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 175                                printk(KERN_WARNING "Parameter %s is obsolete,"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