x86: Use {push,pop}_cfi in more places
[linux-3.10.git] / arch / x86 / lib / csum-partial_64.c
1 /*
2  * arch/x86_64/lib/csum-partial.c
3  *
4  * This file contains network checksum routines that are better done
5  * in an architecture-specific manner due to speed.
6  */
7  
8 #include <linux/compiler.h>
9 #include <linux/module.h>
10 #include <asm/checksum.h>
11
12 static inline unsigned short from32to16(unsigned a) 
13 {
14         unsigned short b = a >> 16; 
15         asm("addw %w2,%w0\n\t"
16             "adcw $0,%w0\n" 
17             : "=r" (b)
18             : "0" (b), "r" (a));
19         return b;
20 }
21
22 /*
23  * Do a 64-bit checksum on an arbitrary memory area.
24  * Returns a 32bit checksum.
25  *
26  * This isn't as time critical as it used to be because many NICs
27  * do hardware checksumming these days.
28  * 
29  * Things tried and found to not make it faster:
30  * Manual Prefetching
31  * Unrolling to an 128 bytes inner loop.
32  * Using interleaving with more registers to break the carry chains.
33  */
34 static unsigned do_csum(const unsigned char *buff, unsigned len)
35 {
36         unsigned odd, count;
37         unsigned long result = 0;
38
39         if (unlikely(len == 0))
40                 return result; 
41         odd = 1 & (unsigned long) buff;
42         if (unlikely(odd)) {
43                 result = *buff << 8;
44                 len--;
45                 buff++;
46         }
47         count = len >> 1;               /* nr of 16-bit words.. */
48         if (count) {
49                 if (2 & (unsigned long) buff) {
50                         result += *(unsigned short *)buff;
51                         count--;
52                         len -= 2;
53                         buff += 2;
54                 }
55                 count >>= 1;            /* nr of 32-bit words.. */
56                 if (count) {
57                         unsigned long zero;
58                         unsigned count64;
59                         if (4 & (unsigned long) buff) {
60                                 result += *(unsigned int *) buff;
61                                 count--;
62                                 len -= 4;
63                                 buff += 4;
64                         }
65                         count >>= 1;    /* nr of 64-bit words.. */
66
67                         /* main loop using 64byte blocks */
68                         zero = 0;
69                         count64 = count >> 3;
70                         while (count64) { 
71                                 asm("addq 0*8(%[src]),%[res]\n\t"
72                                     "adcq 1*8(%[src]),%[res]\n\t"
73                                     "adcq 2*8(%[src]),%[res]\n\t"
74                                     "adcq 3*8(%[src]),%[res]\n\t"
75                                     "adcq 4*8(%[src]),%[res]\n\t"
76                                     "adcq 5*8(%[src]),%[res]\n\t"
77                                     "adcq 6*8(%[src]),%[res]\n\t"
78                                     "adcq 7*8(%[src]),%[res]\n\t"
79                                     "adcq %[zero],%[res]"
80                                     : [res] "=r" (result)
81                                     : [src] "r" (buff), [zero] "r" (zero),
82                                     "[res]" (result));
83                                 buff += 64;
84                                 count64--;
85                         }
86
87                         /* last upto 7 8byte blocks */
88                         count %= 8; 
89                         while (count) { 
90                                 asm("addq %1,%0\n\t"
91                                     "adcq %2,%0\n" 
92                                             : "=r" (result)
93                                     : "m" (*(unsigned long *)buff), 
94                                     "r" (zero),  "0" (result));
95                                 --count; 
96                                         buff += 8;
97                         }
98                         result = add32_with_carry(result>>32,
99                                                   result&0xffffffff); 
100
101                         if (len & 4) {
102                                 result += *(unsigned int *) buff;
103                                 buff += 4;
104                         }
105                 }
106                 if (len & 2) {
107                         result += *(unsigned short *) buff;
108                         buff += 2;
109                 }
110         }
111         if (len & 1)
112                 result += *buff;
113         result = add32_with_carry(result>>32, result & 0xffffffff); 
114         if (unlikely(odd)) { 
115                 result = from32to16(result);
116                 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
117         }
118         return result;
119 }
120
121 /*
122  * computes the checksum of a memory block at buff, length len,
123  * and adds in "sum" (32-bit)
124  *
125  * returns a 32-bit number suitable for feeding into itself
126  * or csum_tcpudp_magic
127  *
128  * this function must be called with even lengths, except
129  * for the last fragment, which may be odd
130  *
131  * it's best to have buff aligned on a 64-bit boundary
132  */
133 __wsum csum_partial(const void *buff, int len, __wsum sum)
134 {
135         return (__force __wsum)add32_with_carry(do_csum(buff, len),
136                                                 (__force u32)sum);
137 }
138
139 /*
140  * this routine is used for miscellaneous IP-like checksums, mainly
141  * in icmp.c
142  */
143 __sum16 ip_compute_csum(const void *buff, int len)
144 {
145         return csum_fold(csum_partial(buff,len,0));
146 }
147 EXPORT_SYMBOL(ip_compute_csum);
148