#define __ASM_POWERPC_MMU_CONTEXT_H
#ifdef __KERNEL__
+#include <asm/mmu.h>
+#include <asm/cputable.h>
+#include <asm-generic/mm_hooks.h>
+
#ifndef CONFIG_PPC64
-#include <asm-ppc/mmu_context.h>
+#include <asm/atomic.h>
+#include <asm/bitops.h>
+
+/*
+ * On 32-bit PowerPC 6xx/7xx/7xxx CPUs, we use a set of 16 VSIDs
+ * (virtual segment identifiers) for each context. Although the
+ * hardware supports 24-bit VSIDs, and thus >1 million contexts,
+ * we only use 32,768 of them. That is ample, since there can be
+ * at most around 30,000 tasks in the system anyway, and it means
+ * that we can use a bitmap to indicate which contexts are in use.
+ * Using a bitmap means that we entirely avoid all of the problems
+ * that we used to have when the context number overflowed,
+ * particularly on SMP systems.
+ * -- paulus.
+ */
+
+/*
+ * 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. Note, if this
+ * function is changed then arch/ppc/mm/hashtable.S will have to be
+ * changed to correspond.
+ */
+#define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
+ & 0xffffff)
+
+/*
+ The MPC8xx has only 16 contexts. We rotate through them on each
+ task switch. A better way would be to keep track of tasks that
+ own contexts, and implement an LRU usage. That way very active
+ tasks don't always have to pay the TLB reload overhead. The
+ kernel pages are mapped shared, so the kernel can run on behalf
+ of any task that makes a kernel entry. Shared does not mean they
+ are not protected, just that the ASID comparison is not performed.
+ -- Dan
+
+ The IBM4xx 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.
+ -- Dan
+ */
+
+static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+}
+
+#ifdef CONFIG_8xx
+#define NO_CONTEXT 16
+#define LAST_CONTEXT 15
+#define FIRST_CONTEXT 0
+
+#elif defined(CONFIG_4xx)
+#define NO_CONTEXT 256
+#define LAST_CONTEXT 255
+#define FIRST_CONTEXT 1
+
+#elif defined(CONFIG_E200) || defined(CONFIG_E500)
+#define NO_CONTEXT 256
+#define LAST_CONTEXT 255
+#define FIRST_CONTEXT 1
+
+#else
+
+/* PPC 6xx, 7xx CPUs */
+#define NO_CONTEXT ((unsigned long) -1)
+#define LAST_CONTEXT 32767
+#define FIRST_CONTEXT 1
+#endif
+
+/*
+ * Set the current MMU context.
+ * On 32-bit PowerPCs (other than the 8xx embedded chips), this is done by
+ * loading 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(unsigned long contextid, 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 unsigned long next_mmu_context;
+
+/*
+ * If 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.
+ */
+#if LAST_CONTEXT < 30000
+#define FEW_CONTEXTS 1
+extern atomic_t nr_free_contexts;
+extern struct mm_struct *context_mm[LAST_CONTEXT+1];
+extern void steal_context(void);
+#endif
+
+/*
+ * Get a new mmu context for the address space described by `mm'.
+ */
+static inline void get_mmu_context(struct mm_struct *mm)
+{
+ unsigned long ctx;
+
+ if (mm->context.id != NO_CONTEXT)
+ return;
+#ifdef FEW_CONTEXTS
+ while (atomic_dec_if_positive(&nr_free_contexts) < 0)
+ steal_context();
+#endif
+ 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.id = ctx;
+#ifdef FEW_CONTEXTS
+ context_mm[ctx] = mm;
+#endif
+}
+
+/*
+ * Set up the context for a new address space.
+ */
+static inline int init_new_context(struct task_struct *t, struct mm_struct *mm)
+{
+ mm->context.id = NO_CONTEXT;
+ mm->context.vdso_base = 0;
+ return 0;
+}
+
+/*
+ * We're finished using the context for an address space.
+ */
+static inline void destroy_context(struct mm_struct *mm)
+{
+ preempt_disable();
+ if (mm->context.id != NO_CONTEXT) {
+ clear_bit(mm->context.id, context_map);
+ mm->context.id = NO_CONTEXT;
+#ifdef FEW_CONTEXTS
+ atomic_inc(&nr_free_contexts);
+#endif
+ }
+ preempt_enable();
+}
+
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+ struct task_struct *tsk)
+{
+#ifdef CONFIG_ALTIVEC
+ if (cpu_has_feature(CPU_FTR_ALTIVEC))
+ asm volatile ("dssall;\n"
+#ifndef CONFIG_POWER4
+ "sync;\n" /* G4 needs a sync here, G5 apparently not */
+#endif
+ : : );
+#endif /* CONFIG_ALTIVEC */
+
+ tsk->thread.pgdir = next->pgd;
+
+ /* No need to flush userspace segments if the mm doesnt change */
+ if (prev == next)
+ return;
+
+ /* Setup new userspace context */
+ get_mmu_context(next);
+ set_context(next->context.id, next->pgd);
+}
+
+#define deactivate_mm(tsk,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.
+ */
+#define activate_mm(active_mm, mm) switch_mm(active_mm, mm, current)
+
+extern void mmu_context_init(void);
+
+
#else
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
-#include <asm/mmu.h>
-#include <asm/cputable.h>
-#include <asm-generic/mm_hooks.h>
/*
* Copyright (C) 2001 PPC 64 Team, IBM Corp
projects / karo-tx-linux.git / commitdiff