diff options
Diffstat (limited to 'arch/arm26/mm/memc.c')
| -rw-r--r-- | arch/arm26/mm/memc.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/arch/arm26/mm/memc.c b/arch/arm26/mm/memc.c new file mode 100644 index 000000000000..8e8a2bb2487d --- /dev/null +++ b/arch/arm26/mm/memc.c @@ -0,0 +1,202 @@ +/* + * 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(); +} |