root/include/linux/init.h

INCLUDED FROM

DEFINITIONS

1. initcall_from_entry
2. initcall_from_entry

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_INIT_H
   3 #define _LINUX_INIT_H
   4 
   5 #include <linux/compiler.h>
   6 #include <linux/types.h>
   7 
   8 /* Built-in __init functions needn't be compiled with retpoline */
   9 #if defined(__noretpoline) && !defined(MODULE)
  10 #define __noinitretpoline __noretpoline
  11 #else
  12 #define __noinitretpoline
  13 #endif
  14 
  15 /* These macros are used to mark some functions or 
  16  * initialized data (doesn't apply to uninitialized data)
  17  * as `initialization' functions. The kernel can take this
  18  * as hint that the function is used only during the initialization
  19  * phase and free up used memory resources after
  20  *
  21  * Usage:
  22  * For functions:
  23  * 
  24  * You should add __init immediately before the function name, like:
  25  *
  26  * static void __init initme(int x, int y)
  27  * {
  28  *    extern int z; z = x * y;
  29  * }
  30  *
  31  * If the function has a prototype somewhere, you can also add
  32  * __init between closing brace of the prototype and semicolon:
  33  *
  34  * extern int initialize_foobar_device(int, int, int) __init;
  35  *
  36  * For initialized data:
  37  * You should insert __initdata or __initconst between the variable name
  38  * and equal sign followed by value, e.g.:
  39  *
  40  * static int init_variable __initdata = 0;
  41  * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
  42  *
  43  * Don't forget to initialize data not at file scope, i.e. within a function,
  44  * as gcc otherwise puts the data into the bss section and not into the init
  45  * section.
  46  */
  47 
  48 /* These are for everybody (although not all archs will actually
  49    discard it in modules) */
  50 #define __init          __section(.init.text) __cold  __latent_entropy __noinitretpoline
  51 #define __initdata      __section(.init.data)
  52 #define __initconst     __section(.init.rodata)
  53 #define __exitdata      __section(.exit.data)
  54 #define __exit_call     __used __section(.exitcall.exit)
  55 
  56 /*
  57  * modpost check for section mismatches during the kernel build.
  58  * A section mismatch happens when there are references from a
  59  * code or data section to an init section (both code or data).
  60  * The init sections are (for most archs) discarded by the kernel
  61  * when early init has completed so all such references are potential bugs.
  62  * For exit sections the same issue exists.
  63  *
  64  * The following markers are used for the cases where the reference to
  65  * the *init / *exit section (code or data) is valid and will teach
  66  * modpost not to issue a warning.  Intended semantics is that a code or
  67  * data tagged __ref* can reference code or data from init section without
  68  * producing a warning (of course, no warning does not mean code is
  69  * correct, so optimally document why the __ref is needed and why it's OK).
  70  *
  71  * The markers follow same syntax rules as __init / __initdata.
  72  */
  73 #define __ref            __section(.ref.text) noinline
  74 #define __refdata        __section(.ref.data)
  75 #define __refconst       __section(.ref.rodata)
  76 
  77 #ifdef MODULE
  78 #define __exitused
  79 #else
  80 #define __exitused  __used
  81 #endif
  82 
  83 #define __exit          __section(.exit.text) __exitused __cold notrace
  84 
  85 /* Used for MEMORY_HOTPLUG */
  86 #define __meminit        __section(.meminit.text) __cold notrace \
  87                                                   __latent_entropy
  88 #define __meminitdata    __section(.meminit.data)
  89 #define __meminitconst   __section(.meminit.rodata)
  90 #define __memexit        __section(.memexit.text) __exitused __cold notrace
  91 #define __memexitdata    __section(.memexit.data)
  92 #define __memexitconst   __section(.memexit.rodata)
  93 
  94 /* For assembly routines */
  95 #define __HEAD          .section        ".head.text","ax"
  96 #define __INIT          .section        ".init.text","ax"
  97 #define __FINIT         .previous
  98 
  99 #define __INITDATA      .section        ".init.data","aw",%progbits
 100 #define __INITRODATA    .section        ".init.rodata","a",%progbits
 101 #define __FINITDATA     .previous
 102 
 103 #define __MEMINIT        .section       ".meminit.text", "ax"
 104 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 105 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 106 
 107 /* silence warnings when references are OK */
 108 #define __REF            .section       ".ref.text", "ax"
 109 #define __REFDATA        .section       ".ref.data", "aw"
 110 #define __REFCONST       .section       ".ref.rodata", "a"
 111 
 112 #ifndef __ASSEMBLY__
 113 /*
 114  * Used for initialization calls..
 115  */
 116 typedef int (*initcall_t)(void);
 117 typedef void (*exitcall_t)(void);
 118 
 119 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
 120 typedef int initcall_entry_t;
 121 
 122 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
 123 {
 124         return offset_to_ptr(entry);
 125 }
 126 #else
 127 typedef initcall_t initcall_entry_t;
 128 
 129 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
 130 {
 131         return *entry;
 132 }
 133 #endif
 134 
 135 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
 136 
 137 /* Used for contructor calls. */
 138 typedef void (*ctor_fn_t)(void);
 139 
 140 struct file_system_type;
 141 
 142 /* Defined in init/main.c */
 143 extern int do_one_initcall(initcall_t fn);
 144 extern char __initdata boot_command_line[];
 145 extern char *saved_command_line;
 146 extern unsigned int reset_devices;
 147 
 148 /* used by init/main.c */
 149 void setup_arch(char **);
 150 void prepare_namespace(void);
 151 void __init init_rootfs(void);
 152 extern struct file_system_type rootfs_fs_type;
 153 
 154 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
 155 extern bool rodata_enabled;
 156 #endif
 157 #ifdef CONFIG_STRICT_KERNEL_RWX
 158 void mark_rodata_ro(void);
 159 #endif
 160 
 161 extern void (*late_time_init)(void);
 162 
 163 extern bool initcall_debug;
 164 
 165 #endif
 166   
 167 #ifndef MODULE
 168 
 169 #ifndef __ASSEMBLY__
 170 
 171 /*
 172  * initcalls are now grouped by functionality into separate
 173  * subsections. Ordering inside the subsections is determined
 174  * by link order. 
 175  * For backwards compatibility, initcall() puts the call in 
 176  * the device init subsection.
 177  *
 178  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 179  * can point at the same handler without causing duplicate-symbol build errors.
 180  *
 181  * Initcalls are run by placing pointers in initcall sections that the
 182  * kernel iterates at runtime. The linker can do dead code / data elimination
 183  * and remove that completely, so the initcall sections have to be marked
 184  * as KEEP() in the linker script.
 185  */
 186 
 187 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
 188 #define ___define_initcall(fn, id, __sec)                       \
 189         __ADDRESSABLE(fn)                                       \
 190         asm(".section   \"" #__sec ".init\", \"a\"      \n"     \
 191         "__initcall_" #fn #id ":                        \n"     \
 192             ".long      " #fn " - .                     \n"     \
 193             ".previous                                  \n");
 194 #else
 195 #define ___define_initcall(fn, id, __sec) \
 196         static initcall_t __initcall_##fn##id __used \
 197                 __attribute__((__section__(#__sec ".init"))) = fn;
 198 #endif
 199 
 200 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
 201 
 202 /*
 203  * Early initcalls run before initializing SMP.
 204  *
 205  * Only for built-in code, not modules.
 206  */
 207 #define early_initcall(fn)              __define_initcall(fn, early)
 208 
 209 /*
 210  * A "pure" initcall has no dependencies on anything else, and purely
 211  * initializes variables that couldn't be statically initialized.
 212  *
 213  * This only exists for built-in code, not for modules.
 214  * Keep main.c:initcall_level_names[] in sync.
 215  */
 216 #define pure_initcall(fn)               __define_initcall(fn, 0)
 217 
 218 #define core_initcall(fn)               __define_initcall(fn, 1)
 219 #define core_initcall_sync(fn)          __define_initcall(fn, 1s)
 220 #define postcore_initcall(fn)           __define_initcall(fn, 2)
 221 #define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
 222 #define arch_initcall(fn)               __define_initcall(fn, 3)
 223 #define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
 224 #define subsys_initcall(fn)             __define_initcall(fn, 4)
 225 #define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
 226 #define fs_initcall(fn)                 __define_initcall(fn, 5)
 227 #define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
 228 #define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
 229 #define device_initcall(fn)             __define_initcall(fn, 6)
 230 #define device_initcall_sync(fn)        __define_initcall(fn, 6s)
 231 #define late_initcall(fn)               __define_initcall(fn, 7)
 232 #define late_initcall_sync(fn)          __define_initcall(fn, 7s)
 233 
 234 #define __initcall(fn) device_initcall(fn)
 235 
 236 #define __exitcall(fn)                                          \
 237         static exitcall_t __exitcall_##fn __exit_call = fn
 238 
 239 #define console_initcall(fn)    ___define_initcall(fn,, .con_initcall)
 240 
 241 struct obs_kernel_param {
 242         const char *str;
 243         int (*setup_func)(char *);
 244         int early;
 245 };
 246 
 247 /*
 248  * Only for really core code.  See moduleparam.h for the normal way.
 249  *
 250  * Force the alignment so the compiler doesn't space elements of the
 251  * obs_kernel_param "array" too far apart in .init.setup.
 252  */
 253 #define __setup_param(str, unique_id, fn, early)                        \
 254         static const char __setup_str_##unique_id[] __initconst         \
 255                 __aligned(1) = str;                                     \
 256         static struct obs_kernel_param __setup_##unique_id              \
 257                 __used __section(.init.setup)                           \
 258                 __attribute__((aligned((sizeof(long)))))                \
 259                 = { __setup_str_##unique_id, fn, early }
 260 
 261 #define __setup(str, fn)                                                \
 262         __setup_param(str, fn, fn, 0)
 263 
 264 /*
 265  * NOTE: fn is as per module_param, not __setup!
 266  * Emits warning if fn returns non-zero.
 267  */
 268 #define early_param(str, fn)                                            \
 269         __setup_param(str, fn, fn, 1)
 270 
 271 #define early_param_on_off(str_on, str_off, var, config)                \
 272                                                                         \
 273         int var = IS_ENABLED(config);                                   \
 274                                                                         \
 275         static int __init parse_##var##_on(char *arg)                   \
 276         {                                                               \
 277                 var = 1;                                                \
 278                 return 0;                                               \
 279         }                                                               \
 280         __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1);   \
 281                                                                         \
 282         static int __init parse_##var##_off(char *arg)                  \
 283         {                                                               \
 284                 var = 0;                                                \
 285                 return 0;                                               \
 286         }                                                               \
 287         __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1)
 288 
 289 /* Relies on boot_command_line being set */
 290 void __init parse_early_param(void);
 291 void __init parse_early_options(char *cmdline);
 292 #endif /* __ASSEMBLY__ */
 293 
 294 #else /* MODULE */
 295 
 296 #define __setup_param(str, unique_id, fn)       /* nothing */
 297 #define __setup(str, func)                      /* nothing */
 298 #endif
 299 
 300 /* Data marked not to be saved by software suspend */
 301 #define __nosavedata __section(.data..nosave)
 302 
 303 #ifdef MODULE
 304 #define __exit_p(x) x
 305 #else
 306 #define __exit_p(x) NULL
 307 #endif
 308 
 309 #endif /* _LINUX_INIT_H */