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 __inittrace __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#define __inittrace notrace
  72#else
  73#define __exitused  __used
  74#define __inittrace
  75#endif
  76
  77#define __exit          __section(.exit.text) __exitused __cold notrace
  78
  79/* Used for MEMORY_HOTPLUG */
  80#define __meminit        __section(.meminit.text) __cold notrace \
  81                                                  __latent_entropy
  82#define __meminitdata    __section(.meminit.data)
  83#define __meminitconst   __section(.meminit.rodata)
  84#define __memexit        __section(.memexit.text) __exitused __cold notrace
  85#define __memexitdata    __section(.memexit.data)
  86#define __memexitconst   __section(.memexit.rodata)
  87
  88/* For assembly routines */
  89#define __HEAD          .section        ".head.text","ax"
  90#define __INIT          .section        ".init.text","ax"
  91#define __FINIT         .previous
  92
  93#define __INITDATA      .section        ".init.data","aw",%progbits
  94#define __INITRODATA    .section        ".init.rodata","a",%progbits
  95#define __FINITDATA     .previous
  96
  97#define __MEMINIT        .section       ".meminit.text", "ax"
  98#define __MEMINITDATA    .section       ".meminit.data", "aw"
  99#define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 100
 101/* silence warnings when references are OK */
 102#define __REF            .section       ".ref.text", "ax"
 103#define __REFDATA        .section       ".ref.data", "aw"
 104#define __REFCONST       .section       ".ref.rodata", "a"
 105
 106#ifndef __ASSEMBLY__
 107/*
 108 * Used for initialization calls..
 109 */
 110typedef int (*initcall_t)(void);
 111typedef void (*exitcall_t)(void);
 112
 113extern initcall_t __con_initcall_start[], __con_initcall_end[];
 114extern initcall_t __security_initcall_start[], __security_initcall_end[];
 115
 116/* Used for contructor calls. */
 117typedef void (*ctor_fn_t)(void);
 118
 119/* Defined in init/main.c */
 120extern int do_one_initcall(initcall_t fn);
 121extern char __initdata boot_command_line[];
 122extern char *saved_command_line;
 123extern unsigned int reset_devices;
 124
 125/* used by init/main.c */
 126void setup_arch(char **);
 127void prepare_namespace(void);
 128void __init load_default_modules(void);
 129int __init init_rootfs(void);
 130
 131#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
 132extern bool rodata_enabled;
 133#endif
 134#ifdef CONFIG_STRICT_KERNEL_RWX
 135void mark_rodata_ro(void);
 136#endif
 137
 138extern void (*late_time_init)(void);
 139
 140extern bool initcall_debug;
 141
 142#endif
 143  
 144#ifndef MODULE
 145
 146#ifndef __ASSEMBLY__
 147
 148/*
 149 * initcalls are now grouped by functionality into separate
 150 * subsections. Ordering inside the subsections is determined
 151 * by link order. 
 152 * For backwards compatibility, initcall() puts the call in 
 153 * the device init subsection.
 154 *
 155 * The `id' arg to __define_initcall() is needed so that multiple initcalls
 156 * can point at the same handler without causing duplicate-symbol build errors.
 157 *
 158 * Initcalls are run by placing pointers in initcall sections that the
 159 * kernel iterates at runtime. The linker can do dead code / data elimination
 160 * and remove that completely, so the initcall sections have to be marked
 161 * as KEEP() in the linker script.
 162 */
 163
 164#define __define_initcall(fn, id) \
 165        static initcall_t __initcall_##fn##id __used \
 166        __attribute__((__section__(".initcall" #id ".init"))) = fn;
 167
 168/*
 169 * Early initcalls run before initializing SMP.
 170 *
 171 * Only for built-in code, not modules.
 172 */
 173#define early_initcall(fn)              __define_initcall(fn, early)
 174
 175/*
 176 * A "pure" initcall has no dependencies on anything else, and purely
 177 * initializes variables that couldn't be statically initialized.
 178 *
 179 * This only exists for built-in code, not for modules.
 180 * Keep main.c:initcall_level_names[] in sync.
 181 */
 182#define pure_initcall(fn)               __define_initcall(fn, 0)
 183
 184#define core_initcall(fn)               __define_initcall(fn, 1)
 185#define core_initcall_sync(fn)          __define_initcall(fn, 1s)
 186#define postcore_initcall(fn)           __define_initcall(fn, 2)
 187#define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
 188#define arch_initcall(fn)               __define_initcall(fn, 3)
 189#define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
 190#define subsys_initcall(fn)             __define_initcall(fn, 4)
 191#define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
 192#define fs_initcall(fn)                 __define_initcall(fn, 5)
 193#define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
 194#define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
 195#define device_initcall(fn)             __define_initcall(fn, 6)
 196#define device_initcall_sync(fn)        __define_initcall(fn, 6s)
 197#define late_initcall(fn)               __define_initcall(fn, 7)
 198#define late_initcall_sync(fn)          __define_initcall(fn, 7s)
 199
 200#define __initcall(fn) device_initcall(fn)
 201
 202#define __exitcall(fn)                                          \
 203        static exitcall_t __exitcall_##fn __exit_call = fn
 204
 205#define console_initcall(fn)                                    \
 206        static initcall_t __initcall_##fn                       \
 207        __used __section(.con_initcall.init) = fn
 208
 209#define security_initcall(fn)                                   \
 210        static initcall_t __initcall_##fn                       \
 211        __used __section(.security_initcall.init) = fn
 212
 213struct obs_kernel_param {
 214        const char *str;
 215        int (*setup_func)(char *);
 216        int early;
 217};
 218
 219/*
 220 * Only for really core code.  See moduleparam.h for the normal way.
 221 *
 222 * Force the alignment so the compiler doesn't space elements of the
 223 * obs_kernel_param "array" too far apart in .init.setup.
 224 */
 225#define __setup_param(str, unique_id, fn, early)                        \
 226        static const char __setup_str_##unique_id[] __initconst         \
 227                __aligned(1) = str;                                     \
 228        static struct obs_kernel_param __setup_##unique_id              \
 229                __used __section(.init.setup)                           \
 230                __attribute__((aligned((sizeof(long)))))                \
 231                = { __setup_str_##unique_id, fn, early }
 232
 233#define __setup(str, fn)                                                \
 234        __setup_param(str, fn, fn, 0)
 235
 236/*
 237 * NOTE: fn is as per module_param, not __setup!
 238 * Emits warning if fn returns non-zero.
 239 */
 240#define early_param(str, fn)                                            \
 241        __setup_param(str, fn, fn, 1)
 242
 243#define early_param_on_off(str_on, str_off, var, config)                \
 244                                                                        \
 245        int var = IS_ENABLED(config);                                   \
 246                                                                        \
 247        static int __init parse_##var##_on(char *arg)                   \
 248        {                                                               \
 249                var = 1;                                                \
 250                return 0;                                               \
 251        }                                                               \
 252        __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1);   \
 253                                                                        \
 254        static int __init parse_##var##_off(char *arg)                  \
 255        {                                                               \
 256                var = 0;                                                \
 257                return 0;                                               \
 258        }                                                               \
 259        __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1)
 260
 261/* Relies on boot_command_line being set */
 262void __init parse_early_param(void);
 263void __init parse_early_options(char *cmdline);
 264#endif /* __ASSEMBLY__ */
 265
 266#else /* MODULE */
 267
 268#define __setup_param(str, unique_id, fn)       /* nothing */
 269#define __setup(str, func)                      /* nothing */
 270#endif
 271
 272/* Data marked not to be saved by software suspend */
 273#define __nosavedata __section(.data..nosave)
 274
 275#ifdef MODULE
 276#define __exit_p(x) x
 277#else
 278#define __exit_p(x) NULL
 279#endif
 280
 281#endif /* _LINUX_INIT_H */
 282