diff options
Diffstat (limited to 'xenolinux-2.4.25-sparse/mm/memory.c')
| -rw-r--r-- | xenolinux-2.4.25-sparse/mm/memory.c | 1549 |
1 files changed, 1549 insertions, 0 deletions
diff --git a/xenolinux-2.4.25-sparse/mm/memory.c b/xenolinux-2.4.25-sparse/mm/memory.c new file mode 100644 index 0000000000..dc09253985 --- /dev/null +++ b/xenolinux-2.4.25-sparse/mm/memory.c @@ -0,0 +1,1549 @@ +/* + * 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); + 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_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)) { + /* 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 defined(CONFIG_XENO_PRIV) + if (pte_io(pte)) { + queue_unchecked_mmu_update(ptep, 0); + continue; + } +#endif + 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) +{ +#ifdef CONFIG_XENO + if ( likely(vma->vm_mm == current->mm) ) { + XENO_flush_page_update_queue(); + HYPERVISOR_update_va_mapping(address>>PAGE_SHIFT, entry, UVMF_INVLPG); + } else { + set_pte(page_table, entry); + flush_tlb_page(vma, address); + } +#else + set_pte(page_table, entry); + flush_tlb_page(vma, address); +#endif + 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); +#ifdef CONFIG_XENO + if ( likely(vma->vm_mm == current->mm) ) { + XENO_flush_page_update_queue(); + HYPERVISOR_update_va_mapping(address>>PAGE_SHIFT, pte, 0); + } else { + set_pte(page_table, pte); + XENO_flush_page_update_queue(); + } +#else + set_pte(page_table, pte); +#endif + + /* 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); + } + +#ifdef CONFIG_XENO + if ( likely(vma->vm_mm == current->mm) ) { + XENO_flush_page_update_queue(); + HYPERVISOR_update_va_mapping(addr>>PAGE_SHIFT, entry, 0); + } else { + set_pte(page_table, entry); + XENO_flush_page_update_queue(); + } +#else + set_pte(page_table, entry); +#endif + + /* 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)); +#ifdef CONFIG_XENO + if ( likely(vma->vm_mm == current->mm) ) { + XENO_flush_page_update_queue(); + HYPERVISOR_update_va_mapping(address>>PAGE_SHIFT, entry, 0); + } else { + set_pte(page_table, entry); + XENO_flush_page_update_queue(); + } +#else + set_pte(page_table, entry); +#endif + } 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) { + 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); + 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; +} |