1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
#ifndef __LINUX_COMPILER_H
#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
#endif
/*
* Common definitions for all gcc versions go here.
*/
#define GCC_VERSION (__GNUC__ * 10000 \
+ __GNUC_MINOR__ * 100 \
+ __GNUC_PATCHLEVEL__)
/* Optimization barrier */
/* The "volatile" is due to gcc bugs */
#define barrier() __asm__ __volatile__("": : :"memory")
/*
* This macro obfuscates arithmetic on a variable address so that gcc
* shouldn't recognize the original var, and make assumptions about it.
*
* This is needed because the C standard makes it undefined to do
* pointer arithmetic on "objects" outside their boundaries and the
* gcc optimizers assume this is the case. In particular they
* assume such arithmetic does not wrap.
*
* A miscompilation has been observed because of this on PPC.
* To work around it we hide the relationship of the pointer and the object
* using this macro.
*
* Versions of the ppc64 compiler before 4.1 had a bug where use of
* RELOC_HIDE could trash r30. The bug can be worked around by changing
* the inline assembly constraint from =g to =r, in this particular
* case either is valid.
*/
#define RELOC_HIDE(ptr, off) \
({ unsigned long __ptr; \
__asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
(typeof(ptr)) (__ptr + (off)); })
#ifdef __CHECKER__
#define __must_be_array(arr) 0
#else
/* &a[0] degrades to a pointer: a different type from an array */
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
#endif
/*
* Force always-inline if the user requests it so via the .config,
* or if gcc is too old:
*/
#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
!defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
# define inline inline __attribute__((always_inline)) notrace
# define __inline__ __inline__ __attribute__((always_inline)) notrace
# define __inline __inline __attribute__((always_inline)) notrace
#else
/* A lot of inline functions can cause havoc with function tracing */
# define inline inline notrace
# define __inline__ __inline__ notrace
# define __inline __inline notrace
#endif
#define __deprecated __attribute__((deprecated))
#define __packed __attribute__((packed))
#define __weak __attribute__((weak))
/*
* it doesn't make sense on ARM (currently the only user of __naked) to trace
* naked functions because then mcount is called without stack and frame pointer
* being set up and there is no chance to restore the lr register to the value
* before mcount was called.
*
* The asm() bodies of naked functions often depend on standard calling conventions,
* therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce
* this, so we must do so ourselves. See GCC PR44290.
*/
#define __naked __attribute__((naked)) noinline __noclone notrace
#define __noreturn __attribute__((noreturn))
/*
* From the GCC manual:
*
* Many functions have no effects except the return value and their
* return value depends only on the parameters and/or global
* variables. Such a function can be subject to common subexpression
* elimination and loop optimization just as an arithmetic operator
* would be.
* [...]
*/
#define __pure __attribute__((pure))
#define __aligned(x) __attribute__((aligned(x)))
#define __printf(a,b) __attribute__((format(printf,a,b)))
#define noinline __attribute__((noinline))
#define __attribute_const__ __attribute__((__const__))
#define __maybe_unused __attribute__((unused))
#define __always_unused __attribute__((unused))
/* gcc version specific checks */
#if GCC_VERSION < 30200
# error Sorry, your compiler is too old - please upgrade it.
#endif
#if GCC_VERSION < 30300
# define __used __attribute__((__unused__))
#else
# define __used __attribute__((__used__))
#endif
#ifdef CONFIG_GCOV_KERNEL
# if GCC_VERSION < 30400
# error "GCOV profiling support for gcc versions below 3.4 not included"
# endif /* __GNUC_MINOR__ */
#endif /* CONFIG_GCOV_KERNEL */
#if GCC_VERSION >= 30400
#define __must_check __attribute__((warn_unused_result))
#endif
#if GCC_VERSION >= 40000
/* GCC 4.1.[01] miscompiles __weak */
#ifdef __KERNEL__
# if GCC_VERSION >= 40100 && GCC_VERSION <= 40101
# error Your version of gcc miscompiles the __weak directive
# endif
#endif
#define __used __attribute__((__used__))
#define __compiler_offsetof(a, b) \
__builtin_offsetof(a, b)
#if GCC_VERSION >= 40100 && GCC_VERSION < 40600
# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
#endif
#if GCC_VERSION >= 40300
/* Mark functions as cold. gcc will assume any path leading to a call
* to them will be unlikely. This means a lot of manual unlikely()s
* are unnecessary now for any paths leading to the usual suspects
* like BUG(), printk(), panic() etc. [but let's keep them for now for
* older compilers]
*
* Early snapshots of gcc 4.3 don't support this and we can't detect this
* in the preprocessor, but we can live with this because they're unreleased.
* Maketime probing would be overkill here.
*
* gcc also has a __attribute__((__hot__)) to move hot functions into
* a special section, but I don't see any sense in this right now in
* the kernel context
*/
#define __cold __attribute__((__cold__))
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
#ifndef __CHECKER__
# define __compiletime_warning(message) __attribute__((warning(message)))
# define __compiletime_error(message) __attribute__((error(message)))
#endif /* __CHECKER__ */
#endif /* GCC_VERSION >= 40300 */
#if GCC_VERSION >= 40500
/*
* Mark a position in code as unreachable. This can be used to
* suppress control flow warnings after asm blocks that transfer
* control elsewhere.
*
* Early snapshots of gcc 4.5 don't support this and we can't detect
* this in the preprocessor, but we can live with this because they're
* unreleased. Really, we need to have autoconf for the kernel.
*/
#define unreachable() __builtin_unreachable()
/* Mark a function definition as prohibited from being cloned. */
#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
#endif /* GCC_VERSION >= 40500 */
#if GCC_VERSION >= 40600
/*
* Tell the optimizer that something else uses this function or variable.
*/
#define __visible __attribute__((externally_visible))
#endif
/*
* GCC 'asm goto' miscompiles certain code sequences:
*
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
*
* (asm goto is automatically volatile - the naming reflects this.)
*/
#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
#if GCC_VERSION >= 40400
#define __HAVE_BUILTIN_BSWAP32__
#define __HAVE_BUILTIN_BSWAP64__
#endif
#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
#define __HAVE_BUILTIN_BSWAP16__
#endif
#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
#endif /* gcc version >= 40000 specific checks */
#if !defined(__noclone)
#define __noclone /* not needed */
#endif
/*
* A trick to suppress uninitialized variable warning without generating any
* code
*/
#define uninitialized_var(x) x = x
#define __always_inline inline __attribute__((always_inline))
|
