URL https://opencores.org/ocsvn/or1k/or1k/trunk
Subversion Repositories or1k

[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [mm/] [memory.c] - Blame information for rev 1765

Details | Compare with Previous | View Log

/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */
 
/*
 * demand-loading started 01.12.91 - seems it is high on the list of
 * things wanted, and it should be easy to implement. - Linus
 */
 
/*
 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 * pages started 02.12.91, seems to work. - Linus.
 *
 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 * would have taken more than the 6M I have free, but it worked well as
 * far as I could see.
 *
 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 */
 
/*
 * Real VM (paging to/from disk) started 18.12.91. Much more work and
 * thought has to go into this. Oh, well..
 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 *              Found it. Everything seems to work now.
 * 20.12.91  -  Ok, making the swap-device changeable like the root.
 */
 
/*
 * 05.04.94  -  Multi-page memory management added for v1.1.
 *              Idea by Alex Bligh (alex@cconcepts.co.uk)
 *
 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 *              (Gerhard.Wichert@pdb.siemens.de)
 */
 
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/smp_lock.h>
#include <linux/swapctl.h>
#include <linux/iobuf.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/module.h>
 
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
 
unsigned long max_mapnr;
unsigned long num_physpages;
unsigned long num_mappedpages;
void * high_memory;
struct page *highmem_start_page;
 
/*
 * We special-case the C-O-W ZERO_PAGE, because it's such
 * a common occurrence (no need to read the page to know
 * that it's zero - better for the cache and memory subsystem).
 */
static inline void copy_cow_page(struct page * from, struct page * to, unsigned long address)
{
        if (from == ZERO_PAGE(address)) {
                clear_user_highpage(to, address);
                return;
        }
        copy_user_highpage(to, from, address);
}
 
mem_map_t * mem_map;
 
/*
 * Called by TLB shootdown
 */
void __free_pte(pte_t pte)
{
        struct page *page = pte_page(pte);
        if ((!VALID_PAGE(page)) || PageReserved(page))
                return;
        if (pte_dirty(pte))
                set_page_dirty(page);
        free_page_and_swap_cache(page);
}
 
 
/*
 * Note: this doesn't free the actual pages themselves. That
 * has been handled earlier when unmapping all the memory regions.
 */
static inline void free_one_pmd(pmd_t * dir)
{
        pte_t * pte;
 
        if (pmd_none(*dir))
                return;
        if (pmd_bad(*dir)) {
                pmd_ERROR(*dir);
                pmd_clear(dir);
                return;
        }
        pte = pte_offset(dir, 0);
        pmd_clear(dir);
        pte_free(pte);
}
 
static inline void free_one_pgd(pgd_t * dir)
{
        int j;
        pmd_t * pmd;
 
        if (pgd_none(*dir))
                return;
        if (pgd_bad(*dir)) {
                pgd_ERROR(*dir);
                pgd_clear(dir);
                return;
        }
        pmd = pmd_offset(dir, 0);
        pgd_clear(dir);
        for (j = 0; j < PTRS_PER_PMD ; j++) {
                prefetchw(pmd+j+(PREFETCH_STRIDE/16));
                free_one_pmd(pmd+j);
        }
        pmd_free(pmd);
}
 
/* Low and high watermarks for page table cache.
   The system should try to have pgt_water[0] <= cache elements <= pgt_water[1]
 */
int pgt_cache_water[2] = { 25, 50 };
 
/* Returns the number of pages freed */
int check_pgt_cache(void)
{
        return do_check_pgt_cache(pgt_cache_water[0], pgt_cache_water[1]);
}
 
 
/*
 * This function clears all user-level page tables of a process - this
 * is needed by execve(), so that old pages aren't in the way.
 */
void clear_page_tables(struct mm_struct *mm, unsigned long first, int nr)
{
        pgd_t * page_dir = mm->pgd;
 
        spin_lock(&mm->page_table_lock);
        page_dir += first;
        do {
                free_one_pgd(page_dir);
                page_dir++;
        } while (--nr);
        spin_unlock(&mm->page_table_lock);
 
        /* keep the page table cache within bounds */
        check_pgt_cache();
}
 
#define PTE_TABLE_MASK  ((PTRS_PER_PTE-1) * sizeof(pte_t))
#define PMD_TABLE_MASK  ((PTRS_PER_PMD-1) * sizeof(pmd_t))
 
/*
 * copy one vm_area from one task to the other. Assumes the page tables
 * already present in the new task to be cleared in the whole range
 * covered by this vma.
 *
 * 08Jan98 Merged into one routine from several inline routines to reduce
 *         variable count and make things faster. -jj
 *
 * dst->page_table_lock is held on entry and exit,
 * but may be dropped within pmd_alloc() and pte_alloc().
 */
int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
                        struct vm_area_struct *vma)
{
        pgd_t * src_pgd, * dst_pgd;
        unsigned long address = vma->vm_start;
        unsigned long end = vma->vm_end;
        unsigned long cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 
        src_pgd = pgd_offset(src, address)-1;
        dst_pgd = pgd_offset(dst, address)-1;
 
        for (;;) {
                pmd_t * src_pmd, * dst_pmd;
 
                src_pgd++; dst_pgd++;
 
                /* copy_pmd_range */
 
                if (pgd_none(*src_pgd))
                        goto skip_copy_pmd_range;
                if (pgd_bad(*src_pgd)) {
                        pgd_ERROR(*src_pgd);
                        pgd_clear(src_pgd);
skip_copy_pmd_range:    address = (address + PGDIR_SIZE) & PGDIR_MASK;
                        if (!address || (address >= end))
                                goto out;
                        continue;
                }
 
                src_pmd = pmd_offset(src_pgd, address);
                dst_pmd = pmd_alloc(dst, dst_pgd, address);
                if (!dst_pmd)
                        goto nomem;
 
                do {
                        pte_t * src_pte, * dst_pte;
 
                        /* copy_pte_range */
 
                        if (pmd_none(*src_pmd))
                                goto skip_copy_pte_range;
                        if (pmd_bad(*src_pmd)) {
                                pmd_ERROR(*src_pmd);
                                pmd_clear(src_pmd);
skip_copy_pte_range:            address = (address + PMD_SIZE) & PMD_MASK;
                                if (address >= end)
                                        goto out;
                                goto cont_copy_pmd_range;
                        }
 
                        src_pte = pte_offset(src_pmd, address);
                        dst_pte = pte_alloc(dst, dst_pmd, address);
                        if (!dst_pte)
                                goto nomem;
 
                        spin_lock(&src->page_table_lock);
                        do {
                                pte_t pte = *src_pte;
                                struct page *ptepage;
 
                                /* copy_one_pte */
 
                                if (pte_none(pte))
                                        goto cont_copy_pte_range_noset;
                                if (!pte_present(pte)) {
                                        swap_duplicate(pte_to_swp_entry(pte));
                                        goto cont_copy_pte_range;
                                }
                                ptepage = pte_page(pte);
                                if ((!VALID_PAGE(ptepage)) ||
                                    PageReserved(ptepage))
                                        goto cont_copy_pte_range;
 
                                /* If it's a COW mapping, write protect it both in the parent and the child */
                                if (cow && pte_write(pte)) {
                                        ptep_set_wrprotect(src_pte);
                                        pte = *src_pte;
                                }
 
                                /* If it's a shared mapping, mark it clean in the child */
                                if (vma->vm_flags & VM_SHARED)
                                        pte = pte_mkclean(pte);
                                pte = pte_mkold(pte);
                                get_page(ptepage);
                                dst->rss++;
 
cont_copy_pte_range:            set_pte(dst_pte, pte);
cont_copy_pte_range_noset:      address += PAGE_SIZE;
                                if (address >= end)
                                        goto out_unlock;
                                src_pte++;
                                dst_pte++;
                        } while ((unsigned long)src_pte & PTE_TABLE_MASK);
                        spin_unlock(&src->page_table_lock);
 
cont_copy_pmd_range:    src_pmd++;
                        dst_pmd++;
                } while ((unsigned long)src_pmd & PMD_TABLE_MASK);
        }
out_unlock:
        spin_unlock(&src->page_table_lock);
out:
        return 0;
nomem:
        return -ENOMEM;
}
 
/*
 * Return indicates whether a page was freed so caller can adjust rss
 */
static inline void forget_pte(pte_t page)
{
        if (!pte_none(page)) {
                printk("forget_pte: old mapping existed!\n");
                BUG();
        }
}
 
static inline int zap_pte_range(mmu_gather_t *tlb, pmd_t * pmd, unsigned long address, unsigned long size)
{
        unsigned long offset;
        pte_t * ptep;
        int freed = 0;
 
        if (pmd_none(*pmd))
                return 0;
        if (pmd_bad(*pmd)) {
                pmd_ERROR(*pmd);
                pmd_clear(pmd);
                return 0;
        }
        ptep = pte_offset(pmd, address);
        offset = address & ~PMD_MASK;
        if (offset + size > PMD_SIZE)
                size = PMD_SIZE - offset;
        size &= PAGE_MASK;
        for (offset=0; offset < size; ptep++, offset += PAGE_SIZE) {
                pte_t pte = *ptep;
                if (pte_none(pte))
                        continue;
                if (pte_present(pte)) {
                        struct page *page = pte_page(pte);
                        if (VALID_PAGE(page) && !PageReserved(page))
                                freed ++;
                        /* This will eventually call __free_pte on the pte. */
                        tlb_remove_page(tlb, ptep, address + offset);
                } else {
                        free_swap_and_cache(pte_to_swp_entry(pte));
                        pte_clear(ptep);
                }
        }
 
        return freed;
}
 
static inline int zap_pmd_range(mmu_gather_t *tlb, pgd_t * dir, unsigned long address, unsigned long size)
{
        pmd_t * pmd;
        unsigned long end;
        int freed;
 
        if (pgd_none(*dir))
                return 0;
        if (pgd_bad(*dir)) {
                pgd_ERROR(*dir);
                pgd_clear(dir);
                return 0;
        }
        pmd = pmd_offset(dir, address);
        end = address + size;
        if (end > ((address + PGDIR_SIZE) & PGDIR_MASK))
                end = ((address + PGDIR_SIZE) & PGDIR_MASK);
        freed = 0;
        do {
                freed += zap_pte_range(tlb, pmd, address, end - address);
                address = (address + PMD_SIZE) & PMD_MASK;
                pmd++;
        } while (address < end);
        return freed;
}
 
/*
 * remove user pages in a given range.
 */
void zap_page_range(struct mm_struct *mm, unsigned long address, unsigned long size)
{
        mmu_gather_t *tlb;
        pgd_t * dir;
        unsigned long start = address, end = address + size;
        int freed = 0;
 
        dir = pgd_offset(mm, address);
 
        /*
         * This is a long-lived spinlock. That's fine.
         * There's no contention, because the page table
         * lock only protects against kswapd anyway, and
         * even if kswapd happened to be looking at this
         * process we _want_ it to get stuck.
         */
        if (address >= end)
                BUG();
        spin_lock(&mm->page_table_lock);
        flush_cache_range(mm, address, end);
        tlb = tlb_gather_mmu(mm);
 
        do {
                freed += zap_pmd_range(tlb, dir, address, end - address);
                address = (address + PGDIR_SIZE) & PGDIR_MASK;
                dir++;
        } while (address && (address < end));
 
        /* this will flush any remaining tlb entries */
        tlb_finish_mmu(tlb, start, end);
 
        /*
         * Update rss for the mm_struct (not necessarily current->mm)
         * Notice that rss is an unsigned long.
         */
        if (mm->rss > freed)
                mm->rss -= freed;
        else
                mm->rss = 0;
        spin_unlock(&mm->page_table_lock);
}
 
/*
 * Do a quick page-table lookup for a single page.
 */
static struct page * follow_page(struct mm_struct *mm, unsigned long address, int write)
{
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *ptep, pte;
 
        pgd = pgd_offset(mm, address);
        if (pgd_none(*pgd) || pgd_bad(*pgd))
                goto out;
 
        pmd = pmd_offset(pgd, address);
        if (pmd_none(*pmd) || pmd_bad(*pmd))
                goto out;
 
        ptep = pte_offset(pmd, address);
        if (!ptep)
                goto out;
 
        pte = *ptep;
        if (pte_present(pte)) {
                if (!write ||
                    (pte_write(pte) && pte_dirty(pte)))
                        return pte_page(pte);
        }
 
out:
        return 0;
}
 
/*
 * Given a physical address, is there a useful struct page pointing to
 * it?  This may become more complex in the future if we start dealing
 * with IO-aperture pages in kiobufs.
 */
 
static inline struct page * get_page_map(struct page *page)
{
        if (!VALID_PAGE(page))
                return 0;
        return page;
}
 
/*
 * Please read Documentation/cachetlb.txt before using this function,
 * accessing foreign memory spaces can cause cache coherency problems.
 *
 * Accessing a VM_IO area is even more dangerous, therefore the function
 * fails if pages is != NULL and a VM_IO area is found.
 */
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start,
                int len, int write, int force, struct page **pages, struct vm_area_struct **vmas)
{
        int i;
        unsigned int flags;
 
        /*
         * Require read or write permissions.
         * If 'force' is set, we only require the "MAY" flags.
         */
        flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
        flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
        i = 0;
 
        do {
                struct vm_area_struct * vma;
 
                vma = find_extend_vma(mm, start);
 
                if ( !vma || (pages && vma->vm_flags & VM_IO) || !(flags & vma->vm_flags) )
                        return i ? : -EFAULT;
 
                spin_lock(&mm->page_table_lock);
                do {
                        struct page *map;
                        while (!(map = follow_page(mm, start, write))) {
                                spin_unlock(&mm->page_table_lock);
                                switch (handle_mm_fault(mm, vma, start, write)) {
                                case 1:
                                        tsk->min_flt++;
                                        break;
                                case 2:
                                        tsk->maj_flt++;
                                        break;
                                case 0:
                                        if (i) return i;
                                        return -EFAULT;
                                default:
                                        if (i) return i;
                                        return -ENOMEM;
                                }
                                spin_lock(&mm->page_table_lock);
                        }
                        if (pages) {
                                pages[i] = get_page_map(map);
                                /* FIXME: call the correct function,
                                 * depending on the type of the found page
                                 */
                                if (!pages[i])
                                        goto bad_page;
                                page_cache_get(pages[i]);
                        }
                        if (vmas)
                                vmas[i] = vma;
                        i++;
                        start += PAGE_SIZE;
                        len--;
                } while(len && start < vma->vm_end);
                spin_unlock(&mm->page_table_lock);
        } while(len);
out:
        return i;
 
        /*
         * We found an invalid page in the VMA.  Release all we have
         * so far and fail.
         */
bad_page:
        spin_unlock(&mm->page_table_lock);
        while (i--)
                page_cache_release(pages[i]);
        i = -EFAULT;
        goto out;
}
 
EXPORT_SYMBOL(get_user_pages);
 
/*
 * Force in an entire range of pages from the current process's user VA,
 * and pin them in physical memory.
 */
#define dprintk(x...)
 
int map_user_kiobuf(int rw, struct kiobuf *iobuf, unsigned long va, size_t len)
{
        int pgcount, err;
        struct mm_struct *      mm;
 
        /* Make sure the iobuf is not already mapped somewhere. */
        if (iobuf->nr_pages)
                return -EINVAL;
 
        mm = current->mm;
        dprintk ("map_user_kiobuf: begin\n");
 
        pgcount = (va + len + PAGE_SIZE - 1)/PAGE_SIZE - va/PAGE_SIZE;
        /* mapping 0 bytes is not permitted */
        if (!pgcount) BUG();
        err = expand_kiobuf(iobuf, pgcount);
        if (err)
                return err;
 
        iobuf->locked = 0;
        iobuf->offset = va & (PAGE_SIZE-1);
        iobuf->length = len;
 
        /* Try to fault in all of the necessary pages */
        down_read(&mm->mmap_sem);
        /* rw==READ means read from disk, write into memory area */
        err = get_user_pages(current, mm, va, pgcount,
                        (rw==READ), 0, iobuf->maplist, NULL);
        up_read(&mm->mmap_sem);
        if (err < 0) {
                unmap_kiobuf(iobuf);
                dprintk ("map_user_kiobuf: end %d\n", err);
                return err;
        }
        iobuf->nr_pages = err;
        while (pgcount--) {
                /* FIXME: flush superflous for rw==READ,
                 * probably wrong function for rw==WRITE
                 */
                flush_dcache_page(iobuf->maplist[pgcount]);
        }
        dprintk ("map_user_kiobuf: end OK\n");
        return 0;
}
 
/*
 * Mark all of the pages in a kiobuf as dirty
 *
 * We need to be able to deal with short reads from disk: if an IO error
 * occurs, the number of bytes read into memory may be less than the
 * size of the kiobuf, so we have to stop marking pages dirty once the
 * requested byte count has been reached.
 *
 * Must be called from process context - set_page_dirty() takes VFS locks.
 */
 
void mark_dirty_kiobuf(struct kiobuf *iobuf, int bytes)
{
        int index, offset, remaining;
        struct page *page;
 
        index = iobuf->offset >> PAGE_SHIFT;
        offset = iobuf->offset & ~PAGE_MASK;
        remaining = bytes;
        if (remaining > iobuf->length)
                remaining = iobuf->length;
 
        while (remaining > 0 && index < iobuf->nr_pages) {
                page = iobuf->maplist[index];
 
                if (!PageReserved(page))
                        set_page_dirty(page);
 
                remaining -= (PAGE_SIZE - offset);
                offset = 0;
                index++;
        }
}
 
/*
 * Unmap all of the pages referenced by a kiobuf.  We release the pages,
 * and unlock them if they were locked.
 */
 
void unmap_kiobuf (struct kiobuf *iobuf)
{
        int i;
        struct page *map;
 
        for (i = 0; i < iobuf->nr_pages; i++) {
                map = iobuf->maplist[i];
                if (map) {
                        if (iobuf->locked)
                                UnlockPage(map);
                        /* FIXME: cache flush missing for rw==READ
                         * FIXME: call the correct reference counting function
                         */
                        page_cache_release(map);
                }
        }
 
        iobuf->nr_pages = 0;
        iobuf->locked = 0;
}
 
 
/*
 * Lock down all of the pages of a kiovec for IO.
 *
 * If any page is mapped twice in the kiovec, we return the error -EINVAL.
 *
 * The optional wait parameter causes the lock call to block until all
 * pages can be locked if set.  If wait==0, the lock operation is
 * aborted if any locked pages are found and -EAGAIN is returned.
 */
 
int lock_kiovec(int nr, struct kiobuf *iovec[], int wait)
{
        struct kiobuf *iobuf;
        int i, j;
        struct page *page, **ppage;
        int doublepage = 0;
        int repeat = 0;
 
 repeat:
 
        for (i = 0; i < nr; i++) {
                iobuf = iovec[i];
 
                if (iobuf->locked)
                        continue;
 
                ppage = iobuf->maplist;
                for (j = 0; j < iobuf->nr_pages; ppage++, j++) {
                        page = *ppage;
                        if (!page)
                                continue;
 
                        if (TryLockPage(page)) {
                                while (j--) {
                                        struct page *tmp = *--ppage;
                                        if (tmp)
                                                UnlockPage(tmp);
                                }
                                goto retry;
                        }
                }
                iobuf->locked = 1;
        }
 
        return 0;
 
 retry:
 
        /*
         * We couldn't lock one of the pages.  Undo the locking so far,
         * wait on the page we got to, and try again.
         */
 
        unlock_kiovec(nr, iovec);
        if (!wait)
                return -EAGAIN;
 
        /*
         * Did the release also unlock the page we got stuck on?
         */
        if (!PageLocked(page)) {
                /*
                 * If so, we may well have the page mapped twice
                 * in the IO address range.  Bad news.  Of
                 * course, it _might_ just be a coincidence,
                 * but if it happens more than once, chances
                 * are we have a double-mapped page.
                 */
                if (++doublepage >= 3)
                        return -EINVAL;
 
                /* Try again...  */
                wait_on_page(page);
        }
 
        if (++repeat < 16)
                goto repeat;
        return -EAGAIN;
}
 
/*
 * Unlock all of the pages of a kiovec after IO.
 */
 
int unlock_kiovec(int nr, struct kiobuf *iovec[])
{
        struct kiobuf *iobuf;
        int i, j;
        struct page *page, **ppage;
 
        for (i = 0; i < nr; i++) {
                iobuf = iovec[i];
 
                if (!iobuf->locked)
                        continue;
                iobuf->locked = 0;
 
                ppage = iobuf->maplist;
                for (j = 0; j < iobuf->nr_pages; ppage++, j++) {
                        page = *ppage;
                        if (!page)
                                continue;
                        UnlockPage(page);
                }
        }
        return 0;
}
 
static inline void zeromap_pte_range(pte_t * pte, unsigned long address,
                                     unsigned long size, pgprot_t prot)
{
        unsigned long end;
 
        address &= ~PMD_MASK;
        end = address + size;
        if (end > PMD_SIZE)
                end = PMD_SIZE;
        do {
                pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(address), prot));
                pte_t oldpage = ptep_get_and_clear(pte);
                set_pte(pte, zero_pte);
                forget_pte(oldpage);
                address += PAGE_SIZE;
                pte++;
        } while (address && (address < end));
}
 
static inline int zeromap_pmd_range(struct mm_struct *mm, pmd_t * pmd, unsigned long address,
                                    unsigned long size, pgprot_t prot)
{
        unsigned long end;
 
        address &= ~PGDIR_MASK;
        end = address + size;
        if (end > PGDIR_SIZE)
                end = PGDIR_SIZE;
        do {
                pte_t * pte = pte_alloc(mm, pmd, address);
                if (!pte)
                        return -ENOMEM;
                zeromap_pte_range(pte, address, end - address, prot);
                address = (address + PMD_SIZE) & PMD_MASK;
                pmd++;
        } while (address && (address < end));
        return 0;
}
 
int zeromap_page_range(unsigned long address, unsigned long size, pgprot_t prot)
{
        int error = 0;
        pgd_t * dir;
        unsigned long beg = address;
        unsigned long end = address + size;
        struct mm_struct *mm = current->mm;
 
        dir = pgd_offset(mm, address);
        flush_cache_range(mm, beg, end);
        if (address >= end)
                BUG();
 
        spin_lock(&mm->page_table_lock);
        do {
                pmd_t *pmd = pmd_alloc(mm, dir, address);
                error = -ENOMEM;
                if (!pmd)
                        break;
                error = zeromap_pmd_range(mm, pmd, address, end - address, prot);
                if (error)
                        break;
                address = (address + PGDIR_SIZE) & PGDIR_MASK;
                dir++;
        } while (address && (address < end));
        spin_unlock(&mm->page_table_lock);
        flush_tlb_range(mm, beg, end);
        return error;
}
 
/*
 * maps a range of physical memory into the requested pages. the old
 * mappings are removed. any references to nonexistent pages results
 * in null mappings (currently treated as "copy-on-access")
 */
static inline void remap_pte_range(pte_t * pte, unsigned long address, unsigned long size,
        unsigned long phys_addr, pgprot_t prot)
{
        unsigned long end;
 
        address &= ~PMD_MASK;
        end = address + size;
        if (end > PMD_SIZE)
                end = PMD_SIZE;
        do {
                struct page *page;
                pte_t oldpage;
                oldpage = ptep_get_and_clear(pte);
 
                page = virt_to_page(__va(phys_addr));
                if ((!VALID_PAGE(page)) || PageReserved(page))
                        set_pte(pte, mk_pte_phys(phys_addr, prot));
                forget_pte(oldpage);
                address += PAGE_SIZE;
                phys_addr += PAGE_SIZE;
                pte++;
        } while (address && (address < end));
}
 
static inline int remap_pmd_range(struct mm_struct *mm, pmd_t * pmd, unsigned long address, unsigned long size,
        unsigned long phys_addr, pgprot_t prot)
{
        unsigned long end;
 
        address &= ~PGDIR_MASK;
        end = address + size;
        if (end > PGDIR_SIZE)
                end = PGDIR_SIZE;
        phys_addr -= address;
        do {
                pte_t * pte = pte_alloc(mm, pmd, address);
                if (!pte)
                        return -ENOMEM;
                remap_pte_range(pte, address, end - address, address + phys_addr, prot);
                address = (address + PMD_SIZE) & PMD_MASK;
                pmd++;
        } while (address && (address < end));
        return 0;
}
 
/*  Note: this is only safe if the mm semaphore is held when called. */
int remap_page_range(unsigned long from, unsigned long phys_addr, unsigned long size, pgprot_t prot)
{
        int error = 0;
        pgd_t * dir;
        unsigned long beg = from;
        unsigned long end = from + size;
        struct mm_struct *mm = current->mm;
 
        phys_addr -= from;
        dir = pgd_offset(mm, from);
        flush_cache_range(mm, beg, end);
        if (from >= end)
                BUG();
 
        spin_lock(&mm->page_table_lock);
        do {
                pmd_t *pmd = pmd_alloc(mm, dir, from);
                error = -ENOMEM;
                if (!pmd)
                        break;
                error = remap_pmd_range(mm, pmd, from, end - from, phys_addr + from, prot);
                if (error)
                        break;
                from = (from + PGDIR_SIZE) & PGDIR_MASK;
                dir++;
        } while (from && (from < end));
        spin_unlock(&mm->page_table_lock);
        flush_tlb_range(mm, beg, end);
        return error;
}
 
/*
 * Establish a new mapping:
 *  - flush the old one
 *  - update the page tables
 *  - inform the TLB about the new one
 *
 * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock
 */
static inline void establish_pte(struct vm_area_struct * vma, unsigned long address, pte_t *page_table, pte_t entry)
{
        set_pte(page_table, entry);
        flush_tlb_page(vma, address);
        update_mmu_cache(vma, address, entry);
}
 
/*
 * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock
 */
static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address,
                pte_t *page_table)
{
        flush_page_to_ram(new_page);
        flush_cache_page(vma, address);
        establish_pte(vma, address, page_table, pte_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot))));
}
 
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Goto-purists beware: the only reason for goto's here is that it results
 * in better assembly code.. The "default" path will see no jumps at all.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
 * We hold the mm semaphore and the page_table_lock on entry and exit
 * with the page_table_lock released.
 */
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
        unsigned long address, pte_t *page_table, pte_t pte)
{
        struct page *old_page, *new_page;
 
        old_page = pte_page(pte);
        if (!VALID_PAGE(old_page))
                goto bad_wp_page;
 
        if (!TryLockPage(old_page)) {
                int reuse = can_share_swap_page(old_page);
                unlock_page(old_page);
                if (reuse) {
                        flush_cache_page(vma, address);
                        establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
                        spin_unlock(&mm->page_table_lock);
                        return 1;       /* Minor fault */
                }
        }
 
        /*
         * Ok, we need to copy. Oh, well..
         */
        page_cache_get(old_page);
        spin_unlock(&mm->page_table_lock);
 
        new_page = alloc_page(GFP_HIGHUSER);
        if (!new_page)
                goto no_mem;
        copy_cow_page(old_page,new_page,address);
 
        /*
         * Re-check the pte - we dropped the lock
         */
        spin_lock(&mm->page_table_lock);
        if (pte_same(*page_table, pte)) {
                if (PageReserved(old_page))
                        ++mm->rss;
                break_cow(vma, new_page, address, page_table);
                lru_cache_add(new_page);
 
                /* Free the old page.. */
                new_page = old_page;
        }
        spin_unlock(&mm->page_table_lock);
        page_cache_release(new_page);
        page_cache_release(old_page);
        return 1;       /* Minor fault */
 
bad_wp_page:
        spin_unlock(&mm->page_table_lock);
        printk("do_wp_page: bogus page at address %08lx (page 0x%lx)\n",address,(unsigned long)old_page);
        return -1;
no_mem:
        page_cache_release(old_page);
        return -1;
}
 
static void vmtruncate_list(struct vm_area_struct *mpnt, unsigned long pgoff)
{
        do {
                struct mm_struct *mm = mpnt->vm_mm;
                unsigned long start = mpnt->vm_start;
                unsigned long end = mpnt->vm_end;
                unsigned long len = end - start;
                unsigned long diff;
 
                /* mapping wholly truncated? */
                if (mpnt->vm_pgoff >= pgoff) {
                        zap_page_range(mm, start, len);
                        continue;
                }
 
                /* mapping wholly unaffected? */
                len = len >> PAGE_SHIFT;
                diff = pgoff - mpnt->vm_pgoff;
                if (diff >= len)
                        continue;
 
                /* Ok, partially affected.. */
                start += diff << PAGE_SHIFT;
                len = (len - diff) << PAGE_SHIFT;
                zap_page_range(mm, start, len);
        } while ((mpnt = mpnt->vm_next_share) != NULL);
}
 
/*
 * Handle all mappings that got truncated by a "truncate()"
 * system call.
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
        unsigned long pgoff;
        struct address_space *mapping = inode->i_mapping;
        unsigned long limit;
 
        if (inode->i_size < offset)
                goto do_expand;
        inode->i_size = offset;
        spin_lock(&mapping->i_shared_lock);
        if (!mapping->i_mmap && !mapping->i_mmap_shared)
                goto out_unlock;
 
        pgoff = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
        if (mapping->i_mmap != NULL)
                vmtruncate_list(mapping->i_mmap, pgoff);
        if (mapping->i_mmap_shared != NULL)
                vmtruncate_list(mapping->i_mmap_shared, pgoff);
 
out_unlock:
        spin_unlock(&mapping->i_shared_lock);
        truncate_inode_pages(mapping, offset);
        goto out_truncate;
 
do_expand:
        limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
        if (limit != RLIM_INFINITY && offset > limit)
                goto out_sig;
        if (offset > inode->i_sb->s_maxbytes)
                goto out;
        inode->i_size = offset;
 
out_truncate:
        if (inode->i_op && inode->i_op->truncate) {
                lock_kernel();
                inode->i_op->truncate(inode);
                unlock_kernel();
        }
        return 0;
out_sig:
        send_sig(SIGXFSZ, current, 0);
out:
        return -EFBIG;
}
 
/*
 * Primitive swap readahead code. We simply read an aligned block of
 * (1 << page_cluster) entries in the swap area. This method is chosen
 * because it doesn't cost us any seek time.  We also make sure to queue
 * the 'original' request together with the readahead ones...
 */
void swapin_readahead(swp_entry_t entry)
{
        int i, num;
        struct page *new_page;
        unsigned long offset;
 
        /*
         * Get the number of handles we should do readahead io to.
         */
        num = valid_swaphandles(entry, &offset);
        for (i = 0; i < num; offset++, i++) {
                /* Ok, do the async read-ahead now */
                new_page = read_swap_cache_async(SWP_ENTRY(SWP_TYPE(entry), offset));
                if (!new_page)
                        break;
                page_cache_release(new_page);
        }
        return;
}
 
/*
 * We hold the mm semaphore and the page_table_lock on entry and
 * should release the pagetable lock on exit..
 */
static int do_swap_page(struct mm_struct * mm,
        struct vm_area_struct * vma, unsigned long address,
        pte_t * page_table, pte_t orig_pte, int write_access)
{
        struct page *page;
        swp_entry_t entry = pte_to_swp_entry(orig_pte);
        pte_t pte;
        int ret = 1;
 
        spin_unlock(&mm->page_table_lock);
        page = lookup_swap_cache(entry);
        if (!page) {
                swapin_readahead(entry);
                page = read_swap_cache_async(entry);
                if (!page) {
                        /*
                         * Back out if somebody else faulted in this pte while
                         * we released the page table lock.
                         */
                        int retval;
                        spin_lock(&mm->page_table_lock);
                        retval = pte_same(*page_table, orig_pte) ? -1 : 1;
                        spin_unlock(&mm->page_table_lock);
                        return retval;
                }
 
                /* Had to read the page from swap area: Major fault */
                ret = 2;
        }
 
        mark_page_accessed(page);
 
        lock_page(page);
 
        /*
         * Back out if somebody else faulted in this pte while we
         * released the page table lock.
         */
        spin_lock(&mm->page_table_lock);
        if (!pte_same(*page_table, orig_pte)) {
                spin_unlock(&mm->page_table_lock);
                unlock_page(page);
                page_cache_release(page);
                return 1;
        }
 
        /* The page isn't present yet, go ahead with the fault. */
 
        swap_free(entry);
        if (vm_swap_full())
                remove_exclusive_swap_page(page);
 
        mm->rss++;
        pte = mk_pte(page, vma->vm_page_prot);
        if (write_access && can_share_swap_page(page))
                pte = pte_mkdirty(pte_mkwrite(pte));
        unlock_page(page);
 
        flush_page_to_ram(page);
        flush_icache_page(vma, page);
        set_pte(page_table, pte);
 
        /* No need to invalidate - it was non-present before */
        update_mmu_cache(vma, address, pte);
        spin_unlock(&mm->page_table_lock);
        return ret;
}
 
/*
 * We are called with the MM semaphore and page_table_lock
 * spinlock held to protect against concurrent faults in
 * multithreaded programs.
 */
static int do_anonymous_page(struct mm_struct * mm, struct vm_area_struct * vma, pte_t *page_table, int write_access, unsigned long addr)
{
        pte_t entry;
 
        /* Read-only mapping of ZERO_PAGE. */
        entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot));
 
        /* ..except if it's a write access */
        if (write_access) {
                struct page *page;
 
                /* Allocate our own private page. */
                spin_unlock(&mm->page_table_lock);
 
                page = alloc_page(GFP_HIGHUSER);
                if (!page)
                        goto no_mem;
                clear_user_highpage(page, addr);
 
                spin_lock(&mm->page_table_lock);
                if (!pte_none(*page_table)) {
                        page_cache_release(page);
                        spin_unlock(&mm->page_table_lock);
                        return 1;
                }
                mm->rss++;
                flush_page_to_ram(page);
                entry = pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
                lru_cache_add(page);
                mark_page_accessed(page);
        }
 
        set_pte(page_table, entry);
 
        /* No need to invalidate - it was non-present before */
        update_mmu_cache(vma, addr, entry);
        spin_unlock(&mm->page_table_lock);
        return 1;       /* Minor fault */
 
no_mem:
        return -1;
}
 
/*
 * do_no_page() tries to create a new page mapping. It aggressively
 * tries to share with existing pages, but makes a separate copy if
 * the "write_access" parameter is true in order to avoid the next
 * page fault.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
 * This is called with the MM semaphore held and the page table
 * spinlock held. Exit with the spinlock released.
 */
static int do_no_page(struct mm_struct * mm, struct vm_area_struct * vma,
        unsigned long address, int write_access, pte_t *page_table)
{
        struct page * new_page;
        pte_t entry;
 
        if (!vma->vm_ops || !vma->vm_ops->nopage)
                return do_anonymous_page(mm, vma, page_table, write_access, address);
        spin_unlock(&mm->page_table_lock);
 
        new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, 0);
 
        if (new_page == NULL)   /* no page was available -- SIGBUS */
                return 0;
        if (new_page == NOPAGE_OOM)
                return -1;
 
        /*
         * Should we do an early C-O-W break?
         */
        if (write_access && !(vma->vm_flags & VM_SHARED)) {
                struct page * page = alloc_page(GFP_HIGHUSER);
                if (!page) {
                        page_cache_release(new_page);
                        return -1;
                }
                copy_user_highpage(page, new_page, address);
                page_cache_release(new_page);
                lru_cache_add(page);
                new_page = page;
        }
 
        spin_lock(&mm->page_table_lock);
        /*
         * This silly early PAGE_DIRTY setting removes a race
         * due to the bad i386 page protection. But it's valid
         * for other architectures too.
         *
         * Note that if write_access is true, we either now have
         * an exclusive copy of the page, or this is a shared mapping,
         * so we can make it writable and dirty to avoid having to
         * handle that later.
         */
        /* Only go through if we didn't race with anybody else... */
        if (pte_none(*page_table)) {
                if (!PageReserved(new_page))
                        ++mm->rss;
                flush_page_to_ram(new_page);
                flush_icache_page(vma, new_page);
                entry = mk_pte(new_page, vma->vm_page_prot);
                if (write_access)
                        entry = pte_mkwrite(pte_mkdirty(entry));
                set_pte(page_table, entry);
        } else {
                /* One of our sibling threads was faster, back out. */
                page_cache_release(new_page);
                spin_unlock(&mm->page_table_lock);
                return 1;
        }
 
        /* no need to invalidate: a not-present page shouldn't be cached */
        update_mmu_cache(vma, address, entry);
        spin_unlock(&mm->page_table_lock);
        return 2;       /* Major fault */
}
 
/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
 * Note the "page_table_lock". It is to protect against kswapd removing
 * pages from under us. Note that kswapd only ever _removes_ pages, never
 * adds them. As such, once we have noticed that the page is not present,
 * we can drop the lock early.
 *
 * The adding of pages is protected by the MM semaphore (which we hold),
 * so we don't need to worry about a page being suddenly been added into
 * our VM.
 *
 * We enter with the pagetable spinlock held, we are supposed to
 * release it when done.
 */
static inline int handle_pte_fault(struct mm_struct *mm,
        struct vm_area_struct * vma, unsigned long address,
        int write_access, pte_t * pte)
{
        pte_t entry;
 
        entry = *pte;
        if (!pte_present(entry)) {
                /*
                 * If it truly wasn't present, we know that kswapd
                 * and the PTE updates will not touch it later. So
                 * drop the lock.
                 */
                if (pte_none(entry))
                        return do_no_page(mm, vma, address, write_access, pte);
                return do_swap_page(mm, vma, address, pte, entry, write_access);
        }
 
        if (write_access) {
                if (!pte_write(entry))
                        return do_wp_page(mm, vma, address, pte, entry);
 
                entry = pte_mkdirty(entry);
        }
        entry = pte_mkyoung(entry);
        establish_pte(vma, address, pte, entry);
        spin_unlock(&mm->page_table_lock);
        return 1;
}
 
/*
 * By the time we get here, we already hold the mm semaphore
 */
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
        unsigned long address, int write_access)
{
        pgd_t *pgd;
        pmd_t *pmd;
 
        current->state = TASK_RUNNING;
        pgd = pgd_offset(mm, address);
 
        /*
         * We need the page table lock to synchronize with kswapd
         * and the SMP-safe atomic PTE updates.
         */
        spin_lock(&mm->page_table_lock);
        pmd = pmd_alloc(mm, pgd, address);
 
        if (pmd) {
                pte_t * pte = pte_alloc(mm, pmd, address);
                if (pte)
                        return handle_pte_fault(mm, vma, address, write_access, pte);
        }
        spin_unlock(&mm->page_table_lock);
        return -1;
}
 
/*
 * Allocate page middle directory.
 *
 * We've already handled the fast-path in-line, and we own the
 * page table lock.
 *
 * On a two-level page table, this ends up actually being entirely
 * optimized away.
 */
pmd_t *__pmd_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
        pmd_t *new;
 
        /* "fast" allocation can happen without dropping the lock.. */
        new = pmd_alloc_one_fast(mm, address);
        if (!new) {
                spin_unlock(&mm->page_table_lock);
                new = pmd_alloc_one(mm, address);
                spin_lock(&mm->page_table_lock);
                if (!new)
                        return NULL;
 
                /*
                 * Because we dropped the lock, we should re-check the
                 * entry, as somebody else could have populated it..
                 */
                if (!pgd_none(*pgd)) {
                        pmd_free(new);
                        check_pgt_cache();
                        goto out;
                }
        }
        pgd_populate(mm, pgd, new);
out:
        return pmd_offset(pgd, address);
}
 
/*
 * Allocate the page table directory.
 *
 * We've already handled the fast-path in-line, and we own the
 * page table lock.
 */
pte_t *pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
{
        if (pmd_none(*pmd)) {
                pte_t *new;
 
                /* "fast" allocation can happen without dropping the lock.. */
                new = pte_alloc_one_fast(mm, address);
                if (!new) {
                        spin_unlock(&mm->page_table_lock);
                        new = pte_alloc_one(mm, address);
                        spin_lock(&mm->page_table_lock);
                        if (!new)
                                return NULL;
 
                        /*
                         * Because we dropped the lock, we should re-check the
                         * entry, as somebody else could have populated it..
                         */
                        if (!pmd_none(*pmd)) {
                                pte_free(new);
                                check_pgt_cache();
                                goto out;
                        }
                }
                pmd_populate(mm, pmd, new);
        }
out:
        return pte_offset(pmd, address);
}
 
int make_pages_present(unsigned long addr, unsigned long end)
{
        int ret, len, write;
        struct vm_area_struct * vma;
 
        vma = find_vma(current->mm, addr);
        write = (vma->vm_flags & VM_WRITE) != 0;
        if (addr >= end)
                BUG();
        if (end > vma->vm_end)
                BUG();
        len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
        ret = get_user_pages(current, current->mm, addr,
                        len, write, 0, NULL, NULL);
        return ret == len ? 0 : -1;
}
 
struct page * vmalloc_to_page(void * vmalloc_addr)
{
        unsigned long addr = (unsigned long) vmalloc_addr;
        struct page *page = NULL;
        pmd_t *pmd;
        pte_t *pte;
        pgd_t *pgd;
 
        pgd = pgd_offset_k(addr);
        if (!pgd_none(*pgd)) {
                pmd = pmd_offset(pgd, addr);
                if (!pmd_none(*pmd)) {
                        pte = pte_offset(pmd, addr);
                        if (pte_present(*pte)) {
                                page = pte_page(*pte);
                        }
                }
        }
        return page;
}
Browse

Tools

Subversion Repositories or1k

[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [mm/] [memory.c] - Blame information for rev 1765

Line No.	Rev	Author	Line
1	1275	phoenix	`/*`
2			`* linux/mm/memory.c`
3			`*`
4			`* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds`
5			`*/`
6
7			`/*`
8			`* demand-loading started 01.12.91 - seems it is high on the list of`
9			`* things wanted, and it should be easy to implement. - Linus`
10			`*/`
11
12			`/*`
13			`* Ok, demand-loading was easy, shared pages a little bit tricker. Shared`
14			`* pages started 02.12.91, seems to work. - Linus.`
15			`*`
16			`* Tested sharing by executing about 30 /bin/sh: under the old kernel it`
17			`* would have taken more than the 6M I have free, but it worked well as`
18			`* far as I could see.`
19			`*`
20			`* Also corrected some "invalidate()"s - I wasn't doing enough of them.`
21			`*/`
22
23			`/*`
24			`* Real VM (paging to/from disk) started 18.12.91. Much more work and`
25			`* thought has to go into this. Oh, well..`
26			`* 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.`
27			`* Found it. Everything seems to work now.`
28			`* 20.12.91 - Ok, making the swap-device changeable like the root.`
29			`*/`
30
31			`/*`
32			`* 05.04.94 - Multi-page memory management added for v1.1.`
33			`* Idea by Alex Bligh (alex@cconcepts.co.uk)`
34			`*`
35			`* 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG`
36			`* (Gerhard.Wichert@pdb.siemens.de)`
37			`*/`
38
39			`#include <linux/mm.h>`
40			`#include <linux/mman.h>`