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18aecc2b CM |
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. | |
efb734d8 CM |
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. | |
18aecc2b CM |
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\";" \ | |
d4d9eab4 | 34 | ".align 8;" \ |
18aecc2b CM |
35 | ".quad 1b, 2b;" \ |
36 | ".popsection" \ | |
37 | : "=m" (*(p)) : "r" (v), "r" (n)); \ | |
38 | }) | |
39 | ||
40 | #define _LD(p, inst) \ | |
41 | ({ \ | |
42 | unsigned long __v; \ | |
43 | asm("1: " #inst " %0, %1;" \ | |
44 | ".pushsection .coldtext.memcpy,\"ax\";" \ | |
45 | "2: { move r0, %2; jrp lr };" \ | |
46 | ".section __ex_table,\"a\";" \ | |
d4d9eab4 | 47 | ".align 8;" \ |
18aecc2b CM |
48 | ".quad 1b, 2b;" \ |
49 | ".popsection" \ | |
50 | : "=r" (__v) : "m" (*(p)), "r" (n)); \ | |
51 | __v; \ | |
52 | }) | |
53 | ||
54 | #define USERCOPY_FUNC __copy_to_user_inatomic | |
55 | #define ST1(p, v) _ST((p), st1, (v)) | |
56 | #define ST2(p, v) _ST((p), st2, (v)) | |
57 | #define ST4(p, v) _ST((p), st4, (v)) | |
58 | #define ST8(p, v) _ST((p), st, (v)) | |
59 | #define LD1 LD | |
60 | #define LD2 LD | |
61 | #define LD4 LD | |
62 | #define LD8 LD | |
63 | #include "memcpy_64.c" | |
64 | ||
65 | #define USERCOPY_FUNC __copy_from_user_inatomic | |
66 | #define ST1 ST | |
67 | #define ST2 ST | |
68 | #define ST4 ST | |
69 | #define ST8 ST | |
70 | #define LD1(p) _LD((p), ld1u) | |
71 | #define LD2(p) _LD((p), ld2u) | |
72 | #define LD4(p) _LD((p), ld4u) | |
73 | #define LD8(p) _LD((p), ld) | |
74 | #include "memcpy_64.c" | |
75 | ||
76 | #define USERCOPY_FUNC __copy_in_user_inatomic | |
77 | #define ST1(p, v) _ST((p), st1, (v)) | |
78 | #define ST2(p, v) _ST((p), st2, (v)) | |
79 | #define ST4(p, v) _ST((p), st4, (v)) | |
80 | #define ST8(p, v) _ST((p), st, (v)) | |
81 | #define LD1(p) _LD((p), ld1u) | |
82 | #define LD2(p) _LD((p), ld2u) | |
83 | #define LD4(p) _LD((p), ld4u) | |
84 | #define LD8(p) _LD((p), ld) | |
85 | #include "memcpy_64.c" | |
86 | ||
87 | unsigned long __copy_from_user_zeroing(void *to, const void __user *from, | |
88 | unsigned long n) | |
89 | { | |
90 | unsigned long rc = __copy_from_user_inatomic(to, from, n); | |
91 | if (unlikely(rc)) | |
92 | memset(to + n - rc, 0, rc); | |
93 | return rc; | |
94 | } |