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1 /*
2  * Copyright (c) 1992, 1993, 1994, 1995, 1996
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that: (1) source code distributions
7  * retain the above copyright notice and this paragraph in its entirety, (2)
8  * distributions including binary code include the above copyright notice and
9  * this paragraph in its entirety in the documentation or other materials
10  * provided with the distribution, and (3) all advertising materials mentioning
11  * features or use of this software display the following acknowledgement:
12  * ``This product includes software developed by the University of California,
13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14  * the University nor the names of its contributors may be used to endorse
15  * or promote products derived from this software without specific prior
16  * written permission.
17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20  */
21 
22 /*
23  * For 8-bit values; provided for the sake of completeness.  Byte order
24  * isn't relevant, and alignment isn't an issue.
25  */
26 #define EXTRACT_8BITS(p)	(*(p))
27 #define EXTRACT_LE_8BITS(p)	(*(p))
28 
29 /*
30  * Inline functions or macros to extract possibly-unaligned big-endian
31  * integral values.
32  */
33 #include "funcattrs.h"
34 
35 /*
36  * If we have versions of GCC or Clang that support an __attribute__
37  * to say "if we're building with unsigned behavior sanitization,
38  * don't complain about undefined behavior in this function", we
39  * label these functions with that attribute - we *know* it's undefined
40  * in the C standard, but we *also* know it does what we want with
41  * the ISA we're targeting and the compiler we're using.
42  *
43  * For GCC 4.9.0 and later, we use __attribute__((no_sanitize_undefined));
44  * pre-5.0 GCC doesn't have __has_attribute, and I'm not sure whether
45  * GCC or Clang first had __attribute__((no_sanitize(XXX)).
46  *
47  * For Clang, we check for __attribute__((no_sanitize(XXX)) with
48  * __has_attribute, as there are versions of Clang that support
49  * __attribute__((no_sanitize("undefined")) but don't support
50  * __attribute__((no_sanitize_undefined)).
51  *
52  * We define this here, rather than in funcattrs.h, because we
53  * only want it used here, we don't want it to be broadly used.
54  * (Any printer will get this defined, but this should at least
55  * make it harder for people to find.)
56  */
57 #if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 409)
58 #define UNALIGNED_OK	__attribute__((no_sanitize_undefined))
59 #elif __has_attribute(no_sanitize)
60 #define UNALIGNED_OK	__attribute__((no_sanitize("undefined")))
61 #else
62 #define UNALIGNED_OK
63 #endif
64 
65 #ifdef LBL_ALIGN
66 /*
67  * The processor doesn't natively handle unaligned loads.
68  */
69 #if defined(__GNUC__) && defined(HAVE___ATTRIBUTE__) && \
70     (defined(__alpha) || defined(__alpha__) || \
71      defined(__mips) || defined(__mips__))
72 
73 /*
74 * This is a GCC-compatible compiler and we have __attribute__, which
75  * we assume that mean we have __attribute__((packed)), and this is
76  * MIPS or Alpha, which has instructions that can help when doing
77  * unaligned loads.
78  *
79  * Declare packed structures containing a uint16_t and a uint32_t,
80  * cast the pointer to point to one of those, and fetch through it;
81  * the GCC manual doesn't appear to explicitly say that
82  * __attribute__((packed)) causes the compiler to generate unaligned-safe
83  * code, but it apppears to do so.
84  *
85  * We do this in case the compiler can generate code using those
86  * instructions to do an unaligned load and pass stuff to "ntohs()" or
87  * "ntohl()", which might be better than than the code to fetch the
88  * bytes one at a time and assemble them.  (That might not be the
89  * case on a little-endian platform, such as DEC's MIPS machines and
90  * Alpha machines, where "ntohs()" and "ntohl()" might not be done
91  * inline.)
92  *
93  * We do this only for specific architectures because, for example,
94  * at least some versions of GCC, when compiling for 64-bit SPARC,
95  * generate code that assumes alignment if we do this.
96  *
97  * XXX - add other architectures and compilers as possible and
98  * appropriate.
99  *
100  * HP's C compiler, indicated by __HP_cc being defined, supports
101  * "#pragma unaligned N" in version A.05.50 and later, where "N"
102  * specifies a number of bytes at which the typedef on the next
103  * line is aligned, e.g.
104  *
105  *	#pragma unalign 1
106  *	typedef uint16_t unaligned_uint16_t;
107  *
108  * to define unaligned_uint16_t as a 16-bit unaligned data type.
109  * This could be presumably used, in sufficiently recent versions of
110  * the compiler, with macros similar to those below.  This would be
111  * useful only if that compiler could generate better code for PA-RISC
112  * or Itanium than would be generated by a bunch of shifts-and-ORs.
113  *
114  * DEC C, indicated by __DECC being defined, has, at least on Alpha,
115  * an __unaligned qualifier that can be applied to pointers to get the
116  * compiler to generate code that does unaligned loads and stores when
117  * dereferencing the pointer in question.
118  *
119  * XXX - what if the native C compiler doesn't support
120  * __attribute__((packed))?  How can we get it to generate unaligned
121  * accesses for *specific* items?
122  */
123 typedef struct {
124 	uint16_t	val;
125 } __attribute__((packed)) unaligned_uint16_t;
126 
127 typedef struct {
128 	uint32_t	val;
129 } __attribute__((packed)) unaligned_uint32_t;
130 
131 UNALIGNED_OK static inline uint16_t
EXTRACT_16BITS(const void * p)132 EXTRACT_16BITS(const void *p)
133 {
134 	return ((uint16_t)ntohs(((const unaligned_uint16_t *)(p))->val));
135 }
136 
137 UNALIGNED_OK static inline uint32_t
EXTRACT_32BITS(const void * p)138 EXTRACT_32BITS(const void *p)
139 {
140 	return ((uint32_t)ntohl(((const unaligned_uint32_t *)(p))->val));
141 }
142 
143 UNALIGNED_OK static inline uint64_t
EXTRACT_64BITS(const void * p)144 EXTRACT_64BITS(const void *p)
145 {
146 	return ((uint64_t)(((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 0)->val)) << 32 |
147 		((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 1)->val)) << 0));
148 }
149 
150 #else /* have to do it a byte at a time */
151 /*
152  * This isn't a GCC-compatible compiler, we don't have __attribute__,
153  * or we do but we don't know of any better way with this instruction
154  * set to do unaligned loads, so do unaligned loads of big-endian
155  * quantities the hard way - fetch the bytes one at a time and
156  * assemble them.
157  */
158 #define EXTRACT_16BITS(p) \
159 	((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 0)) << 8) | \
160 	            ((uint16_t)(*((const uint8_t *)(p) + 1)) << 0)))
161 #define EXTRACT_32BITS(p) \
162 	((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 24) | \
163 	            ((uint32_t)(*((const uint8_t *)(p) + 1)) << 16) | \
164 	            ((uint32_t)(*((const uint8_t *)(p) + 2)) << 8) | \
165 	            ((uint32_t)(*((const uint8_t *)(p) + 3)) << 0)))
166 #define EXTRACT_64BITS(p) \
167 	((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 56) | \
168 	            ((uint64_t)(*((const uint8_t *)(p) + 1)) << 48) | \
169 	            ((uint64_t)(*((const uint8_t *)(p) + 2)) << 40) | \
170 	            ((uint64_t)(*((const uint8_t *)(p) + 3)) << 32) | \
171 	            ((uint64_t)(*((const uint8_t *)(p) + 4)) << 24) | \
172 	            ((uint64_t)(*((const uint8_t *)(p) + 5)) << 16) | \
173 	            ((uint64_t)(*((const uint8_t *)(p) + 6)) << 8) | \
174 	            ((uint64_t)(*((const uint8_t *)(p) + 7)) << 0)))
175 #endif /* must special-case unaligned accesses */
176 #else /* LBL_ALIGN */
177 /*
178  * The processor natively handles unaligned loads, so we can just
179  * cast the pointer and fetch through it.
180  */
181 static inline uint16_t UNALIGNED_OK
EXTRACT_16BITS(const void * p)182 EXTRACT_16BITS(const void *p)
183 {
184 	return ((uint16_t)ntohs(*(const uint16_t *)(p)));
185 }
186 
187 static inline uint32_t UNALIGNED_OK
EXTRACT_32BITS(const void * p)188 EXTRACT_32BITS(const void *p)
189 {
190 	return ((uint32_t)ntohl(*(const uint32_t *)(p)));
191 }
192 
193 static inline uint64_t UNALIGNED_OK
EXTRACT_64BITS(const void * p)194 EXTRACT_64BITS(const void *p)
195 {
196 	return ((uint64_t)(((uint64_t)ntohl(*((const uint32_t *)(p) + 0))) << 32 |
197 		((uint64_t)ntohl(*((const uint32_t *)(p) + 1))) << 0));
198 
199 }
200 
201 #endif /* LBL_ALIGN */
202 
203 #define EXTRACT_24BITS(p) \
204 	((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 16) | \
205 	            ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
206 	            ((uint32_t)(*((const uint8_t *)(p) + 2)) << 0)))
207 
208 #define EXTRACT_40BITS(p) \
209 	((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 32) | \
210 	            ((uint64_t)(*((const uint8_t *)(p) + 1)) << 24) | \
211 	            ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \
212 	            ((uint64_t)(*((const uint8_t *)(p) + 3)) << 8) | \
213 	            ((uint64_t)(*((const uint8_t *)(p) + 4)) << 0)))
214 
215 #define EXTRACT_48BITS(p) \
216 	((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 40) | \
217 	            ((uint64_t)(*((const uint8_t *)(p) + 1)) << 32) | \
218 	            ((uint64_t)(*((const uint8_t *)(p) + 2)) << 24) | \
219 	            ((uint64_t)(*((const uint8_t *)(p) + 3)) << 16) | \
220 	            ((uint64_t)(*((const uint8_t *)(p) + 4)) << 8) | \
221 	            ((uint64_t)(*((const uint8_t *)(p) + 5)) << 0)))
222 
223 #define EXTRACT_56BITS(p) \
224 	((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 48) | \
225 	            ((uint64_t)(*((const uint8_t *)(p) + 1)) << 40) | \
226 	            ((uint64_t)(*((const uint8_t *)(p) + 2)) << 32) | \
227 	            ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \
228 	            ((uint64_t)(*((const uint8_t *)(p) + 4)) << 16) | \
229 	            ((uint64_t)(*((const uint8_t *)(p) + 5)) << 8) | \
230 	            ((uint64_t)(*((const uint8_t *)(p) + 6)) << 0)))
231 
232 /*
233  * Macros to extract possibly-unaligned little-endian integral values.
234  * XXX - do loads on little-endian machines that support unaligned loads?
235  */
236 #define EXTRACT_LE_16BITS(p) \
237 	((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 1)) << 8) | \
238 	            ((uint16_t)(*((const uint8_t *)(p) + 0)) << 0)))
239 #define EXTRACT_LE_32BITS(p) \
240 	((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 3)) << 24) | \
241 	            ((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \
242 	            ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
243 	            ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0)))
244 #define EXTRACT_LE_24BITS(p) \
245 	((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \
246 	            ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
247 	            ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0)))
248 #define EXTRACT_LE_64BITS(p) \
249 	((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 7)) << 56) | \
250 	            ((uint64_t)(*((const uint8_t *)(p) + 6)) << 48) | \
251 	            ((uint64_t)(*((const uint8_t *)(p) + 5)) << 40) | \
252 	            ((uint64_t)(*((const uint8_t *)(p) + 4)) << 32) | \
253 	            ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \
254 	            ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \
255 	            ((uint64_t)(*((const uint8_t *)(p) + 1)) << 8) | \
256 	            ((uint64_t)(*((const uint8_t *)(p) + 0)) << 0)))
257 
258 /*
259  * Macros to check the presence of the values in question.
260  */
261 #define ND_TTEST_8BITS(p) ND_TTEST2(*(p), 1)
262 #define ND_TCHECK_8BITS(p) ND_TCHECK2(*(p), 1)
263 
264 #define ND_TTEST_16BITS(p) ND_TTEST2(*(p), 2)
265 #define ND_TCHECK_16BITS(p) ND_TCHECK2(*(p), 2)
266 
267 #define ND_TTEST_24BITS(p) ND_TTEST2(*(p), 3)
268 #define ND_TCHECK_24BITS(p) ND_TCHECK2(*(p), 3)
269 
270 #define ND_TTEST_32BITS(p) ND_TTEST2(*(p), 4)
271 #define ND_TCHECK_32BITS(p) ND_TCHECK2(*(p), 4)
272 
273 #define ND_TTEST_40BITS(p) ND_TTEST2(*(p), 5)
274 #define ND_TCHECK_40BITS(p) ND_TCHECK2(*(p), 5)
275 
276 #define ND_TTEST_48BITS(p) ND_TTEST2(*(p), 6)
277 #define ND_TCHECK_48BITS(p) ND_TCHECK2(*(p), 6)
278 
279 #define ND_TTEST_56BITS(p) ND_TTEST2(*(p), 7)
280 #define ND_TCHECK_56BITS(p) ND_TCHECK2(*(p), 7)
281 
282 #define ND_TTEST_64BITS(p) ND_TTEST2(*(p), 8)
283 #define ND_TCHECK_64BITS(p) ND_TCHECK2(*(p), 8)
284 
285 #define ND_TTEST_128BITS(p) ND_TTEST2(*(p), 16)
286 #define ND_TCHECK_128BITS(p) ND_TCHECK2(*(p), 16)
287