+++ /dev/null
-#ifdef __KERNEL__
-#ifndef __PPC_MMU_CONTEXT_H
-#define __PPC_MMU_CONTEXT_H
-
-#include <linux/bitops.h>
-
-#include <asm/atomic.h>
-#include <asm/mmu.h>
-#include <asm/cputable.h>
-#include <asm-generic/mm_hooks.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
-
-#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);
-
-#endif /* __PPC_MMU_CONTEXT_H */
-#endif /* __KERNEL__ */
projects / karo-tx-linux.git / blobdiff