diff options
Diffstat (limited to 'old/xenolinux-2.4.16-sparse/mm/memory.c')
| -rw-r--r-- | old/xenolinux-2.4.16-sparse/mm/memory.c | 1442 |
1 files changed, 0 insertions, 1442 deletions
diff --git a/old/xenolinux-2.4.16-sparse/mm/memory.c b/old/xenolinux-2.4.16-sparse/mm/memory.c deleted file mode 100644 index 58eb472e2d..0000000000 --- a/old/xenolinux-2.4.16-sparse/mm/memory.c +++ /dev/null @@ -1,1442 +0,0 @@ -/* - * 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 <asm/pgalloc.h> -#include <asm/uaccess.h> -#include <asm/tlb.h> - -unsigned long max_mapnr; -unsigned long num_physpages; -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); - XENO_flush_page_update_queue(); - 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_WRITE)) == VM_WRITE; - - 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) { - /* XENO modification: modified ordering here to avoid RaW hazard. */ - pte = *src_pte; - pte = pte_wrprotect(pte); - ptep_set_wrprotect(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(unsigned long address, int write) -{ - pgd_t *pgd; - pmd_t *pmd; - pte_t *ptep, pte; - - pgd = pgd_offset(current->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; -} - -/* - * 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) -{ - unsigned long ptr, end; - int err; - struct mm_struct * mm; - struct vm_area_struct * vma = 0; - struct page * map; - int i; - int datain = (rw == READ); - - /* Make sure the iobuf is not already mapped somewhere. */ - if (iobuf->nr_pages) - return -EINVAL; - - mm = current->mm; - dprintk ("map_user_kiobuf: begin\n"); - - ptr = va & PAGE_MASK; - end = (va + len + PAGE_SIZE - 1) & PAGE_MASK; - err = expand_kiobuf(iobuf, (end - ptr) >> PAGE_SHIFT); - if (err) - return err; - - down_read(&mm->mmap_sem); - - err = -EFAULT; - iobuf->locked = 0; - iobuf->offset = va & ~PAGE_MASK; - iobuf->length = len; - - i = 0; - - /* - * First of all, try to fault in all of the necessary pages - */ - while (ptr < end) { - if (!vma || ptr >= vma->vm_end) { - vma = find_vma(current->mm, ptr); - if (!vma) - goto out_unlock; - if (vma->vm_start > ptr) { - if (!(vma->vm_flags & VM_GROWSDOWN)) - goto out_unlock; - if (expand_stack(vma, ptr)) - goto out_unlock; - } - if (((datain) && (!(vma->vm_flags & VM_WRITE))) || - (!(vma->vm_flags & VM_READ))) { - err = -EACCES; - goto out_unlock; - } - } - spin_lock(&mm->page_table_lock); - while (!(map = follow_page(ptr, datain))) { - int ret; - - spin_unlock(&mm->page_table_lock); - ret = handle_mm_fault(current->mm, vma, ptr, datain); - if (ret <= 0) { - if (!ret) - goto out_unlock; - else { - err = -ENOMEM; - goto out_unlock; - } - } - spin_lock(&mm->page_table_lock); - } - map = get_page_map(map); - if (map) { - flush_dcache_page(map); - page_cache_get(map); - } else - printk (KERN_INFO "Mapped page missing [%d]\n", i); - spin_unlock(&mm->page_table_lock); - iobuf->maplist[i] = map; - iobuf->nr_pages = ++i; - - ptr += PAGE_SIZE; - } - - up_read(&mm->mmap_sem); - dprintk ("map_user_kiobuf: end OK\n"); - return 0; - - out_unlock: - up_read(&mm->mmap_sem); - unmap_kiobuf(iobuf); - dprintk ("map_user_kiobuf: end %d\n", err); - return err; -} - -/* - * 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. - */ - -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)) - SetPageDirty(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); - 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) { - if (inode->i_size >= limit) { - send_sig(SIGXFSZ, current, 0); - goto out; - } - if (offset > limit) { - send_sig(SIGXFSZ, current, 0); - offset = limit; - } - } - inode->i_size = offset; - -out_truncate: - if (inode->i_op && inode->i_op->truncate) { - lock_kernel(); - inode->i_op->truncate(inode); - unlock_kernel(); - } -out: - return 0; -} - -/* - * 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; - } - - 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); - XENO_flush_page_update_queue(); - 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); - } - - set_pte(page_table, entry); - - /* No need to invalidate - it was non-present before */ - update_mmu_cache(vma, addr, entry); - XENO_flush_page_update_queue(); - 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) - return -1; - copy_highpage(page, new_page); - 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)) { - ++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); - XENO_flush_page_update_queue(); - 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); - XENO_flush_page_update_queue(); - 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); - 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) { - XENO_flush_page_update_queue(); - 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); - goto out; - } - } - pmd_populate(mm, pmd, new); - } -out: - return pte_offset(pmd, address); -} - -/* - * Simplistic page force-in.. - */ -int make_pages_present(unsigned long addr, unsigned long end) -{ - int write; - struct mm_struct *mm = current->mm; - struct vm_area_struct * vma; - - vma = find_vma(mm, addr); - write = (vma->vm_flags & VM_WRITE) != 0; - if (addr >= end) - BUG(); - do { - if (handle_mm_fault(mm, vma, addr, write) < 0) - return -1; - addr += PAGE_SIZE; - } while (addr < end); - return 0; -} |