memory.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

/*
 *  linux/arch/m68k/mm/memory.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 */

#include <linux/config.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/pagemap.h>

#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/io.h>
#include <asm/machdep.h>
#ifdef CONFIG_AMIGA
#include <asm/amigahw.h>
#endif

struct pgtable_cache_struct quicklists;

void __bad_pte(pmd_t *pmd)
{
	printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
	pmd_set(pmd, BAD_PAGETABLE);
}

void __bad_pmd(pgd_t *pgd)
{
	printk("Bad pgd in pmd_alloc: %08lx\n", pgd_val(*pgd));
	pgd_set(pgd, (pmd_t *)BAD_PAGETABLE);
}

#if 0
pte_t *get_pte_slow(pmd_t *pmd, unsigned long offset)
{
	pte_t *pte;

	pte = (pte_t *) __get_free_page(GFP_KERNEL);
	if (pmd_none(*pmd)) {
		if (pte) {
			clear_page(pte);
			__flush_page_to_ram((unsigned long)pte);
			flush_tlb_kernel_page((unsigned long)pte);
			nocache_page((unsigned long)pte);
			pmd_set(pmd, pte);
			return pte + offset;
		}
		pmd_set(pmd, BAD_PAGETABLE);
		return NULL;
	}
	free_page((unsigned long)pte);
	if (pmd_bad(*pmd)) {
		__bad_pte(pmd);
		return NULL;
	}
	return (pte_t *)__pmd_page(*pmd) + offset;
}
#endif

#if 0
pmd_t *get_pmd_slow(pgd_t *pgd, unsigned long offset)
{
	pmd_t *pmd;

	pmd = get_pointer_table();
	if (pgd_none(*pgd)) {
		if (pmd) {
			pgd_set(pgd, pmd);
			return pmd + offset;
		}
		pgd_set(pgd, (pmd_t *)BAD_PAGETABLE);
		return NULL;
	}
	free_pointer_table(pmd);
	if (pgd_bad(*pgd)) {
		__bad_pmd(pgd);
		return NULL;
	}
	return (pmd_t *)__pgd_page(*pgd) + offset;
}
#endif

/* ++andreas: {get,free}_pointer_table rewritten to use unused fields from
   struct page instead of separately kmalloced struct.  Stolen from
   arch/sparc/mm/srmmu.c ... */

typedef struct list_head ptable_desc;
static LIST_HEAD(ptable_list);

#define PD_PTABLE(page) ((ptable_desc *)virt_to_page(page))
#define PD_PAGE(ptable) (list_entry(ptable, struct page, list))
#define PD_MARKBITS(dp) (*(unsigned char *)&PD_PAGE(dp)->index)

#define PTABLE_SIZE (PTRS_PER_PMD * sizeof(pmd_t))

void __init init_pointer_table(unsigned long ptable)
{
	ptable_desc *dp;
	unsigned long page = ptable & PAGE_MASK;
	unsigned char mask = 1 << ((ptable - page)/PTABLE_SIZE);

	dp = PD_PTABLE(page);
	if (!(PD_MARKBITS(dp) & mask)) {
		PD_MARKBITS(dp) = 0xff;
		list_add(dp, &ptable_list);
	}

	PD_MARKBITS(dp) &= ~mask;
#ifdef DEBUG
	printk("init_pointer_table: %lx, %x\n", ptable, PD_MARKBITS(dp));
#endif

	/* unreserve the page so it's possible to free that page */
	PD_PAGE(dp)->flags &= ~(1 << PG_reserved);
	atomic_set(&PD_PAGE(dp)->count, 1);

	return;
}

pmd_t *get_pointer_table (void)
{
	ptable_desc *dp = ptable_list.next;
	unsigned char mask = PD_MARKBITS (dp);
	unsigned char tmp;
	unsigned int off;

	/*
	 * For a pointer table for a user process address space, a
	 * table is taken from a page allocated for the purpose.  Each
	 * page can hold 8 pointer tables.  The page is remapped in
	 * virtual address space to be noncacheable.
	 */
	if (mask == 0) {
		unsigned long page;
		ptable_desc *new;

		if (!(page = get_free_page (GFP_KERNEL)))
			return 0;

		flush_tlb_kernel_page(page);
		nocache_page (page);

		new = PD_PTABLE(page);
		PD_MARKBITS(new) = 0xfe;
		list_add_tail(new, dp);

		return (pmd_t *)page;
	}

	for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += PTABLE_SIZE)
		;
	PD_MARKBITS(dp) = mask & ~tmp;
	if (!PD_MARKBITS(dp)) {
		/* move to end of list */
		list_del(dp);
		list_add_tail(dp, &ptable_list);
	}
	return (pmd_t *) (page_address(PD_PAGE(dp)) + off);
}

int free_pointer_table (pmd_t *ptable)
{
	ptable_desc *dp;
	unsigned long page = (unsigned long)ptable & PAGE_MASK;
	unsigned char mask = 1 << (((unsigned long)ptable - page)/PTABLE_SIZE);

	dp = PD_PTABLE(page);
	if (PD_MARKBITS (dp) & mask)
		panic ("table already free!");

	PD_MARKBITS (dp) |= mask;

	if (PD_MARKBITS(dp) == 0xff) {
		/* all tables in page are free, free page */
		list_del(dp);
		cache_page (page);
		free_page (page);
		return 1;
	} else if (ptable_list.next != dp) {
		/*
		 * move this descriptor to the front of the list, since
		 * it has one or more free tables.
		 */
		list_del(dp);
		list_add(dp, &ptable_list);
	}
	return 0;
}

static unsigned long transp_transl_matches( unsigned long regval,
					    unsigned long vaddr )
{
    unsigned long base, mask;

    /* enabled? */
    if (!(regval & 0x8000))
	return( 0 );

    if (CPU_IS_030) {
	/* function code match? */
	base = (regval >> 4) & 7;
	mask = ~(regval & 7);
	if (((SUPER_DATA ^ base) & mask) != 0)
	    return 0;
    }
    else {
	/* must not be user-only */
	if ((regval & 0x6000) == 0)
	    return( 0 );
    }

    /* address match? */
    base = regval & 0xff000000;
    mask = ~(regval << 8) & 0xff000000;
    return (((unsigned long)vaddr ^ base) & mask) == 0;
}

#if DEBUG_INVALID_PTOV
int mm_inv_cnt = 5;
#endif

#ifndef CONFIG_SINGLE_MEMORY_CHUNK
/*
 * The following two routines map from a physical address to a kernel
 * virtual address and vice versa.
 */
unsigned long mm_vtop(unsigned long vaddr)
{
	int i=0;
	unsigned long voff = (unsigned long)vaddr - PAGE_OFFSET;

	do {
		if (voff < m68k_memory[i].size) {
#ifdef DEBUGPV
			printk ("VTOP(%p)=%lx\n", vaddr,
				m68k_memory[i].addr + voff);
#endif
			return m68k_memory[i].addr + voff;
		}
		voff -= m68k_memory[i].size;
	} while (++i < m68k_num_memory);

	/* As a special case allow `__pa(high_memory)'.  */
	if (voff == 0)
		return m68k_memory[i-1].addr + m68k_memory[i-1].size;

	/* As a special case allow `__pa(high_memory)'.  */
	if (voff == 0)
		return m68k_memory[i-1].addr + m68k_memory[i-1].size;

	return mm_vtop_fallback(vaddr);
}
#endif

/* Separate function to make the common case faster (needs to save less
   registers) */
unsigned long mm_vtop_fallback(unsigned long vaddr)
{
	/* not in one of the memory chunks; test for applying transparent
	 * translation */

	if (CPU_IS_030) {
	    unsigned long ttreg;
	    
	    asm volatile( ".chip 68030\n\t"
			  "pmove %/tt0,%0@\n\t"
			  ".chip 68k"
			  : : "a" (&ttreg) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return (unsigned long)vaddr;
	    asm volatile( ".chip 68030\n\t"
			  "pmove %/tt1,%0@\n\t"
			  ".chip 68k"
			  : : "a" (&ttreg) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return (unsigned long)vaddr;
	}
	else if (CPU_IS_040_OR_060) {
	    unsigned long ttreg;
	    
	    asm volatile( ".chip 68040\n\t"
			  "movec %%dtt0,%0\n\t"
			  ".chip 68k"
			  : "=d" (ttreg) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return (unsigned long)vaddr;
	    asm volatile( ".chip 68040\n\t"
			  "movec %%dtt1,%0\n\t"
			  ".chip 68k"
			  : "=d" (ttreg) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return (unsigned long)vaddr;
	}

	/* no match, too, so get the actual physical address from the MMU. */

	if (CPU_IS_060) {
	  mm_segment_t fs = get_fs();
	  unsigned long  paddr;