include/lttng/align.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _UST_ALIGN_H
   8 #define _UST_ALIGN_H
   9
  10 #include <lttng/bug.h>
  11 #include <unistd.h>
  12 #include <limits.h>
  13
  14 #ifdef __FreeBSD__
  15 #include <machine/param.h>
  16 #endif
  17
  18 #ifdef _SC_PAGE_SIZE
  19 #define LTTNG_UST_PAGE_SIZE     sysconf(_SC_PAGE_SIZE)
  20 #elif defined(PAGE_SIZE)
  21 #define LTTNG_UST_PAGE_SIZE     PAGE_SIZE
  22 #else
  23 #error "Please add page size detection for your OS."
  24 #endif
  25
  26 #define LTTNG_UST_PAGE_MASK     (~(LTTNG_UST_PAGE_SIZE - 1))
  27
  28 #define __LTTNG_UST_ALIGN_MASK(v, mask) (((v) + (mask)) & ~(mask))
  29 #define LTTNG_UST_ALIGN(v, align)       __LTTNG_UST_ALIGN_MASK(v, (__typeof__(v)) (align) - 1)
  30 #define LTTNG_UST_PAGE_ALIGN(addr)      LTTNG_UST_ALIGN(addr, LTTNG_UST_PAGE_SIZE)
  31
  32 /**
  33  * lttng_ust_offset_align - Calculate the offset needed to align an object on
  34  *                its natural alignment towards higher addresses.
  35  * @align_drift:  object offset from an "alignment"-aligned address.
  36  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  37  *
  38  * Returns the offset that must be added to align towards higher
  39  * addresses.
  40  */
  41 #define lttng_ust_offset_align(align_drift, alignment)                         \
  42         ({                                                                     \
  43                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  44                                    || ((alignment) & ((alignment) - 1)));      \
  45                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  46         })
  47
  48 /**
  49  * lttng_ust_offset_align_floor - Calculate the offset needed to align an
  50  *                object on its natural alignment towards lower addresses.
  51  * @align_drift:  object offset from an "alignment"-aligned address.
  52  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  53  *
  54  * Returns the offset that must be substracted to align towards lower addresses.
  55  */
  56 #define lttng_ust_offset_align_floor(align_drift, alignment)                   \
  57         ({                                                                     \
  58                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  59                                    || ((alignment) & ((alignment) - 1)));      \
  60                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  61         })
  62
  63 /*
  64  * Non-namespaced defines for backwards compatibility,
  65  * introduced in 2.13, should be removed in the future.
  66  */
  67
  68 /* Cygwin limits.h defines its own PAGE_SIZE */
  69 #ifndef PAGE_SIZE
  70 #define PAGE_SIZE       LTTNG_UST_PAGE_SIZE
  71 #endif
  72
  73 /* FreeBSD and macOS defines their own PAGE_MASK. */
  74 #ifndef PAGE_MASK
  75 #define PAGE_MASK       LTTNG_UST_PAGE_MASK
  76 #endif
  77
  78 /* FreeBSD machine/param.h defines its own ALIGN */
  79 #ifndef ALIGN
  80 #define ALIGN           LTTNG_UST_ALIGN
  81 #endif
  82
  83 #ifndef PAGE_ALIGN
  84 #define PAGE_ALIGN      LTTNG_UST_PAGE_ALIGN
  85 #endif
  86
  87 #ifndef offset_align
  88 #define offset_align lttng_ust_offset_align
  89 #endif
  90
  91 #ifndef offset_align_floor
  92 #define offset_align_floor lttng_ust_offset_align_floor
  93 #endif
  94
  95 #endif /* _UST_ALIGN_H */