tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright 2011 Tilera Corporation. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
12 * more details.
13 *
14 * Do memcpy(), but trap and return "n" when a load or store faults.
15 *
16 * Note: this idiom only works when memcpy() compiles to a leaf function.
17 * Here leaf function not only means it does not have calls, but also
18 * requires no stack operations (sp, stack frame pointer) and no
19 * use of callee-saved registers, else "jrp lr" will be incorrect since
20 * unwinding stack frame is bypassed. Since memcpy() is not complex so
21 * these conditions are satisfied here, but we need to be careful when
22 * modifying this file. This is not a clean solution but is the best
23 * one so far.
24 *
25 * Also note that we are capturing "n" from the containing scope here.
26 */
27
28#define _ST(p, inst, v) \
29 ({ \
30 asm("1: " #inst " %0, %1;" \
31 ".pushsection .coldtext.memcpy,\"ax\";" \
32 "2: { move r0, %2; jrp lr };" \
33 ".section __ex_table,\"a\";" \
34 ".quad 1b, 2b;" \
35 ".popsection" \
36 : "=m" (*(p)) : "r" (v), "r" (n)); \
37 })
38
39#define _LD(p, inst) \
40 ({ \
41 unsigned long __v; \
42 asm("1: " #inst " %0, %1;" \
43 ".pushsection .coldtext.memcpy,\"ax\";" \
44 "2: { move r0, %2; jrp lr };" \
45 ".section __ex_table,\"a\";" \
46 ".quad 1b, 2b;" \
47 ".popsection" \
48 : "=r" (__v) : "m" (*(p)), "r" (n)); \
49 __v; \
50 })
51
52#define USERCOPY_FUNC __copy_to_user_inatomic
53#define ST1(p, v) _ST((p), st1, (v))
54#define ST2(p, v) _ST((p), st2, (v))
55#define ST4(p, v) _ST((p), st4, (v))
56#define ST8(p, v) _ST((p), st, (v))
57#define LD1 LD
58#define LD2 LD
59#define LD4 LD
60#define LD8 LD
61#include "memcpy_64.c"
62
63#define USERCOPY_FUNC __copy_from_user_inatomic
64#define ST1 ST
65#define ST2 ST
66#define ST4 ST
67#define ST8 ST
68#define LD1(p) _LD((p), ld1u)
69#define LD2(p) _LD((p), ld2u)
70#define LD4(p) _LD((p), ld4u)
71#define LD8(p) _LD((p), ld)
72#include "memcpy_64.c"
73
74#define USERCOPY_FUNC __copy_in_user_inatomic
75#define ST1(p, v) _ST((p), st1, (v))
76#define ST2(p, v) _ST((p), st2, (v))
77#define ST4(p, v) _ST((p), st4, (v))
78#define ST8(p, v) _ST((p), st, (v))
79#define LD1(p) _LD((p), ld1u)
80#define LD2(p) _LD((p), ld2u)
81#define LD4(p) _LD((p), ld4u)
82#define LD8(p) _LD((p), ld)
83#include "memcpy_64.c"
84
85unsigned long __copy_from_user_zeroing(void *to, const void __user *from,
86 unsigned long n)
87{
88 unsigned long rc = __copy_from_user_inatomic(to, from, n);
89 if (unlikely(rc))
90 memset(to + n - rc, 0, rc);
91 return rc;
92}