/*
* linux/arch/arm26/mm/memc.c
*
* Copyright (C) 1998-2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Page table sludge for older ARM processor architectures.
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/memory.h>
#include <asm/hardware.h>
#include <asm/map.h>
#define MEMC_TABLE_SIZE (256*sizeof(unsigned long))
kmem_cache_t *pte_cache, *pgd_cache;
int page_nr;
/*
* Allocate space for a page table and a MEMC table.
* Note that we place the MEMC
* table before the page directory. This means we can
* easily get to both tightly-associated data structures
* with a single pointer.
*/
static inline pgd_t *alloc_pgd_table(void)
{
void *pg2k = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
if (pg2k)
pg2k += MEMC_TABLE_SIZE;
return (pgd_t *)pg2k;
}
/*
* Free a page table. this function is the counterpart to get_pgd_slow
* below, not alloc_pgd_table above.
*/
void free_pgd_slow(pgd_t *pgd)
{
unsigned long tbl = (unsigned long)pgd;
tbl -= MEMC_TABLE_SIZE;
kmem_cache_free(pgd_cache, (void *)tbl);
}
/*
* Allocate a new pgd and fill it in ready for use
*
* A new tasks pgd is completely empty (all pages !present) except for:
*
* o The machine vectors at virtual address 0x0
* o The vmalloc region at the top of address space
*
*/
#define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
pgd_t *get_pgd_slow(struct mm_struct *mm)
{
pgd_t *new_pgd, *init_pgd;
pmd_t *new_pmd, *init_pmd;
pte_t *new_pte, *init_pte;
new_pgd = alloc_pgd_table();
if (!new_pgd)
goto no_pgd;
/*
* This lock is here just to satisfy pmd_alloc and pte_lock
* FIXME: I bet we could avoid taking it pretty much altogether
*/
spin_lock(&mm->page_table_lock);
/*
* On ARM, first page must always be allocated since it contains
* the machine vectors.
*/
new_pmd = pmd_alloc(mm, new_pgd, 0);
if (!new_pmd)
goto no_pmd;
new_pte = pte_alloc_kernel(mm, new_pmd, 0);
if (!new_pte)
goto no_pte;
init_pgd = pgd_offset(&init_mm, 0);
init_pmd = pmd_offset(init_pgd, 0);
init_pte = pte_offset(init_pmd, 0);
set_pte(new_pte, *init_pte);
/*
* the page table entries are zeroed
* when the table is created. (see the cache_ctor functions below)
* Now we need to plonk the kernel (vmalloc) area at the end of
* the address space. We copy this from the init thread, just like
* the init_pte we copied above...
*/
memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
spin_unlock(&mm->page_table_lock);
/* update MEMC tables */
cpu_memc_update_all(new_pgd);
return new_pgd;
no_pte:
spin_unlock(&mm->page_table_lock);
pmd_free(new_pmd);
free_pgd_slow(new_pgd);
return NULL;
no_pmd:
spin_unlock(&mm->page_table_lock);
free_pgd_slow(new_pgd);
return NULL;
no_pgd:
return NULL;
}
/*
* No special code is required here.
*/
void setup_mm_for_reboot(char mode)
{
}
/*
* This contains the code to setup the memory map on an ARM2/ARM250/ARM3
* o swapper_pg_dir = 0x0207d000
* o kernel proper starts at 0x0208000
* o create (allocate) a pte to contain the machine vectors
* o populate the pte (points to 0x02078000) (FIXME - is it zeroed?)
* o populate the init tasks page directory (pgd) with the new pte
* o zero the rest of the init tasks pgdir (FIXME - what about vmalloc?!)
*/
void __init memtable_init(struct meminfo *mi)
{
pte_t *pte;
int i;
page_nr = max_low_pfn;
pte = alloc_bootmem_low_pages(PTRS_PER_PTE * sizeof(pte_t));
pte[0] = mk_pte_phys(PAGE_OFFSET + SCREEN_SIZE, PAGE_READONLY);
pmd_populate(&init_mm, pmd_offset(swapper_pg_dir, 0), pte);
for (i = 1; i < PTRS_PER_PGD; i++)
pgd_val(swapper_pg_dir[i]) = 0;
}
void __init iotable_init(struct map_desc *io_desc)
{
/* nothing to do */
}
/*
* We never have holes in the memmap
*/
void __init create_memmap_holes(struct meminfo *mi)
{
}
static void pte_cache_ctor(void *pte, kmem_cache_t *cache, unsigned long flags)
{
memzero(pte, sizeof(pte_t) * PTRS_PER_PTE);
}
static void pgd_cache_ctor(void *pgd, kmem_cache_t *cache, unsigned long flags)
{
memzero(pgd + MEMC_TABLE_SIZE, USER_PTRS_PER_PGD * sizeof(pgd_t));
}
void __init pgtable_cache_init(void)
{
pte_cache = kmem_cache_create("pte-cache",
sizeof(pte_t) * PTRS_PER_PTE,
0, 0, pte_cache_ctor, NULL);
if (!pte_cache)
BUG();
pgd_cache = kmem_cache_create("pgd-cache", MEMC_TABLE_SIZE +
sizeof(pgd_t) * PTRS_PER_PGD,
0, 0, pgd_cache_ctor, NULL);
if (!pgd_cache)
BUG();
}
