include/linux/init.h

   1 #ifndef _LINUX_INIT_H
   2 #define _LINUX_INIT_H
   3
   4 #include <linux/compiler.h>
   5 #include <linux/types.h>
   6
   7 /* Built-in __init functions needn't be compiled with retpoline */
   8 #if defined(__noretpoline) && !defined(MODULE)
   9 #define __noinitretpoline __noretpoline
  10 #else
  11 #define __noinitretpoline
  12 #endif
  13
  14 /* These macros are used to mark some functions or
  15  * initialized data (doesn't apply to uninitialized data)
  16  * as `initialization' functions. The kernel can take this
  17  * as hint that the function is used only during the initialization
  18  * phase and free up used memory resources after
  19  *
  20  * Usage:
  21  * For functions:
  22  *
  23  * You should add __init immediately before the function name, like:
  24  *
  25  * static void __init initme(int x, int y)
  26  * {
  27  *    extern int z; z = x * y;
  28  * }
  29  *
  30  * If the function has a prototype somewhere, you can also add
  31  * __init between closing brace of the prototype and semicolon:
  32  *
  33  * extern int initialize_foobar_device(int, int, int) __init;
  34  *
  35  * For initialized data:
  36  * You should insert __initdata or __initconst between the variable name
  37  * and equal sign followed by value, e.g.:
  38  *
  39  * static int init_variable __initdata = 0;
  40  * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
  41  *
  42  * Don't forget to initialize data not at file scope, i.e. within a function,
  43  * as gcc otherwise puts the data into the bss section and not into the init
  44  * section.
  45  */
  46
  47 /* These are for everybody (although not all archs will actually
  48    discard it in modules) */
  49 #define __init          __section(.init.text) __cold notrace __latent_entropy __noinitretpoline __nocfi
  50 #define __initdata      __section(.init.data)
  51 #define __initconst     __section(.init.rodata)
  52 #define __exitdata      __section(.exit.data)
  53 #define __exit_call     __used __section(.exitcall.exit)
  54
  55 /*
  56  * modpost check for section mismatches during the kernel build.
  57  * A section mismatch happens when there are references from a
  58  * code or data section to an init section (both code or data).
  59  * The init sections are (for most archs) discarded by the kernel
  60  * when early init has completed so all such references are potential bugs.
  61  * For exit sections the same issue exists.
  62  *
  63  * The following markers are used for the cases where the reference to
  64  * the *init / *exit section (code or data) is valid and will teach
  65  * modpost not to issue a warning.  Intended semantics is that a code or
  66  * data tagged __ref* can reference code or data from init section without
  67  * producing a warning (of course, no warning does not mean code is
  68  * correct, so optimally document why the __ref is needed and why it's OK).
  69  *
  70  * The markers follow same syntax rules as __init / __initdata.
  71  */
  72 #define __ref            __section(.ref.text) noinline
  73 #define __refdata        __section(.ref.data)
  74 #define __refconst       __section(.ref.rodata)
  75
  76 #ifdef MODULE
  77 #define __exitused
  78 #else
  79 #define __exitused  __used
  80 #endif
  81
  82 #define __exit          __section(.exit.text) __exitused __cold notrace
  83
  84 /* Used for MEMORY_HOTPLUG */
  85 #define __meminit        __section(.meminit.text) __cold notrace \
  86                                                   __latent_entropy
  87 #define __meminitdata    __section(.meminit.data)
  88 #define __meminitconst   __section(.meminit.rodata)
  89 #define __memexit        __section(.memexit.text) __exitused __cold notrace
  90 #define __memexitdata    __section(.memexit.data)
  91 #define __memexitconst   __section(.memexit.rodata)
  92
  93 /* For assembly routines */
  94 #define __HEAD          .section        ".head.text","ax"
  95 #define __INIT          .section        ".init.text","ax"
  96 #define __FINIT         .previous
  97
  98 #define __INITDATA      .section        ".init.data","aw",%progbits
  99 #define __INITRODATA    .section        ".init.rodata","a",%progbits
 100 #define __FINITDATA     .previous
 101
 102 #define __MEMINIT        .section       ".meminit.text", "ax"
 103 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 104 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 105
 106 /* silence warnings when references are OK */
 107 #define __REF            .section       ".ref.text", "ax"
 108 #define __REFDATA        .section       ".ref.data", "aw"
 109 #define __REFCONST       .section       ".ref.rodata", "a"
 110
 111 #ifndef __ASSEMBLY__
 112 /*
 113  * Used for initialization calls..
 114  */
 115 typedef int (*initcall_t)(void);
 116 typedef void (*exitcall_t)(void);
 117
 118 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 119 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 120
 121 /* Used for contructor calls. */
 122 typedef void (*ctor_fn_t)(void);
 123
 124 /* Defined in init/main.c */
 125 extern int do_one_initcall(initcall_t fn);
 126 extern char __initdata boot_command_line[];
 127 extern char *saved_command_line;
 128 extern unsigned int reset_devices;
 129
 130 /* used by init/main.c */
 131 void setup_arch(char **);
 132 void prepare_namespace(void);
 133 void __init load_default_modules(void);
 134 int __init init_rootfs(void);
 135
 136 #if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
 137 extern bool rodata_enabled;
 138 #endif
 139 #ifdef CONFIG_DEBUG_RODATA
 140 void mark_rodata_ro(void);
 141 #endif
 142
 143 extern void (*late_time_init)(void);
 144
 145 extern bool initcall_debug;
 146
 147 #endif
 148
 149 #ifndef MODULE
 150
 151 #ifndef __ASSEMBLY__
 152
 153 #ifdef CONFIG_LTO_CLANG
 154   /* prepend the variable name with __COUNTER__ to ensure correct ordering */
 155   #define ___initcall_name2(c, fn, id)  __initcall_##c##_##fn##id
 156   #define ___initcall_name1(c, fn, id)  ___initcall_name2(c, fn, id)
 157   #define __initcall_name(fn, id)       ___initcall_name1(__COUNTER__, fn, id)
 158 #else
 159   #define __initcall_name(fn, id)       __initcall_##fn##id
 160 #endif
 161
 162 /*
 163  * initcalls are now grouped by functionality into separate
 164  * subsections. Ordering inside the subsections is determined
 165  * by link order.
 166  * For backwards compatibility, initcall() puts the call in
 167  * the device init subsection.
 168  *
 169  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 170  * can point at the same handler without causing duplicate-symbol build errors.
 171  *
 172  * Initcalls are run by placing pointers in initcall sections that the
 173  * kernel iterates at runtime. The linker can do dead code / data elimination
 174  * and remove that completely, so the initcall sections have to be marked
 175  * as KEEP() in the linker script.
 176  */
 177
 178 #define __define_initcall(fn, id) \
 179         static initcall_t __initcall_name(fn, id) __used \
 180         __attribute__((__section__(".initcall" #id ".init"))) = fn;
 181
 182 /*
 183  * Early initcalls run before initializing SMP.
 184  *
 185  * Only for built-in code, not modules.
 186  */
 187 #define early_initcall(fn)              __define_initcall(fn, early)
 188
 189 /*
 190  * A "pure" initcall has no dependencies on anything else, and purely
 191  * initializes variables that couldn't be statically initialized.
 192  *
 193  * This only exists for built-in code, not for modules.
 194  * Keep main.c:initcall_level_names[] in sync.
 195  */
 196 #define pure_initcall(fn)               __define_initcall(fn, 0)
 197
 198 #define core_initcall(fn)               __define_initcall(fn, 1)
 199 #define core_initcall_sync(fn)          __define_initcall(fn, 1s)
 200 #define postcore_initcall(fn)           __define_initcall(fn, 2)
 201 #define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
 202 #define arch_initcall(fn)               __define_initcall(fn, 3)
 203 #define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
 204 #define subsys_initcall(fn)             __define_initcall(fn, 4)
 205 #define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
 206 #define fs_initcall(fn)                 __define_initcall(fn, 5)
 207 #define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
 208 #define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
 209 #define device_initcall(fn)             __define_initcall(fn, 6)
 210 #define device_initcall_sync(fn)        __define_initcall(fn, 6s)
 211 #define late_initcall(fn)               __define_initcall(fn, 7)
 212 #define late_initcall_sync(fn)          __define_initcall(fn, 7s)
 213
 214 #define __initcall(fn) device_initcall(fn)
 215
 216 #define __exitcall(fn)                                          \
 217         static exitcall_t __exitcall_##fn __exit_call = fn
 218
 219 #define console_initcall(fn)                                    \
 220         static initcall_t __initcall_##fn                       \
 221         __used __section(.con_initcall.init) = fn
 222
 223 #define security_initcall(fn)                                   \
 224         static initcall_t __initcall_##fn                       \
 225         __used __section(.security_initcall.init) = fn
 226
 227 struct obs_kernel_param {
 228         const char *str;
 229         int (*setup_func)(char *);
 230         int early;
 231 };
 232
 233 /*
 234  * Only for really core code.  See moduleparam.h for the normal way.
 235  *
 236  * Force the alignment so the compiler doesn't space elements of the
 237  * obs_kernel_param "array" too far apart in .init.setup.
 238  */
 239 #define __setup_param(str, unique_id, fn, early)                        \
 240         static const char __setup_str_##unique_id[] __initconst         \
 241                 __aligned(1) = str;                                     \
 242         static struct obs_kernel_param __setup_##unique_id              \
 243                 __used __section(.init.setup)                           \
 244                 __attribute__((aligned((sizeof(long)))))                \
 245                 = { __setup_str_##unique_id, fn, early }
 246
 247 #define __setup(str, fn)                                                \
 248         __setup_param(str, fn, fn, 0)
 249
 250 /*
 251  * NOTE: fn is as per module_param, not __setup!
 252  * Emits warning if fn returns non-zero.
 253  */
 254 #define early_param(str, fn)                                            \
 255         __setup_param(str, fn, fn, 1)
 256
 257 #define early_param_on_off(str_on, str_off, var, config)                \
 258                                                                         \
 259         int var = IS_ENABLED(config);                                   \
 260                                                                         \
 261         static int __init parse_##var##_on(char *arg)                   \
 262         {                                                               \
 263                 var = 1;                                                \
 264                 return 0;                                               \
 265         }                                                               \
 266         __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1);   \
 267                                                                         \
 268         static int __init parse_##var##_off(char *arg)                  \
 269         {                                                               \
 270                 var = 0;                                                \
 271                 return 0;                                               \
 272         }                                                               \
 273         __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1)
 274
 275 /* Relies on boot_command_line being set */
 276 void __init parse_early_param(void);
 277 void __init parse_early_options(char *cmdline);
 278 #endif /* __ASSEMBLY__ */
 279
 280 #else /* MODULE */
 281
 282 #define __setup_param(str, unique_id, fn)       /* nothing */
 283 #define __setup(str, func)                      /* nothing */
 284 #endif
 285
 286 /* Data marked not to be saved by software suspend */
 287 #define __nosavedata __section(.data..nosave)
 288
 289 #ifdef MODULE
 290 #define __exit_p(x) x
 291 #else
 292 #define __exit_p(x) NULL
 293 #endif
 294
 295 #endif /* _LINUX_INIT_H */