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-rw-r--r--include/asm-mn10300/mmu_context.h138
1 files changed, 138 insertions, 0 deletions
diff --git a/include/asm-mn10300/mmu_context.h b/include/asm-mn10300/mmu_context.h
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+++ b/include/asm-mn10300/mmu_context.h
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+/* MN10300 MMU context management
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Modified by David Howells (dhowells@redhat.com)
+ * - Derived from include/asm-m32r/mmu_context.h
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ *
+ *
+ * This implements an algorithm to provide TLB PID mappings to provide
+ * selective access to the TLB for processes, thus reducing the number of TLB
+ * flushes required.
+ *
+ * Note, however, that the M32R algorithm is technically broken as it does not
+ * handle version wrap-around, and could, theoretically, have a problem with a
+ * very long lived program that sleeps long enough for the version number to
+ * wrap all the way around so that its TLB mappings appear valid once again.
+ */
+#ifndef _ASM_MMU_CONTEXT_H
+#define _ASM_MMU_CONTEXT_H
+
+#include <asm/atomic.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+#include <asm-generic/mm_hooks.h>
+
+#define MMU_CONTEXT_TLBPID_MASK 0x000000ffUL
+#define MMU_CONTEXT_VERSION_MASK 0xffffff00UL
+#define MMU_CONTEXT_FIRST_VERSION 0x00000100UL
+#define MMU_NO_CONTEXT 0x00000000UL
+
+extern unsigned long mmu_context_cache[NR_CPUS];
+#define mm_context(mm) (mm->context.tlbpid[smp_processor_id()])
+
+#define enter_lazy_tlb(mm, tsk) do {} while (0)
+
+#ifdef CONFIG_SMP
+#define cpu_ran_vm(cpu, task) \
+ cpu_set((cpu), (task)->cpu_vm_mask)
+#define cpu_maybe_ran_vm(cpu, task) \
+ cpu_test_and_set((cpu), (task)->cpu_vm_mask)
+#else
+#define cpu_ran_vm(cpu, task) do {} while (0)
+#define cpu_maybe_ran_vm(cpu, task) true
+#endif /* CONFIG_SMP */
+
+/*
+ * allocate an MMU context
+ */
+static inline unsigned long allocate_mmu_context(struct mm_struct *mm)
+{
+ unsigned long *pmc = &mmu_context_cache[smp_processor_id()];
+ unsigned long mc = ++(*pmc);
+
+ if (!(mc & MMU_CONTEXT_TLBPID_MASK)) {
+ /* we exhausted the TLB PIDs of this version on this CPU, so we
+ * flush this CPU's TLB in its entirety and start new cycle */
+ flush_tlb_all();
+
+ /* fix the TLB version if needed (we avoid version #0 so as to
+ * distingush MMU_NO_CONTEXT) */
+ if (!mc)
+ *pmc = mc = MMU_CONTEXT_FIRST_VERSION;
+ }
+ mm_context(mm) = mc;
+ return mc;
+}
+
+/*
+ * get an MMU context if one is needed
+ */
+static inline unsigned long get_mmu_context(struct mm_struct *mm)
+{
+ unsigned long mc = MMU_NO_CONTEXT, cache;
+
+ if (mm) {
+ cache = mmu_context_cache[smp_processor_id()];
+ mc = mm_context(mm);
+
+ /* if we have an old version of the context, replace it */
+ if ((mc ^ cache) & MMU_CONTEXT_VERSION_MASK)
+ mc = allocate_mmu_context(mm);
+ }
+ return mc;
+}
+
+/*
+ * initialise the context related info for a new mm_struct instance
+ */
+static inline int init_new_context(struct task_struct *tsk,
+ struct mm_struct *mm)
+{
+ int num_cpus = NR_CPUS, i;
+
+ for (i = 0; i < num_cpus; i++)
+ mm->context.tlbpid[i] = MMU_NO_CONTEXT;
+ return 0;
+}
+
+/*
+ * destroy context related info for an mm_struct that is about to be put to
+ * rest
+ */
+#define destroy_context(mm) do { } while (0)
+
+/*
+ * after we have set current->mm to a new value, this activates the context for
+ * the new mm so we see the new mappings.
+ */
+static inline void activate_context(struct mm_struct *mm, int cpu)
+{
+ PIDR = get_mmu_context(mm) & MMU_CONTEXT_TLBPID_MASK;
+}
+
+/*
+ * change between virtual memory sets
+ */
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+ struct task_struct *tsk)
+{
+ int cpu = smp_processor_id();
+
+ if (prev != next) {
+ cpu_ran_vm(cpu, next);
+ activate_context(next, cpu);
+ PTBR = (unsigned long) next->pgd;
+ } else if (!cpu_maybe_ran_vm(cpu, next)) {
+ activate_context(next, cpu);
+ }
+}
+
+#define deactivate_mm(tsk, mm) do {} while (0)
+#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
+
+#endif /* _ASM_MMU_CONTEXT_H */