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>
320 lines
7.9 KiB
C
320 lines
7.9 KiB
C
/*
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* arch/s390/lib/uaccess_std.c
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*
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* Standard user space access functions based on mvcp/mvcs and doing
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* interesting things in the secondary space mode.
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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 <linux/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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size_t copy_from_user_std(size_t size, const void __user *ptr, void *x)
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{
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unsigned long tmp1, tmp2;
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tmp1 = -256UL;
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asm volatile(
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"0: mvcp 0(%0,%2),0(%1),%3\n"
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"10:jz 8f\n"
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"1:"ALR" %0,%3\n"
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" la %1,256(%1)\n"
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" la %2,256(%2)\n"
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"2: mvcp 0(%0,%2),0(%1),%3\n"
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"11:jnz 1b\n"
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" j 8f\n"
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"3: la %4,255(%1)\n" /* %4 = ptr + 255 */
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" "LHI" %3,-4096\n"
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" nr %4,%3\n" /* %4 = (ptr + 255) & -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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"4: mvcp 0(%4,%2),0(%1),%3\n"
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"12:"SLR" %0,%4\n"
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" "ALR" %2,%4\n"
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"5:"LHI" %4,-1\n"
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" "ALR" %4,%0\n" /* copy remaining size, subtract 1 */
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" bras %3,7f\n" /* memset loop */
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" xc 0(1,%2),0(%2)\n"
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"6: xc 0(256,%2),0(%2)\n"
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" la %2,256(%2)\n"
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"7:"AHI" %4,-256\n"
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" jnm 6b\n"
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" ex %4,0(%3)\n"
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" j 9f\n"
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"8:"SLR" %0,%0\n"
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"9: \n"
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EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b)
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EX_TABLE(10b,3b) EX_TABLE(11b,3b) EX_TABLE(12b,5b)
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: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
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: : "cc", "memory");
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return size;
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}
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static size_t copy_from_user_std_check(size_t size, const void __user *ptr,
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void *x)
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{
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if (size <= 1024)
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return copy_from_user_std(size, ptr, x);
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return copy_from_user_pt(size, ptr, x);
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}
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size_t copy_to_user_std(size_t size, void __user *ptr, const void *x)
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{
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unsigned long tmp1, tmp2;
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tmp1 = -256UL;
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asm volatile(
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"0: mvcs 0(%0,%1),0(%2),%3\n"
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"7: jz 5f\n"
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"1:"ALR" %0,%3\n"
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" la %1,256(%1)\n"
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" la %2,256(%2)\n"
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"2: mvcs 0(%0,%1),0(%2),%3\n"
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"8: jnz 1b\n"
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" j 5f\n"
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"3: la %4,255(%1)\n" /* %4 = ptr + 255 */
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" "LHI" %3,-4096\n"
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" nr %4,%3\n" /* %4 = (ptr + 255) & -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 6f\n"
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"4: mvcs 0(%4,%1),0(%2),%3\n"
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"9:"SLR" %0,%4\n"
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" j 6f\n"
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"5:"SLR" %0,%0\n"
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"6: \n"
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EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
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EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
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: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
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: : "cc", "memory");
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return size;
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}
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static size_t copy_to_user_std_check(size_t size, void __user *ptr,
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const void *x)
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{
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if (size <= 1024)
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return copy_to_user_std(size, ptr, x);
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return copy_to_user_pt(size, ptr, x);
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}
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static size_t copy_in_user_std(size_t size, 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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" sacf 256\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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" sacf 0\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" (size), "+a" (to), "+a" (from), "=a" (tmp1)
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: : "cc", "memory");
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return size;
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}
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static size_t clear_user_std(size_t size, void __user *to)
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{
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unsigned long tmp1, tmp2;
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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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" sacf 256\n"
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" bras %3,3f\n"
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" xc 0(1,%1),0(%1)\n"
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"0:"AHI" %0,257\n"
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" la %2,255(%1)\n" /* %2 = ptr + 255 */
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" srl %2,12\n"
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" sll %2,12\n" /* %2 = (ptr + 255) & -4096 */
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" "SLR" %2,%1\n"
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" "CLR" %0,%2\n" /* clear crosses next page boundary? */
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" jnh 5f\n"
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" "AHI" %2,-1\n"
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"1: ex %2,0(%3)\n"
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" "AHI" %2,1\n"
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" "SLR" %0,%2\n"
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" j 5f\n"
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"2: xc 0(256,%1),0(%1)\n"
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" la %1,256(%1)\n"
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"3:"AHI" %0,-256\n"
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" jnm 2b\n"
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"4: ex %0,0(%3)\n"
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" sacf 0\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" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
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: : "cc", "memory");
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return size;
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}
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size_t strnlen_user_std(size_t size, 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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" sacf 256\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_user results includes \0 */
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" "SLR" %0,%1\n"
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"1: sacf 0\n"
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EX_TABLE(0b,1b)
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: "+a" (size), "+a" (src), "=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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size_t strncpy_from_user_std(size_t size, const char __user *src, char *dst)
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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 %3,0(%1)\n"
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" la %4,0(%0,%1)\n"
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" sacf 256\n"
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"0: srst %4,%3\n"
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" jo 0b\n"
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" sacf 0\n"
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" la %0,0(%4)\n"
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" jh 1f\n" /* found \0 in string ? */
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" "AHI" %4,1\n" /* include \0 in copy */
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"1:"SLR" %0,%1\n" /* %0 = return length (without \0) */
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" "SLR" %4,%1\n" /* %4 = copy length (including \0) */
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"2: mvcp 0(%4,%2),0(%1),%5\n"
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" jz 9f\n"
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"3:"AHI" %4,-256\n"
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" la %1,256(%1)\n"
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" la %2,256(%2)\n"
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"4: mvcp 0(%4,%2),0(%1),%5\n"
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" jnz 3b\n"
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" j 9f\n"
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"7: sacf 0\n"
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"8:"LHI" %0,%6\n"
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"9:\n"
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EX_TABLE(0b,7b) EX_TABLE(2b,8b) EX_TABLE(4b,8b)
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: "+a" (size), "+a" (src), "+d" (dst), "=a" (tmp1), "=a" (tmp2)
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: "d" (reg0), "K" (-EFAULT) : "cc", "memory");
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return size;
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}
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#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
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asm volatile( \
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" sacf 256\n" \
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"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: sacf 0\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_std(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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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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*old = oldval;
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return ret;
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}
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int futex_atomic_cmpxchg_std(int __user *uaddr, int oldval, int newval)
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{
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int ret;
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asm volatile(
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" sacf 256\n"
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"0: cs %1,%4,0(%5)\n"
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"1: lr %0,%1\n"
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"2: sacf 0\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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return ret;
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}
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struct uaccess_ops uaccess_std = {
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.copy_from_user = copy_from_user_std_check,
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.copy_from_user_small = copy_from_user_std,
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.copy_to_user = copy_to_user_std_check,
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.copy_to_user_small = copy_to_user_std,
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.copy_in_user = copy_in_user_std,
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.clear_user = clear_user_std,
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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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