include/linux/compiler-gcc.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __LINUX_COMPILER_TYPES_H
   3 #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
   4 #endif
   5
   6 /*
   7  * Common definitions for all gcc versions go here.
   8  */
   9 #define GCC_VERSION (__GNUC__ * 10000           \
  10                      + __GNUC_MINOR__ * 100     \
  11                      + __GNUC_PATCHLEVEL__)
  12
  13 /*
  14  * This macro obfuscates arithmetic on a variable address so that gcc
  15  * shouldn't recognize the original var, and make assumptions about it.
  16  *
  17  * This is needed because the C standard makes it undefined to do
  18  * pointer arithmetic on "objects" outside their boundaries and the
  19  * gcc optimizers assume this is the case. In particular they
  20  * assume such arithmetic does not wrap.
  21  *
  22  * A miscompilation has been observed because of this on PPC.
  23  * To work around it we hide the relationship of the pointer and the object
  24  * using this macro.
  25  *
  26  * Versions of the ppc64 compiler before 4.1 had a bug where use of
  27  * RELOC_HIDE could trash r30. The bug can be worked around by changing
  28  * the inline assembly constraint from =g to =r, in this particular
  29  * case either is valid.
  30  */
  31 #define RELOC_HIDE(ptr, off)                                            \
  32 ({                                                                      \
  33         unsigned long __ptr;                                            \
  34         __asm__ ("" : "=r"(__ptr) : "0"(ptr));                          \
  35         (typeof(ptr)) (__ptr + (off));                                  \
  36 })
  37
  38 #ifdef CONFIG_RETPOLINE
  39 #define __noretpoline __attribute__((__indirect_branch__("keep")))
  40 #endif
  41
  42 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
  43
  44 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
  45
  46 #define __compiletime_warning(message) __attribute__((__warning__(message)))
  47 #define __compiletime_error(message) __attribute__((__error__(message)))
  48
  49 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  50 #define __latent_entropy __attribute__((latent_entropy))
  51 #endif
  52
  53 /*
  54  * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
  55  * confuse the stack allocation in gcc, leading to overly large stack
  56  * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
  57  *
  58  * Adding an empty inline assembly before it works around the problem
  59  */
  60 #define barrier_before_unreachable() asm volatile("")
  61
  62 /*
  63  * Mark a position in code as unreachable.  This can be used to
  64  * suppress control flow warnings after asm blocks that transfer
  65  * control elsewhere.
  66  */
  67 #define unreachable() \
  68         do {                                    \
  69                 annotate_unreachable();         \
  70                 barrier_before_unreachable();   \
  71                 __builtin_unreachable();        \
  72         } while (0)
  73
  74 #if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
  75 #define __randomize_layout __attribute__((randomize_layout))
  76 #define __no_randomize_layout __attribute__((no_randomize_layout))
  77 /* This anon struct can add padding, so only enable it under randstruct. */
  78 #define randomized_struct_fields_start  struct {
  79 #define randomized_struct_fields_end    } __randomize_layout;
  80 #endif
  81
  82 /*
  83  * GCC 'asm goto' miscompiles certain code sequences:
  84  *
  85  *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
  86  *
  87  * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
  88  *
  89  * (asm goto is automatically volatile - the naming reflects this.)
  90  */
  91 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
  92
  93 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
  94 #define __HAVE_BUILTIN_BSWAP32__
  95 #define __HAVE_BUILTIN_BSWAP64__
  96 #define __HAVE_BUILTIN_BSWAP16__
  97 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
  98
  99 #if GCC_VERSION >= 70000
 100 #define KASAN_ABI_VERSION 5
 101 #elif GCC_VERSION >= 50000
 102 #define KASAN_ABI_VERSION 4
 103 #elif GCC_VERSION >= 40902
 104 #define KASAN_ABI_VERSION 3
 105 #endif
 106
 107 #if __has_attribute(__no_sanitize_address__)
 108 #define __no_sanitize_address __attribute__((no_sanitize_address))
 109 #else
 110 #define __no_sanitize_address
 111 #endif
 112
 113 #if defined(__SANITIZE_THREAD__) && __has_attribute(__no_sanitize_thread__)
 114 #define __no_sanitize_thread __attribute__((no_sanitize_thread))
 115 #else
 116 #define __no_sanitize_thread
 117 #endif
 118
 119 #if __has_attribute(__no_sanitize_undefined__)
 120 #define __no_sanitize_undefined __attribute__((no_sanitize_undefined))
 121 #else
 122 #define __no_sanitize_undefined
 123 #endif
 124
 125 #if GCC_VERSION >= 50100
 126 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
 127 #endif
 128
 129 /*
 130  * Turn individual warnings and errors on and off locally, depending
 131  * on version.
 132  */
 133 #define __diag_GCC(version, severity, s) \
 134         __diag_GCC_ ## version(__diag_GCC_ ## severity s)
 135
 136 /* Severity used in pragma directives */
 137 #define __diag_GCC_ignore       ignored
 138 #define __diag_GCC_warn         warning
 139 #define __diag_GCC_error        error
 140
 141 #define __diag_str1(s)          #s
 142 #define __diag_str(s)           __diag_str1(s)
 143 #define __diag(s)               _Pragma(__diag_str(GCC diagnostic s))
 144
 145 #if GCC_VERSION >= 80000
 146 #define __diag_GCC_8(s)         __diag(s)
 147 #else
 148 #define __diag_GCC_8(s)
 149 #endif