diff options
Diffstat (limited to 'arch/microblaze/include/asm/mmu_context_mm.h')
| -rw-r--r-- | arch/microblaze/include/asm/mmu_context_mm.h | 140 |
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 new file mode 100644 index 00000000000..3e5c254e8d1 --- /dev/null +++ b/arch/microblaze/include/asm/mmu_context_mm.h @@ -0,0 +1,140 @@ +/* + * 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 */ |