LXR linux/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/*
  94 * sparse (__CHECKER__) pretends to be gcc, but can't do constant
  95 * folding in __builtin_bswap*() (yet), so don't set these for it.
  96 */
  97#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
  98#define __HAVE_BUILTIN_BSWAP32__
  99#define __HAVE_BUILTIN_BSWAP64__
 100#define __HAVE_BUILTIN_BSWAP16__
 101#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
 102
 103#if GCC_VERSION >= 70000
 104#define KASAN_ABI_VERSION 5
 105#elif GCC_VERSION >= 50000
 106#define KASAN_ABI_VERSION 4
 107#elif GCC_VERSION >= 40902
 108#define KASAN_ABI_VERSION 3
 109#endif
 110
 111#if __has_attribute(__no_sanitize_address__)
 112#define __no_sanitize_address __attribute__((no_sanitize_address))
 113#else
 114#define __no_sanitize_address
 115#endif
 116
 117#if defined(__SANITIZE_THREAD__) && __has_attribute(__no_sanitize_thread__)
 118#define __no_sanitize_thread __attribute__((no_sanitize_thread))
 119#else
 120#define __no_sanitize_thread
 121#endif
 122
 123#if __has_attribute(__no_sanitize_undefined__)
 124#define __no_sanitize_undefined __attribute__((no_sanitize_undefined))
 125#else
 126#define __no_sanitize_undefined
 127#endif
 128
 129#if GCC_VERSION >= 50100
 130#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
 131#endif
 132
 133/*
 134 * Turn individual warnings and errors on and off locally, depending
 135 * on version.
 136 */
 137#define __diag_GCC(version, severity, s) \
 138        __diag_GCC_ ## version(__diag_GCC_ ## severity s)
 139
 140/* Severity used in pragma directives */
 141#define __diag_GCC_ignore       ignored
 142#define __diag_GCC_warn         warning
 143#define __diag_GCC_error        error
 144
 145#define __diag_str1(s)          #s
 146#define __diag_str(s)           __diag_str1(s)
 147#define __diag(s)               _Pragma(__diag_str(GCC diagnostic s))
 148
 149#if GCC_VERSION >= 80000
 150#define __diag_GCC_8(s)         __diag(s)
 151#else
 152#define __diag_GCC_8(s)
 153#endif
 154