src/rseq-utils.h

   1 // SPDX-License-Identifier: MIT
   2 // SPDX-FileCopyrightText: 2024 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3
   4 #ifndef _RSEQ_COMMON_UTILS_H
   5 #define _RSEQ_COMMON_UTILS_H
   6
   7 #include <stdbool.h>
   8 #include <stdint.h>
   9
  10 #define RSEQ_ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
  11
  12 #define __rseq_align_mask(v, mask)      (((v) + (mask)) & ~(mask))
  13 #define rseq_align(v, align)            __rseq_align_mask(v, (__typeof__(v)) (align) - 1)
  14
  15 static inline
  16 unsigned int rseq_fls_u64(uint64_t x)
  17 {
  18         unsigned int r = 64;
  19
  20         if (!x)
  21                 return 0;
  22
  23         if (!(x & 0xFFFFFFFF00000000ULL)) {
  24                 x <<= 32;
  25                 r -= 32;
  26         }
  27         if (!(x & 0xFFFF000000000000ULL)) {
  28                 x <<= 16;
  29                 r -= 16;
  30         }
  31         if (!(x & 0xFF00000000000000ULL)) {
  32                 x <<= 8;
  33                 r -= 8;
  34         }
  35         if (!(x & 0xF000000000000000ULL)) {
  36                 x <<= 4;
  37                 r -= 4;
  38         }
  39         if (!(x & 0xC000000000000000ULL)) {
  40                 x <<= 2;
  41                 r -= 2;
  42         }
  43         if (!(x & 0x8000000000000000ULL)) {
  44                 x <<= 1;
  45                 r -= 1;
  46         }
  47         return r;
  48 }
  49
  50 static inline
  51 unsigned int rseq_fls_u32(uint32_t x)
  52 {
  53         unsigned int r = 32;
  54
  55         if (!x)
  56                 return 0;
  57         if (!(x & 0xFFFF0000U)) {
  58                 x <<= 16;
  59                 r -= 16;
  60         }
  61         if (!(x & 0xFF000000U)) {
  62                 x <<= 8;
  63                 r -= 8;
  64         }
  65         if (!(x & 0xF0000000U)) {
  66                 x <<= 4;
  67                 r -= 4;
  68         }
  69         if (!(x & 0xC0000000U)) {
  70                 x <<= 2;
  71                 r -= 2;
  72         }
  73         if (!(x & 0x80000000U)) {
  74                 x <<= 1;
  75                 r -= 1;
  76         }
  77         return r;
  78 }
  79
  80 static inline
  81 unsigned int rseq_fls_ulong(unsigned long x)
  82 {
  83 #if RSEQ_BITS_PER_LONG == 32
  84         return rseq_fls_u32(x);
  85 #else
  86         return rseq_fls_u64(x);
  87 #endif
  88 }
  89
  90 /*
  91  * Return the minimum order for which x <= (1UL << order).
  92  * Return -1 if x is 0.
  93  */
  94 static inline
  95 int rseq_get_count_order_ulong(unsigned long x)
  96 {
  97         if (!x)
  98                 return -1;
  99
 100         return rseq_fls_ulong(x - 1);
 101 }
 102
 103 #define RSEQ_DEFAULT_PAGE_SIZE  4096
 104
 105 static inline
 106 unsigned long rseq_get_page_len(void)
 107 {
 108         long page_len = sysconf(_SC_PAGE_SIZE);
 109
 110         if (page_len < 0)
 111                 page_len = RSEQ_DEFAULT_PAGE_SIZE;
 112         return (unsigned long) page_len;
 113 }
 114
 115 static inline
 116 int rseq_hweight_ulong(unsigned long v)
 117 {
 118         return __builtin_popcountl(v);
 119 }
 120
 121 static inline
 122 bool is_pow2(uint64_t x)
 123 {
 124         return !(x & (x - 1));
 125 }
 126
 127 /*
 128  * Calculate offset needed to align p on alignment towards higher
 129  * addresses. Alignment must be a power of 2
 130  */
 131 static inline
 132 off_t offset_align(uintptr_t p, size_t alignment)
 133 {
 134         return (alignment - p) & (alignment - 1);
 135 }
 136
 137 #endif /* _RSEQ_COMMON_UTILS_H */