1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_BITOPS_H
3 #define _LINUX_BITOPS_H
4
5 #include <asm/types.h>
6 #include <linux/bits.h>
7 #include <linux/typecheck.h>
8
9 #include <uapi/linux/kernel.h>
10
11 #define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
12 #define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
13 #define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
14 #define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
15 #define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
16
17 #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_BYTE)
18
19 extern unsigned int __sw_hweight8(unsigned int w);
20 extern unsigned int __sw_hweight16(unsigned int w);
21 extern unsigned int __sw_hweight32(unsigned int w);
22 extern unsigned long __sw_hweight64(__u64 w);
23
24 /*
25 * Defined here because those may be needed by architecture-specific static
26 * inlines.
27 */
28
29 #include <asm-generic/bitops/generic-non-atomic.h>
30
31 /*
32 * Many architecture-specific non-atomic bitops contain inline asm code and due
33 * to that the compiler can't optimize them to compile-time expressions or
34 * constants. In contrary, generic_*() helpers are defined in pure C and
35 * compilers optimize them just well.
36 * Therefore, to make `unsigned long foo = 0; __set_bit(BAR, &foo)` effectively
37 * equal to `unsigned long foo = BIT(BAR)`, pick the generic C alternative when
38 * the arguments can be resolved at compile time. That expression itself is a
39 * constant and doesn't bring any functional changes to the rest of cases.
40 * The casts to `uintptr_t` are needed to mitigate `-Waddress` warnings when
41 * passing a bitmap from .bss or .data (-> `!!addr` is always true).
42 */
43 #define bitop(op, nr, addr) \
44 ((__builtin_constant_p(nr) && \
45 __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \
46 (uintptr_t)(addr) != (uintptr_t)NULL && \
47 __builtin_constant_p(*(const unsigned long *)(addr))) ? \
48 const##op(nr, addr) : op(nr, addr))
49
50 /*
51 * The following macros are non-atomic versions of their non-underscored
52 * counterparts.
53 */
54 #define __set_bit(nr, addr) bitop(___set_bit, nr, addr)
55 #define __clear_bit(nr, addr) bitop(___clear_bit, nr, addr)
56 #define __change_bit(nr, addr) bitop(___change_bit, nr, addr)
57 #define __test_and_set_bit(nr, addr) bitop(___test_and_set_bit, nr, addr)
58 #define __test_and_clear_bit(nr, addr) bitop(___test_and_clear_bit, nr, addr)
59 #define __test_and_change_bit(nr, addr) bitop(___test_and_change_bit, nr, addr)
60
61 #define test_bit(nr, addr) bitop(_test_bit, nr, addr)
62 #define test_bit_acquire(nr, addr) bitop(_test_bit_acquire, nr, addr)
63
64 /*
65 * Include this here because some architectures need generic_ffs/fls in
66 * scope
67 */
68 #include <asm/bitops.h>
69
70 /* Check that the bitops prototypes are sane */
71 #define __check_bitop_pr(name) \
72 static_assert(__same_type(arch_##name, generic_##name) && \
73 __same_type(const_##name, generic_##name) && \
74 __same_type(_##name, generic_##name))
75
76 __check_bitop_pr(__set_bit);
77 __check_bitop_pr(__clear_bit);
78 __check_bitop_pr(__change_bit);
79 __check_bitop_pr(__test_and_set_bit);
80 __check_bitop_pr(__test_and_clear_bit);
81 __check_bitop_pr(__test_and_change_bit);
82 __check_bitop_pr(test_bit);
83 __check_bitop_pr(test_bit_acquire);
84
85 #undef __check_bitop_pr
86
get_bitmask_order(unsigned int count)87 static inline int get_bitmask_order(unsigned int count)
88 {
89 int order;
90
91 order = fls(count);
92 return order; /* We could be slightly more clever with -1 here... */
93 }
94
hweight_long(unsigned long w)95 static __always_inline unsigned long hweight_long(unsigned long w)
96 {
97 return sizeof(w) == 4 ? hweight32(w) : hweight64((__u64)w);
98 }
99
100 /**
101 * rol64 - rotate a 64-bit value left
102 * @word: value to rotate
103 * @shift: bits to roll
104 */
rol64(__u64 word,unsigned int shift)105 static inline __u64 rol64(__u64 word, unsigned int shift)
106 {
107 return (word << (shift & 63)) | (word >> ((-shift) & 63));
108 }
109
110 /**
111 * ror64 - rotate a 64-bit value right
112 * @word: value to rotate
113 * @shift: bits to roll
114 */
ror64(__u64 word,unsigned int shift)115 static inline __u64 ror64(__u64 word, unsigned int shift)
116 {
117 return (word >> (shift & 63)) | (word << ((-shift) & 63));
118 }
119
120 /**
121 * rol32 - rotate a 32-bit value left
122 * @word: value to rotate
123 * @shift: bits to roll
124 */
rol32(__u32 word,unsigned int shift)125 static inline __u32 rol32(__u32 word, unsigned int shift)
126 {
127 return (word << (shift & 31)) | (word >> ((-shift) & 31));
128 }
129
130 /**
131 * ror32 - rotate a 32-bit value right
132 * @word: value to rotate
133 * @shift: bits to roll
134 */
ror32(__u32 word,unsigned int shift)135 static inline __u32 ror32(__u32 word, unsigned int shift)
136 {
137 return (word >> (shift & 31)) | (word << ((-shift) & 31));
138 }
139
140 /**
141 * rol16 - rotate a 16-bit value left
142 * @word: value to rotate
143 * @shift: bits to roll
144 */
rol16(__u16 word,unsigned int shift)145 static inline __u16 rol16(__u16 word, unsigned int shift)
146 {
147 return (word << (shift & 15)) | (word >> ((-shift) & 15));
148 }
149
150 /**
151 * ror16 - rotate a 16-bit value right
152 * @word: value to rotate
153 * @shift: bits to roll
154 */
ror16(__u16 word,unsigned int shift)155 static inline __u16 ror16(__u16 word, unsigned int shift)
156 {
157 return (word >> (shift & 15)) | (word << ((-shift) & 15));
158 }
159
160 /**
161 * rol8 - rotate an 8-bit value left
162 * @word: value to rotate
163 * @shift: bits to roll
164 */
rol8(__u8 word,unsigned int shift)165 static inline __u8 rol8(__u8 word, unsigned int shift)
166 {
167 return (word << (shift & 7)) | (word >> ((-shift) & 7));
168 }
169
170 /**
171 * ror8 - rotate an 8-bit value right
172 * @word: value to rotate
173 * @shift: bits to roll
174 */
ror8(__u8 word,unsigned int shift)175 static inline __u8 ror8(__u8 word, unsigned int shift)
176 {
177 return (word >> (shift & 7)) | (word << ((-shift) & 7));
178 }
179
180 /**
181 * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
182 * @value: value to sign extend
183 * @index: 0 based bit index (0<=index<32) to sign bit
184 *
185 * This is safe to use for 16- and 8-bit types as well.
186 */
sign_extend32(__u32 value,int index)187 static __always_inline __s32 sign_extend32(__u32 value, int index)
188 {
189 __u8 shift = 31 - index;
190 return (__s32)(value << shift) >> shift;
191 }
192
193 /**
194 * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
195 * @value: value to sign extend
196 * @index: 0 based bit index (0<=index<64) to sign bit
197 */
sign_extend64(__u64 value,int index)198 static __always_inline __s64 sign_extend64(__u64 value, int index)
199 {
200 __u8 shift = 63 - index;
201 return (__s64)(value << shift) >> shift;
202 }
203
fls_long(unsigned long l)204 static inline unsigned int fls_long(unsigned long l)
205 {
206 if (sizeof(l) == 4)
207 return fls(l);
208 return fls64(l);
209 }
210
get_count_order(unsigned int count)211 static inline int get_count_order(unsigned int count)
212 {
213 if (count == 0)
214 return -1;
215
216 return fls(--count);
217 }
218
219 /**
220 * get_count_order_long - get order after rounding @l up to power of 2
221 * @l: parameter
222 *
223 * it is same as get_count_order() but with long type parameter
224 */
get_count_order_long(unsigned long l)225 static inline int get_count_order_long(unsigned long l)
226 {
227 if (l == 0UL)
228 return -1;
229 return (int)fls_long(--l);
230 }
231
232 /**
233 * parity8 - get the parity of an u8 value
234 * @value: the value to be examined
235 *
236 * Determine the parity of the u8 argument.
237 *
238 * Returns:
239 * 0 for even parity, 1 for odd parity
240 *
241 * Note: This function informs you about the current parity. Example to bail
242 * out when parity is odd:
243 *
244 * if (parity8(val) == 1)
245 * return -EBADMSG;
246 *
247 * If you need to calculate a parity bit, you need to draw the conclusion from
248 * this result yourself. Example to enforce odd parity, parity bit is bit 7:
249 *
250 * if (parity8(val) == 0)
251 * val ^= BIT(7);
252 */
parity8(u8 val)253 static inline int parity8(u8 val)
254 {
255 /*
256 * One explanation of this algorithm:
257 * https://funloop.org/codex/problem/parity/README.html
258 */
259 val ^= val >> 4;
260 return (0x6996 >> (val & 0xf)) & 1;
261 }
262
263 /**
264 * __ffs64 - find first set bit in a 64 bit word
265 * @word: The 64 bit word
266 *
267 * On 64 bit arches this is a synonym for __ffs
268 * The result is not defined if no bits are set, so check that @word
269 * is non-zero before calling this.
270 */
__ffs64(u64 word)271 static inline unsigned int __ffs64(u64 word)
272 {
273 #if BITS_PER_LONG == 32
274 if (((u32)word) == 0UL)
275 return __ffs((u32)(word >> 32)) + 32;
276 #elif BITS_PER_LONG != 64
277 #error BITS_PER_LONG not 32 or 64
278 #endif
279 return __ffs((unsigned long)word);
280 }
281
282 /**
283 * fns - find N'th set bit in a word
284 * @word: The word to search
285 * @n: Bit to find
286 */
fns(unsigned long word,unsigned int n)287 static inline unsigned int fns(unsigned long word, unsigned int n)
288 {
289 while (word && n--)
290 word &= word - 1;
291
292 return word ? __ffs(word) : BITS_PER_LONG;
293 }
294
295 /**
296 * assign_bit - Assign value to a bit in memory
297 * @nr: the bit to set
298 * @addr: the address to start counting from
299 * @value: the value to assign
300 */
301 #define assign_bit(nr, addr, value) \
302 ((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr)))
303
304 #define __assign_bit(nr, addr, value) \
305 ((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr)))
306
307 /**
308 * __ptr_set_bit - Set bit in a pointer's value
309 * @nr: the bit to set
310 * @addr: the address of the pointer variable
311 *
312 * Example:
313 * void *p = foo();
314 * __ptr_set_bit(bit, &p);
315 */
316 #define __ptr_set_bit(nr, addr) \
317 ({ \
318 typecheck_pointer(*(addr)); \
319 __set_bit(nr, (unsigned long *)(addr)); \
320 })
321
322 /**
323 * __ptr_clear_bit - Clear bit in a pointer's value
324 * @nr: the bit to clear
325 * @addr: the address of the pointer variable
326 *
327 * Example:
328 * void *p = foo();
329 * __ptr_clear_bit(bit, &p);
330 */
331 #define __ptr_clear_bit(nr, addr) \
332 ({ \
333 typecheck_pointer(*(addr)); \
334 __clear_bit(nr, (unsigned long *)(addr)); \
335 })
336
337 /**
338 * __ptr_test_bit - Test bit in a pointer's value
339 * @nr: the bit to test
340 * @addr: the address of the pointer variable
341 *
342 * Example:
343 * void *p = foo();
344 * if (__ptr_test_bit(bit, &p)) {
345 * ...
346 * } else {
347 * ...
348 * }
349 */
350 #define __ptr_test_bit(nr, addr) \
351 ({ \
352 typecheck_pointer(*(addr)); \
353 test_bit(nr, (unsigned long *)(addr)); \
354 })
355
356 #ifdef __KERNEL__
357
358 #ifndef set_mask_bits
359 #define set_mask_bits(ptr, mask, bits) \
360 ({ \
361 const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \
362 typeof(*(ptr)) old__, new__; \
363 \
364 old__ = READ_ONCE(*(ptr)); \
365 do { \
366 new__ = (old__ & ~mask__) | bits__; \
367 } while (!try_cmpxchg(ptr, &old__, new__)); \
368 \
369 old__; \
370 })
371 #endif
372
373 #ifndef bit_clear_unless
374 #define bit_clear_unless(ptr, clear, test) \
375 ({ \
376 const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
377 typeof(*(ptr)) old__, new__; \
378 \
379 old__ = READ_ONCE(*(ptr)); \
380 do { \
381 if (old__ & test__) \
382 break; \
383 new__ = old__ & ~clear__; \
384 } while (!try_cmpxchg(ptr, &old__, new__)); \
385 \
386 !(old__ & test__); \
387 })
388 #endif
389
390 #endif /* __KERNEL__ */
391 #endif
392