include/lttng/align.h

   1 #ifndef _UST_ALIGN_H
   2 #define _UST_ALIGN_H
   3
   4 /*
   5  * lttng/align.h
   6  *
   7  * (C) Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  25  * SOFTWARE.
  26  */
  27
  28 #include <lttng/bug.h>
  29 #include <unistd.h>
  30 #include <limits.h>
  31
  32 #ifdef __FreeBSD__
  33 #include <machine/param.h>
  34 #endif
  35
  36 #ifdef _SC_PAGE_SIZE
  37 #define LTTNG_UST_PAGE_SIZE     sysconf(_SC_PAGE_SIZE)
  38 #elif defined(PAGE_SIZE)
  39 #define LTTNG_UST_PAGE_SIZE     PAGE_SIZE
  40 #else
  41 #error "Please add page size detection for your OS."
  42 #endif
  43
  44 #define LTTNG_UST_PAGE_MASK     (~(LTTNG_UST_PAGE_SIZE - 1))
  45
  46 #define __LTTNG_UST_ALIGN_MASK(v, mask) (((v) + (mask)) & ~(mask))
  47 #define LTTNG_UST_ALIGN(v, align)       __LTTNG_UST_ALIGN_MASK(v, (__typeof__(v)) (align) - 1)
  48 #define LTTNG_UST_PAGE_ALIGN(addr)      LTTNG_UST_ALIGN(addr, LTTNG_UST_PAGE_SIZE)
  49
  50 /**
  51  * lttng_ust_offset_align - Calculate the offset needed to align an object on
  52  *                its natural alignment towards higher addresses.
  53  * @align_drift:  object offset from an "alignment"-aligned address.
  54  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  55  *
  56  * Returns the offset that must be added to align towards higher
  57  * addresses.
  58  */
  59 #define lttng_ust_offset_align(align_drift, alignment)                         \
  60         ({                                                                     \
  61                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  62                                    || ((alignment) & ((alignment) - 1)));      \
  63                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  64         })
  65
  66 /**
  67  * lttng_ust_offset_align_floor - Calculate the offset needed to align an
  68  *                object on its natural alignment towards lower addresses.
  69  * @align_drift:  object offset from an "alignment"-aligned address.
  70  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  71  *
  72  * Returns the offset that must be substracted to align towards lower addresses.
  73  */
  74 #define lttng_ust_offset_align_floor(align_drift, alignment)                   \
  75         ({                                                                     \
  76                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  77                                    || ((alignment) & ((alignment) - 1)));      \
  78                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  79         })
  80
  81 /*
  82  * Non-namespaced defines for backwards compatibility,
  83  * introduced in 2.13, should be removed in the future.
  84  */
  85
  86 /* Cygwin limits.h defines its own PAGE_SIZE */
  87 #ifndef PAGE_SIZE
  88 #define PAGE_SIZE       LTTNG_UST_PAGE_SIZE
  89 #endif
  90
  91 /* FreeBSD and macOS defines their own PAGE_MASK. */
  92 #ifndef PAGE_MASK
  93 #define PAGE_MASK       LTTNG_UST_PAGE_MASK
  94 #endif
  95
  96 /* FreeBSD machine/param.h defines its own ALIGN */
  97 #ifndef ALIGN
  98 #define ALIGN           LTTNG_UST_ALIGN
  99 #endif
 100
 101 #ifndef PAGE_ALIGN
 102 #define PAGE_ALIGN      LTTNG_UST_PAGE_ALIGN
 103 #endif
 104
 105 #ifndef offset_align
 106 #define offset_align lttng_ust_offset_align
 107 #endif
 108
 109 #ifndef offset_align_floor
 110 #define offset_align_floor lttng_ust_offset_align_floor
 111 #endif
 112
 113 #endif /* _UST_ALIGN_H */