main.c 24.6 KB
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/*
 *  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
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 *  Simplified starting of init:  Michael A. Griffith <grif@acm.org>
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 */

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#define DEBUG		/* Enable initcall_debug */

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#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
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#include <linux/stackprotector.h>
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#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/bootmem.h>
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#include <linux/acpi.h>
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#include <linux/tty.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
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#include <linux/vmalloc.h>
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#include <linux/kernel_stat.h>
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#include <linux/start_kernel.h>
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#include <linux/security.h>
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#include <linux/smp.h>
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#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>
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#include <linux/cgroup.h>
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#include <linux/efi.h>
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#include <linux/tick.h>
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#include <linux/interrupt.h>
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#include <linux/taskstats_kern.h>
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#include <linux/delayacct.h>
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#include <linux/unistd.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
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#include <linux/buffer_head.h>
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#include <linux/page_cgroup.h>
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#include <linux/debug_locks.h>
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#include <linux/debugobjects.h>
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#include <linux/lockdep.h>
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#include <linux/kmemleak.h>
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#include <linux/pid_namespace.h>
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#include <linux/device.h>
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#include <linux/kthread.h>
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#include <linux/sched.h>
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#include <linux/signal.h>
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#include <linux/idr.h>
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#include <linux/kgdb.h>
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#include <linux/ftrace.h>
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#include <linux/async.h>
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#include <linux/kmemcheck.h>
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#include <linux/sfi.h>
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#include <linux/shmem_fs.h>
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#include <linux/slab.h>
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#include <linux/perf_event.h>
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#include <linux/file.h>
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#include <linux/ptrace.h>
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#include <linux/blkdev.h>
#include <linux/elevator.h>
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#include <linux/sched_clock.h>
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#include <linux/context_tracking.h>
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#include <linux/random.h>
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#include <linux/list.h>
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#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
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#include <asm/sections.h>
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#include <asm/cacheflush.h>
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#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/smp.h>
#endif

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static int kernel_init(void *);
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extern void init_IRQ(void);
extern void fork_init(unsigned long);
extern void radix_tree_init(void);
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#ifndef CONFIG_DEBUG_RODATA
static inline void mark_rodata_ro(void) { }
#endif
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/*
 * Debug helper: via this flag we know that we are in 'early bootup code'
 * where only the boot processor is running with IRQ disabled.  This means
 * two things - IRQ must not be enabled before the flag is cleared and some
 * operations which are not allowed with IRQ disabled are allowed while the
 * flag is set.
 */
bool early_boot_irqs_disabled __read_mostly;

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enum system_states system_state __read_mostly;
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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. */
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void (*__initdata late_time_init)(void);
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/* 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;
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/* Command line for per-initcall parameter parsing */
static char *initcall_command_line;
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static char *execute_command;
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static char *ramdisk_execute_command;
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/*
 * Used to generate warnings if static_key manipulation functions are used
 * before jump_label_init is called.
 */
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bool static_key_initialized __read_mostly;
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EXPORT_SYMBOL_GPL(static_key_initialized);

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

__setup("reset_devices", set_reset_devices);

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

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extern const struct obs_kernel_param __setup_start[], __setup_end[];
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static int __init obsolete_checksetup(char *line)
{
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	const struct obs_kernel_param *p;
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	int had_early_param = 0;
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	p = __setup_start;
	do {
		int n = strlen(p->str);
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		if (parameqn(line, p->str, n)) {
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			if (p->early) {
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				/* 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( */
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				if (line[n] == '\0' || line[n] == '=')
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					had_early_param = 1;
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			} else if (!p->setup_func) {
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				pr_warn("Parameter %s is obsolete, ignored\n",
					p->str);
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				return 1;
			} else if (p->setup_func(line + n))
				return 1;
		}
		p++;
	} while (p < __setup_end);
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	return had_early_param;
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}

/*
 * 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)
{
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	console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
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	return 0;
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}

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

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early_param("debug", debug_kernel);
early_param("quiet", quiet_kernel);
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static int __init loglevel(char *str)
{
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	int newlevel;

	/*
	 * Only update loglevel value when a correct setting was passed,
	 * to prevent blind crashes (when loglevel being set to 0) that
	 * are quite hard to debug
	 */
	if (get_option(&str, &newlevel)) {
		console_loglevel = newlevel;
		return 0;
	}

	return -EINVAL;
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}

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early_param("loglevel", loglevel);
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/* Change NUL term back to "=", to make "param" the whole string. */
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static int __init repair_env_string(char *param, char *val, const char *unused)
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{
	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();
	}
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	return 0;
}

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/* Anything after -- gets handed straight to init. */
static int __init set_init_arg(char *param, char *val, const char *unused)
{
	unsigned int i;

	if (panic_later)
		return 0;

	repair_env_string(param, val, unused);

	for (i = 0; argv_init[i]; i++) {
		if (i == MAX_INIT_ARGS) {
			panic_later = "init";
			panic_param = param;
			return 0;
		}
	}
	argv_init[i] = param;
	return 0;
}

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/*
 * Unknown boot options get handed to init, unless they look like
 * unused parameters (modprobe will find them in /proc/cmdline).
 */
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static int __init unknown_bootoption(char *param, char *val, const char *unused)
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{
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	repair_env_string(param, val, unused);
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	/* Handle obsolete-style parameters */
	if (obsolete_checksetup(param))
		return 0;

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	/* Unused module parameter. */
	if (strchr(param, '.') && (!val || strchr(param, '.') < val))
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		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) {
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				panic_later = "env";
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				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) {
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				panic_later = "init";
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				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);

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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);

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#ifndef CONFIG_SMP
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static const unsigned int setup_max_cpus = NR_CPUS;
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#ifdef CONFIG_X86_LOCAL_APIC
static void __init smp_init(void)
{
	APIC_init_uniprocessor();
}
#else
#define smp_init()	do { } while (0)
#endif

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static inline void setup_nr_cpu_ids(void) { }
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static inline void smp_prepare_cpus(unsigned int maxcpus) { }
#endif

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/*
 * 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)
{
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	saved_command_line =
		memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
	initcall_command_line =
		memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
	static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
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	strcpy(saved_command_line, boot_command_line);
	strcpy(static_command_line, command_line);
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}

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/*
 * 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.
 */

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static __initdata DECLARE_COMPLETION(kthreadd_done);

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

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	rcu_scheduler_starting();
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	/*
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	 * We need to spawn init first so that it obtains pid 1, however
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	 * the init task will end up wanting to create kthreads, which, if
	 * we schedule it before we create kthreadd, will OOPS.
	 */
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	kernel_thread(kernel_init, NULL, CLONE_FS);
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	numa_default_policy();
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	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
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	rcu_read_lock();
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	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
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	rcu_read_unlock();
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	complete(&kthreadd_done);
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	/*
	 * The boot idle thread must execute schedule()
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	 * at least once to get things moving:
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	 */
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	init_idle_bootup_task(current);
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	schedule_preempt_disabled();
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	/* Call into cpu_idle with preempt disabled */
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	cpu_startup_entry(CPUHP_ONLINE);
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}
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/* Check for early params. */
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static int __init do_early_param(char *param, char *val, const char *unused)
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{
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	const struct obs_kernel_param *p;
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	for (p = __setup_start; p < __setup_end; p++) {
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		if ((p->early && parameq(param, p->str)) ||
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		    (strcmp(param, "console") == 0 &&
		     strcmp(p->str, "earlycon") == 0)
		) {
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			if (p->setup_func(val) != 0)
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				pr_warn("Malformed early option '%s'\n", param);
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		}
	}
	/* We accept everything at this stage. */
	return 0;
}

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void __init parse_early_options(char *cmdline)
{
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	parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
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}

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

	/* All fall through to do_early_param. */
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	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
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	parse_early_options(tmp_cmdline);
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	done = 1;
}

/*
 *	Activate the first processor.
 */

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static void __init boot_cpu_init(void)
{
	int cpu = smp_processor_id();
	/* Mark the boot cpu "present", "online" etc for SMP and UP case */
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	set_cpu_online(cpu, true);
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	set_cpu_active(cpu, true);
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	set_cpu_present(cpu, true);
	set_cpu_possible(cpu, true);
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}

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void __init __weak smp_setup_processor_id(void)
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{
}

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# if THREAD_SIZE >= PAGE_SIZE
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void __init __weak thread_info_cache_init(void)
{
}
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#endif
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/*
 * Set up kernel memory allocators
 */
static void __init mm_init(void)
{
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	/*
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	 * page_cgroup requires contiguous pages,
	 * bigger than MAX_ORDER unless SPARSEMEM.
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	 */
	page_cgroup_init_flatmem();
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	mem_init();
	kmem_cache_init();
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	percpu_init_late();
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	pgtable_init();
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	vmalloc_init();
}

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asmlinkage __visible void __init start_kernel(void)
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{
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	char *command_line;
	char *after_dashes;
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	/*
	 * Need to run as early as possible, to initialize the
	 * lockdep hash:
	 */
	lockdep_init();
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	set_task_stack_end_magic(&init_task);
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	smp_setup_processor_id();
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	debug_objects_early_init();
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	/*
	 * Set up the the initial canary ASAP:
	 */
	boot_init_stack_canary();

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	cgroup_init_early();
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	local_irq_disable();
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	early_boot_irqs_disabled = true;
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/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
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	boot_cpu_init();
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	page_address_init();
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	pr_notice("%s", linux_banner);
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	setup_arch(&command_line);
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	mm_init_cpumask(&init_mm);
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	setup_command_line(command_line);
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	setup_nr_cpu_ids();
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	setup_per_cpu_areas();
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	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
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	build_all_zonelists(NULL, NULL);
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	page_alloc_init();

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	pr_notice("Kernel command line: %s\n", boot_command_line);
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	parse_early_param();
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	after_dashes = parse_args("Booting kernel",
				  static_command_line, __start___param,
				  __stop___param - __start___param,
				  -1, -1, &unknown_bootoption);
	if (after_dashes)
		parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
			   set_init_arg);
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	jump_label_init();

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	/*
	 * These use large bootmem allocations and must precede
	 * kmem_cache_init()
	 */
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	setup_log_buf(0);
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	pidhash_init();
	vfs_caches_init_early();
	sort_main_extable();
	trap_init();
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	mm_init();
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	/*
	 * 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();
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	if (WARN(!irqs_disabled(),
		 "Interrupts were enabled *very* early, fixing it\n"))
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		local_irq_disable();
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	idr_init_cache();
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	rcu_init();
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	context_tracking_init();
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	radix_tree_init();
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	/* init some links before init_ISA_irqs() */
	early_irq_init();
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	init_IRQ();
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	tick_init();
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	rcu_init_nohz();
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	init_timers();
588
	hrtimers_init();
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	softirq_init();
590
	timekeeping_init();
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591
	time_init();
592
	sched_clock_postinit();
593
	perf_event_init();
594
	profile_init();
595
	call_function_init();
596
	WARN(!irqs_disabled(), "Interrupts were enabled early\n");
597
	early_boot_irqs_disabled = false;
598
	local_irq_enable();
599

600
	kmem_cache_init_late();
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	/*
	 * 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)
609 610
		panic("Too many boot %s vars at `%s'", panic_later,
		      panic_param);
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Ingo Molnar 已提交
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	lockdep_info();

614 615 616 617 618 619 620
	/*
	 * 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();

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#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_start && !initrd_below_start_ok &&
623
	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
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Andrew Morton 已提交
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		pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
625 626
		    page_to_pfn(virt_to_page((void *)initrd_start)),
		    min_low_pfn);
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		initrd_start = 0;
	}
#endif
630
	page_cgroup_init();
631
	debug_objects_mem_init();
632
	kmemleak_init();
633
	setup_per_cpu_pageset();
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	numa_policy_init();
	if (late_time_init)
		late_time_init();
637
	sched_clock_init();
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	calibrate_delay();
	pidmap_init();
	anon_vma_init();
641
	acpi_early_init();
642
#ifdef CONFIG_X86
643
	if (efi_enabled(EFI_RUNTIME_SERVICES))
644
		efi_enter_virtual_mode();
645
#endif
646
#ifdef CONFIG_X86_ESPFIX64
647 648
	/* Should be run before the first non-init thread is created */
	init_espfix_bsp();
649
#endif
650
	thread_info_cache_init();
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	cred_init();
652
	fork_init(totalram_pages);
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	proc_caches_init();
	buffer_init();
	key_init();
	security_init();
657
	dbg_late_init();
658
	vfs_caches_init(totalram_pages);
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	signals_init();
	/* rootfs populating might need page-writeback */
	page_writeback_init();
	proc_root_init();
663
	cgroup_init();
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	cpuset_init();
665
	taskstats_init_early();
666
	delayacct_init();
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	check_bugs();

670
	sfi_init_late();
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672
	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
673
		efi_late_init();
674
		efi_free_boot_services();
675
	}
676

677 678
	ftrace_init();

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

683 684 685 686
/* Call all constructor functions linked into the kernel. */
static void __init do_ctors(void)
{
#ifdef CONFIG_CONSTRUCTORS
687
	ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
688

689 690
	for (; fn < (ctor_fn_t *) __ctors_end; fn++)
		(*fn)();
691 692 693
#endif
}

694
bool initcall_debug;
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core_param(initcall_debug, initcall_debug, bool, 0644);
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697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760
#ifdef CONFIG_KALLSYMS
struct blacklist_entry {
	struct list_head next;
	char *buf;
};

static __initdata_or_module LIST_HEAD(blacklisted_initcalls);

static int __init initcall_blacklist(char *str)
{
	char *str_entry;
	struct blacklist_entry *entry;

	/* str argument is a comma-separated list of functions */
	do {
		str_entry = strsep(&str, ",");
		if (str_entry) {
			pr_debug("blacklisting initcall %s\n", str_entry);
			entry = alloc_bootmem(sizeof(*entry));
			entry->buf = alloc_bootmem(strlen(str_entry) + 1);
			strcpy(entry->buf, str_entry);
			list_add(&entry->next, &blacklisted_initcalls);
		}
	} while (str_entry);

	return 0;
}

static bool __init_or_module initcall_blacklisted(initcall_t fn)
{
	struct list_head *tmp;
	struct blacklist_entry *entry;
	char *fn_name;

	fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
	if (!fn_name)
		return false;

	list_for_each(tmp, &blacklisted_initcalls) {
		entry = list_entry(tmp, struct blacklist_entry, next);
		if (!strcmp(fn_name, entry->buf)) {
			pr_debug("initcall %s blacklisted\n", fn_name);
			kfree(fn_name);
			return true;
		}
	}

	kfree(fn_name);
	return false;
}
#else
static int __init initcall_blacklist(char *str)
{
	pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
	return 0;
}

static bool __init_or_module initcall_blacklisted(initcall_t fn)
{
	return false;
}
#endif
__setup("initcall_blacklist=", initcall_blacklist);

761
static int __init_or_module do_one_initcall_debug(initcall_t fn)
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{
763
	ktime_t calltime, delta, rettime;
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Américo Wang 已提交
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	unsigned long long duration;
	int ret;
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767
	printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
768
	calltime = ktime_get();
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Américo Wang 已提交
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	ret = fn();
770 771 772
	rettime = ktime_get();
	delta = ktime_sub(rettime, calltime);
	duration = (unsigned long long) ktime_to_ns(delta) >> 10;
773
	printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n",
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		 fn, ret, duration);
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776 777 778
	return ret;
}

779
int __init_or_module do_one_initcall(initcall_t fn)
780 781 782
{
	int count = preempt_count();
	int ret;
783
	char msgbuf[64];
784

785 786 787
	if (initcall_blacklisted(fn))
		return -EPERM;

788 789 790 791
	if (initcall_debug)
		ret = do_one_initcall_debug(fn);
	else
		ret = fn();
792

793
	msgbuf[0] = 0;
794

795
	if (preempt_count() != count) {
796
		sprintf(msgbuf, "preemption imbalance ");
797
		preempt_count_set(count);
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798
	}
799
	if (irqs_disabled()) {
800
		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
801 802
		local_irq_enable();
	}
803
	WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
804

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Américo Wang 已提交
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	return ret;
806 807 808
}


809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831
extern initcall_t __initcall_start[];
extern initcall_t __initcall0_start[];
extern initcall_t __initcall1_start[];
extern initcall_t __initcall2_start[];
extern initcall_t __initcall3_start[];
extern initcall_t __initcall4_start[];
extern initcall_t __initcall5_start[];
extern initcall_t __initcall6_start[];
extern initcall_t __initcall7_start[];
extern initcall_t __initcall_end[];

static initcall_t *initcall_levels[] __initdata = {
	__initcall0_start,
	__initcall1_start,
	__initcall2_start,
	__initcall3_start,
	__initcall4_start,
	__initcall5_start,
	__initcall6_start,
	__initcall7_start,
	__initcall_end,
};

832
/* Keep these in sync with initcalls in include/linux/init.h */
833
static char *initcall_level_names[] __initdata = {
834 835 836 837 838 839 840 841
	"early",
	"core",
	"postcore",
	"arch",
	"subsys",
	"fs",
	"device",
	"late",
842 843 844
};

static void __init do_initcall_level(int level)
845
{
846
	initcall_t *fn;
847

848
	strcpy(initcall_command_line, saved_command_line);
849
	parse_args(initcall_level_names[level],
850
		   initcall_command_line, __start___param,
851 852
		   __stop___param - __start___param,
		   level, level,
853
		   &repair_env_string);
854 855

	for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
856
		do_one_initcall(*fn);
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}

859 860 861 862
static void __init do_initcalls(void)
{
	int level;

863
	for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
864 865 866
		do_initcall_level(level);
}

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/*
 * 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)
{
876
	cpuset_init_smp();
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877
	usermodehelper_init();
878
	shmem_init();
L
Linus Torvalds 已提交
879
	driver_init();
880
	init_irq_proc();
881
	do_ctors();
882
	usermodehelper_enable();
883
	do_initcalls();
884
	random_int_secret_init();
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Linus Torvalds 已提交
885 886
}

887
static void __init do_pre_smp_initcalls(void)
888
{
889
	initcall_t *fn;
890

891
	for (fn = __initcall_start; fn < __initcall0_start; fn++)
892
		do_one_initcall(*fn);
893 894
}

895 896 897 898 899 900 901 902 903 904 905
/*
 * This function requests modules which should be loaded by default and is
 * called twice right after initrd is mounted and right before init is
 * exec'd.  If such modules are on either initrd or rootfs, they will be
 * loaded before control is passed to userland.
 */
void __init load_default_modules(void)
{
	load_default_elevator_module();
}

906
static int run_init_process(const char *init_filename)
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Linus Torvalds 已提交
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{
	argv_init[0] = init_filename;
909
	return do_execve(getname_kernel(init_filename),
910 911
		(const char __user *const __user *)argv_init,
		(const char __user *const __user *)envp_init);
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}

914 915 916 917 918 919 920 921 922 923 924 925 926 927
static int try_to_run_init_process(const char *init_filename)
{
	int ret;

	ret = run_init_process(init_filename);

	if (ret && ret != -ENOENT) {
		pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
		       init_filename, ret);
	}

	return ret;
}

928
static noinline void __init kernel_init_freeable(void);
929 930

static int __ref kernel_init(void *unused)
931
{
932 933
	int ret;

934
	kernel_init_freeable();
935 936
	/* need to finish all async __init code before freeing the memory */
	async_synchronize_full();
937 938 939 940 941
	free_initmem();
	mark_rodata_ro();
	system_state = SYSTEM_RUNNING;
	numa_default_policy();

A
Al Viro 已提交
942
	flush_delayed_fput();
943

944
	if (ramdisk_execute_command) {
945 946
		ret = run_init_process(ramdisk_execute_command);
		if (!ret)
947
			return 0;
948 949
		pr_err("Failed to execute %s (error %d)\n",
		       ramdisk_execute_command, ret);
950 951 952 953 954 955 956 957 958
	}

	/*
	 * 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) {
959 960
		ret = run_init_process(execute_command);
		if (!ret)
961
			return 0;
962 963
		pr_err("Failed to execute %s (error %d).  Attempting defaults...\n",
			execute_command, ret);
964
	}
965 966 967 968
	if (!try_to_run_init_process("/sbin/init") ||
	    !try_to_run_init_process("/etc/init") ||
	    !try_to_run_init_process("/bin/init") ||
	    !try_to_run_init_process("/bin/sh"))
969
		return 0;
970

971
	panic("No working init found.  Try passing init= option to kernel. "
972
	      "See Linux Documentation/init.txt for guidance.");
973 974
}

975
static noinline void __init kernel_init_freeable(void)
L
Linus Torvalds 已提交
976
{
977 978 979 980
	/*
	 * Wait until kthreadd is all set-up.
	 */
	wait_for_completion(&kthreadd_done);
981 982 983 984

	/* Now the scheduler is fully set up and can do blocking allocations */
	gfp_allowed_mask = __GFP_BITS_MASK;

985 986 987
	/*
	 * init can allocate pages on any node
	 */
988
	set_mems_allowed(node_states[N_MEMORY]);
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989 990 991
	/*
	 * init can run on any cpu.
	 */
992
	set_cpus_allowed_ptr(current, cpu_all_mask);
L
Linus Torvalds 已提交
993

994 995
	cad_pid = task_pid(current);

996
	smp_prepare_cpus(setup_max_cpus);
L
Linus Torvalds 已提交
997 998

	do_pre_smp_initcalls();
999
	lockup_detector_init();
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1000 1001 1002 1003 1004 1005

	smp_init();
	sched_init_smp();

	do_basic_setup();

1006 1007
	/* Open the /dev/console on the rootfs, this should never fail */
	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
A
Andrew Morton 已提交
1008
		pr_err("Warning: unable to open an initial console.\n");
1009 1010 1011

	(void) sys_dup(0);
	(void) sys_dup(0);
L
Linus Torvalds 已提交
1012 1013 1014 1015
	/*
	 * check if there is an early userspace init.  If yes, let it do all
	 * the work
	 */
1016 1017 1018 1019 1020 1021

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

	if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
		ramdisk_execute_command = NULL;
L
Linus Torvalds 已提交
1022
		prepare_namespace();
1023
	}
L
Linus Torvalds 已提交
1024 1025 1026 1027 1028 1029

	/*
	 * 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..
	 */
1030 1031 1032

	/* rootfs is available now, try loading default modules */
	load_default_modules();
L
Linus Torvalds 已提交
1033
}