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mmu_context.h

/*
 * Copyright 2004-2009 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#ifndef __BLACKFIN_MMU_CONTEXT_H__
#define __BLACKFIN_MMU_CONTEXT_H__

#include <linux/slab.h>
#include <linux/sched.h>
#include <asm/setup.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/cplbinit.h>
#include <asm/sections.h>

/* Note: L1 stacks are CPU-private things, so we bluntly disable this
   feature in SMP mode, and use the per-CPU scratch SRAM bank only to
   store the PDA instead. */

extern void *current_l1_stack_save;
extern int nr_l1stack_tasks;
extern void *l1_stack_base;
extern unsigned long l1_stack_len;

extern int l1sram_free(const void*);
extern void *l1sram_alloc_max(void*);

static inline void free_l1stack(void)
{
      nr_l1stack_tasks--;
      if (nr_l1stack_tasks == 0)
            l1sram_free(l1_stack_base);
}

static inline unsigned long
alloc_l1stack(unsigned long length, unsigned long *stack_base)
{
      if (nr_l1stack_tasks == 0) {
            l1_stack_base = l1sram_alloc_max(&l1_stack_len);
            if (!l1_stack_base)
                  return 0;
      }

      if (l1_stack_len < length) {
            if (nr_l1stack_tasks == 0)
                  l1sram_free(l1_stack_base);
            return 0;
      }
      *stack_base = (unsigned long)l1_stack_base;
      nr_l1stack_tasks++;
      return l1_stack_len;
}

static inline int
activate_l1stack(struct mm_struct *mm, unsigned long sp_base)
{
      if (current_l1_stack_save)
            memcpy(current_l1_stack_save, l1_stack_base, l1_stack_len);
      mm->context.l1_stack_save = current_l1_stack_save = (void*)sp_base;
      memcpy(l1_stack_base, current_l1_stack_save, l1_stack_len);
      return 1;
}

#define deactivate_mm(tsk,mm) do { } while (0)

#define activate_mm(prev, next) switch_mm(prev, next, NULL)

static inline void __switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
                         struct task_struct *tsk)
{
#ifdef CONFIG_MPU
      unsigned int cpu = smp_processor_id();
#endif
      if (prev_mm == next_mm)
            return;
#ifdef CONFIG_MPU
      if (prev_mm->context.page_rwx_mask == current_rwx_mask[cpu]) {
            flush_switched_cplbs(cpu);
            set_mask_dcplbs(next_mm->context.page_rwx_mask, cpu);
      }
#endif

#ifdef CONFIG_APP_STACK_L1
      /* L1 stack switching.  */
      if (!next_mm->context.l1_stack_save)
            return;
      if (next_mm->context.l1_stack_save == current_l1_stack_save)
            return;
      if (current_l1_stack_save) {
            memcpy(current_l1_stack_save, l1_stack_base, l1_stack_len);
      }
      current_l1_stack_save = next_mm->context.l1_stack_save;
      memcpy(l1_stack_base, current_l1_stack_save, l1_stack_len);
#endif
}

#ifdef CONFIG_IPIPE
#define lock_mm_switch(flags) flags = hard_local_irq_save_cond()
#define unlock_mm_switch(flags)     hard_local_irq_restore_cond(flags)
#else
#define lock_mm_switch(flags) do { (void)(flags); } while (0)
#define unlock_mm_switch(flags)     do { (void)(flags); } while (0)
#endif /* CONFIG_IPIPE */

#ifdef CONFIG_MPU
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
                       struct task_struct *tsk)
{
      unsigned long flags;
      lock_mm_switch(flags);
      __switch_mm(prev, next, tsk);
      unlock_mm_switch(flags);
}

static inline void protect_page(struct mm_struct *mm, unsigned long addr,
                        unsigned long flags)
{
      unsigned long *mask = mm->context.page_rwx_mask;
      unsigned long page;
      unsigned long idx;
      unsigned long bit;

      if (unlikely(addr >= ASYNC_BANK0_BASE && addr < ASYNC_BANK3_BASE + ASYNC_BANK3_SIZE))
            page = (addr - (ASYNC_BANK0_BASE - _ramend)) >> 12;
      else
            page = addr >> 12;
      idx = page >> 5;
      bit = 1 << (page & 31);

      if (flags & VM_READ)
            mask[idx] |= bit;
      else
            mask[idx] &= ~bit;
      mask += page_mask_nelts;
      if (flags & VM_WRITE)
            mask[idx] |= bit;
      else
            mask[idx] &= ~bit;
      mask += page_mask_nelts;
      if (flags & VM_EXEC)
            mask[idx] |= bit;
      else
            mask[idx] &= ~bit;
}

static inline void update_protections(struct mm_struct *mm)
{
      unsigned int cpu = smp_processor_id();
      if (mm->context.page_rwx_mask == current_rwx_mask[cpu]) {
            flush_switched_cplbs(cpu);
            set_mask_dcplbs(mm->context.page_rwx_mask, cpu);
      }
}
#else /* !CONFIG_MPU */
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
                       struct task_struct *tsk)
{
      __switch_mm(prev, next, tsk);
}
#endif

static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
}

/* Called when creating a new context during fork() or execve().  */
static inline int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
#ifdef CONFIG_MPU
      unsigned long p = __get_free_pages(GFP_KERNEL, page_mask_order);
      mm->context.page_rwx_mask = (unsigned long *)p;
      memset(mm->context.page_rwx_mask, 0,
             page_mask_nelts * 3 * sizeof(long));
#endif
      return 0;
}

static inline void destroy_context(struct mm_struct *mm)
{
      struct sram_list_struct *tmp;
#ifdef CONFIG_MPU
      unsigned int cpu = smp_processor_id();
#endif

#ifdef CONFIG_APP_STACK_L1
      if (current_l1_stack_save == mm->context.l1_stack_save)
            current_l1_stack_save = 0;
      if (mm->context.l1_stack_save)
            free_l1stack();
#endif

      while ((tmp = mm->context.sram_list)) {
            mm->context.sram_list = tmp->next;
            sram_free(tmp->addr);
            kfree(tmp);
      }
#ifdef CONFIG_MPU
      if (current_rwx_mask[cpu] == mm->context.page_rwx_mask)
            current_rwx_mask[cpu] = NULL;
      free_pages((unsigned long)mm->context.page_rwx_mask, page_mask_order);
#endif
}

#define ipipe_mm_switch_protect(flags)          \
      flags = hard_local_irq_save_cond()

#define ipipe_mm_switch_unprotect(flags)  \
      hard_local_irq_restore_cond(flags)

#endif

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