init/main.c

   1 /*
   2  *  linux/init/main.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  GK 2/5/95  -  Changed to support mounting root fs via NFS
   7  *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
   8  *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
   9  *  Simplified starting of init:  Michael A. Griffith <grif@acm.org>
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/module.h>
  14 #include <linux/proc_fs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/stackprotector.h>
  18 #include <linux/string.h>
  19 #include <linux/ctype.h>
  20 #include <linux/delay.h>
  21 #include <linux/utsname.h>
  22 #include <linux/ioport.h>
  23 #include <linux/init.h>
  24 #include <linux/smp_lock.h>
  25 #include <linux/initrd.h>
  26 #include <linux/bootmem.h>
  27 #include <linux/tty.h>
  28 #include <linux/gfp.h>
  29 #include <linux/percpu.h>
  30 #include <linux/kmod.h>
  31 #include <linux/vmalloc.h>
  32 #include <linux/kernel_stat.h>
  33 #include <linux/start_kernel.h>
  34 #include <linux/security.h>
  35 #include <linux/smp.h>
  36 #include <linux/workqueue.h>
  37 #include <linux/profile.h>
  38 #include <linux/rcupdate.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/kallsyms.h>
  41 #include <linux/writeback.h>
  42 #include <linux/cpu.h>
  43 #include <linux/cpuset.h>
  44 #include <linux/cgroup.h>
  45 #include <linux/efi.h>
  46 #include <linux/tick.h>
  47 #include <linux/interrupt.h>
  48 #include <linux/taskstats_kern.h>
  49 #include <linux/delayacct.h>
  50 #include <linux/unistd.h>
  51 #include <linux/rmap.h>
  52 #include <linux/mempolicy.h>
  53 #include <linux/key.h>
  54 #include <linux/buffer_head.h>
  55 #include <linux/page_cgroup.h>
  56 #include <linux/debug_locks.h>
  57 #include <linux/debugobjects.h>
  58 #include <linux/lockdep.h>
  59 #include <linux/kmemleak.h>
  60 #include <linux/pid_namespace.h>
  61 #include <linux/device.h>
  62 #include <linux/kthread.h>
  63 #include <linux/sched.h>
  64 #include <linux/signal.h>
  65 #include <linux/idr.h>
  66 #include <linux/ftrace.h>
  67 #include <linux/async.h>
  68 #include <linux/kmemtrace.h>
  69 #include <trace/boot.h>
  70
  71 #include <asm/io.h>
  72 #include <asm/bugs.h>
  73 #include <asm/setup.h>
  74 #include <asm/sections.h>
  75 #include <asm/cacheflush.h>
  76
  77 #ifdef CONFIG_X86_LOCAL_APIC
  78 #include <asm/smp.h>
  79 #endif
  80
  81 static int kernel_init(void *);
  82
  83 extern void init_IRQ(void);
  84 extern void fork_init(unsigned long);
  85 extern void mca_init(void);
  86 extern void sbus_init(void);
  87 extern void prio_tree_init(void);
  88 extern void radix_tree_init(void);
  89 extern void free_initmem(void);
  90 #ifdef  CONFIG_ACPI
  91 extern void acpi_early_init(void);
  92 #else
  93 static inline void acpi_early_init(void) { }
  94 #endif
  95 #ifndef CONFIG_DEBUG_RODATA
  96 static inline void mark_rodata_ro(void) { }
  97 #endif
  98
  99 #ifdef CONFIG_TC
 100 extern void tc_init(void);
 101 #endif
 102
 103 enum system_states system_state __read_mostly;
 104 EXPORT_SYMBOL(system_state);
 105
 106 /*
 107  * Boot command-line arguments
 108  */
 109 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 110 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 111
 112 extern void time_init(void);
 113 /* Default late time init is NULL. archs can override this later. */
 114 void (*__initdata late_time_init)(void);
 115 extern void softirq_init(void);
 116
 117 /* Untouched command line saved by arch-specific code. */
 118 char __initdata boot_command_line[COMMAND_LINE_SIZE];
 119 /* Untouched saved command line (eg. for /proc) */
 120 char *saved_command_line;
 121 /* Command line for parameter parsing */
 122 static char *static_command_line;
 123
 124 static char *execute_command;
 125 static char *ramdisk_execute_command;
 126
 127 #ifdef CONFIG_SMP
 128 /* Setup configured maximum number of CPUs to activate */
 129 unsigned int __initdata setup_max_cpus = NR_CPUS;
 130
 131 /*
 132  * Setup routine for controlling SMP activation
 133  *
 134  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 135  * activation entirely (the MPS table probe still happens, though).
 136  *
 137  * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 138  * greater than 0, limits the maximum number of CPUs activated in
 139  * SMP mode to <NUM>.
 140  */
 141
 142 void __weak arch_disable_smp_support(void) { }
 143
 144 static int __init nosmp(char *str)
 145 {
 146         setup_max_cpus = 0;
 147         arch_disable_smp_support();
 148
 149         return 0;
 150 }
 151
 152 early_param("nosmp", nosmp);
 153
 154 static int __init maxcpus(char *str)
 155 {
 156         get_option(&str, &setup_max_cpus);
 157         if (setup_max_cpus == 0)
 158                 arch_disable_smp_support();
 159
 160         return 0;
 161 }
 162
 163 early_param("maxcpus", maxcpus);
 164 #else
 165 const unsigned int setup_max_cpus = NR_CPUS;
 166 #endif
 167
 168 /*
 169  * If set, this is an indication to the drivers that reset the underlying
 170  * device before going ahead with the initialization otherwise driver might
 171  * rely on the BIOS and skip the reset operation.
 172  *
 173  * This is useful if kernel is booting in an unreliable environment.
 174  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 175  * skipped and devices will be in unknown state.
 176  */
 177 unsigned int reset_devices;
 178 EXPORT_SYMBOL(reset_devices);
 179
 180 static int __init set_reset_devices(char *str)
 181 {
 182         reset_devices = 1;
 183         return 1;
 184 }
 185
 186 __setup("reset_devices", set_reset_devices);
 187
 188 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 189 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 190 static const char *panic_later, *panic_param;
 191
 192 extern struct obs_kernel_param __setup_start[], __setup_end[];
 193
 194 static int __init obsolete_checksetup(char *line)
 195 {
 196         struct obs_kernel_param *p;
 197         int had_early_param = 0;
 198
 199         p = __setup_start;
 200         do {
 201                 int n = strlen(p->str);
 202                 if (!strncmp(line, p->str, n)) {
 203                         if (p->early) {
 204                                 /* Already done in parse_early_param?
 205                                  * (Needs exact match on param part).
 206                                  * Keep iterating, as we can have early
 207                                  * params and __setups of same names 8( */
 208                                 if (line[n] == '\0' || line[n] == '=')
 209                                         had_early_param = 1;
 210                         } else if (!p->setup_func) {
 211                                 printk(KERN_WARNING "Parameter %s is obsolete,"
 212                                        " ignored\n", p->str);
 213                                 return 1;
 214                         } else if (p->setup_func(line + n))
 215                                 return 1;
 216                 }
 217                 p++;
 218         } while (p < __setup_end);
 219
 220         return had_early_param;
 221 }
 222
 223 /*
 224  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 225  * still work even if initially too large, it will just take slightly longer
 226  */
 227 unsigned long loops_per_jiffy = (1<<12);
 228
 229 EXPORT_SYMBOL(loops_per_jiffy);
 230
 231 static int __init debug_kernel(char *str)
 232 {
 233         console_loglevel = 10;
 234         return 0;
 235 }
 236
 237 static int __init quiet_kernel(char *str)
 238 {
 239         console_loglevel = 4;
 240         return 0;
 241 }
 242
 243 early_param("debug", debug_kernel);
 244 early_param("quiet", quiet_kernel);
 245
 246 static int __init loglevel(char *str)
 247 {
 248         get_option(&str, &console_loglevel);
 249         return 0;
 250 }
 251
 252 early_param("loglevel", loglevel);
 253
 254 /*
 255  * Unknown boot options get handed to init, unless they look like
 256  * failed parameters
 257  */
 258 static int __init unknown_bootoption(char *param, char *val)
 259 {
 260         /* Change NUL term back to "=", to make "param" the whole string. */
 261         if (val) {
 262                 /* param=val or param="val"? */
 263                 if (val == param+strlen(param)+1)
 264                         val[-1] = '=';
 265                 else if (val == param+strlen(param)+2) {
 266                         val[-2] = '=';
 267                         memmove(val-1, val, strlen(val)+1);
 268                         val--;
 269                 } else
 270                         BUG();
 271         }
 272
 273         /* Handle obsolete-style parameters */
 274         if (obsolete_checksetup(param))
 275                 return 0;
 276
 277         /*
 278          * Preemptive maintenance for "why didn't my misspelled command
 279          * line work?"
 280          */
 281         if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
 282                 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
 283                 return 0;
 284         }
 285
 286         if (panic_later)
 287                 return 0;
 288
 289         if (val) {
 290                 /* Environment option */
 291                 unsigned int i;
 292                 for (i = 0; envp_init[i]; i++) {
 293                         if (i == MAX_INIT_ENVS) {
 294                                 panic_later = "Too many boot env vars at `%s'";
 295                                 panic_param = param;
 296                         }
 297                         if (!strncmp(param, envp_init[i], val - param))
 298                                 break;
 299                 }
 300                 envp_init[i] = param;
 301         } else {
 302                 /* Command line option */
 303                 unsigned int i;
 304                 for (i = 0; argv_init[i]; i++) {
 305                         if (i == MAX_INIT_ARGS) {
 306                                 panic_later = "Too many boot init vars at `%s'";
 307                                 panic_param = param;
 308                         }
 309                 }
 310                 argv_init[i] = param;
 311         }
 312         return 0;
 313 }
 314
 315 #ifdef CONFIG_DEBUG_PAGEALLOC
 316 int __read_mostly debug_pagealloc_enabled = 0;
 317 #endif
 318
 319 static int __init init_setup(char *str)
 320 {
 321         unsigned int i;
 322
 323         execute_command = str;
 324         /*
 325          * In case LILO is going to boot us with default command line,
 326          * it prepends "auto" before the whole cmdline which makes
 327          * the shell think it should execute a script with such name.
 328          * So we ignore all arguments entered _before_ init=... [MJ]
 329          */
 330         for (i = 1; i < MAX_INIT_ARGS; i++)
 331                 argv_init[i] = NULL;
 332         return 1;
 333 }
 334 __setup("init=", init_setup);
 335
 336 static int __init rdinit_setup(char *str)
 337 {
 338         unsigned int i;
 339
 340         ramdisk_execute_command = str;
 341         /* See "auto" comment in init_setup */
 342         for (i = 1; i < MAX_INIT_ARGS; i++)
 343                 argv_init[i] = NULL;
 344         return 1;
 345 }
 346 __setup("rdinit=", rdinit_setup);
 347
 348 #ifndef CONFIG_SMP
 349
 350 #ifdef CONFIG_X86_LOCAL_APIC
 351 static void __init smp_init(void)
 352 {
 353         APIC_init_uniprocessor();
 354 }
 355 #else
 356 #define smp_init()      do { } while (0)
 357 #endif
 358
 359 static inline void setup_per_cpu_areas(void) { }
 360 static inline void setup_nr_cpu_ids(void) { }
 361 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 362
 363 #else
 364
 365 #if NR_CPUS > BITS_PER_LONG
 366 cpumask_t cpu_mask_all __read_mostly = CPU_MASK_ALL;
 367 EXPORT_SYMBOL(cpu_mask_all);
 368 #endif
 369
 370 /* Setup number of possible processor ids */
 371 int nr_cpu_ids __read_mostly = NR_CPUS;
 372 EXPORT_SYMBOL(nr_cpu_ids);
 373
 374 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
 375 static void __init setup_nr_cpu_ids(void)
 376 {
 377         nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
 378 }
 379
 380 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 381 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
 382
 383 EXPORT_SYMBOL(__per_cpu_offset);
 384
 385 static void __init setup_per_cpu_areas(void)
 386 {
 387         unsigned long size, i;
 388         char *ptr;
 389         unsigned long nr_possible_cpus = num_possible_cpus();
 390
 391         /* Copy section for each CPU (we discard the original) */
 392         size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
 393         ptr = alloc_bootmem_pages(size * nr_possible_cpus);
 394
 395         for_each_possible_cpu(i) {
 396                 __per_cpu_offset[i] = ptr - __per_cpu_start;
 397                 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
 398                 ptr += size;
 399         }
 400 }
 401 #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
 402
 403 /* Called by boot processor to activate the rest. */
 404 static void __init smp_init(void)
 405 {
 406         unsigned int cpu;
 407
 408         /*
 409          * Set up the current CPU as possible to migrate to.
 410          * The other ones will be done by cpu_up/cpu_down()
 411          */
 412         set_cpu_active(smp_processor_id(), true);
 413
 414         /* FIXME: This should be done in userspace --RR */
 415         for_each_present_cpu(cpu) {
 416                 if (num_online_cpus() >= setup_max_cpus)
 417                         break;
 418                 if (!cpu_online(cpu))
 419                         cpu_up(cpu);
 420         }
 421
 422         /* Any cleanup work */
 423         printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
 424         smp_cpus_done(setup_max_cpus);
 425 }
 426
 427 #endif
 428
 429 /*
 430  * We need to store the untouched command line for future reference.
 431  * We also need to store the touched command line since the parameter
 432  * parsing is performed in place, and we should allow a component to
 433  * store reference of name/value for future reference.
 434  */
 435 static void __init setup_command_line(char *command_line)
 436 {
 437         saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 438         static_command_line = alloc_bootmem(strlen (command_line)+1);
 439         strcpy (saved_command_line, boot_command_line);
 440         strcpy (static_command_line, command_line);
 441 }
 442
 443 /*
 444  * We need to finalize in a non-__init function or else race conditions
 445  * between the root thread and the init thread may cause start_kernel to
 446  * be reaped by free_initmem before the root thread has proceeded to
 447  * cpu_idle.
 448  *
 449  * gcc-3.4 accidentally inlines this function, so use noinline.
 450  */
 451
 452 static noinline void __init_refok rest_init(void)
 453         __releases(kernel_lock)
 454 {
 455         int pid;
 456
 457         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 458         numa_default_policy();
 459         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 460         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 461         unlock_kernel();
 462
 463         /*
 464          * The boot idle thread must execute schedule()
 465          * at least once to get things moving:
 466          */
 467         init_idle_bootup_task(current);
 468         rcu_scheduler_starting();
 469         preempt_enable_no_resched();
 470         schedule();
 471         preempt_disable();
 472
 473         /* Call into cpu_idle with preempt disabled */
 474         cpu_idle();
 475 }
 476
 477 /* Check for early params. */
 478 static int __init do_early_param(char *param, char *val)
 479 {
 480         struct obs_kernel_param *p;
 481
 482         for (p = __setup_start; p < __setup_end; p++) {
 483                 if ((p->early && strcmp(param, p->str) == 0) ||
 484                     (strcmp(param, "console") == 0 &&
 485                      strcmp(p->str, "earlycon") == 0)
 486                 ) {
 487                         if (p->setup_func(val) != 0)
 488                                 printk(KERN_WARNING
 489                                        "Malformed early option '%s'\n", param);
 490                 }
 491         }
 492         /* We accept everything at this stage. */
 493         return 0;
 494 }
 495
 496 void __init parse_early_options(char *cmdline)
 497 {
 498         parse_args("early options", cmdline, NULL, 0, do_early_param);
 499 }
 500
 501 /* Arch code calls this early on, or if not, just before other parsing. */
 502 void __init parse_early_param(void)
 503 {
 504         static __initdata int done = 0;
 505         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 506
 507         if (done)
 508                 return;
 509
 510         /* All fall through to do_early_param. */
 511         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 512         parse_early_options(tmp_cmdline);
 513         done = 1;
 514 }
 515
 516 /*
 517  *      Activate the first processor.
 518  */
 519
 520 static void __init boot_cpu_init(void)
 521 {
 522         int cpu = smp_processor_id();
 523         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 524         set_cpu_online(cpu, true);
 525         set_cpu_present(cpu, true);
 526         set_cpu_possible(cpu, true);
 527 }
 528
 529 void __init __weak smp_setup_processor_id(void)
 530 {
 531 }
 532
 533 void __init __weak thread_info_cache_init(void)
 534 {
 535 }
 536
 537 /*
 538  * Set up kernel memory allocators
 539  */
 540 static void __init mm_init(void)
 541 {
 542         /*
 543          * page_cgroup requires countinous pages as memmap
 544          * and it's bigger than MAX_ORDER unless SPARSEMEM.
 545          */
 546         page_cgroup_init_flatmem();
 547         mem_init();
 548         kmem_cache_init();
 549         vmalloc_init();
 550 }
 551
 552 asmlinkage void __init start_kernel(void)
 553 {
 554         char * command_line;
 555         extern struct kernel_param __start___param[], __stop___param[];
 556
 557         smp_setup_processor_id();
 558
 559         /*
 560          * Need to run as early as possible, to initialize the
 561          * lockdep hash:
 562          */
 563         lockdep_init();
 564         debug_objects_early_init();
 565
 566         /*
 567          * Set up the the initial canary ASAP:
 568          */
 569         boot_init_stack_canary();
 570
 571         cgroup_init_early();
 572
 573         local_irq_disable();
 574         early_boot_irqs_off();
 575         early_init_irq_lock_class();
 576
 577 /*
 578  * Interrupts are still disabled. Do necessary setups, then
 579  * enable them
 580  */
 581         lock_kernel();
 582         tick_init();
 583         boot_cpu_init();
 584         page_address_init();
 585         printk(KERN_NOTICE "%s", linux_banner);
 586         setup_arch(&command_line);
 587         mm_init_owner(&init_mm, &init_task);
 588         setup_command_line(command_line);
 589         setup_per_cpu_areas();
 590         setup_nr_cpu_ids();
 591         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 592
 593         build_all_zonelists();
 594         page_alloc_init();
 595
 596         printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
 597         parse_early_param();
 598         parse_args("Booting kernel", static_command_line, __start___param,
 599                    __stop___param - __start___param,
 600                    &unknown_bootoption);
 601         /*
 602          * These use large bootmem allocations and must precede
 603          * kmem_cache_init()
 604          */
 605         pidhash_init();
 606         vfs_caches_init_early();
 607         sort_main_extable();
 608         trap_init();
 609         mm_init();
 610         /*
 611          * Set up the scheduler prior starting any interrupts (such as the
 612          * timer interrupt). Full topology setup happens at smp_init()
 613          * time - but meanwhile we still have a functioning scheduler.
 614          */
 615         sched_init();
 616         /*
 617          * Disable preemption - early bootup scheduling is extremely
 618          * fragile until we cpu_idle() for the first time.
 619          */
 620         preempt_disable();
 621         if (!irqs_disabled()) {
 622                 printk(KERN_WARNING "start_kernel(): bug: interrupts were "
 623                                 "enabled *very* early, fixing it\n");
 624                 local_irq_disable();
 625         }
 626         rcu_init();
 627         /* init some links before init_ISA_irqs() */
 628         early_irq_init();
 629         init_IRQ();
 630         prio_tree_init();
 631         init_timers();
 632         hrtimers_init();
 633         softirq_init();
 634         timekeeping_init();
 635         time_init();
 636         sched_clock_init();
 637         profile_init();
 638         if (!irqs_disabled())
 639                 printk(KERN_CRIT "start_kernel(): bug: interrupts were "
 640                                  "enabled early\n");
 641         early_boot_irqs_on();
 642         local_irq_enable();
 643         kmem_cache_init_late();
 644
 645         /*
 646          * HACK ALERT! This is early. We're enabling the console before
 647          * we've done PCI setups etc, and console_init() must be aware of
 648          * this. But we do want output early, in case something goes wrong.
 649          */
 650         console_init();
 651         if (panic_later)
 652                 panic(panic_later, panic_param);
 653
 654         lockdep_info();
 655
 656         /*
 657          * Need to run this when irqs are enabled, because it wants
 658          * to self-test [hard/soft]-irqs on/off lock inversion bugs
 659          * too:
 660          */
 661         locking_selftest();
 662
 663 #ifdef CONFIG_BLK_DEV_INITRD
 664         if (initrd_start && !initrd_below_start_ok &&
 665             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 666                 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
 667                     "disabling it.\n",
 668                     page_to_pfn(virt_to_page((void *)initrd_start)),
 669                     min_low_pfn);
 670                 initrd_start = 0;
 671         }
 672 #endif
 673         page_cgroup_init();
 674         enable_debug_pagealloc();
 675         cpu_hotplug_init();
 676         kmemtrace_init();
 677         kmemleak_init();
 678         debug_objects_mem_init();
 679         idr_init_cache();
 680         setup_per_cpu_pageset();
 681         numa_policy_init();
 682         if (late_time_init)
 683                 late_time_init();
 684         calibrate_delay();
 685         pidmap_init();
 686         pgtable_cache_init();
 687         anon_vma_init();
 688 #ifdef CONFIG_X86
 689         if (efi_enabled)
 690                 efi_enter_virtual_mode();
 691 #endif
 692         thread_info_cache_init();
 693         cred_init();
 694         fork_init(num_physpages);
 695         proc_caches_init();
 696         buffer_init();
 697         key_init();
 698         security_init();
 699         vfs_caches_init(num_physpages);
 700         radix_tree_init();
 701         signals_init();
 702         /* rootfs populating might need page-writeback */
 703         page_writeback_init();
 704 #ifdef CONFIG_PROC_FS
 705         proc_root_init();
 706 #endif
 707         cgroup_init();
 708         cpuset_init();
 709         taskstats_init_early();
 710         delayacct_init();
 711
 712         check_bugs();
 713
 714         acpi_early_init(); /* before LAPIC and SMP init */
 715
 716         ftrace_init();
 717
 718         /* Do the rest non-__init'ed, we're now alive */
 719         rest_init();
 720 }
 721
 722 int initcall_debug;
 723 core_param(initcall_debug, initcall_debug, bool, 0644);
 724
 725 int do_one_initcall(initcall_t fn)
 726 {
 727         int count = preempt_count();
 728         ktime_t calltime, delta, rettime;
 729         char msgbuf[64];
 730         struct boot_trace_call call;
 731         struct boot_trace_ret ret;
 732
 733         if (initcall_debug) {
 734                 call.caller = task_pid_nr(current);
 735                 printk("calling  %pF @ %i\n", fn, call.caller);
 736                 calltime = ktime_get();
 737                 trace_boot_call(&call, fn);
 738                 enable_boot_trace();
 739         }
 740
 741         ret.result = fn();
 742
 743         if (initcall_debug) {
 744                 disable_boot_trace();
 745                 rettime = ktime_get();
 746                 delta = ktime_sub(rettime, calltime);
 747                 ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 748                 trace_boot_ret(&ret, fn);
 749                 printk("initcall %pF returned %d after %Ld usecs\n", fn,
 750                         ret.result, ret.duration);
 751         }
 752
 753         msgbuf[0] = 0;
 754
 755         if (ret.result && ret.result != -ENODEV && initcall_debug)
 756                 sprintf(msgbuf, "error code %d ", ret.result);
 757
 758         if (preempt_count() != count) {
 759                 strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
 760                 preempt_count() = count;
 761         }
 762         if (irqs_disabled()) {
 763                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 764                 local_irq_enable();
 765         }
 766         if (msgbuf[0]) {
 767                 printk("initcall %pF returned with %s\n", fn, msgbuf);
 768         }
 769
 770         return ret.result;
 771 }
 772
 773
 774 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
 775
 776 static void __init do_initcalls(void)
 777 {
 778         initcall_t *call;
 779
 780         for (call = __early_initcall_end; call < __initcall_end; call++)
 781                 do_one_initcall(*call);
 782
 783         /* Make sure there is no pending stuff from the initcall sequence */
 784         flush_scheduled_work();
 785 }
 786
 787 /*
 788  * Ok, the machine is now initialized. None of the devices
 789  * have been touched yet, but the CPU subsystem is up and
 790  * running, and memory and process management works.
 791  *
 792  * Now we can finally start doing some real work..
 793  */
 794 static void __init do_basic_setup(void)
 795 {
 796         rcu_init_sched(); /* needed by module_init stage. */
 797         init_workqueues();
 798         cpuset_init_smp();
 799         usermodehelper_init();
 800         driver_init();
 801         init_irq_proc();
 802         do_initcalls();
 803 }
 804
 805 static void __init do_pre_smp_initcalls(void)
 806 {
 807         initcall_t *call;
 808
 809         for (call = __initcall_start; call < __early_initcall_end; call++)
 810                 do_one_initcall(*call);
 811 }
 812
 813 static void run_init_process(char *init_filename)
 814 {
 815         argv_init[0] = init_filename;
 816         kernel_execve(init_filename, argv_init, envp_init);
 817 }
 818
 819 /* This is a non __init function. Force it to be noinline otherwise gcc
 820  * makes it inline to init() and it becomes part of init.text section
 821  */
 822 static noinline int init_post(void)
 823         __releases(kernel_lock)
 824 {
 825         /* need to finish all async __init code before freeing the memory */
 826         async_synchronize_full();
 827         free_initmem();
 828         unlock_kernel();
 829         mark_rodata_ro();
 830         system_state = SYSTEM_RUNNING;
 831         numa_default_policy();
 832
 833         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 834                 printk(KERN_WARNING "Warning: unable to open an initial console.\n");
 835
 836         (void) sys_dup(0);
 837         (void) sys_dup(0);
 838
 839         current->signal->flags |= SIGNAL_UNKILLABLE;
 840
 841         if (ramdisk_execute_command) {
 842                 run_init_process(ramdisk_execute_command);
 843                 printk(KERN_WARNING "Failed to execute %s\n",
 844                                 ramdisk_execute_command);
 845         }
 846
 847         /*
 848          * We try each of these until one succeeds.
 849          *
 850          * The Bourne shell can be used instead of init if we are
 851          * trying to recover a really broken machine.
 852          */
 853         if (execute_command) {
 854                 run_init_process(execute_command);
 855                 printk(KERN_WARNING "Failed to execute %s.  Attempting "
 856                                         "defaults...\n", execute_command);
 857         }
 858         run_init_process("/sbin/init");
 859         run_init_process("/etc/init");
 860         run_init_process("/bin/init");
 861         run_init_process("/bin/sh");
 862
 863         panic("No init found.  Try passing init= option to kernel.");
 864 }
 865
 866 static int __init kernel_init(void * unused)
 867 {
 868         lock_kernel();
 869
 870         /*
 871          * init can allocate pages on any node
 872          */
 873         set_mems_allowed(node_possible_map);
 874         /*
 875          * init can run on any cpu.
 876          */
 877         set_cpus_allowed_ptr(current, cpu_all_mask);
 878         /*
 879          * Tell the world that we're going to be the grim
 880          * reaper of innocent orphaned children.
 881          *
 882          * We don't want people to have to make incorrect
 883          * assumptions about where in the task array this
 884          * can be found.
 885          */
 886         init_pid_ns.child_reaper = current;
 887
 888         cad_pid = task_pid(current);
 889
 890         smp_prepare_cpus(setup_max_cpus);
 891
 892         do_pre_smp_initcalls();
 893         start_boot_trace();
 894
 895         smp_init();
 896         sched_init_smp();
 897
 898         do_basic_setup();
 899
 900         /*
 901          * check if there is an early userspace init.  If yes, let it do all
 902          * the work
 903          */
 904
 905         if (!ramdisk_execute_command)
 906                 ramdisk_execute_command = "/init";
 907
 908         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 909                 ramdisk_execute_command = NULL;
 910                 prepare_namespace();
 911         }
 912
 913         /*
 914          * Ok, we have completed the initial bootup, and
 915          * we're essentially up and running. Get rid of the
 916          * initmem segments and start the user-mode stuff..
 917          */
 918
 919         init_post();
 920         return 0;
 921 }