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 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  45 #define __latent_entropy __attribute__((latent_entropy))
  46 #endif
  47
  48 /*
  49  * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
  50  * confuse the stack allocation in gcc, leading to overly large stack
  51  * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
  52  *
  53  * Adding an empty inline assembly before it works around the problem
  54  */
  55 #define barrier_before_unreachable() asm volatile("")
  56
  57 /*
  58  * Mark a position in code as unreachable.  This can be used to
  59  * suppress control flow warnings after asm blocks that transfer
  60  * control elsewhere.
  61  */
  62 #define unreachable() \
  63         do {                                    \
  64                 annotate_unreachable();         \
  65                 barrier_before_unreachable();   \
  66                 __builtin_unreachable();        \
  67         } while (0)
  68
  69 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
  70 #define __HAVE_BUILTIN_BSWAP32__
  71 #define __HAVE_BUILTIN_BSWAP64__
  72 #define __HAVE_BUILTIN_BSWAP16__
  73 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
  74
  75 #if GCC_VERSION >= 70000
  76 #define KASAN_ABI_VERSION 5
  77 #else
  78 #define KASAN_ABI_VERSION 4
  79 #endif
  80
  81 #ifdef CONFIG_SHADOW_CALL_STACK
  82 #define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
  83 #endif
  84
  85 #define __no_sanitize_address __attribute__((__no_sanitize_address__))
  86
  87 #if defined(__SANITIZE_THREAD__) && __has_attribute(__no_sanitize_thread__)
  88 #define __no_sanitize_thread __attribute__((__no_sanitize_thread__))
  89 #else
  90 #define __no_sanitize_thread
  91 #endif
  92
  93 #if __has_attribute(__no_sanitize_undefined__)
  94 #define __no_sanitize_undefined __attribute__((__no_sanitize_undefined__))
  95 #else
  96 #define __no_sanitize_undefined
  97 #endif
  98
  99 #if defined(CONFIG_KCOV) && __has_attribute(__no_sanitize_coverage__)
 100 #define __no_sanitize_coverage __attribute__((__no_sanitize_coverage__))
 101 #else
 102 #define __no_sanitize_coverage
 103 #endif
 104
 105 /*
 106  * Treat __SANITIZE_HWADDRESS__ the same as __SANITIZE_ADDRESS__ in the kernel,
 107  * matching the defines used by Clang.
 108  */
 109 #ifdef __SANITIZE_HWADDRESS__
 110 #define __SANITIZE_ADDRESS__
 111 #endif
 112
 113 /*
 114  * GCC does not support KMSAN.
 115  */
 116 #define __no_sanitize_memory
 117 #define __no_kmsan_checks
 118
 119 /*
 120  * Turn individual warnings and errors on and off locally, depending
 121  * on version.
 122  */
 123 #define __diag_GCC(version, severity, s) \
 124         __diag_GCC_ ## version(__diag_GCC_ ## severity s)
 125
 126 /* Severity used in pragma directives */
 127 #define __diag_GCC_ignore       ignored
 128 #define __diag_GCC_warn         warning
 129 #define __diag_GCC_error        error
 130
 131 #define __diag_str1(s)          #s
 132 #define __diag_str(s)           __diag_str1(s)
 133 #define __diag(s)               _Pragma(__diag_str(GCC diagnostic s))
 134
 135 #if GCC_VERSION >= 80000
 136 #define __diag_GCC_8(s)         __diag(s)
 137 #else
 138 #define __diag_GCC_8(s)
 139 #endif
 140
 141 #define __diag_ignore_all(option, comment) \
 142         __diag_GCC(8, ignore, option)
 143
 144 /*
 145  * Prior to 9.1, -Wno-alloc-size-larger-than (and therefore the "alloc_size"
 146  * attribute) do not work, and must be disabled.
 147  */
 148 #if GCC_VERSION < 90100
 149 #undef __alloc_size__
 150 #endif