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linux/arch/s390/lib/uaccess_std.c
Heiko Carstens d5b02b3ff1 [S390] Fix futex_atomic_cmpxchg_std inline assembly. 
Add missing exception table entry so that the kernel can handle
proctection exceptions as well on the cs instruction. Currently only
specification exceptions are handled correctly.
The missing entry allows user space to crash the kernel.

Cc: stable <stable@kernel.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-02-19 15:29:35 +01:00

318 lines
7.8 KiB
C
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/*
* arch/s390/lib/uaccess_std.c
*
* Standard user space access functions based on mvcp/mvcs and doing
* interesting things in the secondary space mode.
*
* Copyright (C) IBM Corp. 2006
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
* Gerald Schaefer (gerald.schaefer@de.ibm.com)
*/
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <asm/futex.h>
#include "uaccess.h"
#ifndef __s390x__
#define AHI "ahi"
#define ALR "alr"
#define CLR "clr"
#define LHI "lhi"
#define SLR "slr"
#else
#define AHI "aghi"
#define ALR "algr"
#define CLR "clgr"
#define LHI "lghi"
#define SLR "slgr"
#endif
size_t copy_from_user_std(size_t size, const void __user *ptr, void *x)
{
unsigned long tmp1, tmp2;
tmp1 = -256UL;
asm volatile(
"0: mvcp 0(%0,%2),0(%1),%3\n"
" jz 8f\n"
"1:"ALR" %0,%3\n"
" la %1,256(%1)\n"
" la %2,256(%2)\n"
"2: mvcp 0(%0,%2),0(%1),%3\n"
" jnz 1b\n"
" j 8f\n"
"3: la %4,255(%1)\n" /* %4 = ptr + 255 */
" "LHI" %3,-4096\n"
" nr %4,%3\n" /* %4 = (ptr + 255) & -4096 */
" "SLR" %4,%1\n"
" "CLR" %0,%4\n" /* copy crosses next page boundary? */
" jnh 5f\n"
"4: mvcp 0(%4,%2),0(%1),%3\n"
" "SLR" %0,%4\n"
" "ALR" %2,%4\n"
"5:"LHI" %4,-1\n"
" "ALR" %4,%0\n" /* copy remaining size, subtract 1 */
" bras %3,7f\n" /* memset loop */
" xc 0(1,%2),0(%2)\n"
"6: xc 0(256,%2),0(%2)\n"
" la %2,256(%2)\n"
"7:"AHI" %4,-256\n"
" jnm 6b\n"
" ex %4,0(%3)\n"
" j 9f\n"
"8:"SLR" %0,%0\n"
"9: \n"
EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b)
: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
: : "cc", "memory");
return size;
}
static size_t copy_from_user_std_check(size_t size, const void __user *ptr,
void *x)
{
if (size <= 1024)
return copy_from_user_std(size, ptr, x);
return copy_from_user_pt(size, ptr, x);
}
size_t copy_to_user_std(size_t size, void __user *ptr, const void *x)
{
unsigned long tmp1, tmp2;
tmp1 = -256UL;
asm volatile(
"0: mvcs 0(%0,%1),0(%2),%3\n"
" jz 5f\n"
"1:"ALR" %0,%3\n"
" la %1,256(%1)\n"
" la %2,256(%2)\n"
"2: mvcs 0(%0,%1),0(%2),%3\n"
" jnz 1b\n"
" j 5f\n"
"3: la %4,255(%1)\n" /* %4 = ptr + 255 */
" "LHI" %3,-4096\n"
" nr %4,%3\n" /* %4 = (ptr + 255) & -4096 */
" "SLR" %4,%1\n"
" "CLR" %0,%4\n" /* copy crosses next page boundary? */
" jnh 6f\n"
"4: mvcs 0(%4,%1),0(%2),%3\n"
" "SLR" %0,%4\n"
" j 6f\n"
"5:"SLR" %0,%0\n"
"6: \n"
EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
: : "cc", "memory");
return size;
}
static size_t copy_to_user_std_check(size_t size, void __user *ptr,
const void *x)
{
if (size <= 1024)
return copy_to_user_std(size, ptr, x);
return copy_to_user_pt(size, ptr, x);
}
static size_t copy_in_user_std(size_t size, void __user *to,
const void __user *from)
{
unsigned long tmp1;
asm volatile(
" "AHI" %0,-1\n"
" jo 5f\n"
" sacf 256\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"
" sacf 0\n"
"5: "SLR" %0,%0\n"
"6:\n"
EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
: "+a" (size), "+a" (to), "+a" (from), "=a" (tmp1)
: : "cc", "memory");
return size;
}
static size_t clear_user_std(size_t size, void __user *to)
{
unsigned long tmp1, tmp2;
asm volatile(
" "AHI" %0,-1\n"
" jo 5f\n"
" sacf 256\n"
" bras %3,3f\n"
" xc 0(1,%1),0(%1)\n"
"0:"AHI" %0,257\n"
" la %2,255(%1)\n" /* %2 = ptr + 255 */
" srl %2,12\n"
" sll %2,12\n" /* %2 = (ptr + 255) & -4096 */
" "SLR" %2,%1\n"
" "CLR" %0,%2\n" /* clear crosses next page boundary? */
" jnh 5f\n"
" "AHI" %2,-1\n"
"1: ex %2,0(%3)\n"
" "AHI" %2,1\n"
" "SLR" %0,%2\n"
" j 5f\n"
"2: xc 0(256,%1),0(%1)\n"
" la %1,256(%1)\n"
"3:"AHI" %0,-256\n"
" jnm 2b\n"
"4: ex %0,0(%3)\n"
" sacf 0\n"
"5: "SLR" %0,%0\n"
"6:\n"
EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
: "+a" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
: : "cc", "memory");
return size;
}
size_t strnlen_user_std(size_t size, 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"
" sacf 256\n"
"0: srst %3,%2\n"
" jo 0b\n"
" la %0,1(%3)\n" /* strnlen_user results includes \0 */
" "SLR" %0,%1\n"
"1: sacf 0\n"
EX_TABLE(0b,1b)
: "+a" (size), "+a" (src), "=a" (tmp1), "=a" (tmp2)
: "d" (reg0) : "cc", "memory");
return size;
}
size_t strncpy_from_user_std(size_t size, const char __user *src, char *dst)
{
register unsigned long reg0 asm("0") = 0UL;
unsigned long tmp1, tmp2;
asm volatile(
" la %3,0(%1)\n"
" la %4,0(%0,%1)\n"
" sacf 256\n"
"0: srst %4,%3\n"
" jo 0b\n"
" sacf 0\n"
" la %0,0(%4)\n"
" jh 1f\n" /* found \0 in string ? */
" "AHI" %4,1\n" /* include \0 in copy */
"1:"SLR" %0,%1\n" /* %0 = return length (without \0) */
" "SLR" %4,%1\n" /* %4 = copy length (including \0) */
"2: mvcp 0(%4,%2),0(%1),%5\n"
" jz 9f\n"
"3:"AHI" %4,-256\n"
" la %1,256(%1)\n"
" la %2,256(%2)\n"
"4: mvcp 0(%4,%2),0(%1),%5\n"
" jnz 3b\n"
" j 9f\n"
"7: sacf 0\n"
"8:"LHI" %0,%6\n"
"9:\n"
EX_TABLE(0b,7b) EX_TABLE(2b,8b) EX_TABLE(4b,8b)
: "+a" (size), "+a" (src), "+d" (dst), "=a" (tmp1), "=a" (tmp2)
: "d" (reg0), "K" (-EFAULT) : "cc", "memory");
return size;
}
#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
asm volatile( \
" sacf 256\n" \
"0: l %1,0(%6)\n" \
"1:"insn \
"2: cs %1,%2,0(%6)\n" \
"3: jl 1b\n" \
" lhi %0,0\n" \
"4: sacf 0\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");
int futex_atomic_op_std(int op, int __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;
}
*old = oldval;
return ret;
}
int futex_atomic_cmpxchg_std(int __user *uaddr, int oldval, int newval)
{
int ret;
asm volatile(
" sacf 256\n"
"0: cs %1,%4,0(%5)\n"
"1: lr %0,%1\n"
"2: sacf 0\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" );
return ret;
}
struct uaccess_ops uaccess_std = {
.copy_from_user = copy_from_user_std_check,
.copy_from_user_small = copy_from_user_std,
.copy_to_user = copy_to_user_std_check,
.copy_to_user_small = copy_to_user_std,
.copy_in_user = copy_in_user_std,
.clear_user = clear_user_std,
.strnlen_user = strnlen_user_std,
.strncpy_from_user = strncpy_from_user_std,
.futex_atomic_op = futex_atomic_op_std,
.futex_atomic_cmpxchg = futex_atomic_cmpxchg_std,
};
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