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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [mm/] [mremap.c] - Rev 1765
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/* * linux/mm/remap.c * * (C) Copyright 1996 Linus Torvalds */ #include <linux/stat.h> #include <linux/sched.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/shm.h> #include <linux/errno.h> #include <linux/mman.h> #include <linux/string.h> #include <linux/malloc.h> #include <linux/swap.h> #include <asm/segment.h> #include <asm/system.h> #include <asm/pgtable.h> extern int vm_enough_memory(long pages); static inline pte_t *get_one_pte(struct mm_struct *mm, unsigned long addr) { pgd_t * pgd; pmd_t * pmd; pte_t * pte = NULL; pgd = pgd_offset(mm, addr); if (pgd_none(*pgd)) goto end; if (pgd_bad(*pgd)) { printk("move_one_page: bad source pgd (%08lx)\n", pgd_val(*pgd)); pgd_clear(pgd); goto end; } pmd = pmd_offset(pgd, addr); if (pmd_none(*pmd)) goto end; if (pmd_bad(*pmd)) { printk("move_one_page: bad source pmd (%08lx)\n", pmd_val(*pmd)); pmd_clear(pmd); goto end; } pte = pte_offset(pmd, addr); if (pte_none(*pte)) pte = NULL; end: return pte; } static inline pte_t *alloc_one_pte(struct mm_struct *mm, unsigned long addr) { pmd_t * pmd; pte_t * pte = NULL; pmd = pmd_alloc(pgd_offset(mm, addr), addr); if (pmd) pte = pte_alloc(pmd, addr); return pte; } static inline int copy_one_pte(pte_t * src, pte_t * dst) { int error = 0; pte_t pte = *src; if (!pte_none(pte)) { error++; if (dst) { pte_clear(src); set_pte(dst, pte); error--; } } return error; } static int move_one_page(struct mm_struct *mm, unsigned long old_addr, unsigned long new_addr) { int error = 0; pte_t * src; src = get_one_pte(mm, old_addr); if (src) error = copy_one_pte(src, alloc_one_pte(mm, new_addr)); return error; } static int move_page_tables(struct mm_struct * mm, unsigned long new_addr, unsigned long old_addr, unsigned long len) { unsigned long offset = len; flush_cache_range(mm, old_addr, old_addr + len); flush_tlb_range(mm, old_addr, old_addr + len); /* * This is not the clever way to do this, but we're taking the * easy way out on the assumption that most remappings will be * only a few pages.. This also makes error recovery easier. */ while (offset) { offset -= PAGE_SIZE; if (move_one_page(mm, old_addr + offset, new_addr + offset)) goto oops_we_failed; } return 0; /* * Ok, the move failed because we didn't have enough pages for * the new page table tree. This is unlikely, but we have to * take the possibility into account. In that case we just move * all the pages back (this will work, because we still have * the old page tables) */ oops_we_failed: flush_cache_range(mm, new_addr, new_addr + len); while ((offset += PAGE_SIZE) < len) move_one_page(mm, new_addr + offset, old_addr + offset); flush_tlb_range(mm, new_addr, new_addr + len); zap_page_range(mm, new_addr, new_addr + len); return -1; } static inline unsigned long move_vma(struct vm_area_struct * vma, unsigned long addr, unsigned long old_len, unsigned long new_len) { struct vm_area_struct * new_vma; new_vma = (struct vm_area_struct *) kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); if (new_vma) { unsigned long new_addr = get_unmapped_area(addr, new_len); if (new_addr && !move_page_tables(current->mm, new_addr, addr, old_len)) { *new_vma = *vma; new_vma->vm_start = new_addr; new_vma->vm_end = new_addr+new_len; new_vma->vm_offset = vma->vm_offset + (addr - vma->vm_start); if (new_vma->vm_inode) new_vma->vm_inode->i_count++; if (new_vma->vm_ops && new_vma->vm_ops->open) new_vma->vm_ops->open(new_vma); insert_vm_struct(current->mm, new_vma); merge_segments(current->mm, new_vma->vm_start, new_vma->vm_end); do_munmap(addr, old_len); current->mm->total_vm += new_len >> PAGE_SHIFT; return new_addr; } kfree(new_vma); } return -ENOMEM; } /* * Expand (or shrink) an existing mapping, potentially moving it at the * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) */ asmlinkage unsigned long sys_mremap(unsigned long addr, unsigned long old_len, unsigned long new_len, unsigned long flags) { struct vm_area_struct *vma; if (addr & ~PAGE_MASK) return -EINVAL; old_len = PAGE_ALIGN(old_len); new_len = PAGE_ALIGN(new_len); /* * Always allow a shrinking remap: that just unmaps * the unnecessary pages.. */ if (old_len >= new_len) { do_munmap(addr+new_len, old_len - new_len); return addr; } /* * Ok, we need to grow.. */ vma = find_vma(current->mm, addr); if (!vma || vma->vm_start > addr) return -EFAULT; /* We can't remap across vm area boundaries */ if (old_len > vma->vm_end - addr) return -EFAULT; if (vma->vm_flags & VM_LOCKED) { unsigned long locked = current->mm->locked_vm << PAGE_SHIFT; locked += new_len - old_len; if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur) return -EAGAIN; } if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len) > current->rlim[RLIMIT_AS].rlim_cur) return -ENOMEM; /* Private writable mapping? Check memory availability.. */ if ((vma->vm_flags & (VM_SHARED | VM_WRITE)) == VM_WRITE) { if (!vm_enough_memory((new_len - old_len) >> PAGE_SHIFT)) return -ENOMEM; } /* old_len exactly to the end of the area.. */ if (old_len == vma->vm_end - addr && (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { unsigned long max_addr = MAX_USER_ADDR; if (vma->vm_next) max_addr = vma->vm_next->vm_start; /* can we just expand the current mapping? */ if (max_addr - addr >= new_len) { int pages = (new_len - old_len) >> PAGE_SHIFT; vma->vm_end = addr + new_len; current->mm->total_vm += pages; if (vma->vm_flags & VM_LOCKED) current->mm->locked_vm += pages; return addr; } } /* * We weren't able to just expand or shrink the area, * we need to create a new one and move it.. */ if (flags & MREMAP_MAYMOVE) return move_vma(vma, addr, old_len, new_len); return -ENOMEM; }