mmu_context.h

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/*
 * 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);
        l1_stack_base = NULL;
        l1_stack_len = 0;
    }
}

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