This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / arch / s390 / lib / uaccess_pt.c

diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
new file mode 100644 (file)
index 0000000..49c3e46
--- /dev/null
+++ b/arch/s390/lib/uaccess_pt.c
@@ -0,0 +1,157 @@
+/*
+ *  arch/s390/lib/uaccess_pt.c
+ *
+ *  User access functions based on page table walks.
+ *
+ *    Copyright IBM Corp. 2006
+ *    Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
+ */
+
+#include <linux/errno.h>
+#include <linux/hardirq.h>
+#include <linux/mm.h>
+#include <asm/uaccess.h>
+#include <asm/futex.h>
+
+static inline int __handle_fault(struct mm_struct *mm, unsigned long address,
+                                int write_access)
+{
+       struct vm_area_struct *vma;
+       int ret = -EFAULT;
+
+       if (in_atomic())
+               return ret;
+       down_read(&mm->mmap_sem);
+       vma = find_vma(mm, address);
+       if (unlikely(!vma))
+               goto out;
+       if (unlikely(vma->vm_start > address)) {
+               if (!(vma->vm_flags & VM_GROWSDOWN))
+                       goto out;
+               if (expand_stack(vma, address))
+                       goto out;
+       }
+
+       if (!write_access) {
+               /* page not present, check vm flags */
+               if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+                       goto out;
+       } else {
+               if (!(vma->vm_flags & VM_WRITE))
+                       goto out;
+       }
+
+survive:
+       switch (handle_mm_fault(mm, vma, address, write_access)) {
+       case VM_FAULT_MINOR:
+               current->min_flt++;
+               break;
+       case VM_FAULT_MAJOR:
+               current->maj_flt++;
+               break;
+       case VM_FAULT_SIGBUS:
+               goto out_sigbus;
+       case VM_FAULT_OOM:
+               goto out_of_memory;
+       default:
+               BUG();
+       }
+       ret = 0;
+out:
+       up_read(&mm->mmap_sem);
+       return ret;
+
+out_of_memory:
+       up_read(&mm->mmap_sem);
+       if (is_init(current)) {
+               yield();
+               down_read(&mm->mmap_sem);
+               goto survive;
+       }
+       printk("VM: killing process %s\n", current->comm);
+       return ret;
+
+out_sigbus:
+       up_read(&mm->mmap_sem);
+       current->thread.prot_addr = address;
+       current->thread.trap_no = 0x11;
+       force_sig(SIGBUS, current);
+       return ret;
+}
+
+static inline size_t __user_copy_pt(unsigned long uaddr, void *kptr,
+                                   size_t n, int write_user)
+{
+       struct mm_struct *mm = current->mm;
+       unsigned long offset, pfn, done, size;
+       pgd_t *pgd;
+       pmd_t *pmd;
+       pte_t *pte;
+       void *from, *to;
+
+       done = 0;
+retry:
+       spin_lock(&mm->page_table_lock);
+       do {
+               pgd = pgd_offset(mm, uaddr);
+               if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+                       goto fault;
+
+               pmd = pmd_offset(pgd, uaddr);
+               if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+                       goto fault;
+
+               pte = pte_offset_map(pmd, uaddr);
+               if (!pte || !pte_present(*pte) ||
+                   (write_user && !pte_write(*pte)))
+                       goto fault;
+
+               pfn = pte_pfn(*pte);
+               if (!pfn_valid(pfn))
+                       goto out;
+
+               offset = uaddr & (PAGE_SIZE - 1);
+               size = min(n - done, PAGE_SIZE - offset);
+               if (write_user) {
+                       to = (void *)((pfn << PAGE_SHIFT) + offset);
+                       from = kptr + done;
+               } else {
+                       from = (void *)((pfn << PAGE_SHIFT) + offset);
+                       to = kptr + done;
+               }
+               memcpy(to, from, size);
+               done += size;
+               uaddr += size;
+       } while (done < n);
+out:
+       spin_unlock(&mm->page_table_lock);
+       return n - done;
+fault:
+       spin_unlock(&mm->page_table_lock);
+       if (__handle_fault(mm, uaddr, write_user))
+               return n - done;
+       goto retry;
+}
+
+size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
+{
+       size_t rc;
+
+       if (segment_eq(get_fs(), KERNEL_DS)) {
+               memcpy(to, (void __kernel __force *) from, n);
+               return 0;
+       }
+       rc = __user_copy_pt((unsigned long) from, to, n, 0);
+       if (unlikely(rc))
+               memset(to + n - rc, 0, rc);
+       return rc;
+}
+
+size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
+{
+       if (segment_eq(get_fs(), KERNEL_DS)) {
+               memcpy((void __kernel __force *) to, from, n);
+               return 0;
+       }
+       return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
+}