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 /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 */
  14 #if GCC_VERSION < 40800
  15 # error Sorry, your compiler is too old - please upgrade it.
  16 #endif
  17
  18 /* Optimization barrier */
  19
  20 /* The "volatile" is due to gcc bugs */
  21 #define barrier() __asm__ __volatile__("": : :"memory")
  22 /*
  23  * This version is i.e. to prevent dead stores elimination on @ptr
  24  * where gcc and llvm may behave differently when otherwise using
  25  * normal barrier(): while gcc behavior gets along with a normal
  26  * barrier(), llvm needs an explicit input variable to be assumed
  27  * clobbered. The issue is as follows: while the inline asm might
  28  * access any memory it wants, the compiler could have fit all of
  29  * @ptr into memory registers instead, and since @ptr never escaped
  30  * from that, it proved that the inline asm wasn't touching any of
  31  * it. This version works well with both compilers, i.e. we're telling
  32  * the compiler that the inline asm absolutely may see the contents
  33  * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
  34  */
  35 #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
  36
  37 /*
  38  * This macro obfuscates arithmetic on a variable address so that gcc
  39  * shouldn't recognize the original var, and make assumptions about it.
  40  *
  41  * This is needed because the C standard makes it undefined to do
  42  * pointer arithmetic on "objects" outside their boundaries and the
  43  * gcc optimizers assume this is the case. In particular they
  44  * assume such arithmetic does not wrap.
  45  *
  46  * A miscompilation has been observed because of this on PPC.
  47  * To work around it we hide the relationship of the pointer and the object
  48  * using this macro.
  49  *
  50  * Versions of the ppc64 compiler before 4.1 had a bug where use of
  51  * RELOC_HIDE could trash r30. The bug can be worked around by changing
  52  * the inline assembly constraint from =g to =r, in this particular
  53  * case either is valid.
  54  */
  55 #define RELOC_HIDE(ptr, off)                                            \
  56 ({                                                                      \
  57         unsigned long __ptr;                                            \
  58         __asm__ ("" : "=r"(__ptr) : "0"(ptr));                          \
  59         (typeof(ptr)) (__ptr + (off));                                  \
  60 })
  61
  62 /*
  63  * A trick to suppress uninitialized variable warning without generating any
  64  * code
  65  */
  66 #define uninitialized_var(x) x = x
  67
  68 #ifdef CONFIG_RETPOLINE
  69 #define __noretpoline __attribute__((__indirect_branch__("keep")))
  70 #endif
  71
  72 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
  73
  74 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
  75
  76 #define __compiletime_warning(message) __attribute__((__warning__(message)))
  77 #define __compiletime_error(message) __attribute__((__error__(message)))
  78
  79 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  80 #define __latent_entropy __attribute__((latent_entropy))
  81 #endif
  82
  83 /*
  84  * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
  85  * confuse the stack allocation in gcc, leading to overly large stack
  86  * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
  87  *
  88  * Adding an empty inline assembly before it works around the problem
  89  */
  90 #define barrier_before_unreachable() asm volatile("")
  91
  92 /*
  93  * Mark a position in code as unreachable.  This can be used to
  94  * suppress control flow warnings after asm blocks that transfer
  95  * control elsewhere.
  96  */
  97 #define unreachable() \
  98         do {                                    \
  99                 annotate_unreachable();         \
 100                 barrier_before_unreachable();   \
 101                 __builtin_unreachable();        \
 102         } while (0)
 103
 104 #if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
 105 #define __randomize_layout __attribute__((randomize_layout))
 106 #define __no_randomize_layout __attribute__((no_randomize_layout))
 107 /* This anon struct can add padding, so only enable it under randstruct. */
 108 #define randomized_struct_fields_start  struct {
 109 #define randomized_struct_fields_end    } __randomize_layout;
 110 #endif
 111
 112 /*
 113  * GCC 'asm goto' miscompiles certain code sequences:
 114  *
 115  *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
 116  *
 117  * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
 118  *
 119  * (asm goto is automatically volatile - the naming reflects this.)
 120  */
 121 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
 122
 123 /*
 124  * sparse (__CHECKER__) pretends to be gcc, but can't do constant
 125  * folding in __builtin_bswap*() (yet), so don't set these for it.
 126  */
 127 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
 128 #define __HAVE_BUILTIN_BSWAP32__
 129 #define __HAVE_BUILTIN_BSWAP64__
 130 #define __HAVE_BUILTIN_BSWAP16__
 131 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
 132
 133 #if GCC_VERSION >= 70000
 134 #define KASAN_ABI_VERSION 5
 135 #elif GCC_VERSION >= 50000
 136 #define KASAN_ABI_VERSION 4
 137 #elif GCC_VERSION >= 40902
 138 #define KASAN_ABI_VERSION 3
 139 #endif
 140
 141 #if __has_attribute(__no_sanitize_address__)
 142 #define __no_sanitize_address __attribute__((no_sanitize_address))
 143 #else
 144 #define __no_sanitize_address
 145 #endif
 146
 147 #if GCC_VERSION >= 50100
 148 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
 149 #endif
 150
 151 /*
 152  * Turn individual warnings and errors on and off locally, depending
 153  * on version.
 154  */
 155 #define __diag_GCC(version, severity, s) \
 156         __diag_GCC_ ## version(__diag_GCC_ ## severity s)
 157
 158 /* Severity used in pragma directives */
 159 #define __diag_GCC_ignore       ignored
 160 #define __diag_GCC_warn         warning
 161 #define __diag_GCC_error        error
 162
 163 #define __diag_str1(s)          #s
 164 #define __diag_str(s)           __diag_str1(s)
 165 #define __diag(s)               _Pragma(__diag_str(GCC diagnostic s))
 166
 167 #if GCC_VERSION >= 80000
 168 #define __diag_GCC_8(s)         __diag(s)
 169 #else
 170 #define __diag_GCC_8(s)
 171 #endif
 172
 173 #define __no_fgcse __attribute__((optimize("-fno-gcse")))