af9d2ff9af
This patch adds an EX_TABLE entry to mvc{p|s|os} usercopy functions that
may be called with KERNEL_DS. In combination with collaborative memory
management, kernel pages marked as unused may trigger an adressing exception
in the usercopy functions. This fixes an unhandled addressing exception bug
where strncpy_from_user() is used with len > strnlen and KERNEL_DS, crossing
a page boundary to an unused page.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
232 lines
6.0 KiB
C
232 lines
6.0 KiB
C
/*
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* arch/s390/lib/uaccess_mvcos.c
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*
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* Optimized user space space access functions based on mvcos.
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*
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* Copyright (C) IBM Corp. 2006
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
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* 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/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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#ifndef __s390x__
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#define AHI "ahi"
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#define ALR "alr"
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#define CLR "clr"
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#define LHI "lhi"
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#define SLR "slr"
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#else
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#define AHI "aghi"
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#define ALR "algr"
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#define CLR "clgr"
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#define LHI "lghi"
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#define SLR "slgr"
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#endif
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static size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x)
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{
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register unsigned long reg0 asm("0") = 0x81UL;
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unsigned long tmp1, tmp2;
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tmp1 = -4096UL;
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asm volatile(
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"0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
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"9: jz 7f\n"
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"1:"ALR" %0,%3\n"
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" "SLR" %1,%3\n"
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" "SLR" %2,%3\n"
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" j 0b\n"
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"2: la %4,4095(%1)\n"/* %4 = ptr + 4095 */
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" nr %4,%3\n" /* %4 = (ptr + 4095) & -4096 */
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" "SLR" %4,%1\n"
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" "CLR" %0,%4\n" /* copy crosses next page boundary? */
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" jnh 4f\n"
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"3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
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"10:"SLR" %0,%4\n"
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" "ALR" %2,%4\n"
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"4:"LHI" %4,-1\n"
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" "ALR" %4,%0\n" /* copy remaining size, subtract 1 */
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" bras %3,6f\n" /* memset loop */
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" xc 0(1,%2),0(%2)\n"
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"5: xc 0(256,%2),0(%2)\n"
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" la %2,256(%2)\n"
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"6:"AHI" %4,-256\n"
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" jnm 5b\n"
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" ex %4,0(%3)\n"
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" j 8f\n"
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"7:"SLR" %0,%0\n"
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"8: \n"
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EX_TABLE(0b,2b) EX_TABLE(3b,4b) EX_TABLE(9b,2b) EX_TABLE(10b,4b)
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: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
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: "d" (reg0) : "cc", "memory");
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return size;
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}
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static size_t copy_from_user_mvcos_check(size_t size, const void __user *ptr, void *x)
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{
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if (size <= 256)
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return copy_from_user_std(size, ptr, x);
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return copy_from_user_mvcos(size, ptr, x);
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}
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static size_t copy_to_user_mvcos(size_t size, void __user *ptr, const void *x)
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{
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register unsigned long reg0 asm("0") = 0x810000UL;
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unsigned long tmp1, tmp2;
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tmp1 = -4096UL;
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asm volatile(
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"0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
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"6: jz 4f\n"
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"1:"ALR" %0,%3\n"
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" "SLR" %1,%3\n"
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" "SLR" %2,%3\n"
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" j 0b\n"
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"2: la %4,4095(%1)\n"/* %4 = ptr + 4095 */
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" nr %4,%3\n" /* %4 = (ptr + 4095) & -4096 */
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" "SLR" %4,%1\n"
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" "CLR" %0,%4\n" /* copy crosses next page boundary? */
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" jnh 5f\n"
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"3: .insn ss,0xc80000000000,0(%4,%1),0(%2),0\n"
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"7:"SLR" %0,%4\n"
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" j 5f\n"
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"4:"SLR" %0,%0\n"
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"5: \n"
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EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
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: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
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: "d" (reg0) : "cc", "memory");
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return size;
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}
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static size_t copy_to_user_mvcos_check(size_t size, void __user *ptr,
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const void *x)
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{
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if (size <= 256)
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return copy_to_user_std(size, ptr, x);
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return copy_to_user_mvcos(size, ptr, x);
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}
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static size_t copy_in_user_mvcos(size_t size, void __user *to,
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const void __user *from)
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{
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register unsigned long reg0 asm("0") = 0x810081UL;
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unsigned long tmp1, tmp2;
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tmp1 = -4096UL;
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/* FIXME: copy with reduced length. */
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asm volatile(
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"0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
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" jz 2f\n"
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"1:"ALR" %0,%3\n"
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" "SLR" %1,%3\n"
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" "SLR" %2,%3\n"
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" j 0b\n"
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"2:"SLR" %0,%0\n"
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"3: \n"
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EX_TABLE(0b,3b)
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: "+a" (size), "+a" (to), "+a" (from), "+a" (tmp1), "=a" (tmp2)
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: "d" (reg0) : "cc", "memory");
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return size;
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}
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static size_t clear_user_mvcos(size_t size, void __user *to)
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{
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register unsigned long reg0 asm("0") = 0x810000UL;
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unsigned long tmp1, tmp2;
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tmp1 = -4096UL;
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asm volatile(
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"0: .insn ss,0xc80000000000,0(%0,%1),0(%4),0\n"
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" jz 4f\n"
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"1:"ALR" %0,%2\n"
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" "SLR" %1,%2\n"
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" j 0b\n"
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"2: la %3,4095(%1)\n"/* %4 = to + 4095 */
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" nr %3,%2\n" /* %4 = (to + 4095) & -4096 */
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" "SLR" %3,%1\n"
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" "CLR" %0,%3\n" /* copy crosses next page boundary? */
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" jnh 5f\n"
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"3: .insn ss,0xc80000000000,0(%3,%1),0(%4),0\n"
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" "SLR" %0,%3\n"
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" j 5f\n"
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"4:"SLR" %0,%0\n"
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"5: \n"
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EX_TABLE(0b,2b) EX_TABLE(3b,5b)
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: "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)
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: "a" (empty_zero_page), "d" (reg0) : "cc", "memory");
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return size;
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}
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#ifdef CONFIG_S390_SWITCH_AMODE
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static size_t strnlen_user_mvcos(size_t count, const char __user *src)
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{
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char buf[256];
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int rc;
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size_t done, len, len_str;
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done = 0;
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do {
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len = min(count - done, (size_t) 256);
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rc = uaccess.copy_from_user(len, src + done, buf);
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if (unlikely(rc == len))
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return 0;
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len -= rc;
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len_str = strnlen(buf, len);
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done += len_str;
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} while ((len_str == len) && (done < count));
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return done + 1;
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}
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static size_t strncpy_from_user_mvcos(size_t count, const char __user *src,
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char *dst)
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{
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int rc;
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size_t done, len, len_str;
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done = 0;
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do {
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len = min(count - done, (size_t) 4096);
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rc = uaccess.copy_from_user(len, src + done, dst);
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if (unlikely(rc == len))
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return -EFAULT;
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len -= rc;
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len_str = strnlen(dst, len);
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done += 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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#endif /* CONFIG_S390_SWITCH_AMODE */
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struct uaccess_ops uaccess_mvcos = {
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.copy_from_user = copy_from_user_mvcos_check,
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.copy_from_user_small = copy_from_user_std,
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.copy_to_user = copy_to_user_mvcos_check,
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.copy_to_user_small = copy_to_user_std,
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.copy_in_user = copy_in_user_mvcos,
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.clear_user = clear_user_mvcos,
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.strnlen_user = strnlen_user_std,
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.strncpy_from_user = strncpy_from_user_std,
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.futex_atomic_op = futex_atomic_op_std,
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.futex_atomic_cmpxchg = futex_atomic_cmpxchg_std,
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};
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#ifdef CONFIG_S390_SWITCH_AMODE
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struct uaccess_ops uaccess_mvcos_switch = {
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.copy_from_user = copy_from_user_mvcos,
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.copy_from_user_small = copy_from_user_mvcos,
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.copy_to_user = copy_to_user_mvcos,
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.copy_to_user_small = copy_to_user_mvcos,
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.copy_in_user = copy_in_user_mvcos,
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.clear_user = clear_user_mvcos,
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.strnlen_user = strnlen_user_mvcos,
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.strncpy_from_user = strncpy_from_user_mvcos,
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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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#endif
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