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main.c

/*
 *  linux/init/main.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  GK 2/5/95  -  Changed to support mounting root fs via NFS
 *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
 *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
 *  Simplified starting of init:  Michael A. Griffith <grif@acm.org> 
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/utsname.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/initrd.h>
#include <linux/hdreg.h>
#include <linux/bootmem.h>
#include <linux/tty.h>
#include <linux/gfp.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
#include <linux/kernel_stat.h>
#include <linux/start_kernel.h>
#include <linux/security.h>
#include <linux/workqueue.h>
#include <linux/profile.h>
#include <linux/rcupdate.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cgroup.h>
#include <linux/efi.h>
#include <linux/tick.h>
#include <linux/interrupt.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
#include <linux/unwind.h>
#include <linux/buffer_head.h>
#include <linux/debug_locks.h>
#include <linux/lockdep.h>
#include <linux/pid_namespace.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <linux/sched.h>

#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>

#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/smp.h>
#endif

/*
 * This is one of the first .c files built. Error out early if we have compiler
 * trouble.
 */

#if __GNUC__ == 4 && __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ == 0
#warning gcc-4.1.0 is known to miscompile the kernel.  A different compiler version is recommended.
#endif

static int kernel_init(void *);

extern void init_IRQ(void);
extern void fork_init(unsigned long);
extern void mca_init(void);
extern void sbus_init(void);
extern void signals_init(void);
extern void pidhash_init(void);
extern void pidmap_init(void);
extern void prio_tree_init(void);
extern void radix_tree_init(void);
extern void free_initmem(void);
#ifdef      CONFIG_ACPI
extern void acpi_early_init(void);
#else
static inline void acpi_early_init(void) { }
#endif
#ifndef CONFIG_DEBUG_RODATA
static inline void mark_rodata_ro(void) { }
#endif

#ifdef CONFIG_TC
extern void tc_init(void);
#endif

enum system_states system_state;
EXPORT_SYMBOL(system_state);

/*
 * Boot command-line arguments
 */
#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT

extern void time_init(void);
/* Default late time init is NULL. archs can override this later. */
void (*late_time_init)(void);
extern void softirq_init(void);

/* Untouched command line saved by arch-specific code. */
char __initdata boot_command_line[COMMAND_LINE_SIZE];
/* Untouched saved command line (eg. for /proc) */
char *saved_command_line;
/* Command line for parameter parsing */
static char *static_command_line;

static char *execute_command;
static char *ramdisk_execute_command;

#ifdef CONFIG_SMP
/* Setup configured maximum number of CPUs to activate */
static unsigned int __initdata max_cpus = NR_CPUS;

/*
 * Setup routine for controlling SMP activation
 *
 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 * activation entirely (the MPS table probe still happens, though).
 *
 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 * greater than 0, limits the maximum number of CPUs activated in
 * SMP mode to <NUM>.
 */
#ifndef CONFIG_X86_IO_APIC
static inline void disable_ioapic_setup(void) {};
#endif

static int __init nosmp(char *str)
{
      max_cpus = 0;
      disable_ioapic_setup();
      return 0;
}

early_param("nosmp", nosmp);

static int __init maxcpus(char *str)
{
      get_option(&str, &max_cpus);
      if (max_cpus == 0)
            disable_ioapic_setup();

      return 0;
}

early_param("maxcpus", maxcpus);
#else
#define max_cpus NR_CPUS
#endif

/*
 * If set, this is an indication to the drivers that reset the underlying
 * device before going ahead with the initialization otherwise driver might
 * rely on the BIOS and skip the reset operation.
 *
 * This is useful if kernel is booting in an unreliable environment.
 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 * skipped and devices will be in unknown state.
 */
unsigned int reset_devices;
EXPORT_SYMBOL(reset_devices);

static int __init set_reset_devices(char *str)
{
      reset_devices = 1;
      return 1;
}

__setup("reset_devices", set_reset_devices);

static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
static const char *panic_later, *panic_param;

extern struct obs_kernel_param __setup_start[], __setup_end[];

static int __init obsolete_checksetup(char *line)
{
      struct obs_kernel_param *p;
      int had_early_param = 0;

      p = __setup_start;
      do {
            int n = strlen(p->str);
            if (!strncmp(line, p->str, n)) {
                  if (p->early) {
                        /* Already done in parse_early_param?
                         * (Needs exact match on param part).
                         * Keep iterating, as we can have early
                         * params and __setups of same names 8( */
                        if (line[n] == '\0' || line[n] == '=')
                              had_early_param = 1;
                  } else if (!p->setup_func) {
                        printk(KERN_WARNING "Parameter %s is obsolete,"
                               " ignored\n", p->str);
                        return 1;
                  } else if (p->setup_func(line + n))
                        return 1;
            }
            p++;
      } while (p < __setup_end);

      return had_early_param;
}

/*
 * This should be approx 2 Bo*oMips to start (note initial shift), and will
 * still work even if initially too large, it will just take slightly longer
 */
unsigned long loops_per_jiffy = (1<<12);

EXPORT_SYMBOL(loops_per_jiffy);

static int __init debug_kernel(char *str)
{
      if (*str)
            return 0;
      console_loglevel = 10;
      return 1;
}

static int __init quiet_kernel(char *str)
{
      if (*str)
            return 0;
      console_loglevel = 4;
      return 1;
}

__setup("debug", debug_kernel);
__setup("quiet", quiet_kernel);

static int __init loglevel(char *str)
{
      get_option(&str, &console_loglevel);
      return 1;
}

__setup("loglevel=", loglevel);

/*
 * Unknown boot options get handed to init, unless they look like
 * failed parameters
 */
static int __init unknown_bootoption(char *param, char *val)
{
      /* Change NUL term back to "=", to make "param" the whole string. */
      if (val) {
            /* param=val or param="val"? */
            if (val == param+strlen(param)+1)
                  val[-1] = '=';
            else if (val == param+strlen(param)+2) {
                  val[-2] = '=';
                  memmove(val-1, val, strlen(val)+1);
                  val--;
            } else
                  BUG();
      }

      /* Handle obsolete-style parameters */
      if (obsolete_checksetup(param))
            return 0;

      /*
       * Preemptive maintenance for "why didn't my misspelled command
       * line work?"
       */
      if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
            printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
            return 0;
      }

      if (panic_later)
            return 0;

      if (val) {
            /* Environment option */
            unsigned int i;
            for (i = 0; envp_init[i]; i++) {
                  if (i == MAX_INIT_ENVS) {
                        panic_later = "Too many boot env vars at `%s'";
                        panic_param = param;
                  }
                  if (!strncmp(param, envp_init[i], val - param))
                        break;
            }
            envp_init[i] = param;
      } else {
            /* Command line option */
            unsigned int i;
            for (i = 0; argv_init[i]; i++) {
                  if (i == MAX_INIT_ARGS) {
                        panic_later = "Too many boot init vars at `%s'";
                        panic_param = param;
                  }
            }
            argv_init[i] = param;
      }
      return 0;
}

static int __init init_setup(char *str)
{
      unsigned int i;

      execute_command = str;
      /*
       * In case LILO is going to boot us with default command line,
       * it prepends "auto" before the whole cmdline which makes
       * the shell think it should execute a script with such name.
       * So we ignore all arguments entered _before_ init=... [MJ]
       */
      for (i = 1; i < MAX_INIT_ARGS; i++)
            argv_init[i] = NULL;
      return 1;
}
__setup("init=", init_setup);

static int __init rdinit_setup(char *str)
{
      unsigned int i;

      ramdisk_execute_command = str;
      /* See "auto" comment in init_setup */
      for (i = 1; i < MAX_INIT_ARGS; i++)
            argv_init[i] = NULL;
      return 1;
}
__setup("rdinit=", rdinit_setup);

#ifndef CONFIG_SMP

#ifdef CONFIG_X86_LOCAL_APIC
static void __init smp_init(void)
{
      APIC_init_uniprocessor();
}
#else
#define smp_init()      do { } while (0)
#endif

static inline void setup_per_cpu_areas(void) { }
static inline void smp_prepare_cpus(unsigned int maxcpus) { }

#else

#ifdef __GENERIC_PER_CPU
unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;

EXPORT_SYMBOL(__per_cpu_offset);

static void __init setup_per_cpu_areas(void)
{
      unsigned long size, i;
      char *ptr;
      unsigned long nr_possible_cpus = num_possible_cpus();

      /* Copy section for each CPU (we discard the original) */
      size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
      ptr = alloc_bootmem_pages(size * nr_possible_cpus);

      for_each_possible_cpu(i) {
            __per_cpu_offset[i] = ptr - __per_cpu_start;
            memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
            ptr += size;
      }
}
#endif /* !__GENERIC_PER_CPU */

/* Called by boot processor to activate the rest. */
static void __init smp_init(void)
{
      unsigned int cpu;

      /* FIXME: This should be done in userspace --RR */
      for_each_present_cpu(cpu) {
            if (num_online_cpus() >= max_cpus)
                  break;
            if (!cpu_online(cpu))
                  cpu_up(cpu);
      }

      /* Any cleanup work */
      printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
      smp_cpus_done(max_cpus);
}

#endif

/*
 * We need to store the untouched command line for future reference.
 * We also need to store the touched command line since the parameter
 * parsing is performed in place, and we should allow a component to
 * store reference of name/value for future reference.
 */
static void __init setup_command_line(char *command_line)
{
      saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
      static_command_line = alloc_bootmem(strlen (command_line)+1);
      strcpy (saved_command_line, boot_command_line);
      strcpy (static_command_line, command_line);
}

/*
 * We need to finalize in a non-__init function or else race conditions
 * between the root thread and the init thread may cause start_kernel to
 * be reaped by free_initmem before the root thread has proceeded to
 * cpu_idle.
 *
 * gcc-3.4 accidentally inlines this function, so use noinline.
 */

static void noinline __init_refok rest_init(void)
      __releases(kernel_lock)
{
      int pid;

      kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
      numa_default_policy();
      pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
      kthreadd_task = find_task_by_pid(pid);
      unlock_kernel();

      /*
       * The boot idle thread must execute schedule()
       * at least once to get things moving:
       */
      init_idle_bootup_task(current);
      preempt_enable_no_resched();
      schedule();
      preempt_disable();

      /* Call into cpu_idle with preempt disabled */
      cpu_idle();
}

/* Check for early params. */
static int __init do_early_param(char *param, char *val)
{
      struct obs_kernel_param *p;

      for (p = __setup_start; p < __setup_end; p++) {
            if ((p->early && strcmp(param, p->str) == 0) ||
                (strcmp(param, "console") == 0 &&
                 strcmp(p->str, "earlycon") == 0)
            ) {
                  if (p->setup_func(val) != 0)
                        printk(KERN_WARNING
                               "Malformed early option '%s'\n", param);
            }
      }
      /* We accept everything at this stage. */
      return 0;
}

/* Arch code calls this early on, or if not, just before other parsing. */
void __init parse_early_param(void)
{
      static __initdata int done = 0;
      static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];

      if (done)
            return;

      /* All fall through to do_early_param. */
      strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
      parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);
      done = 1;
}

/*
 *    Activate the first processor.
 */

static void __init boot_cpu_init(void)
{
      int cpu = smp_processor_id();
      /* Mark the boot cpu "present", "online" etc for SMP and UP case */
      cpu_set(cpu, cpu_online_map);
      cpu_set(cpu, cpu_present_map);
      cpu_set(cpu, cpu_possible_map);
}

void __init __attribute__((weak)) smp_setup_processor_id(void)
{
}

asmlinkage void __init start_kernel(void)
{
      char * command_line;
      extern struct kernel_param __start___param[], __stop___param[];

      smp_setup_processor_id();

      /*
       * Need to run as early as possible, to initialize the
       * lockdep hash:
       */
      unwind_init();
      lockdep_init();
      cgroup_init_early();

      local_irq_disable();
      early_boot_irqs_off();
      early_init_irq_lock_class();

/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
      lock_kernel();
      tick_init();
      boot_cpu_init();
      page_address_init();
      printk(KERN_NOTICE);
      printk(linux_banner);
      setup_arch(&command_line);
      setup_command_line(command_line);
      unwind_setup();
      setup_per_cpu_areas();
      smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */

      /*
       * Set up the scheduler prior starting any interrupts (such as the
       * timer interrupt). Full topology setup happens at smp_init()
       * time - but meanwhile we still have a functioning scheduler.
       */
      sched_init();
      /*
       * Disable preemption - early bootup scheduling is extremely
       * fragile until we cpu_idle() for the first time.
       */
      preempt_disable();
      build_all_zonelists();
      page_alloc_init();
      printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
      parse_early_param();
      parse_args("Booting kernel", static_command_line, __start___param,
               __stop___param - __start___param,
               &unknown_bootoption);
      if (!irqs_disabled()) {
            printk(KERN_WARNING "start_kernel(): bug: interrupts were "
                        "enabled *very* early, fixing it\n");
            local_irq_disable();
      }
      sort_main_extable();
      trap_init();
      rcu_init();
      init_IRQ();
      pidhash_init();
      init_timers();
      hrtimers_init();
      softirq_init();
      timekeeping_init();
      time_init();
      profile_init();
      if (!irqs_disabled())
            printk("start_kernel(): bug: interrupts were enabled early\n");
      early_boot_irqs_on();
      local_irq_enable();

      /*
       * HACK ALERT! This is early. We're enabling the console before
       * we've done PCI setups etc, and console_init() must be aware of
       * this. But we do want output early, in case something goes wrong.
       */
      console_init();
      if (panic_later)
            panic(panic_later, panic_param);

      lockdep_info();

      /*
       * Need to run this when irqs are enabled, because it wants
       * to self-test [hard/soft]-irqs on/off lock inversion bugs
       * too:
       */
      locking_selftest();

#ifdef CONFIG_BLK_DEV_INITRD
      if (initrd_start && !initrd_below_start_ok &&
                  initrd_start < min_low_pfn << PAGE_SHIFT) {
            printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
                "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
            initrd_start = 0;
      }
#endif
      vfs_caches_init_early();
      cpuset_init_early();
      mem_init();
      kmem_cache_init();
      setup_per_cpu_pageset();
      numa_policy_init();
      if (late_time_init)
            late_time_init();
      calibrate_delay();
      pidmap_init();
      pgtable_cache_init();
      prio_tree_init();
      anon_vma_init();
#ifdef CONFIG_X86
      if (efi_enabled)
            efi_enter_virtual_mode();
#endif
      fork_init(num_physpages);
      proc_caches_init();
      buffer_init();
      unnamed_dev_init();
      key_init();
      security_init();
      vfs_caches_init(num_physpages);
      radix_tree_init();
      signals_init();
      /* rootfs populating might need page-writeback */
      page_writeback_init();
#ifdef CONFIG_PROC_FS
      proc_root_init();
#endif
      cgroup_init();
      cpuset_init();
      taskstats_init_early();
      delayacct_init();

      check_bugs();

      acpi_early_init(); /* before LAPIC and SMP init */

      /* Do the rest non-__init'ed, we're now alive */
      rest_init();
}

static int __initdata initcall_debug;

static int __init initcall_debug_setup(char *str)
{
      initcall_debug = 1;
      return 1;
}
__setup("initcall_debug", initcall_debug_setup);

extern initcall_t __initcall_start[], __initcall_end[];

static void __init do_initcalls(void)
{
      initcall_t *call;
      int count = preempt_count();

      for (call = __initcall_start; call < __initcall_end; call++) {
            ktime_t t0, t1, delta;
            char *msg = NULL;
            char msgbuf[40];
            int result;

            if (initcall_debug) {
                  printk("Calling initcall 0x%p", *call);
                  print_fn_descriptor_symbol(": %s()",
                              (unsigned long) *call);
                  printk("\n");
                  t0 = ktime_get();
            }

            result = (*call)();

            if (initcall_debug) {
                  t1 = ktime_get();
                  delta = ktime_sub(t1, t0);

                  printk("initcall 0x%p", *call);
                  print_fn_descriptor_symbol(": %s()",
                              (unsigned long) *call);
                  printk(" returned %d.\n", result);

                  printk("initcall 0x%p ran for %Ld msecs: ",
                        *call, (unsigned long long)delta.tv64 >> 20);
                  print_fn_descriptor_symbol("%s()\n",
                        (unsigned long) *call);
            }

            if (result && result != -ENODEV && initcall_debug) {
                  sprintf(msgbuf, "error code %d", result);
                  msg = msgbuf;
            }
            if (preempt_count() != count) {
                  msg = "preemption imbalance";
                  preempt_count() = count;
            }
            if (irqs_disabled()) {
                  msg = "disabled interrupts";
                  local_irq_enable();
            }
            if (msg) {
                  printk(KERN_WARNING "initcall at 0x%p", *call);
                  print_fn_descriptor_symbol(": %s()",
                              (unsigned long) *call);
                  printk(": returned with %s\n", msg);
            }
      }

      /* Make sure there is no pending stuff from the initcall sequence */
      flush_scheduled_work();
}

/*
 * Ok, the machine is now initialized. None of the devices
 * have been touched yet, but the CPU subsystem is up and
 * running, and memory and process management works.
 *
 * Now we can finally start doing some real work..
 */
static void __init do_basic_setup(void)
{
      /* drivers will send hotplug events */
      init_workqueues();
      usermodehelper_init();
      driver_init();
      init_irq_proc();
      do_initcalls();
}

static int __initdata nosoftlockup;

static int __init nosoftlockup_setup(char *str)
{
      nosoftlockup = 1;
      return 1;
}
__setup("nosoftlockup", nosoftlockup_setup);

static void __init do_pre_smp_initcalls(void)
{
      extern int spawn_ksoftirqd(void);

      migration_init();
      spawn_ksoftirqd();
      if (!nosoftlockup)
            spawn_softlockup_task();
}

static void run_init_process(char *init_filename)
{
      argv_init[0] = init_filename;
      kernel_execve(init_filename, argv_init, envp_init);
}

/* This is a non __init function. Force it to be noinline otherwise gcc
 * makes it inline to init() and it becomes part of init.text section
 */
static int noinline init_post(void)
{
      free_initmem();
      unlock_kernel();
      mark_rodata_ro();
      system_state = SYSTEM_RUNNING;
      numa_default_policy();

      if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
            printk(KERN_WARNING "Warning: unable to open an initial console.\n");

      (void) sys_dup(0);
      (void) sys_dup(0);

      if (ramdisk_execute_command) {
            run_init_process(ramdisk_execute_command);
            printk(KERN_WARNING "Failed to execute %s\n",
                        ramdisk_execute_command);
      }

      /*
       * We try each of these until one succeeds.
       *
       * The Bourne shell can be used instead of init if we are
       * trying to recover a really broken machine.
       */
      if (execute_command) {
            run_init_process(execute_command);
            printk(KERN_WARNING "Failed to execute %s.  Attempting "
                              "defaults...\n", execute_command);
      }
      run_init_process("/sbin/init");
      run_init_process("/etc/init");
      run_init_process("/bin/init");
      run_init_process("/bin/sh");

      panic("No init found.  Try passing init= option to kernel.");
}

static int __init kernel_init(void * unused)
{
      lock_kernel();
      /*
       * init can run on any cpu.
       */
      set_cpus_allowed(current, CPU_MASK_ALL);
      /*
       * Tell the world that we're going to be the grim
       * reaper of innocent orphaned children.
       *
       * We don't want people to have to make incorrect
       * assumptions about where in the task array this
       * can be found.
       */
      init_pid_ns.child_reaper = current;

      __set_special_pids(1, 1);
      cad_pid = task_pid(current);

      smp_prepare_cpus(max_cpus);

      do_pre_smp_initcalls();

      smp_init();
      sched_init_smp();

      cpuset_init_smp();

      do_basic_setup();

      /*
       * check if there is an early userspace init.  If yes, let it do all
       * the work
       */

      if (!ramdisk_execute_command)
            ramdisk_execute_command = "/init";

      if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
            ramdisk_execute_command = NULL;
            prepare_namespace();
      }

      /*
       * Ok, we have completed the initial bootup, and
       * we're essentially up and running. Get rid of the
       * initmem segments and start the user-mode stuff..
       */
      init_post();
      return 0;
}

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