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140 lines
3.8 KiB
140 lines
3.8 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* Copyright (C) 2008-2009 Michal Simek <[email protected]> |
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* Copyright (C) 2008-2009 PetaLogix |
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* Copyright (C) 2006 Atmark Techno, Inc. |
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*/ |
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#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H |
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#define _ASM_MICROBLAZE_MMU_CONTEXT_H |
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#include <linux/atomic.h> |
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#include <linux/mm_types.h> |
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#include <linux/sched.h> |
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#include <asm/bitops.h> |
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#include <asm/mmu.h> |
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#include <asm-generic/mm_hooks.h> |
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# ifdef __KERNEL__ |
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/* |
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* This function defines the mapping from contexts to VSIDs (virtual |
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* segment IDs). We use a skew on both the context and the high 4 bits |
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* of the 32-bit virtual address (the "effective segment ID") in order |
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* to spread out the entries in the MMU hash table. |
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*/ |
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# define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \ |
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& 0xffffff) |
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/* |
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MicroBlaze has 256 contexts, so we can just rotate through these |
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as a way of "switching" contexts. If the TID of the TLB is zero, |
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the PID/TID comparison is disabled, so we can use a TID of zero |
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to represent all kernel pages as shared among all contexts. |
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*/ |
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# define NO_CONTEXT 256 |
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# define LAST_CONTEXT 255 |
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# define FIRST_CONTEXT 1 |
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/* |
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* Set the current MMU context. |
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* This is done byloading up the segment registers for the user part of the |
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* address space. |
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* |
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* Since the PGD is immediately available, it is much faster to simply |
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* pass this along as a second parameter, which is required for 8xx and |
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* can be used for debugging on all processors (if you happen to have |
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* an Abatron). |
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*/ |
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extern void set_context(mm_context_t context, pgd_t *pgd); |
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/* |
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* Bitmap of contexts in use. |
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* The size of this bitmap is LAST_CONTEXT + 1 bits. |
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*/ |
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extern unsigned long context_map[]; |
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/* |
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* This caches the next context number that we expect to be free. |
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* Its use is an optimization only, we can't rely on this context |
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* number to be free, but it usually will be. |
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*/ |
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extern mm_context_t next_mmu_context; |
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/* |
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* Since we don't have sufficient contexts to give one to every task |
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* that could be in the system, we need to be able to steal contexts. |
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* These variables support that. |
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*/ |
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extern atomic_t nr_free_contexts; |
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extern struct mm_struct *context_mm[LAST_CONTEXT+1]; |
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extern void steal_context(void); |
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/* |
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* Get a new mmu context for the address space described by `mm'. |
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*/ |
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static inline void get_mmu_context(struct mm_struct *mm) |
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{ |
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mm_context_t ctx; |
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if (mm->context != NO_CONTEXT) |
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return; |
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while (atomic_dec_if_positive(&nr_free_contexts) < 0) |
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steal_context(); |
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ctx = next_mmu_context; |
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while (test_and_set_bit(ctx, context_map)) { |
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ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx); |
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if (ctx > LAST_CONTEXT) |
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ctx = 0; |
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} |
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next_mmu_context = (ctx + 1) & LAST_CONTEXT; |
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mm->context = ctx; |
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context_mm[ctx] = mm; |
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} |
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/* |
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* Set up the context for a new address space. |
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*/ |
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# define init_new_context(tsk, mm) (((mm)->context = NO_CONTEXT), 0) |
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/* |
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* We're finished using the context for an address space. |
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*/ |
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#define destroy_context destroy_context |
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static inline void destroy_context(struct mm_struct *mm) |
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{ |
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if (mm->context != NO_CONTEXT) { |
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clear_bit(mm->context, context_map); |
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mm->context = NO_CONTEXT; |
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atomic_inc(&nr_free_contexts); |
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} |
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} |
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static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, |
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struct task_struct *tsk) |
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{ |
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tsk->thread.pgdir = next->pgd; |
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get_mmu_context(next); |
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set_context(next->context, next->pgd); |
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} |
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/* |
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* After we have set current->mm to a new value, this activates |
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* the context for the new mm so we see the new mappings. |
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*/ |
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#define activate_mm activate_mm |
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static inline void activate_mm(struct mm_struct *active_mm, |
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struct mm_struct *mm) |
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{ |
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current->thread.pgdir = mm->pgd; |
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get_mmu_context(mm); |
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set_context(mm->context, mm->pgd); |
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} |
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extern void mmu_context_init(void); |
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#include <asm-generic/mmu_context.h> |
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# endif /* __KERNEL__ */ |
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#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */
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