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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/tile/lib/memcpy_user_64.c
10817 views
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/*

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 * Copyright 2011 Tilera Corporation. All Rights Reserved.

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 *

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 *   This program is free software; you can redistribute it and/or

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 *   modify it under the terms of the GNU General Public License

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 *   as published by the Free Software Foundation, version 2.

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 *

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 *   This program is distributed in the hope that it will be useful, but

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 *   WITHOUT ANY WARRANTY; without even the implied warranty of

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 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or

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 *   NON INFRINGEMENT.  See the GNU General Public License for

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 *   more details.

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 *

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 * Do memcpy(), but trap and return "n" when a load or store faults.

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 *

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 * Note: this idiom only works when memcpy() compiles to a leaf function.

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 * If "sp" is updated during memcpy, the "jrp lr" will be incorrect.

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 *

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 * Also note that we are capturing "n" from the containing scope here.

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 */

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#define _ST(p, inst, v)						\

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	({							\

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		asm("1: " #inst " %0, %1;"			\

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		    ".pushsection .coldtext.memcpy,\"ax\";"	\

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		    "2: { move r0, %2; jrp lr };"		\

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		    ".section __ex_table,\"a\";"		\

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		    ".quad 1b, 2b;"				\

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		    ".popsection"				\

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		    : "=m" (*(p)) : "r" (v), "r" (n));		\

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	})

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#define _LD(p, inst)						\

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	({							\

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		unsigned long __v;				\

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		asm("1: " #inst " %0, %1;"			\

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		    ".pushsection .coldtext.memcpy,\"ax\";"	\

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		    "2: { move r0, %2; jrp lr };"		\

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		    ".section __ex_table,\"a\";"		\

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		    ".quad 1b, 2b;"				\

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		    ".popsection"				\

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		    : "=r" (__v) : "m" (*(p)), "r" (n));	\

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		__v;						\

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	})

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#define USERCOPY_FUNC __copy_to_user_inatomic

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#define ST1(p, v) _ST((p), st1, (v))

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#define ST2(p, v) _ST((p), st2, (v))

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#define ST4(p, v) _ST((p), st4, (v))

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#define ST8(p, v) _ST((p), st, (v))

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#define LD1 LD

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#define LD2 LD

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#define LD4 LD

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#define LD8 LD

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#include "memcpy_64.c"

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#define USERCOPY_FUNC __copy_from_user_inatomic

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#define ST1 ST

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#define ST2 ST

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#define ST4 ST

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#define ST8 ST

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#define LD1(p) _LD((p), ld1u)

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#define LD2(p) _LD((p), ld2u)

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#define LD4(p) _LD((p), ld4u)

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#define LD8(p) _LD((p), ld)

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#include "memcpy_64.c"

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#define USERCOPY_FUNC __copy_in_user_inatomic

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#define ST1(p, v) _ST((p), st1, (v))

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#define ST2(p, v) _ST((p), st2, (v))

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#define ST4(p, v) _ST((p), st4, (v))

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#define ST8(p, v) _ST((p), st, (v))

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#define LD1(p) _LD((p), ld1u)

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#define LD2(p) _LD((p), ld2u)

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#define LD4(p) _LD((p), ld4u)

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#define LD8(p) _LD((p), ld)

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#include "memcpy_64.c"

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unsigned long __copy_from_user_zeroing(void *to, const void __user *from,

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				       unsigned long n)

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{

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	unsigned long rc = __copy_from_user_inatomic(to, from, n);

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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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