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kernel add
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/*
* Copyright 2011 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* Do memcpy(), but trap and return "n" when a load or store faults.
*
* Note: this idiom only works when memcpy() compiles to a leaf function.
* Here leaf function not only means it does not have calls, but also
* requires no stack operations (sp, stack frame pointer) and no
* use of callee-saved registers, else "jrp lr" will be incorrect since
* unwinding stack frame is bypassed. Since memcpy() is not complex so
* these conditions are satisfied here, but we need to be careful when
* modifying this file. This is not a clean solution but is the best
* one so far.
*
* Also note that we are capturing "n" from the containing scope here.
*/
#define _ST(p, inst, v) \
({ \
asm("1: " #inst " %0, %1;" \
".pushsection .coldtext,\"ax\";" \
"2: { move r0, %2; jrp lr };" \
".section __ex_table,\"a\";" \
".align 8;" \
".quad 1b, 2b;" \
".popsection" \
: "=m" (*(p)) : "r" (v), "r" (n)); \
})
#define _LD(p, inst) \
({ \
unsigned long __v; \
asm("1: " #inst " %0, %1;" \
".pushsection .coldtext,\"ax\";" \
"2: { move r0, %2; jrp lr };" \
".section __ex_table,\"a\";" \
".align 8;" \
".quad 1b, 2b;" \
".popsection" \
: "=r" (__v) : "m" (*(p)), "r" (n)); \
__v; \
})
#define USERCOPY_FUNC __copy_to_user_inatomic
#define ST1(p, v) _ST((p), st1, (v))
#define ST2(p, v) _ST((p), st2, (v))
#define ST4(p, v) _ST((p), st4, (v))
#define ST8(p, v) _ST((p), st, (v))
#define LD1 LD
#define LD2 LD
#define LD4 LD
#define LD8 LD
#include "memcpy_64.c"
#define USERCOPY_FUNC __copy_from_user_inatomic
#define ST1 ST
#define ST2 ST
#define ST4 ST
#define ST8 ST
#define LD1(p) _LD((p), ld1u)
#define LD2(p) _LD((p), ld2u)
#define LD4(p) _LD((p), ld4u)
#define LD8(p) _LD((p), ld)
#include "memcpy_64.c"
#define USERCOPY_FUNC __copy_in_user_inatomic
#define ST1(p, v) _ST((p), st1, (v))
#define ST2(p, v) _ST((p), st2, (v))
#define ST4(p, v) _ST((p), st4, (v))
#define ST8(p, v) _ST((p), st, (v))
#define LD1(p) _LD((p), ld1u)
#define LD2(p) _LD((p), ld2u)
#define LD4(p) _LD((p), ld4u)
#define LD8(p) _LD((p), ld)
#include "memcpy_64.c"
unsigned long __copy_from_user_zeroing(void *to, const void __user *from,
unsigned long n)
{
unsigned long rc = __copy_from_user_inatomic(to, from, n);
if (unlikely(rc))
memset(to + n - rc, 0, rc);
return rc;
}
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