476 lines
11 KiB
C
476 lines
11 KiB
C
/*
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* arch/s390/lib/uaccess_pt.c
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*
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* User access functions based on page table walks for enhanced
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* system layout without hardware support.
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*
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* Copyright IBM Corp. 2006
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* Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
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*/
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#include <linux/errno.h>
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#include <linux/hardirq.h>
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#include <linux/mm.h>
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#include <asm/uaccess.h>
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#include <asm/futex.h>
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#include "uaccess.h"
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static int __handle_fault(struct mm_struct *mm, unsigned long address,
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int write_access)
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{
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struct vm_area_struct *vma;
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int ret = -EFAULT;
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int fault;
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if (in_atomic())
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return ret;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (unlikely(!vma))
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goto out;
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if (unlikely(vma->vm_start > address)) {
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto out;
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if (expand_stack(vma, address))
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goto out;
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}
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if (!write_access) {
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/* page not present, check vm flags */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto out;
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} else {
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if (!(vma->vm_flags & VM_WRITE))
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goto out;
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}
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survive:
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fault = handle_mm_fault(mm, vma, address, write_access);
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGBUS)
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goto out_sigbus;
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BUG();
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}
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if (fault & VM_FAULT_MAJOR)
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current->maj_flt++;
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else
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current->min_flt++;
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ret = 0;
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out:
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up_read(&mm->mmap_sem);
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return ret;
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (is_init(current)) {
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yield();
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down_read(&mm->mmap_sem);
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goto survive;
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}
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printk("VM: killing process %s\n", current->comm);
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return ret;
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out_sigbus:
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up_read(&mm->mmap_sem);
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current->thread.prot_addr = address;
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current->thread.trap_no = 0x11;
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force_sig(SIGBUS, current);
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return ret;
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}
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static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
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size_t n, int write_user)
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{
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struct mm_struct *mm = current->mm;
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unsigned long offset, pfn, done, size;
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pgd_t *pgd;
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pmd_t *pmd;
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pte_t *pte;
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void *from, *to;
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done = 0;
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retry:
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spin_lock(&mm->page_table_lock);
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do {
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pgd = pgd_offset(mm, uaddr);
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if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
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goto fault;
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pmd = pmd_offset(pgd, uaddr);
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if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
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goto fault;
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pte = pte_offset_map(pmd, uaddr);
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if (!pte || !pte_present(*pte) ||
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(write_user && !pte_write(*pte)))
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goto fault;
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pfn = pte_pfn(*pte);
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if (!pfn_valid(pfn))
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goto out;
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offset = uaddr & (PAGE_SIZE - 1);
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size = min(n - done, PAGE_SIZE - offset);
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if (write_user) {
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to = (void *)((pfn << PAGE_SHIFT) + offset);
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from = kptr + done;
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} else {
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from = (void *)((pfn << PAGE_SHIFT) + offset);
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to = kptr + done;
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}
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memcpy(to, from, size);
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done += size;
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uaddr += size;
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} while (done < n);
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out:
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spin_unlock(&mm->page_table_lock);
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return n - done;
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fault:
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spin_unlock(&mm->page_table_lock);
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if (__handle_fault(mm, uaddr, write_user))
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return n - done;
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goto retry;
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}
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/*
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* Do DAT for user address by page table walk, return kernel address.
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* This function needs to be called with current->mm->page_table_lock held.
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*/
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static unsigned long __dat_user_addr(unsigned long uaddr)
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{
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struct mm_struct *mm = current->mm;
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unsigned long pfn, ret;
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pgd_t *pgd;
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pmd_t *pmd;
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pte_t *pte;
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int rc;
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ret = 0;
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retry:
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pgd = pgd_offset(mm, uaddr);
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if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
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goto fault;
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pmd = pmd_offset(pgd, uaddr);
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if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
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goto fault;
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pte = pte_offset_map(pmd, uaddr);
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if (!pte || !pte_present(*pte))
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goto fault;
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pfn = pte_pfn(*pte);
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if (!pfn_valid(pfn))
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goto out;
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ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
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out:
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return ret;
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fault:
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spin_unlock(&mm->page_table_lock);
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rc = __handle_fault(mm, uaddr, 0);
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spin_lock(&mm->page_table_lock);
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if (rc)
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goto out;
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goto retry;
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}
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size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
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{
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size_t rc;
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if (segment_eq(get_fs(), KERNEL_DS)) {
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memcpy(to, (void __kernel __force *) from, n);
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return 0;
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}
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rc = __user_copy_pt((unsigned long) from, to, n, 0);
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if (unlikely(rc))
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memset(to + n - rc, 0, rc);
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return rc;
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}
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size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
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{
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if (segment_eq(get_fs(), KERNEL_DS)) {
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memcpy((void __kernel __force *) to, from, n);
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return 0;
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}
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return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
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}
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static size_t clear_user_pt(size_t n, void __user *to)
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{
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long done, size, ret;
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if (segment_eq(get_fs(), KERNEL_DS)) {
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memset((void __kernel __force *) to, 0, n);
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return 0;
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}
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done = 0;
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do {
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if (n - done > PAGE_SIZE)
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size = PAGE_SIZE;
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else
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size = n - done;
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ret = __user_copy_pt((unsigned long) to + done,
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&empty_zero_page, size, 1);
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done += size;
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if (ret)
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return ret + n - done;
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} while (done < n);
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return 0;
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}
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static size_t strnlen_user_pt(size_t count, const char __user *src)
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{
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char *addr;
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unsigned long uaddr = (unsigned long) src;
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struct mm_struct *mm = current->mm;
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unsigned long offset, pfn, done, len;
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pgd_t *pgd;
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pmd_t *pmd;
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pte_t *pte;
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size_t len_str;
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if (segment_eq(get_fs(), KERNEL_DS))
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return strnlen((const char __kernel __force *) src, count) + 1;
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done = 0;
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retry:
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spin_lock(&mm->page_table_lock);
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do {
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pgd = pgd_offset(mm, uaddr);
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if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
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goto fault;
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pmd = pmd_offset(pgd, uaddr);
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if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
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goto fault;
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pte = pte_offset_map(pmd, uaddr);
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if (!pte || !pte_present(*pte))
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goto fault;
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pfn = pte_pfn(*pte);
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if (!pfn_valid(pfn)) {
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done = -1;
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goto out;
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}
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offset = uaddr & (PAGE_SIZE-1);
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addr = (char *)(pfn << PAGE_SHIFT) + offset;
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len = min(count - done, PAGE_SIZE - offset);
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len_str = strnlen(addr, len);
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done += len_str;
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uaddr += len_str;
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} while ((len_str == len) && (done < count));
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out:
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spin_unlock(&mm->page_table_lock);
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return done + 1;
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fault:
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spin_unlock(&mm->page_table_lock);
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if (__handle_fault(mm, uaddr, 0)) {
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return 0;
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}
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goto retry;
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}
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static size_t strncpy_from_user_pt(size_t count, const char __user *src,
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char *dst)
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{
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size_t n = strnlen_user_pt(count, src);
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if (!n)
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return -EFAULT;
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if (n > count)
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n = count;
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if (segment_eq(get_fs(), KERNEL_DS)) {
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memcpy(dst, (const char __kernel __force *) src, n);
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if (dst[n-1] == '\0')
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return n-1;
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else
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return n;
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}
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if (__user_copy_pt((unsigned long) src, dst, n, 0))
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return -EFAULT;
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if (dst[n-1] == '\0')
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return n-1;
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else
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return n;
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}
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static size_t copy_in_user_pt(size_t n, void __user *to,
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const void __user *from)
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{
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struct mm_struct *mm = current->mm;
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unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
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uaddr, done, size;
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unsigned long uaddr_from = (unsigned long) from;
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unsigned long uaddr_to = (unsigned long) to;
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pgd_t *pgd_from, *pgd_to;
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pmd_t *pmd_from, *pmd_to;
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pte_t *pte_from, *pte_to;
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int write_user;
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done = 0;
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retry:
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spin_lock(&mm->page_table_lock);
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do {
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pgd_from = pgd_offset(mm, uaddr_from);
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if (pgd_none(*pgd_from) || unlikely(pgd_bad(*pgd_from))) {
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uaddr = uaddr_from;
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write_user = 0;
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goto fault;
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}
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pgd_to = pgd_offset(mm, uaddr_to);
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if (pgd_none(*pgd_to) || unlikely(pgd_bad(*pgd_to))) {
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uaddr = uaddr_to;
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write_user = 1;
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goto fault;
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}
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pmd_from = pmd_offset(pgd_from, uaddr_from);
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if (pmd_none(*pmd_from) || unlikely(pmd_bad(*pmd_from))) {
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uaddr = uaddr_from;
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write_user = 0;
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goto fault;
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}
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pmd_to = pmd_offset(pgd_to, uaddr_to);
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if (pmd_none(*pmd_to) || unlikely(pmd_bad(*pmd_to))) {
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uaddr = uaddr_to;
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write_user = 1;
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goto fault;
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}
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pte_from = pte_offset_map(pmd_from, uaddr_from);
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if (!pte_from || !pte_present(*pte_from)) {
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uaddr = uaddr_from;
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write_user = 0;
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goto fault;
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}
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pte_to = pte_offset_map(pmd_to, uaddr_to);
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if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
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uaddr = uaddr_to;
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write_user = 1;
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goto fault;
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}
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pfn_from = pte_pfn(*pte_from);
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if (!pfn_valid(pfn_from))
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goto out;
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pfn_to = pte_pfn(*pte_to);
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if (!pfn_valid(pfn_to))
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goto out;
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offset_from = uaddr_from & (PAGE_SIZE-1);
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offset_to = uaddr_from & (PAGE_SIZE-1);
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offset_max = max(offset_from, offset_to);
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size = min(n - done, PAGE_SIZE - offset_max);
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memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
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(void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
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done += size;
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uaddr_from += size;
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uaddr_to += size;
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} while (done < n);
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out:
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spin_unlock(&mm->page_table_lock);
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return n - done;
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fault:
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spin_unlock(&mm->page_table_lock);
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if (__handle_fault(mm, uaddr, write_user))
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return n - done;
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goto retry;
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}
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#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
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asm volatile("0: l %1,0(%6)\n" \
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"1: " insn \
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"2: cs %1,%2,0(%6)\n" \
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"3: jl 1b\n" \
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" lhi %0,0\n" \
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"4:\n" \
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EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
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: "=d" (ret), "=&d" (oldval), "=&d" (newval), \
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"=m" (*uaddr) \
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: "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
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"m" (*uaddr) : "cc" );
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int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
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{
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int oldval = 0, newval, ret;
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spin_lock(¤t->mm->page_table_lock);
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uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
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if (!uaddr) {
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spin_unlock(¤t->mm->page_table_lock);
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return -EFAULT;
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}
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get_page(virt_to_page(uaddr));
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spin_unlock(¤t->mm->page_table_lock);
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switch (op) {
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case FUTEX_OP_SET:
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__futex_atomic_op("lr %2,%5\n",
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ret, oldval, newval, uaddr, oparg);
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break;
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case FUTEX_OP_ADD:
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__futex_atomic_op("lr %2,%1\nar %2,%5\n",
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ret, oldval, newval, uaddr, oparg);
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break;
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case FUTEX_OP_OR:
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__futex_atomic_op("lr %2,%1\nor %2,%5\n",
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ret, oldval, newval, uaddr, oparg);
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break;
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case FUTEX_OP_ANDN:
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__futex_atomic_op("lr %2,%1\nnr %2,%5\n",
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ret, oldval, newval, uaddr, oparg);
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break;
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case FUTEX_OP_XOR:
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__futex_atomic_op("lr %2,%1\nxr %2,%5\n",
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ret, oldval, newval, uaddr, oparg);
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break;
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default:
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ret = -ENOSYS;
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}
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put_page(virt_to_page(uaddr));
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*old = oldval;
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return ret;
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}
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int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
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{
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int ret;
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spin_lock(¤t->mm->page_table_lock);
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uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
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if (!uaddr) {
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spin_unlock(¤t->mm->page_table_lock);
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return -EFAULT;
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}
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get_page(virt_to_page(uaddr));
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spin_unlock(¤t->mm->page_table_lock);
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asm volatile(" cs %1,%4,0(%5)\n"
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"0: lr %0,%1\n"
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"1:\n"
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EX_TABLE(0b,1b)
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: "=d" (ret), "+d" (oldval), "=m" (*uaddr)
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: "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
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: "cc", "memory" );
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put_page(virt_to_page(uaddr));
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return ret;
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}
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struct uaccess_ops uaccess_pt = {
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.copy_from_user = copy_from_user_pt,
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.copy_from_user_small = copy_from_user_pt,
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.copy_to_user = copy_to_user_pt,
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.copy_to_user_small = copy_to_user_pt,
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.copy_in_user = copy_in_user_pt,
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.clear_user = clear_user_pt,
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.strnlen_user = strnlen_user_pt,
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.strncpy_from_user = strncpy_from_user_pt,
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.futex_atomic_op = futex_atomic_op_pt,
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.futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
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};
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