474 lines
12 KiB
C
474 lines
12 KiB
C
/*
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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, 2012
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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 <linux/hugetlb.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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#ifndef CONFIG_64BIT
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#define AHI "ahi"
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#define SLR "slr"
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#else
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#define AHI "aghi"
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#define SLR "slgr"
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#endif
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static size_t strnlen_kernel(size_t count, const char __user *src)
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{
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register unsigned long reg0 asm("0") = 0UL;
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unsigned long tmp1, tmp2;
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asm volatile(
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" la %2,0(%1)\n"
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" la %3,0(%0,%1)\n"
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" "SLR" %0,%0\n"
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"0: srst %3,%2\n"
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" jo 0b\n"
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" la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
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" "SLR" %0,%1\n"
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"1:\n"
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EX_TABLE(0b,1b)
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: "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
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: "d" (reg0) : "cc", "memory");
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return count;
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}
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static size_t copy_in_kernel(size_t count, void __user *to,
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const void __user *from)
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{
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unsigned long tmp1;
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asm volatile(
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" "AHI" %0,-1\n"
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" jo 5f\n"
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" bras %3,3f\n"
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"0:"AHI" %0,257\n"
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"1: mvc 0(1,%1),0(%2)\n"
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" la %1,1(%1)\n"
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" la %2,1(%2)\n"
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" "AHI" %0,-1\n"
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" jnz 1b\n"
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" j 5f\n"
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"2: mvc 0(256,%1),0(%2)\n"
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" la %1,256(%1)\n"
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" la %2,256(%2)\n"
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"3:"AHI" %0,-256\n"
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" jnm 2b\n"
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"4: ex %0,1b-0b(%3)\n"
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"5:"SLR" %0,%0\n"
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"6:\n"
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EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
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: "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
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: : "cc", "memory");
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return count;
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}
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/*
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* Returns kernel address for user virtual address. If the returned address is
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* >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occured and the address
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* contains the (negative) exception code.
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*/
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#ifdef CONFIG_64BIT
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static unsigned long follow_table(struct mm_struct *mm,
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unsigned long address, int write)
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{
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unsigned long *table = (unsigned long *)__pa(mm->pgd);
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switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
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case _ASCE_TYPE_REGION1:
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table = table + ((address >> 53) & 0x7ff);
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if (unlikely(*table & _REGION_ENTRY_INVALID))
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return -0x39UL;
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table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
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/* fallthrough */
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case _ASCE_TYPE_REGION2:
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table = table + ((address >> 42) & 0x7ff);
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if (unlikely(*table & _REGION_ENTRY_INVALID))
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return -0x3aUL;
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table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
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/* fallthrough */
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case _ASCE_TYPE_REGION3:
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table = table + ((address >> 31) & 0x7ff);
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if (unlikely(*table & _REGION_ENTRY_INVALID))
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return -0x3bUL;
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table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
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/* fallthrough */
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case _ASCE_TYPE_SEGMENT:
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table = table + ((address >> 20) & 0x7ff);
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if (unlikely(*table & _SEGMENT_ENTRY_INVALID))
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return -0x10UL;
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if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
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if (write && (*table & _SEGMENT_ENTRY_PROTECT))
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return -0x04UL;
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return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
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(address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
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}
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table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
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}
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table = table + ((address >> 12) & 0xff);
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if (unlikely(*table & _PAGE_INVALID))
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return -0x11UL;
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if (write && (*table & _PAGE_PROTECT))
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return -0x04UL;
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return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
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}
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#else /* CONFIG_64BIT */
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static unsigned long follow_table(struct mm_struct *mm,
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unsigned long address, int write)
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{
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unsigned long *table = (unsigned long *)__pa(mm->pgd);
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table = table + ((address >> 20) & 0x7ff);
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if (unlikely(*table & _SEGMENT_ENTRY_INVALID))
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return -0x10UL;
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table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
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table = table + ((address >> 12) & 0xff);
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if (unlikely(*table & _PAGE_INVALID))
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return -0x11UL;
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if (write && (*table & _PAGE_PROTECT))
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return -0x04UL;
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return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
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}
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#endif /* CONFIG_64BIT */
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static __always_inline 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, done, size, kaddr;
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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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kaddr = follow_table(mm, uaddr, write_user);
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if (IS_ERR_VALUE(kaddr))
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goto fault;
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offset = uaddr & ~PAGE_MASK;
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size = min(n - done, PAGE_SIZE - offset);
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if (write_user) {
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to = (void *) kaddr;
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from = kptr + done;
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} else {
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from = (void *) kaddr;
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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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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(uaddr, -kaddr, 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 __always_inline unsigned long __dat_user_addr(unsigned long uaddr,
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int write)
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{
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struct mm_struct *mm = current->mm;
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unsigned long kaddr;
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int rc;
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retry:
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kaddr = follow_table(mm, uaddr, write);
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if (IS_ERR_VALUE(kaddr))
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goto fault;
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return kaddr;
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fault:
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spin_unlock(&mm->page_table_lock);
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rc = __handle_fault(uaddr, -kaddr, write);
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spin_lock(&mm->page_table_lock);
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if (!rc)
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goto retry;
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return 0;
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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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return copy_in_kernel(n, (void __user *) to, from);
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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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return copy_in_kernel(n, to, (void __user *) from);
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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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void *zpage = (void *) empty_zero_page;
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long done, size, ret;
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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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if (segment_eq(get_fs(), KERNEL_DS))
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ret = copy_in_kernel(n, to, (void __user *) zpage);
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else
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ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
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done += size;
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to += 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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unsigned long uaddr = (unsigned long) src;
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struct mm_struct *mm = current->mm;
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unsigned long offset, done, len, kaddr;
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size_t len_str;
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if (unlikely(!count))
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return 0;
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if (segment_eq(get_fs(), KERNEL_DS))
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return strnlen_kernel(count, src);
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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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kaddr = follow_table(mm, uaddr, 0);
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if (IS_ERR_VALUE(kaddr))
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goto fault;
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offset = uaddr & ~PAGE_MASK;
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len = min(count - done, PAGE_SIZE - offset);
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len_str = strnlen((char *) kaddr, 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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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(uaddr, -kaddr, 0))
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return 0;
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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 done, len, offset, len_str;
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if (unlikely(!count))
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return 0;
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done = 0;
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do {
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offset = (size_t)src & ~PAGE_MASK;
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len = min(count - done, PAGE_SIZE - offset);
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if (segment_eq(get_fs(), KERNEL_DS)) {
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if (copy_in_kernel(len, (void __user *) dst, src))
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return -EFAULT;
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} else {
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if (__user_copy_pt((unsigned long) src, dst, len, 0))
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return -EFAULT;
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}
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len_str = strnlen(dst, len);
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done += len_str;
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src += len_str;
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dst += len_str;
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} while ((len_str == len) && (done < count));
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return done;
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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_max, uaddr, done, size, error_code;
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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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unsigned long kaddr_to, kaddr_from;
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int write_user;
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if (segment_eq(get_fs(), KERNEL_DS))
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return copy_in_kernel(n, to, from);
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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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write_user = 0;
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uaddr = uaddr_from;
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kaddr_from = follow_table(mm, uaddr_from, 0);
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error_code = kaddr_from;
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if (IS_ERR_VALUE(error_code))
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goto fault;
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write_user = 1;
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uaddr = uaddr_to;
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kaddr_to = follow_table(mm, uaddr_to, 1);
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error_code = (unsigned long) kaddr_to;
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if (IS_ERR_VALUE(error_code))
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goto fault;
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offset_max = max(uaddr_from & ~PAGE_MASK,
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uaddr_to & ~PAGE_MASK);
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size = min(n - done, PAGE_SIZE - offset_max);
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memcpy((void *) kaddr_to, (void *) kaddr_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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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(uaddr, -error_code, 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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static int __futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
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{
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int oldval = 0, newval, ret;
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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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if (ret == 0)
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*old = oldval;
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return ret;
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}
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int futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
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{
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int ret;
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if (segment_eq(get_fs(), KERNEL_DS))
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return __futex_atomic_op_pt(op, uaddr, oparg, old);
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spin_lock(¤t->mm->page_table_lock);
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uaddr = (u32 __force __user *)
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__dat_user_addr((__force unsigned long) uaddr, 1);
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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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ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
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put_page(virt_to_page(uaddr));
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return ret;
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}
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static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
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u32 oldval, u32 newval)
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{
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int ret;
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asm volatile("0: cs %1,%4,0(%5)\n"
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"1: la %0,0\n"
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"2:\n"
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EX_TABLE(0b,2b) EX_TABLE(1b,2b)
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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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*uval = oldval;
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return ret;
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}
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int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
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u32 oldval, u32 newval)
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{
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int ret;
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if (segment_eq(get_fs(), KERNEL_DS))
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return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
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spin_lock(¤t->mm->page_table_lock);
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uaddr = (u32 __force __user *)
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__dat_user_addr((__force unsigned long) uaddr, 1);
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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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ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
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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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