xref: /linux/include/linux/compiler-gcc.h (revision dd093fb0)
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__)
88 #define __no_sanitize_thread __attribute__((__no_sanitize_thread__))
89 #else
90 #define __no_sanitize_thread
91 #endif
92 
93 #define __no_sanitize_undefined __attribute__((__no_sanitize_undefined__))
94 
95 /*
96  * Only supported since gcc >= 12
97  */
98 #if defined(CONFIG_KCOV) && __has_attribute(__no_sanitize_coverage__)
99 #define __no_sanitize_coverage __attribute__((__no_sanitize_coverage__))
100 #else
101 #define __no_sanitize_coverage
102 #endif
103 
104 /*
105  * Treat __SANITIZE_HWADDRESS__ the same as __SANITIZE_ADDRESS__ in the kernel,
106  * matching the defines used by Clang.
107  */
108 #ifdef __SANITIZE_HWADDRESS__
109 #define __SANITIZE_ADDRESS__
110 #endif
111 
112 /*
113  * GCC does not support KMSAN.
114  */
115 #define __no_sanitize_memory
116 #define __no_kmsan_checks
117 
118 /*
119  * Turn individual warnings and errors on and off locally, depending
120  * on version.
121  */
122 #define __diag_GCC(version, severity, s) \
123 	__diag_GCC_ ## version(__diag_GCC_ ## severity s)
124 
125 /* Severity used in pragma directives */
126 #define __diag_GCC_ignore	ignored
127 #define __diag_GCC_warn		warning
128 #define __diag_GCC_error	error
129 
130 #define __diag_str1(s)		#s
131 #define __diag_str(s)		__diag_str1(s)
132 #define __diag(s)		_Pragma(__diag_str(GCC diagnostic s))
133 
134 #if GCC_VERSION >= 80000
135 #define __diag_GCC_8(s)		__diag(s)
136 #else
137 #define __diag_GCC_8(s)
138 #endif
139 
140 #define __diag_ignore_all(option, comment) \
141 	__diag_GCC(8, ignore, option)
142 
143 /*
144  * Prior to 9.1, -Wno-alloc-size-larger-than (and therefore the "alloc_size"
145  * attribute) do not work, and must be disabled.
146  */
147 #if GCC_VERSION < 90100
148 #undef __alloc_size__
149 #endif
150