/*
* User access functions based on page table walks for enhanced
* system layout without hardware support.
*
* Copyright IBM Corp. 2006, 2012
* Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
*/
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <asm/uaccess.h>
#include <asm/futex.h>
#include "uaccess.h"
#ifndef CONFIG_64BIT
#define AHI "ahi"
#define SLR "slr"
#else
#define AHI "aghi"
#define SLR "slgr"
#endif
static size_t strnlen_kernel(size_t count, const char __user *src)
{
register unsigned long reg0 asm("0") = 0UL;
unsigned long tmp1, tmp2;
asm volatile(
" la %2,0(%1)\n"
" la %3,0(%0,%1)\n"
" "SLR" %0,%0\n"
"0: srst %3,%2\n"
" jo 0b\n"
" la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
" "SLR" %0,%1\n"
"1:\n"
EX_TABLE(0b,1b)
: "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
: "d" (reg0) : "cc", "memory");
return count;
}
static size_t copy_in_kernel(size_t count, void __user *to,
const void __user *from)
{
unsigned long tmp1;
asm volatile(
" "AHI" %0,-1\n"
" jo 5f\n"
" bras %3,3f\n"
"0:"AHI" %0,257\n"
"1: mvc 0(1,%1),0(%2)\n"
" la %1,1(%1)\n"
" la %2,1(%2)\n"
" "AHI" %0,-1\n"
" jnz 1b\n"
" j 5f\n"
"2: mvc 0(256,%1),0(%2)\n"
" la %1,256(%1)\n"
" la %2,256(%2)\n"
"3:"AHI" %0,-256\n"
" jnm 2b\n"
"4: ex %0,1b-0b(%3)\n"
"5:"SLR" %0,%0\n"
"6:\n"
EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
: "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
: : "cc", "memory");
return count;
}
/*
* Returns kernel address for user virtual address. If the returned address is
* >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occured and the address
* contains the (negative) exception code.
*/
#ifdef CONFIG_64BIT
static unsigned long follow_table(struct mm_struct *mm,
unsigned long address, int write)
{
unsigned long *table = (unsigned long *)__pa(mm->pgd);
switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
case _ASCE_TYPE_REGION1:
table = table + ((address >> 53) & 0x7ff);
if (unlikely(*table & _REGION_ENTRY_INV))
return -0x39UL;
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
/* fallthrough */
case _ASCE_TYPE_REGION2:
table = table + ((address >> 42) & 0x7ff);
if (unlikely(*table & _REGION_ENTRY_INV))
return -0x3aUL;
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
/* fallthrough */
case _ASCE_TYPE_REGION3:
table = table + ((address >> 31) & 0x7ff);
if (unlikely(*table & _REGION_ENTRY_INV))
return -0x3bUL;
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
/* fallthrough */
case _ASCE_TYPE_SEGMENT:
table = table + ((address >> 20) & 0x7ff);
if (unlikely(*table & _SEGMENT_ENTRY_INV))
return -0x10UL;
if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
if (write && (*table & _SEGMENT_ENTRY_RO))
return -0x04UL;
return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
(address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
}
table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
}
table = table + ((address >> 12) & 0xff);
if (unlikely(*table & _PAGE_INVALID))
return -0x11UL;
if (write && (*table & _PAGE_RO))
return -0x04UL;
return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
}
#else /* CONFIG_64BIT */
static unsigned long follow_table(struct mm_struct *mm,
unsigned long address, int write)
{
unsigned long *table = (unsigned long *)__pa(mm->pgd);
table = table + ((address >> 20) & 0x7ff);
if (unlikely(*table & _SEGMENT_ENTRY_INV))
return -0x10UL;
table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
table = table + ((address >> 12) & 0xff);
if (unlikely(*table & _PAGE_INVALID))
return -0x11UL;
if (write && (*table & _PAGE_RO))
return -0x04UL;
return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
}
#endif /* CONFIG_64BIT */
static __always_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, done, size, kaddr;
void *from, *to;
done = 0;
retry:
spin_lock(&mm->page_table_lock);
do {
kaddr = follow_table(mm, uaddr, write_user);
if (IS_ERR_VALUE(kaddr))
goto fault;
offset = uaddr & ~PAGE_MASK;
size = min(n - done, PAGE_SIZE - offset);
if (write_user) {
to = (void *) kaddr;
from = kptr + done;
} else {
from = (void *) kaddr;
to = kptr + done;
}
memcpy(to, from, size);
done += size;
uaddr += size;
} while (done < n);
spin_unlock(&mm->page_table_lock);
return n - done;
fault:
spin_unlock(&mm->page_table_lock);
if (__handle_fault(uaddr, -kaddr, write_user))
return n - done;
goto retry;
}
/*
* Do DAT for user address by page table walk, return kernel address.
* This function needs to be called with current->mm->page_table_lock held.
*/
static __always_inline unsigned long __dat_user_addr(unsigned long uaddr,
int write)
{
struct mm_struct *mm = current->mm;
unsigned long kaddr;
int rc;
retry:
kaddr = follow_table(mm, uaddr, write);
if (IS_ERR_VALUE(kaddr))
goto fault;
return kaddr;
fault:
spin_unlock(&mm->page_table_lock);
rc = __handle_fault(uaddr, -kaddr, write);
spin_lock(&mm->page_table_lock);
if (!rc)
goto retry;
return 0;
}
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))
return copy_in_kernel(n, (void __user *) to, from);
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))
return copy_in_kernel(n, to, (void __user *) from);
return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
}
static size_t clear_user_pt(size_t n, void __user *to)
{
void *zpage = (void *) empty_zero_page;
long done, size, ret;
done = 0;
do {
if (n - done > PAGE_SIZE)
size = PAGE_SIZE;
else
size = n - done;
if (segment_eq(get_fs(), KERNEL_DS))
ret = copy_in_kernel(n, to, (void __user *) zpage);
else
ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
done += size;
to += size;
if (ret)
return ret + n - done;
} while (done < n);
return 0;
}
static size_t strnlen_user_pt(size_t count, const char __user *src)
{
unsigned long uaddr = (unsigned long) src;
struct mm_struct *mm = current->mm;
unsigned long offset, done, len, kaddr;
size_t len_str;
if (unlikely(!count))
return 0;
if (segment_eq(get_fs(), KERNEL_DS))
return strnlen_kernel(count, src);
done = 0;
retry:
spin_lock(&mm->page_table_lock);
do {
kaddr = follow_table(mm, uaddr, 0);
if (IS_ERR_VALUE(kaddr))
goto fault;
offset = uaddr & ~PAGE_MASK;
len = min(count - done, PAGE_SIZE - offset);
len_str = strnlen((char *) kaddr, len);
done += len_str;
uaddr += len_str;
} while ((len_str == len) && (done < count));
spin_unlock(&mm->page_table_lock);
return done + 1;
fault:
spin_unlock(&mm->page_table_lock);
if (__handle_fault(uaddr, -kaddr, 0))
return 0;
goto retry;
}
static size_t strncpy_from_user_pt(size_t count, const char __user *src,
char *dst)
{
size_t done, len, offset, len_str;
if (unlikely(!count))
return 0;
done = 0;
do {
offset = (size_t)src & ~PAGE_MASK;
len = min(count - done, PAGE_SIZE - offset);
if (segment_eq(get_fs(), KERNEL_DS)) {
if (copy_in_kernel(len, (void __user *) dst, src))
return -EFAULT;
} else {
if (__user_copy_pt((unsigned long) src, dst, len, 0))
return -EFAULT;
}
len_str = strnlen(dst, len);
done += len_str;
src += len_str;
dst += len_str;
} while ((len_str == len) && (done < count));
return done;
}
static size_t copy_in_user_pt(size_t n, void __user *to,
const void __user *from)
{
struct mm_struct *mm = current->mm;
unsigned long offset_max, uaddr, done, size, error_code;
unsigned long uaddr_from = (unsigned long) from;
unsigned long uaddr_to = (unsigned long) to;
unsigned long kaddr_to, kaddr_from;
int write_user;
if (segment_eq(get_fs(), KERNEL_DS))
return copy_in_kernel(n, to, from);
done = 0;
retry:
spin_lock(&mm->page_table_lock);
do {
write_user = 0;
uaddr = uaddr_from;
kaddr_from = follow_table(mm, uaddr_from, 0);
error_code = kaddr_from;
if (IS_ERR_VALUE(error_code))
goto fault;
write_user = 1;
uaddr = uaddr_to;
kaddr_to = follow_table(mm, uaddr_to, 1);
error_code = (unsigned long) kaddr_to;
if (IS_ERR_VALUE(error_code))
goto fault;
offset_max = max(uaddr_from & ~PAGE_MASK,
uaddr_to & ~PAGE_MASK);
size = min(n - done, PAGE_SIZE - offset_max);
memcpy((void *) kaddr_to, (void *) kaddr_from, size);
done += size;
uaddr_from += size;
uaddr_to += size;
} while (done < n);
spin_unlock(&mm->page_table_lock);
return n - done;
fault:
spin_unlock(&mm->page_table_lock);
if (__handle_fault(uaddr, -error_code, write_user))
return n - done;
goto retry;
}
#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
asm volatile("0: l %1,0(%6)\n" \
"1: " insn \
"2: cs %1,%2,0(%6)\n" \
"3: jl 1b\n" \
" lhi %0,0\n" \
"4:\n" \
EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
: "=d" (ret), "=&d" (oldval), "=&d" (newval), \
"=m" (*uaddr) \
: "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
"m" (*uaddr) : "cc" );
static int __futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
{
int oldval = 0, newval, ret;
switch (op) {
case FUTEX_OP_SET:
__futex_atomic_op("lr %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
__futex_atomic_op("lr %2,%1\nar %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_OR:
__futex_atomic_op("lr %2,%1\nor %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_ANDN:
__futex_atomic_op("lr %2,%1\nnr %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_XOR:
__futex_atomic_op("lr %2,%1\nxr %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
default:
ret = -ENOSYS;
}
if (ret == 0)
*old = oldval;
return ret;
}
int futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
{
int ret;
if (segment_eq(get_fs(), KERNEL_DS))
return __futex_atomic_op_pt(op, uaddr, oparg, old);
spin_lock(¤t->mm->page_table_lock);
uaddr = (u32 __force __user *)
__dat_user_addr((__force unsigned long) uaddr, 1);
if (!uaddr) {
spin_unlock(¤t->mm->page_table_lock);
return -EFAULT;
}
get_page(virt_to_page(uaddr));
spin_unlock(¤t->mm->page_table_lock);
ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
put_page(virt_to_page(uaddr));
return ret;
}
static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
int ret;
asm volatile("0: cs %1,%4,0(%5)\n"
"1: la %0,0\n"
"2:\n"
EX_TABLE(0b,2b) EX_TABLE(1b,2b)
: "=d" (ret), "+d" (oldval), "=m" (*uaddr)
: "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
: "cc", "memory" );
*uval = oldval;
return ret;
}
int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
int ret;
if (segment_eq(get_fs(), KERNEL_DS))
return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
spin_lock(¤t->mm->page_table_lock);
uaddr = (u32 __force __user *)
__dat_user_addr((__force unsigned long) uaddr, 1);
if (!uaddr) {
spin_unlock(¤t->mm->page_table_lock);
return -EFAULT;
}
get_page(virt_to_page(uaddr));
spin_unlock(¤t->mm->page_table_lock);
ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
put_page(virt_to_page(uaddr));
return ret;
}
struct uaccess_ops uaccess_pt = {
.copy_from_user = copy_from_user_pt,
.copy_from_user_small = copy_from_user_pt,
.copy_to_user = copy_to_user_pt,
.copy_to_user_small = copy_to_user_pt,
.copy_in_user = copy_in_user_pt,
.clear_user = clear_user_pt,
.strnlen_user = strnlen_user_pt,
.strncpy_from_user = strncpy_from_user_pt,
.futex_atomic_op = futex_atomic_op_pt,
.futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
};