include/asm-generic/bitops/instrumented-non-atomic.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 /*
   4  * This file provides wrappers with sanitizer instrumentation for non-atomic
   5  * bit operations.
   6  *
   7  * To use this functionality, an arch's bitops.h file needs to define each of
   8  * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
   9  * arch___set_bit(), etc.).
  10  */
  11 #ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
  12 #define _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
  13
  14 #include <linux/instrumented.h>
  15
  16 /**
  17  * __set_bit - Set a bit in memory
  18  * @nr: the bit to set
  19  * @addr: the address to start counting from
  20  *
  21  * Unlike set_bit(), this function is non-atomic. If it is called on the same
  22  * region of memory concurrently, the effect may be that only one operation
  23  * succeeds.
  24  */
  25 static inline void __set_bit(long nr, volatile unsigned long *addr)
  26 {
  27         instrument_write(addr + BIT_WORD(nr), sizeof(long));
  28         arch___set_bit(nr, addr);
  29 }
  30
  31 /**
  32  * __clear_bit - Clears a bit in memory
  33  * @nr: the bit to clear
  34  * @addr: the address to start counting from
  35  *
  36  * Unlike clear_bit(), this function is non-atomic. If it is called on the same
  37  * region of memory concurrently, the effect may be that only one operation
  38  * succeeds.
  39  */
  40 static inline void __clear_bit(long nr, volatile unsigned long *addr)
  41 {
  42         instrument_write(addr + BIT_WORD(nr), sizeof(long));
  43         arch___clear_bit(nr, addr);
  44 }
  45
  46 /**
  47  * __change_bit - Toggle a bit in memory
  48  * @nr: the bit to change
  49  * @addr: the address to start counting from
  50  *
  51  * Unlike change_bit(), this function is non-atomic. If it is called on the same
  52  * region of memory concurrently, the effect may be that only one operation
  53  * succeeds.
  54  */
  55 static inline void __change_bit(long nr, volatile unsigned long *addr)
  56 {
  57         instrument_write(addr + BIT_WORD(nr), sizeof(long));
  58         arch___change_bit(nr, addr);
  59 }
  60
  61 static inline void __instrument_read_write_bitop(long nr, volatile unsigned long *addr)
  62 {
  63         if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC)) {
  64                 /*
  65                  * We treat non-atomic read-write bitops a little more special.
  66                  * Given the operations here only modify a single bit, assuming
  67                  * non-atomicity of the writer is sufficient may be reasonable
  68                  * for certain usage (and follows the permissible nature of the
  69                  * assume-plain-writes-atomic rule):
  70                  * 1. report read-modify-write races -> check read;
  71                  * 2. do not report races with marked readers, but do report
  72                  *    races with unmarked readers -> check "atomic" write.
  73                  */
  74                 kcsan_check_read(addr + BIT_WORD(nr), sizeof(long));
  75                 /*
  76                  * Use generic write instrumentation, in case other sanitizers
  77                  * or tools are enabled alongside KCSAN.
  78                  */
  79                 instrument_write(addr + BIT_WORD(nr), sizeof(long));
  80         } else {
  81                 instrument_read_write(addr + BIT_WORD(nr), sizeof(long));
  82         }
  83 }
  84
  85 /**
  86  * __test_and_set_bit - Set a bit and return its old value
  87  * @nr: Bit to set
  88  * @addr: Address to count from
  89  *
  90  * This operation is non-atomic. If two instances of this operation race, one
  91  * can appear to succeed but actually fail.
  92  */
  93 static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr)
  94 {
  95         __instrument_read_write_bitop(nr, addr);
  96         return arch___test_and_set_bit(nr, addr);
  97 }
  98
  99 /**
 100  * __test_and_clear_bit - Clear a bit and return its old value
 101  * @nr: Bit to clear
 102  * @addr: Address to count from
 103  *
 104  * This operation is non-atomic. If two instances of this operation race, one
 105  * can appear to succeed but actually fail.
 106  */
 107 static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr)
 108 {
 109         __instrument_read_write_bitop(nr, addr);
 110         return arch___test_and_clear_bit(nr, addr);
 111 }
 112
 113 /**
 114  * __test_and_change_bit - Change a bit and return its old value
 115  * @nr: Bit to change
 116  * @addr: Address to count from
 117  *
 118  * This operation is non-atomic. If two instances of this operation race, one
 119  * can appear to succeed but actually fail.
 120  */
 121 static inline bool __test_and_change_bit(long nr, volatile unsigned long *addr)
 122 {
 123         __instrument_read_write_bitop(nr, addr);
 124         return arch___test_and_change_bit(nr, addr);
 125 }
 126
 127 /**
 128  * test_bit - Determine whether a bit is set
 129  * @nr: bit number to test
 130  * @addr: Address to start counting from
 131  */
 132 static inline bool test_bit(long nr, const volatile unsigned long *addr)
 133 {
 134         instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long));
 135         return arch_test_bit(nr, addr);
 136 }
 137
 138 #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */