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#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  47#define __latent_entropy __attribute__((latent_entropy))
  48#endif
  49
  50/*
  51 * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
  52 * confuse the stack allocation in gcc, leading to overly large stack
  53 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
  54 *
  55 * Adding an empty inline assembly before it works around the problem
  56 */
  57#define barrier_before_unreachable() asm volatile("")
  58
  59/*
  60 * Mark a position in code as unreachable.  This can be used to
  61 * suppress control flow warnings after asm blocks that transfer
  62 * control elsewhere.
  63 */
  64#define unreachable() \
  65        do {                                    \
  66                annotate_unreachable();         \
  67                barrier_before_unreachable();   \
  68                __builtin_unreachable();        \
  69        } while (0)
  70
  71#if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
  72#define __randomize_layout __attribute__((randomize_layout))
  73#define __no_randomize_layout __attribute__((no_randomize_layout))
  74/* This anon struct can add padding, so only enable it under randstruct. */
  75#define randomized_struct_fields_start  struct {
  76#define randomized_struct_fields_end    } __randomize_layout;
  77#endif
  78
  79/*
  80 * GCC 'asm goto' miscompiles certain code sequences:
  81 *
  82 *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
  83 *
  84 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
  85 *
  86 * (asm goto is automatically volatile - the naming reflects this.)
  87 */
  88#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
  89
  90#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
  91#define __HAVE_BUILTIN_BSWAP32__
  92#define __HAVE_BUILTIN_BSWAP64__
  93#define __HAVE_BUILTIN_BSWAP16__
  94#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
  95
  96#if GCC_VERSION >= 70000
  97#define KASAN_ABI_VERSION 5
  98#else
  99#define KASAN_ABI_VERSION 4
 100#endif
 101
 102#if __has_attribute(__no_sanitize_address__)
 103#define __no_sanitize_address __attribute__((no_sanitize_address))
 104#else
 105#define __no_sanitize_address
 106#endif
 107
 108#if defined(__SANITIZE_THREAD__) && __has_attribute(__no_sanitize_thread__)
 109#define __no_sanitize_thread __attribute__((no_sanitize_thread))
 110#else
 111#define __no_sanitize_thread
 112#endif
 113
 114#if __has_attribute(__no_sanitize_undefined__)
 115#define __no_sanitize_undefined __attribute__((no_sanitize_undefined))
 116#else
 117#define __no_sanitize_undefined
 118#endif
 119
 120#if defined(CONFIG_KCOV) && __has_attribute(__no_sanitize_coverage__)
 121#define __no_sanitize_coverage __attribute__((no_sanitize_coverage))
 122#else
 123#define __no_sanitize_coverage
 124#endif
 125
 126/*
 127 * Turn individual warnings and errors on and off locally, depending
 128 * on version.
 129 */
 130#define __diag_GCC(version, severity, s) \
 131        __diag_GCC_ ## version(__diag_GCC_ ## severity s)
 132
 133/* Severity used in pragma directives */
 134#define __diag_GCC_ignore       ignored
 135#define __diag_GCC_warn         warning
 136#define __diag_GCC_error        error
 137
 138#define __diag_str1(s)          #s
 139#define __diag_str(s)           __diag_str1(s)
 140#define __diag(s)               _Pragma(__diag_str(GCC diagnostic s))
 141
 142#if GCC_VERSION >= 80000
 143#define __diag_GCC_8(s)         __diag(s)
 144#else
 145#define __diag_GCC_8(s)
 146#endif
 147