140 lines
3.9 KiB
C
140 lines
3.9 KiB
C
/*
|
|
* 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 */
|