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