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/*
* Based upon linux/arch/m68k/mm/sun3mmu.c
* Based upon linux/arch/ppc/mm/mmu_context.c
*
* Implementations of mm routines specific to the Coldfire MMU.
*
* Copyright (c) 2008 Freescale Semiconductor, Inc.
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/bootmem.h>
#include <asm/setup.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/mcf_pgalloc.h>
#include <asm/tlbflush.h>
#define KMAPAREA(x) ((x >= VMALLOC_START) && (x < KMAP_END))
mm_context_t next_mmu_context;
unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
atomic_t nr_free_contexts;
struct mm_struct *context_mm[LAST_CONTEXT+1];
extern unsigned long num_pages;
/*
* ColdFire paging_init derived from sun3.
*/
void __init paging_init(void)
{
pgd_t *pg_dir;
pte_t *pg_table;
unsigned long address, size;
unsigned long next_pgtable, bootmem_end;
unsigned long zones_size[MAX_NR_ZONES];
enum zone_type zone;
int i;
empty_zero_page = (void *) alloc_bootmem_pages(PAGE_SIZE);
memset((void *) empty_zero_page, 0, PAGE_SIZE);
pg_dir = swapper_pg_dir;
memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
size = num_pages * sizeof(pte_t);
size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
next_pgtable = (unsigned long) alloc_bootmem_pages(size);
bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
address = PAGE_OFFSET;
while (address < (unsigned long)high_memory) {
pg_table = (pte_t *) next_pgtable;
next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
pgd_val(*pg_dir) = (unsigned long) pg_table;
pg_dir++;
/* now change pg_table to kernel virtual addresses */
for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
if (address >= (unsigned long) high_memory)
pte_val(pte) = 0;
set_pte(pg_table, pte);
address += PAGE_SIZE;
}
}
current->mm = NULL;
for (zone = 0; zone < MAX_NR_ZONES; zone++)
zones_size[zone] = 0x0;
zones_size[ZONE_DMA] = num_pages;
free_area_init(zones_size);
}
int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
{
unsigned long flags, mmuar, mmutr;
struct mm_struct *mm;
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
int asid;
local_irq_save(flags);
mmuar = (dtlb) ? mmu_read(MMUAR) :
regs->pc + (extension_word * sizeof(long));
mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
if (!mm) {
local_irq_restore(flags);
return -1;
}
pgd = pgd_offset(mm, mmuar);
if (pgd_none(*pgd)) {
local_irq_restore(flags);
return -1;
}
pmd = pmd_offset(pgd, mmuar);
if (pmd_none(*pmd)) {
local_irq_restore(flags);
return -1;
}
pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
: pte_offset_map(pmd, mmuar);
if (pte_none(*pte) || !pte_present(*pte)) {
local_irq_restore(flags);
return -1;
}
if (write) {
if (!pte_write(*pte)) {
local_irq_restore(flags);
return -1;
}
set_pte(pte, pte_mkdirty(*pte));
}
set_pte(pte, pte_mkyoung(*pte));
asid = mm->context & 0xff;
if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
set_pte(pte, pte_wrprotect(*pte));
mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
mmu_write(MMUTR, mmutr);
mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
if (dtlb)
mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
else
mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
local_irq_restore(flags);
return 0;
}
/*
* Initialize the context management stuff.
* The following was taken from arch/ppc/mmu_context.c
*/
void __init mmu_context_init(void)
{
/*
* Some processors have too few contexts to reserve one for
* init_mm, and require using context 0 for a normal task.
* Other processors reserve the use of context zero for the kernel.
* This code assumes FIRST_CONTEXT < 32.
*/
context_map[0] = (1 << FIRST_CONTEXT) - 1;
next_mmu_context = FIRST_CONTEXT;
atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
}
/*
* Steal a context from a task that has one at the moment.
* This is only used on 8xx and 4xx and we presently assume that
* they don't do SMP. If they do then thicfpgalloc.hs will have to check
* whether the MM we steal is in use.
* We also assume that this is only used on systems that don't
* use an MMU hash table - this is true for 8xx and 4xx.
* This isn't an LRU system, it just frees up each context in
* turn (sort-of pseudo-random replacement :). This would be the
* place to implement an LRU scheme if anyone was motivated to do it.
* -- paulus
*/
void steal_context(void)
{
struct mm_struct *mm;
/*
* free up context `next_mmu_context'
* if we shouldn't free context 0, don't...
*/
if (next_mmu_context < FIRST_CONTEXT)
next_mmu_context = FIRST_CONTEXT;
mm = context_mm[next_mmu_context];
flush_tlb_mm(mm);
destroy_context(mm);
}
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