Linux Kernel  3.7.1
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sha1.c
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1 /*
2  * SHA1 routine optimized to do word accesses rather than byte accesses,
3  * and to avoid unnecessary copies into the context array.
4  *
5  * This was based on the git SHA1 implementation.
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/export.h>
10 #include <linux/bitops.h>
11 #include <linux/cryptohash.h>
12 #include <asm/unaligned.h>
13 
14 /*
15  * If you have 32 registers or more, the compiler can (and should)
16  * try to change the array[] accesses into registers. However, on
17  * machines with less than ~25 registers, that won't really work,
18  * and at least gcc will make an unholy mess of it.
19  *
20  * So to avoid that mess which just slows things down, we force
21  * the stores to memory to actually happen (we might be better off
22  * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
23  * suggested by Artur Skawina - that will also make gcc unable to
24  * try to do the silly "optimize away loads" part because it won't
25  * see what the value will be).
26  *
27  * Ben Herrenschmidt reports that on PPC, the C version comes close
28  * to the optimized asm with this (ie on PPC you don't want that
29  * 'volatile', since there are lots of registers).
30  *
31  * On ARM we get the best code generation by forcing a full memory barrier
32  * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
33  * the stack frame size simply explode and performance goes down the drain.
34  */
35 
36 #ifdef CONFIG_X86
37  #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
38 #elif defined(CONFIG_ARM)
39  #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
40 #else
41  #define setW(x, val) (W(x) = (val))
42 #endif
43 
44 /* This "rolls" over the 512-bit array */
45 #define W(x) (array[(x)&15])
46 
47 /*
48  * Where do we get the source from? The first 16 iterations get it from
49  * the input data, the next mix it from the 512-bit array.
50  */
51 #define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
52 #define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
53 
54 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
55  __u32 TEMP = input(t); setW(t, TEMP); \
56  E += TEMP + rol32(A,5) + (fn) + (constant); \
57  B = ror32(B, 2); } while (0)
58 
59 #define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
60 #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
61 #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
62 #define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
63 #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
64 
81 void sha_transform(__u32 *digest, const char *data, __u32 *array)
82 {
83  __u32 A, B, C, D, E;
84 
85  A = digest[0];
86  B = digest[1];
87  C = digest[2];
88  D = digest[3];
89  E = digest[4];
90 
91  /* Round 1 - iterations 0-16 take their input from 'data' */
92  T_0_15( 0, A, B, C, D, E);
93  T_0_15( 1, E, A, B, C, D);
94  T_0_15( 2, D, E, A, B, C);
95  T_0_15( 3, C, D, E, A, B);
96  T_0_15( 4, B, C, D, E, A);
97  T_0_15( 5, A, B, C, D, E);
98  T_0_15( 6, E, A, B, C, D);
99  T_0_15( 7, D, E, A, B, C);
100  T_0_15( 8, C, D, E, A, B);
101  T_0_15( 9, B, C, D, E, A);
102  T_0_15(10, A, B, C, D, E);
103  T_0_15(11, E, A, B, C, D);
104  T_0_15(12, D, E, A, B, C);
105  T_0_15(13, C, D, E, A, B);
106  T_0_15(14, B, C, D, E, A);
107  T_0_15(15, A, B, C, D, E);
108 
109  /* Round 1 - tail. Input from 512-bit mixing array */
110  T_16_19(16, E, A, B, C, D);
111  T_16_19(17, D, E, A, B, C);
112  T_16_19(18, C, D, E, A, B);
113  T_16_19(19, B, C, D, E, A);
114 
115  /* Round 2 */
116  T_20_39(20, A, B, C, D, E);
117  T_20_39(21, E, A, B, C, D);
118  T_20_39(22, D, E, A, B, C);
119  T_20_39(23, C, D, E, A, B);
120  T_20_39(24, B, C, D, E, A);
121  T_20_39(25, A, B, C, D, E);
122  T_20_39(26, E, A, B, C, D);
123  T_20_39(27, D, E, A, B, C);
124  T_20_39(28, C, D, E, A, B);
125  T_20_39(29, B, C, D, E, A);
126  T_20_39(30, A, B, C, D, E);
127  T_20_39(31, E, A, B, C, D);
128  T_20_39(32, D, E, A, B, C);
129  T_20_39(33, C, D, E, A, B);
130  T_20_39(34, B, C, D, E, A);
131  T_20_39(35, A, B, C, D, E);
132  T_20_39(36, E, A, B, C, D);
133  T_20_39(37, D, E, A, B, C);
134  T_20_39(38, C, D, E, A, B);
135  T_20_39(39, B, C, D, E, A);
136 
137  /* Round 3 */
138  T_40_59(40, A, B, C, D, E);
139  T_40_59(41, E, A, B, C, D);
140  T_40_59(42, D, E, A, B, C);
141  T_40_59(43, C, D, E, A, B);
142  T_40_59(44, B, C, D, E, A);
143  T_40_59(45, A, B, C, D, E);
144  T_40_59(46, E, A, B, C, D);
145  T_40_59(47, D, E, A, B, C);
146  T_40_59(48, C, D, E, A, B);
147  T_40_59(49, B, C, D, E, A);
148  T_40_59(50, A, B, C, D, E);
149  T_40_59(51, E, A, B, C, D);
150  T_40_59(52, D, E, A, B, C);
151  T_40_59(53, C, D, E, A, B);
152  T_40_59(54, B, C, D, E, A);
153  T_40_59(55, A, B, C, D, E);
154  T_40_59(56, E, A, B, C, D);
155  T_40_59(57, D, E, A, B, C);
156  T_40_59(58, C, D, E, A, B);
157  T_40_59(59, B, C, D, E, A);
158 
159  /* Round 4 */
160  T_60_79(60, A, B, C, D, E);
161  T_60_79(61, E, A, B, C, D);
162  T_60_79(62, D, E, A, B, C);
163  T_60_79(63, C, D, E, A, B);
164  T_60_79(64, B, C, D, E, A);
165  T_60_79(65, A, B, C, D, E);
166  T_60_79(66, E, A, B, C, D);
167  T_60_79(67, D, E, A, B, C);
168  T_60_79(68, C, D, E, A, B);
169  T_60_79(69, B, C, D, E, A);
170  T_60_79(70, A, B, C, D, E);
171  T_60_79(71, E, A, B, C, D);
172  T_60_79(72, D, E, A, B, C);
173  T_60_79(73, C, D, E, A, B);
174  T_60_79(74, B, C, D, E, A);
175  T_60_79(75, A, B, C, D, E);
176  T_60_79(76, E, A, B, C, D);
177  T_60_79(77, D, E, A, B, C);
178  T_60_79(78, C, D, E, A, B);
179  T_60_79(79, B, C, D, E, A);
180 
181  digest[0] += A;
182  digest[1] += B;
183  digest[2] += C;
184  digest[3] += D;
185  digest[4] += E;
186 }
188 
194 {
195  buf[0] = 0x67452301;
196  buf[1] = 0xefcdab89;
197  buf[2] = 0x98badcfe;
198  buf[3] = 0x10325476;
199  buf[4] = 0xc3d2e1f0;
200 }