memory.c

arm平台上的uclinux系统全部源代码

/*
 *  linux/arch/m68knommu/mm/memory.c
 *
 *  Copyright (C) 1998  Kenneth Albanowski <[e-mail]>,
 *                      The Silver Hammer Group, Ltd.
 *
 *  Based on:
 *
 *  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/malloc.h>

#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/shglcore.h>

#ifndef NO_MM

extern pte_t *kernel_page_table (unsigned long *memavailp);

/* Strings for `extern inline' functions in <asm/pgtable.h>.  If put
   directly into these functions, they are output for every file that
   includes pgtable.h */

const char PgtabStr_bad_pmd[] = "Bad pmd in pte_alloc: %08lx\n";
const char PgtabStr_bad_pgd[] = "Bad pgd in pmd_alloc: %08lx\n";
const char PgtabStr_bad_pmdk[] = "Bad pmd in pte_alloc_kernel: %08lx\n";
const char PgtabStr_bad_pgdk[] = "Bad pgd in pmd_alloc_kernel: %08lx\n";

static struct ptable_desc {
	struct ptable_desc *prev;
	struct ptable_desc *next;
	unsigned long	   page;
	unsigned char	   alloced;
} ptable_list = { &ptable_list, &ptable_list, 0, 0xff };

#define PD_NONEFREE(dp) ((dp)->alloced == 0xff)
#define PD_ALLFREE(dp) ((dp)->alloced == 0)
#define PD_TABLEFREE(dp,i) (!((dp)->alloced & (1<<(i))))
#define PD_MARKUSED(dp,i) ((dp)->alloced |= (1<<(i)))
#define PD_MARKFREE(dp,i) ((dp)->alloced &= ~(1<<(i)))

#define PTABLE_SIZE (PTRS_PER_PMD * sizeof(pmd_t))

pmd_t *get_pointer_table (void)
{
	pmd_t *pmdp = NULL;
	unsigned long flags;
	struct ptable_desc *dp = ptable_list.next;
	int i;

	/*
	 * 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 (PD_NONEFREE (dp)) {

		if (!(dp = kmalloc (sizeof(struct ptable_desc),GFP_KERNEL))) {
			return 0;
		}

		if (!(dp->page = __get_free_page (GFP_KERNEL))) {
			kfree (dp);
			return 0;
		}

		nocache_page (dp->page);

		dp->alloced = 0;
		/* put at head of list */
		save_flags(flags);
		cli();
		dp->next = ptable_list.next;
		dp->prev = ptable_list.next->prev;
		ptable_list.next->prev = dp;
		ptable_list.next = dp;
		restore_flags(flags);
	}

	for (i = 0; i < 8; i++)
		if (PD_TABLEFREE (dp, i)) {
			PD_MARKUSED (dp, i);
			pmdp = (pmd_t *)(dp->page + PTABLE_SIZE*i);
			break;
		}

	if (PD_NONEFREE (dp)) {
		/* move to end of list */
		save_flags(flags);
		cli();
		dp->prev->next = dp->next;
		dp->next->prev = dp->prev;

		dp->next = ptable_list.next->prev;
		dp->prev = ptable_list.prev;
		ptable_list.prev->next = dp;
		ptable_list.prev = dp;
		restore_flags(flags);
	}

	memset (pmdp, 0, PTABLE_SIZE);

	return pmdp;
}

void free_pointer_table (pmd_t *ptable)
{
	struct ptable_desc *dp;
	unsigned long page = (unsigned long)ptable & PAGE_MASK;
	int index = ((unsigned long)ptable - page)/PTABLE_SIZE;
	unsigned long flags;

	for (dp = ptable_list.next; dp->page && dp->page != page; dp = dp->next)
		;

	if (!dp->page)
		panic ("unable to find desc for ptable %p on list!", ptable);

	if (PD_TABLEFREE (dp, index))
		panic ("table already free!");

	PD_MARKFREE (dp, index);

	if (PD_ALLFREE (dp)) {
		/* all tables in page are free, free page */
		save_flags(flags);
		cli();
		dp->prev->next = dp->next;
		dp->next->prev = dp->prev;
		restore_flags(flags);
		cache_page (dp->page);
		free_page (dp->page);
		kfree (dp);
		return;
	} else {
		/*
		 * move this descriptor the the front of the list, since
		 * it has one or more free tables.
		 */
		save_flags(flags);
		cli();
		dp->prev->next = dp->next;
		dp->next->prev = dp->prev;

		dp->next = ptable_list.next;
		dp->prev = ptable_list.next->prev;
		ptable_list.next->prev = dp;
		ptable_list.next = dp;
		restore_flags(flags);
	}
}

/* maximum pages used for kpointer tables */
#define KPTR_PAGES      4
/* # of reserved slots */
#define RESERVED_KPTR	4
extern pmd_tablepage kernel_pmd_table; /* reserved in head.S */

static struct kpointer_pages {
        pmd_tablepage *page[KPTR_PAGES];
        u_char alloced[KPTR_PAGES];
} kptr_pages;

void init_kpointer_table(void) {
	short i = KPTR_PAGES-1;

	/* first page is reserved in head.S */
	kptr_pages.page[i] = &kernel_pmd_table;
	kptr_pages.alloced[i] = ~(0xff>>RESERVED_KPTR);
	for (i--; i>=0; i--) {
		kptr_pages.page[i] = NULL;
		kptr_pages.alloced[i] = 0;
	}
}

pmd_t *get_kpointer_table (void)
{
	/* For pointer tables for the kernel virtual address space,
	 * use the page that is reserved in head.S that can hold up to
	 * 8 pointer tables. 3 of these tables are always reserved
	 * (kernel_pg_dir, swapper_pg_dir and kernel pointer table for
	 * the first 16 MB of RAM). In addition, the 4th pointer table
	 * in this page is reserved. On Amiga and Atari, it is used to
	 * map in the hardware registers. It may be used for other
	 * purposes on other 68k machines. This leaves 4 pointer tables
	 * available for use by the kernel. 1 of them are usually used
	 * for the vmalloc tables. This allows mapping of 3 * 32 = 96 MB
	 * of physical memory. But these pointer tables are also used
	 * for other purposes, like kernel_map(), so further pages can
	 * now be allocated.
	 */
	pmd_tablepage *page;
	pmd_table *table;
	long nr, offset = -8;
	short i;

	for (i=KPTR_PAGES-1; i>=0; i--) {
		asm volatile("bfffo %1{%2,#8},%0"
			: "=d" (nr)
			: "d" ((u_char)~kptr_pages.alloced[i]), "d" (offset));
		if (nr)
			break;
	}
	if (i < 0) {
		printk("No space for kernel pointer table!\n");
		return NULL;
	}
	if (!(page = kptr_pages.page[i])) {
		if (!(page = (pmd_tablepage *)__get_free_page(GFP_KERNEL))) {
			printk("No space for kernel pointer table!\n");
			return NULL;
		}
		nocache_page((u_long)(kptr_pages.page[i] = page));
	}
	asm volatile("bfset %0@{%1,#1}"
		: /* no output */
		: "a" (&kptr_pages.alloced[i]), "d" (nr-offset));
	table = &(*page)[nr-offset];
	memset(table, 0, sizeof(pmd_table));
	return ((pmd_t *)table);
}

void free_kpointer_table (pmd_t *pmdp)
{
	pmd_table *table = (pmd_table *)pmdp;
	pmd_tablepage *page = (pmd_tablepage *)((u_long)table & PAGE_MASK);
	long nr;
	short i;

	for (i=KPTR_PAGES-1; i>=0; i--) {
		if (kptr_pages.page[i] == page)
			break;
	}
	nr = ((u_long)table - (u_long)page) / sizeof(pmd_table);
	if (!table || i < 0 || (i == KPTR_PAGES-1 && nr < RESERVED_KPTR)) {
		printk("Attempt to free invalid kernel pointer table: %p\n", table);
		return;
	}
	asm volatile("bfclr %0@{%1,#1}"
		: /* no output */
		: "a" (&kptr_pages.alloced[i]), "d" (nr));
	if (!kptr_pages.alloced[i]) {
		kptr_pages.page[i] = 0;
		cache_page ((u_long)page);
		free_page ((u_long)page);
	}
}

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 & mask) != (base & mask))
	    return( 0 );
    }
    else {
	/* must not be user-only */
	if ((regval & 0x6000) == 0)
	    return( 0 );
    }

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

/*
 * 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;
	unsigned long voff = vaddr;
	unsigned long offset = 0;

	for (i = 0; i < boot_info.num_memory; i++)
	{
		if (voff < offset + boot_info.memory[i].size) {
#ifdef DEBUGPV
			printk ("VTOP(%lx)=%lx\n", vaddr,
				boot_info.memory[i].addr + voff - offset);
#endif
			return boot_info.memory[i].addr + voff - offset;
		} else
			offset += boot_info.memory[i].size;
	}

	/* not in one of the memory chunks; test for applying transparent
	 * translation */

	if (CPU_IS_030) {
	    unsigned long ttreg;
	    register unsigned long *ttregptr __asm__( "a2" ) = &ttreg;

	    asm volatile( ".long 0xf0120a00;" /* pmove %/tt0,%a0@ */
			  : "=g" (ttreg) : "a" (ttregptr) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return vaddr;

	    asm volatile( ".long 0xf0120a00" /* pmove %/tt1,%a0@ */
			  : "=g" (ttreg) : "a" (ttregptr) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return vaddr;
	}
	else if (CPU_IS_040_OR_060) {
	    register unsigned long ttreg __asm__( "d0" );
	    
	    asm volatile( ".long 0x4e7a0006" /* movec %dtt0,%d0 */
			  : "=d" (ttreg) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return vaddr;
	    asm volatile( ".long 0x4e7a0007" /* movec %dtt1,%d0 */
			  : "=d" (ttreg) );
	    if (transp_transl_matches( ttreg, vaddr ))
		return vaddr;
	}

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

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

	  set_fs (SUPER_DATA);

	  /* The PLPAR instruction causes an access error if the translation
	   * is not possible. We don't catch that here, so a bad kernel trap
	   * will be reported in this case. */
	  asm volatile ("movel %1,%/a0\n\t"
			".word 0xf5c8\n\t"	/* plpar (a0) */
			"movel %/a0,%0"
			: "=g" (paddr)
			: "g" (vaddr)
			: "a0" );
	  set_fs (fs);

	  return paddr;

	} else if (CPU_IS_040) {
	  unsigned long mmusr;
	  unsigned long fs = get_fs();

	  set_fs (SUPER_DATA);

	  asm volatile ("movel %1,%/a0\n\t"
			".word 0xf568\n\t"	/* ptestr (a0) */
			".long 0x4e7a8805\n\t"	/* movec mmusr, a0 */
			"movel %/a0,%0"
			: "=g" (mmusr)
			: "g" (vaddr)
			: "a0", "d0");
	  set_fs (fs);

	  if (mmusr & MMU_R_040)
	    return (mmusr & PAGE_MASK) | (vaddr & (PAGE_SIZE-1));

	  panic ("VTOP040: bad virtual address %08lx (%lx)", vaddr, mmusr);
	} else {
	  volatile unsigned short temp;
	  unsigned short mmusr;
	  unsigned long *descaddr;

	  asm volatile ("ptestr #5,%2@,#7,%0\n\t"
			"pmove %/psr,%1@"
			: "=a&" (descaddr)
			: "a" (&temp), "a" (vaddr));
	  mmusr = temp;

	  if (mmusr & (MMU_I|MMU_B|MMU_L))
	    panic ("VTOP030: bad virtual address %08lx (%x)", vaddr, mmusr);

	  descaddr = (unsigned long *)PTOV(descaddr);

	  switch (mmusr & MMU_NUM) {
	  case 1:
	    return (*descaddr & 0xfe000000) | (vaddr & 0x01ffffff);
	  case 2:
	    return (*descaddr & 0xfffc0000) | (vaddr & 0x0003ffff);
	  case 3:
	    return (*descaddr & PAGE_MASK) | (vaddr & (PAGE_SIZE-1));
	  default:
	    panic ("VTOP: bad levels (%u) for virtual address %08lx", 
		   mmusr & MMU_NUM, vaddr);
	  }
	}

	panic ("VTOP: bad virtual address %08lx", vaddr);
}

unsigned long mm_ptov (unsigned long paddr)
{
	int i;
	unsigned long offset = 0;

	for (i = 0; i < boot_info.num_memory; i++)
	{
		if (paddr >= boot_info.memory[i].addr &&
		    paddr < (boot_info.memory[i].addr
			     + boot_info.memory[i].size)) {
#ifdef DEBUGPV
			printk ("PTOV(%lx)=%lx\n", paddr,
				(paddr - boot_info.memory[i].addr) + offset);
#endif
			return (paddr - boot_info.memory[i].addr) + offset;
		} else
			offset += boot_info.memory[i].size;
	}

	/*
	 * assume that the kernel virtual address is the same as the
	 * physical address.
	 *
	 * This should be reasonable in most situations:
	 *  1) They shouldn't be dereferencing the virtual address
	 *     unless they are sure that it is valid from kernel space.
	 *  2) The only usage I see so far is converting a page table
	 *     reference to some non-FASTMEM address space when freeing
         *     mmaped "/dev/mem" pages.  These addresses are just passed
	 *     to "free_page", which ignores addresses that aren't in
	 *     the memory list anyway.
	 *
	 */

	/*
	 * if on an amiga and address is in first 16M, move it 
	 * to the ZTWO_ADDR range
	 */
	if (MACH_IS_AMIGA && paddr < 16*1024*1024)
		return ZTWO_VADDR(paddr);
	return paddr;
}

/* invalidate page in both caches */
#define	clear040(paddr) __asm__ __volatile__ ("movel %0,%/a0\n\t"\
					      "nop\n\t"\
					      ".word 0xf4d0"\
					      /* CINVP I/D (a0) */\
					      : : "g" ((paddr))\
					      : "a0")

/* invalidate page in i-cache */
#define	cleari040(paddr) __asm__ __volatile__ ("movel %0,%/a0\n\t"\
					       /* CINVP I (a0) */\
					       "nop\n\t"\
					       ".word 0xf490"\
					       : : "g" ((paddr))\
					       : "a0")

/* push page in both caches */
#define	push040(paddr) __asm__ __volatile__ ("movel %0,%/a0\n\t"\
					      "nop\n\t"\
					     ".word 0xf4f0"\
					     /* CPUSHP I/D (a0) */\
					     : : "g" ((paddr))\
					     : "a0")

/* push and invalidate page in both caches */
#define	pushcl040(paddr) do { push040((paddr));\
			      if (CPU_IS_060) clear040((paddr));\
			 } while(0)

/* push page in both caches, invalidate in i-cache */
#define	pushcli040(paddr) do { push040((paddr));\
			       if (CPU_IS_060) cleari040((paddr));\
			  } while(0)

/* push page defined by virtual address in both caches */
#define	pushv040(vaddr) __asm__ __volatile__ ("movel %0,%/a0\n\t"\
					      /* ptestr (a0) */\
					      "nop\n\t"\
					      ".word 0xf568\n\t"\
					      /* movec mmusr,d0 */\
					      ".long 0x4e7a0805\n\t"\
					      "andw #0xf000,%/d0\n\t"\
					      "movel %/d0,%/a0\n\t"\
					      /* CPUSHP I/D (a0) */\
					      "nop\n\t"\
					      ".word 0xf4f0"\
					      : : "g" ((vaddr))\
					      : "a0", "d0")

/* push page defined by virtual address in both caches */
#define	pushv060(vaddr) __asm__ __volatile__ ("movel %0,%/a0\n\t"\
					      /* plpar (a0) */\
					      ".word 0xf5c8\n\t"\
					      /* CPUSHP I/D (a0) */\
					      ".word 0xf4f0"\
					      : : "g" ((vaddr))\
					      : "a0")


/*
 * 040: Hit every page containing an address in the range paddr..paddr+len-1.
 * (Low order bits of the ea of a CINVP/CPUSHP are "don't care"s).
 * Hit every page until there is a page or less to go. Hit the next page,
 * and the one after that if the range hits it.
 */
/* ++roman: A little bit more care is required here: The CINVP instruction
 * invalidates cache entries WITHOUT WRITING DIRTY DATA BACK! So the beginning
 * and the end of the region must be treated differently if they are not
 * exactly at the beginning or end of a page boundary. Else, maybe too much
 * data becomes invalidated and thus lost forever. CPUSHP does what we need:
 * it invalidates the page after pushing dirty data to memory. (Thanks to Jes
 * for discovering the problem!)
 */
/* ... but on the '060, CPUSH doesn't invalidate (for us, since we have set
 * the DPI bit in the CACR; would it cause problems with temporarily changing
 * this?). So we have to push first and then additionally to invalidate.