linux/init/main.c
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   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/ioport.h>
  22#include <linux/init.h>
  23#include <linux/initrd.h>
  24#include <linux/bootmem.h>
  25#include <linux/acpi.h>
  26#include <linux/tty.h>
  27#include <linux/percpu.h>
  28#include <linux/kmod.h>
  29#include <linux/vmalloc.h>
  30#include <linux/kernel_stat.h>
  31#include <linux/start_kernel.h>
  32#include <linux/security.h>
  33#include <linux/smp.h>
  34#include <linux/profile.h>
  35#include <linux/rcupdate.h>
  36#include <linux/moduleparam.h>
  37#include <linux/kallsyms.h>
  38#include <linux/writeback.h>
  39#include <linux/cpu.h>
  40#include <linux/cpuset.h>
  41#include <linux/cgroup.h>
  42#include <linux/efi.h>
  43#include <linux/tick.h>
  44#include <linux/interrupt.h>
  45#include <linux/taskstats_kern.h>
  46#include <linux/delayacct.h>
  47#include <linux/unistd.h>
  48#include <linux/rmap.h>
  49#include <linux/mempolicy.h>
  50#include <linux/key.h>
  51#include <linux/buffer_head.h>
  52#include <linux/page_cgroup.h>
  53#include <linux/debug_locks.h>
  54#include <linux/debugobjects.h>
  55#include <linux/lockdep.h>
  56#include <linux/kmemleak.h>
  57#include <linux/pid_namespace.h>
  58#include <linux/device.h>
  59#include <linux/kthread.h>
  60#include <linux/sched.h>
  61#include <linux/signal.h>
  62#include <linux/idr.h>
  63#include <linux/kgdb.h>
  64#include <linux/ftrace.h>
  65#include <linux/async.h>
  66#include <linux/kmemcheck.h>
  67#include <linux/sfi.h>
  68#include <linux/shmem_fs.h>
  69#include <linux/slab.h>
  70#include <linux/perf_event.h>
  71
  72#include <asm/io.h>
  73#include <asm/bugs.h>
  74#include <asm/setup.h>
  75#include <asm/sections.h>
  76#include <asm/cacheflush.h>
  77
  78#ifdef CONFIG_X86_LOCAL_APIC
  79#include <asm/smp.h>
  80#endif
  81
  82static int kernel_init(void *);
  83
  84extern void init_IRQ(void);
  85extern void fork_init(unsigned long);
  86extern void mca_init(void);
  87extern void sbus_init(void);
  88extern void prio_tree_init(void);
  89extern void radix_tree_init(void);
  90extern void free_initmem(void);
  91#ifndef CONFIG_DEBUG_RODATA
  92static inline void mark_rodata_ro(void) { }
  93#endif
  94
  95#ifdef CONFIG_TC
  96extern void tc_init(void);
  97#endif
  98
  99/*
 100 * Debug helper: via this flag we know that we are in 'early bootup code'
 101 * where only the boot processor is running with IRQ disabled.  This means
 102 * two things - IRQ must not be enabled before the flag is cleared and some
 103 * operations which are not allowed with IRQ disabled are allowed while the
 104 * flag is set.
 105 */
 106bool early_boot_irqs_disabled __read_mostly;
 107
 108enum system_states system_state __read_mostly;
 109EXPORT_SYMBOL(system_state);
 110
 111/*
 112 * Boot command-line arguments
 113 */
 114#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 115#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 116
 117extern void time_init(void);
 118/* Default late time init is NULL. archs can override this later. */
 119void (*__initdata late_time_init)(void);
 120extern void softirq_init(void);
 121
 122/* Untouched command line saved by arch-specific code. */
 123char __initdata boot_command_line[COMMAND_LINE_SIZE];
 124/* Untouched saved command line (eg. for /proc) */
 125char *saved_command_line;
 126/* Command line for parameter parsing */
 127static char *static_command_line;
 128
 129static char *execute_command;
 130static char *ramdisk_execute_command;
 131
 132#ifdef CONFIG_SMP
 133/* Setup configured maximum number of CPUs to activate */
 134unsigned int setup_max_cpus = NR_CPUS;
 135EXPORT_SYMBOL(setup_max_cpus);
 136
 137
 138/*
 139 * Setup routine for controlling SMP activation
 140 *
 141 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 142 * activation entirely (the MPS table probe still happens, though).
 143 *
 144 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 145 * greater than 0, limits the maximum number of CPUs activated in
 146 * SMP mode to <NUM>.
 147 */
 148
 149void __weak arch_disable_smp_support(void) { }
 150
 151static int __init nosmp(char *str)
 152{
 153        setup_max_cpus = 0;
 154        arch_disable_smp_support();
 155
 156        return 0;
 157}
 158
 159early_param("nosmp", nosmp);
 160
 161/* this is hard limit */
 162static int __init nrcpus(char *str)
 163{
 164        int nr_cpus;
 165
 166        get_option(&str, &nr_cpus);
 167        if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
 168                nr_cpu_ids = nr_cpus;
 169
 170        return 0;
 171}
 172
 173early_param("nr_cpus", nrcpus);
 174
 175static int __init maxcpus(char *str)
 176{
 177        get_option(&str, &setup_max_cpus);
 178        if (setup_max_cpus == 0)
 179                arch_disable_smp_support();
 180
 181        return 0;
 182}
 183
 184early_param("maxcpus", maxcpus);
 185#else
 186static const unsigned int setup_max_cpus = NR_CPUS;
 187#endif
 188
 189/*
 190 * If set, this is an indication to the drivers that reset the underlying
 191 * device before going ahead with the initialization otherwise driver might
 192 * rely on the BIOS and skip the reset operation.
 193 *
 194 * This is useful if kernel is booting in an unreliable environment.
 195 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 196 * skipped and devices will be in unknown state.
 197 */
 198unsigned int reset_devices;
 199EXPORT_SYMBOL(reset_devices);
 200
 201static int __init set_reset_devices(char *str)
 202{
 203        reset_devices = 1;
 204        return 1;
 205}
 206
 207__setup("reset_devices", set_reset_devices);
 208
 209static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 210const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 211static const char *panic_later, *panic_param;
 212
 213extern const struct obs_kernel_param __setup_start[], __setup_end[];
 214
 215static int __init obsolete_checksetup(char *line)
 216{
 217        const struct obs_kernel_param *p;
 218        int had_early_param = 0;
 219
 220        p = __setup_start;
 221        do {
 222                int n = strlen(p->str);
 223                if (!strncmp(line, p->str, n)) {
 224                        if (p->early) {
 225                                /* Already done in parse_early_param?
 226                                 * (Needs exact match on param part).
 227                                 * Keep iterating, as we can have early
 228                                 * params and __setups of same names 8( */
 229                                if (line[n] == '\0' || line[n] == '=')
 230                                        had_early_param = 1;
 231                        } else if (!p->setup_func) {
 232                                printk(KERN_WARNING "Parameter %s is obsolete,"
 233                                       " ignored\n", p->str);
 234                                return 1;
 235                        } else if (p->setup_func(line + n))
 236                                return 1;
 237                }
 238                p++;
 239        } while (p < __setup_end);
 240
 241        return had_early_param;
 242}
 243
 244/*
 245 * This should be approx 2 Bo*oMips to start (note initial shift), and will
 246 * still work even if initially too large, it will just take slightly longer
 247 */
 248unsigned long loops_per_jiffy = (1<<12);
 249
 250EXPORT_SYMBOL(loops_per_jiffy);
 251
 252static int __init debug_kernel(char *str)
 253{
 254        console_loglevel = 10;
 255        return 0;
 256}
 257
 258static int __init quiet_kernel(char *str)
 259{
 260        console_loglevel = 4;
 261        return 0;
 262}
 263
 264early_param("debug", debug_kernel);
 265early_param("quiet", quiet_kernel);
 266
 267static int __init loglevel(char *str)
 268{
 269        get_option(&str, &console_loglevel);
 270        return 0;
 271}
 272
 273early_param("loglevel", loglevel);
 274
 275/*
 276 * Unknown boot options get handed to init, unless they look like
 277 * unused parameters (modprobe will find them in /proc/cmdline).
 278 */
 279static int __init unknown_bootoption(char *param, char *val)
 280{
 281        /* Change NUL term back to "=", to make "param" the whole string. */
 282        if (val) {
 283                /* param=val or param="val"? */
 284                if (val == param+strlen(param)+1)
 285                        val[-1] = '=';
 286                else if (val == param+strlen(param)+2) {
 287                        val[-2] = '=';
 288                        memmove(val-1, val, strlen(val)+1);
 289                        val--;
 290                } else
 291                        BUG();
 292        }
 293
 294        /* Handle obsolete-style parameters */
 295        if (obsolete_checksetup(param))
 296                return 0;
 297
 298        /* Unused module parameter. */
 299        if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 300                return 0;
 301
 302        if (panic_later)
 303                return 0;
 304
 305        if (val) {
 306                /* Environment option */
 307                unsigned int i;
 308                for (i = 0; envp_init[i]; i++) {
 309                        if (i == MAX_INIT_ENVS) {
 310                                panic_later = "Too many boot env vars at `%s'";
 311                                panic_param = param;
 312                        }
 313                        if (!strncmp(param, envp_init[i], val - param))
 314                                break;
 315                }
 316                envp_init[i] = param;
 317        } else {
 318                /* Command line option */
 319                unsigned int i;
 320                for (i = 0; argv_init[i]; i++) {
 321                        if (i == MAX_INIT_ARGS) {
 322                                panic_later = "Too many boot init vars at `%s'";
 323                                panic_param = param;
 324                        }
 325                }
 326                argv_init[i] = param;
 327        }
 328        return 0;
 329}
 330
 331#ifdef CONFIG_DEBUG_PAGEALLOC
 332int __read_mostly debug_pagealloc_enabled = 0;
 333#endif
 334
 335static int __init init_setup(char *str)
 336{
 337        unsigned int i;
 338
 339        execute_command = str;
 340        /*
 341         * In case LILO is going to boot us with default command line,
 342         * it prepends "auto" before the whole cmdline which makes
 343         * the shell think it should execute a script with such name.
 344         * So we ignore all arguments entered _before_ init=... [MJ]
 345         */
 346        for (i = 1; i < MAX_INIT_ARGS; i++)
 347                argv_init[i] = NULL;
 348        return 1;
 349}
 350__setup("init=", init_setup);
 351
 352static int __init rdinit_setup(char *str)
 353{
 354        unsigned int i;
 355
 356        ramdisk_execute_command = str;
 357        /* See "auto" comment in init_setup */
 358        for (i = 1; i < MAX_INIT_ARGS; i++)
 359                argv_init[i] = NULL;
 360        return 1;
 361}
 362__setup("rdinit=", rdinit_setup);
 363
 364#ifndef CONFIG_SMP
 365
 366#ifdef CONFIG_X86_LOCAL_APIC
 367static void __init smp_init(void)
 368{
 369        APIC_init_uniprocessor();
 370}
 371#else
 372#define smp_init()      do { } while (0)
 373#endif
 374
 375static inline void setup_nr_cpu_ids(void) { }
 376static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 377
 378#else
 379
 380/* Setup number of possible processor ids */
 381int nr_cpu_ids __read_mostly = NR_CPUS;
 382EXPORT_SYMBOL(nr_cpu_ids);
 383
 384/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
 385static void __init setup_nr_cpu_ids(void)
 386{
 387        nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
 388}
 389
 390/* Called by boot processor to activate the rest. */
 391static void __init smp_init(void)
 392{
 393        unsigned int cpu;
 394
 395        /* FIXME: This should be done in userspace --RR */
 396        for_each_present_cpu(cpu) {
 397                if (num_online_cpus() >= setup_max_cpus)
 398                        break;
 399                if (!cpu_online(cpu))
 400                        cpu_up(cpu);
 401        }
 402
 403        /* Any cleanup work */
 404        printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
 405        smp_cpus_done(setup_max_cpus);
 406}
 407
 408#endif
 409
 410/*
 411 * We need to store the untouched command line for future reference.
 412 * We also need to store the touched command line since the parameter
 413 * parsing is performed in place, and we should allow a component to
 414 * store reference of name/value for future reference.
 415 */
 416static void __init setup_command_line(char *command_line)
 417{
 418        saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 419        static_command_line = alloc_bootmem(strlen (command_line)+1);
 420        strcpy (saved_command_line, boot_command_line);
 421        strcpy (static_command_line, command_line);
 422}
 423
 424/*
 425 * We need to finalize in a non-__init function or else race conditions
 426 * between the root thread and the init thread may cause start_kernel to
 427 * be reaped by free_initmem before the root thread has proceeded to
 428 * cpu_idle.
 429 *
 430 * gcc-3.4 accidentally inlines this function, so use noinline.
 431 */
 432
 433static __initdata DECLARE_COMPLETION(kthreadd_done);
 434
 435static noinline void __init_refok rest_init(void)
 436{
 437        int pid;
 438
 439        rcu_scheduler_starting();
 440        /*
 441         * We need to spawn init first so that it obtains pid 1, however
 442         * the init task will end up wanting to create kthreads, which, if
 443         * we schedule it before we create kthreadd, will OOPS.
 444         */
 445        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 446        numa_default_policy();
 447        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 448        rcu_read_lock();
 449        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 450        rcu_read_unlock();
 451        complete(&kthreadd_done);
 452
 453        /*
 454         * The boot idle thread must execute schedule()
 455         * at least once to get things moving:
 456         */
 457        init_idle_bootup_task(current);
 458        preempt_enable_no_resched();
 459        schedule();
 460        preempt_disable();
 461
 462        /* Call into cpu_idle with preempt disabled */
 463        cpu_idle();
 464}
 465
 466/* Check for early params. */
 467static int __init do_early_param(char *param, char *val)
 468{
 469        const struct obs_kernel_param *p;
 470
 471        for (p = __setup_start; p < __setup_end; p++) {
 472                if ((p->early && strcmp(param, p->str) == 0) ||
 473                    (strcmp(param, "console") == 0 &&
 474                     strcmp(p->str, "earlycon") == 0)
 475                ) {
 476                        if (p->setup_func(val) != 0)
 477                                printk(KERN_WARNING
 478                                       "Malformed early option '%s'\n", param);
 479                }
 480        }
 481        /* We accept everything at this stage. */
 482        return 0;
 483}
 484
 485void __init parse_early_options(char *cmdline)
 486{
 487        parse_args("early options", cmdline, NULL, 0, do_early_param);
 488}
 489
 490/* Arch code calls this early on, or if not, just before other parsing. */
 491void __init parse_early_param(void)
 492{
 493        static __initdata int done = 0;
 494        static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 495
 496        if (done)
 497                return;
 498
 499        /* All fall through to do_early_param. */
 500        strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 501        parse_early_options(tmp_cmdline);
 502        done = 1;
 503}
 504
 505/*
 506 *      Activate the first processor.
 507 */
 508
 509static void __init boot_cpu_init(void)
 510{
 511        int cpu = smp_processor_id();
 512        /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 513        set_cpu_online(cpu, true);
 514        set_cpu_active(cpu, true);
 515        set_cpu_present(cpu, true);
 516        set_cpu_possible(cpu, true);
 517}
 518
 519void __init __weak smp_setup_processor_id(void)
 520{
 521}
 522
 523void __init __weak thread_info_cache_init(void)
 524{
 525}
 526
 527/*
 528 * Set up kernel memory allocators
 529 */
 530static void __init mm_init(void)
 531{
 532        /*
 533         * page_cgroup requires countinous pages as memmap
 534         * and it's bigger than MAX_ORDER unless SPARSEMEM.
 535         */
 536        page_cgroup_init_flatmem();
 537        mem_init();
 538        kmem_cache_init();
 539        percpu_init_late();
 540        pgtable_cache_init();
 541        vmalloc_init();
 542}
 543
 544asmlinkage void __init start_kernel(void)
 545{
 546        char * command_line;
 547        extern const struct kernel_param __start___param[], __stop___param[];
 548
 549        smp_setup_processor_id();
 550
 551        /*
 552         * Need to run as early as possible, to initialize the
 553         * lockdep hash:
 554         */
 555        lockdep_init();
 556        debug_objects_early_init();
 557
 558        /*
 559         * Set up the the initial canary ASAP:
 560         */
 561        boot_init_stack_canary();
 562
 563        cgroup_init_early();
 564
 565        local_irq_disable();
 566        early_boot_irqs_disabled = true;
 567
 568/*
 569 * Interrupts are still disabled. Do necessary setups, then
 570 * enable them
 571 */
 572        tick_init();
 573        boot_cpu_init();
 574        page_address_init();
 575        printk(KERN_NOTICE "%s", linux_banner);
 576        setup_arch(&command_line);
 577        mm_init_owner(&init_mm, &init_task);
 578        setup_command_line(command_line);
 579        setup_nr_cpu_ids();
 580        setup_per_cpu_areas();
 581        smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 582
 583        build_all_zonelists(NULL);
 584        page_alloc_init();
 585
 586        printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
 587        parse_early_param();
 588        parse_args("Booting kernel", static_command_line, __start___param,
 589                   __stop___param - __start___param,
 590                   &unknown_bootoption);
 591        /*
 592         * These use large bootmem allocations and must precede
 593         * kmem_cache_init()
 594         */
 595        pidhash_init();
 596        vfs_caches_init_early();
 597        sort_main_extable();
 598        trap_init();
 599        mm_init();
 600        /*
 601         * Set up the scheduler prior starting any interrupts (such as the
 602         * timer interrupt). Full topology setup happens at smp_init()
 603         * time - but meanwhile we still have a functioning scheduler.
 604         */
 605        sched_init();
 606        /*
 607         * Disable preemption - early bootup scheduling is extremely
 608         * fragile until we cpu_idle() for the first time.
 609         */
 610        preempt_disable();
 611        if (!irqs_disabled()) {
 612                printk(KERN_WARNING "start_kernel(): bug: interrupts were "
 613                                "enabled *very* early, fixing it\n");
 614                local_irq_disable();
 615        }
 616        idr_init_cache();
 617        perf_event_init();
 618        rcu_init();
 619        radix_tree_init();
 620        /* init some links before init_ISA_irqs() */
 621        early_irq_init();
 622        init_IRQ();
 623        prio_tree_init();
 624        init_timers();
 625        hrtimers_init();
 626        softirq_init();
 627        timekeeping_init();
 628        time_init();
 629        profile_init();
 630        if (!irqs_disabled())
 631                printk(KERN_CRIT "start_kernel(): bug: interrupts were "
 632                                 "enabled early\n");
 633        early_boot_irqs_disabled = false;
 634        local_irq_enable();
 635
 636        /* Interrupts are enabled now so all GFP allocations are safe. */
 637        gfp_allowed_mask = __GFP_BITS_MASK;
 638
 639        kmem_cache_init_late();
 640
 641        /*
 642         * HACK ALERT! This is early. We're enabling the console before
 643         * we've done PCI setups etc, and console_init() must be aware of
 644         * this. But we do want output early, in case something goes wrong.
 645         */
 646        console_init();
 647        if (panic_later)
 648                panic(panic_later, panic_param);
 649
 650        lockdep_info();
 651
 652        /*
 653         * Need to run this when irqs are enabled, because it wants
 654         * to self-test [hard/soft]-irqs on/off lock inversion bugs
 655         * too:
 656         */
 657        locking_selftest();
 658
 659#ifdef CONFIG_BLK_DEV_INITRD
 660        if (initrd_start && !initrd_below_start_ok &&
 661            page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 662                printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
 663                    "disabling it.\n",
 664                    page_to_pfn(virt_to_page((void *)initrd_start)),
 665                    min_low_pfn);
 666                initrd_start = 0;
 667        }
 668#endif
 669        page_cgroup_init();
 670        enable_debug_pagealloc();
 671        kmemleak_init();
 672        debug_objects_mem_init();
 673        setup_per_cpu_pageset();
 674        numa_policy_init();
 675        if (late_time_init)
 676                late_time_init();
 677        sched_clock_init();
 678        calibrate_delay();
 679        pidmap_init();
 680        anon_vma_init();
 681#ifdef CONFIG_X86
 682        if (efi_enabled)
 683                efi_enter_virtual_mode();
 684#endif
 685        thread_info_cache_init();
 686        cred_init();
 687        fork_init(totalram_pages);
 688        proc_caches_init();
 689        buffer_init();
 690        key_init();
 691        security_init();
 692        dbg_late_init();
 693        vfs_caches_init(totalram_pages);
 694        signals_init();
 695        /* rootfs populating might need page-writeback */
 696        page_writeback_init();
 697#ifdef CONFIG_PROC_FS
 698        proc_root_init();
 699#endif
 700        cgroup_init();
 701        cpuset_init();
 702        taskstats_init_early();
 703        delayacct_init();
 704
 705        check_bugs();
 706
 707        acpi_early_init(); /* before LAPIC and SMP init */
 708        sfi_init_late();
 709
 710        ftrace_init();
 711
 712        /* Do the rest non-__init'ed, we're now alive */
 713        rest_init();
 714}
 715
 716/* Call all constructor functions linked into the kernel. */
 717static void __init do_ctors(void)
 718{
 719#ifdef CONFIG_CONSTRUCTORS
 720        ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 721
 722        for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 723                (*fn)();
 724#endif
 725}
 726
 727int initcall_debug;
 728core_param(initcall_debug, initcall_debug, bool, 0644);
 729
 730static char msgbuf[64];
 731
 732static int __init_or_module do_one_initcall_debug(initcall_t fn)
 733{
 734        ktime_t calltime, delta, rettime;
 735        unsigned long long duration;
 736        int ret;
 737
 738        printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
 739        calltime = ktime_get();
 740        ret = fn();
 741        rettime = ktime_get();
 742        delta = ktime_sub(rettime, calltime);
 743        duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 744        printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
 745                ret, duration);
 746
 747        return ret;
 748}
 749
 750int __init_or_module do_one_initcall(initcall_t fn)
 751{
 752        int count = preempt_count();
 753        int ret;
 754
 755        if (initcall_debug)
 756                ret = do_one_initcall_debug(fn);
 757        else
 758                ret = fn();
 759
 760        msgbuf[0] = 0;
 761
 762        if (ret && ret != -ENODEV && initcall_debug)
 763                sprintf(msgbuf, "error code %d ", ret);
 764
 765        if (preempt_count() != count) {
 766                strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
 767                preempt_count() = count;
 768        }
 769        if (irqs_disabled()) {
 770                strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 771                local_irq_enable();
 772        }
 773        if (msgbuf[0]) {
 774                printk("initcall %pF returned with %s\n", fn, msgbuf);
 775        }
 776
 777        return ret;
 778}
 779
 780
 781extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
 782
 783static void __init do_initcalls(void)
 784{
 785        initcall_t *fn;
 786
 787        for (fn = __early_initcall_end; fn < __initcall_end; fn++)
 788                do_one_initcall(*fn);
 789}
 790
 791/*
 792 * Ok, the machine is now initialized. None of the devices
 793 * have been touched yet, but the CPU subsystem is up and
 794 * running, and memory and process management works.
 795 *
 796 * Now we can finally start doing some real work..
 797 */
 798static void __init do_basic_setup(void)
 799{
 800        cpuset_init_smp();
 801        usermodehelper_init();
 802        init_tmpfs();
 803        driver_init();
 804        init_irq_proc();
 805        do_ctors();
 806        do_initcalls();
 807}
 808
 809static void __init do_pre_smp_initcalls(void)
 810{
 811        initcall_t *fn;
 812
 813        for (fn = __initcall_start; fn < __early_initcall_end; fn++)
 814                do_one_initcall(*fn);
 815}
 816
 817static void run_init_process(const char *init_filename)
 818{
 819        argv_init[0] = init_filename;
 820        kernel_execve(init_filename, argv_init, envp_init);
 821}
 822
 823/* This is a non __init function. Force it to be noinline otherwise gcc
 824 * makes it inline to init() and it becomes part of init.text section
 825 */
 826static noinline int init_post(void)
 827{
 828        /* need to finish all async __init code before freeing the memory */
 829        async_synchronize_full();
 830        free_initmem();
 831        mark_rodata_ro();
 832        system_state = SYSTEM_RUNNING;
 833        numa_default_policy();
 834
 835
 836        current->signal->flags |= SIGNAL_UNKILLABLE;
 837
 838        if (ramdisk_execute_command) {
 839                run_init_process(ramdisk_execute_command);
 840                printk(KERN_WARNING "Failed to execute %s\n",
 841                                ramdisk_execute_command);
 842        }
 843
 844        /*
 845         * We try each of these until one succeeds.
 846         *
 847         * The Bourne shell can be used instead of init if we are
 848         * trying to recover a really broken machine.
 849         */
 850        if (execute_command) {
 851                run_init_process(execute_command);
 852                printk(KERN_WARNING "Failed to execute %s.  Attempting "
 853                                        "defaults...\n", execute_command);
 854        }
 855        run_init_process("/sbin/init");
 856        run_init_process("/etc/init");
 857        run_init_process("/bin/init");
 858        run_init_process("/bin/sh");
 859
 860        panic("No init found.  Try passing init= option to kernel. "
 861              "See Linux Documentation/init.txt for guidance.");
 862}
 863
 864static int __init kernel_init(void * unused)
 865{
 866        /*
 867         * Wait until kthreadd is all set-up.
 868         */
 869        wait_for_completion(&kthreadd_done);
 870        /*
 871         * init can allocate pages on any node
 872         */
 873        set_mems_allowed(node_states[N_HIGH_MEMORY]);
 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        lockup_detector_init();
 894
 895        smp_init();
 896        sched_init_smp();
 897
 898        do_basic_setup();
 899
 900        /* Open the /dev/console on the rootfs, this should never fail */
 901        if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 902                printk(KERN_WARNING "Warning: unable to open an initial console.\n");
 903
 904        (void) sys_dup(0);
 905        (void) sys_dup(0);
 906        /*
 907         * check if there is an early userspace init.  If yes, let it do all
 908         * the work
 909         */
 910
 911        if (!ramdisk_execute_command)
 912                ramdisk_execute_command = "/init";
 913
 914        if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 915                ramdisk_execute_command = NULL;
 916                prepare_namespace();
 917        }
 918
 919        /*
 920         * Ok, we have completed the initial bootup, and
 921         * we're essentially up and running. Get rid of the
 922         * initmem segments and start the user-mode stuff..
 923         */
 924
 925        init_post();
 926        return 0;
 927}
 928
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