyright (C) 1998 David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+
+#define IA64_REGION_ID_KERNEL	0 /* the kernel's region id (tlb.c depends on this being 0) */
+
+#define IA64_REGION_ID_BITS	18
+
+#ifdef CONFIG_IA64_TLB_CHECKS_REGION_NUMBER
+# define IA64_HW_CONTEXT_BITS	IA64_REGION_ID_BITS
+#else
+# define IA64_HW_CONTEXT_BITS	(IA64_REGION_ID_BITS - 3)
+#endif
+
+#define IA64_HW_CONTEXT_MASK	((1UL << IA64_HW_CONTEXT_BITS) - 1)
+
+extern unsigned long ia64_next_context;
+
+extern void get_new_mmu_context (struct mm_struct *mm);
+
+extern inline unsigned long
+ia64_rid (unsigned long context, unsigned long region_addr)
+{
+# ifdef CONFIG_IA64_TLB_CHECKS_REGION_NUMBER
+	return context;
+# else
+	return context << 3 | (region_addr >> 61);
+# endif
+}
+
+extern inline void
+get_mmu_context (struct mm_struct *mm)
+{
+	/* check if our ASN is of an older generation and thus invalid: */
+	if (((mm->context ^ ia64_next_context) & ~IA64_HW_CONTEXT_MASK) != 0) {
+		get_new_mmu_context(mm);
+	}
+}
+
+extern inline void
+init_new_context (struct task_struct *p, struct mm_struct *mm)
+{
+	mm->context = 0;
+}
+
+extern inline void
+destroy_context (struct mm_struct *mm)
+{
+	/* Nothing to do.  */
+}
+
+extern inline void
+reload_context (struct mm_struct *mm)
+{
+	unsigned long rid;
+	unsigned long rid_incr = 0;
+	unsigned long rr0, rr1, rr2, rr3, rr4;
+
+	rid = (mm->context & IA64_HW_CONTEXT_MASK);
+
+#ifndef CONFIG_IA64_TLB_CHECKS_REGION_NUMBER
+	rid <<= 3;	/* make space for encoding the region number */
+	rid_incr = 1 << 8;
+#endif
+
+	/* 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;
+	ia64_set_rr(0x0000000000000000, rr0);
+	ia64_set_rr(0x2000000000000000, rr1);
+	ia64_set_rr(0x4000000000000000, rr2);
+	ia64_set_rr(0x6000000000000000, rr3);
+	ia64_set_rr(0x8000000000000000, rr4);
+	ia64_insn_group_barrier();
+	ia64_srlz_i();			/* srlz.i implies srlz.d */
+	ia64_insn_group_barrier();
+}
+
+/*
+ * Switch from address space PREV to address space NEXT.  Note that
+ * TSK may be NULL.
+ */
+static inline void
+switch_mm (struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk, unsigned cpu)
+{
+	/*
+	 * We may get interrupts here, but that's OK because interrupt
+	 * handlers cannot touch user-space.
+	 */
+	__asm__ __volatile__ ("mov ar.k7=%0" :: "r"(__pa(next->pgd)));
+	get_mmu_context(next);
+	reload_context(next);
+}
+
+#define activate_mm(prev,next)					\
+	switch_mm((prev), (next), NULL, smp_processor_id())
+
+#endif /* _ASM_IA64_MMU_CONTEXT_H */