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-rw-r--r--arch/microblaze/include/asm/mmu_context_mm.h140
1 files changed, 140 insertions, 0 deletions
diff --git a/arch/microblaze/include/asm/mmu_context_mm.h b/arch/microblaze/include/asm/mmu_context_mm.h
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+/*
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2008-2009 PetaLogix
+ * Copyright (C) 2006 Atmark Techno, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H
+#define _ASM_MICROBLAZE_MMU_CONTEXT_H
+
+#include <asm/atomic.h>
+#include <asm/bitops.h>
+#include <asm/mmu.h>
+#include <asm-generic/mm_hooks.h>
+
+# ifdef __KERNEL__
+/*
+ * This function defines the mapping from contexts to VSIDs (virtual
+ * segment IDs). We use a skew on both the context and the high 4 bits
+ * of the 32-bit virtual address (the "effective segment ID") in order
+ * to spread out the entries in the MMU hash table.
+ */
+# define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
+ & 0xffffff)
+
+/*
+ MicroBlaze has 256 contexts, so we can just rotate through these
+ as a way of "switching" contexts. If the TID of the TLB is zero,
+ the PID/TID comparison is disabled, so we can use a TID of zero
+ to represent all kernel pages as shared among all contexts.
+ */
+
+static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+}
+
+# define NO_CONTEXT 256
+# define LAST_CONTEXT 255
+# define FIRST_CONTEXT 1
+
+/*
+ * Set the current MMU context.
+ * This is done byloading up the segment registers for the user part of the
+ * address space.
+ *
+ * Since the PGD is immediately available, it is much faster to simply
+ * pass this along as a second parameter, which is required for 8xx and
+ * can be used for debugging on all processors (if you happen to have
+ * an Abatron).
+ */
+extern void set_context(mm_context_t context, pgd_t *pgd);
+
+/*
+ * Bitmap of contexts in use.
+ * The size of this bitmap is LAST_CONTEXT + 1 bits.
+ */
+extern unsigned long context_map[];
+
+/*
+ * This caches the next context number that we expect to be free.
+ * Its use is an optimization only, we can't rely on this context
+ * number to be free, but it usually will be.
+ */
+extern mm_context_t next_mmu_context;
+
+/*
+ * Since we don't have sufficient contexts to give one to every task
+ * that could be in the system, we need to be able to steal contexts.
+ * These variables support that.
+ */
+extern atomic_t nr_free_contexts;
+extern struct mm_struct *context_mm[LAST_CONTEXT+1];
+extern void steal_context(void);
+
+/*
+ * Get a new mmu context for the address space described by `mm'.
+ */
+static inline void get_mmu_context(struct mm_struct *mm)
+{
+ mm_context_t ctx;
+
+ if (mm->context != NO_CONTEXT)
+ return;
+ while (atomic_dec_if_positive(&nr_free_contexts) < 0)
+ steal_context();
+ ctx = next_mmu_context;
+ while (test_and_set_bit(ctx, context_map)) {
+ ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
+ if (ctx > LAST_CONTEXT)
+ ctx = 0;
+ }
+ next_mmu_context = (ctx + 1) & LAST_CONTEXT;
+ mm->context = ctx;
+ context_mm[ctx] = mm;
+}
+
+/*
+ * Set up the context for a new address space.
+ */
+# define init_new_context(tsk, mm) (((mm)->context = NO_CONTEXT), 0)
+
+/*
+ * We're finished using the context for an address space.
+ */
+static inline void destroy_context(struct mm_struct *mm)
+{
+ if (mm->context != NO_CONTEXT) {
+ clear_bit(mm->context, context_map);
+ mm->context = NO_CONTEXT;
+ atomic_inc(&nr_free_contexts);
+ }
+}
+
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+ struct task_struct *tsk)
+{
+ tsk->thread.pgdir = next->pgd;
+ get_mmu_context(next);
+ set_context(next->context, next->pgd);
+}
+
+/*
+ * 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_mm(struct mm_struct *active_mm,
+ struct mm_struct *mm)
+{
+ current->thread.pgdir = mm->pgd;
+ get_mmu_context(mm);
+ set_context(mm->context, mm->pgd);
+}
+
+extern void mmu_context_init(void);
+
+# endif /* __KERNEL__ */
+#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */