4 * Copyright (C) 1991, 1992 Linus Torvalds
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>
12 #define DEBUG /* Enable initcall_debug */
14 #include <linux/types.h>
15 #include <linux/module.h>
16 #include <linux/proc_fs.h>
17 #include <linux/kernel.h>
18 #include <linux/syscalls.h>
19 #include <linux/stackprotector.h>
20 #include <linux/string.h>
21 #include <linux/ctype.h>
22 #include <linux/delay.h>
23 #include <linux/ioport.h>
24 #include <linux/init.h>
25 #include <linux/initrd.h>
26 #include <linux/bootmem.h>
27 #include <linux/acpi.h>
28 #include <linux/tty.h>
29 #include <linux/percpu.h>
30 #include <linux/kmod.h>
31 #include <linux/vmalloc.h>
32 #include <linux/kernel_stat.h>
33 #include <linux/start_kernel.h>
34 #include <linux/security.h>
35 #include <linux/smp.h>
36 #include <linux/profile.h>
37 #include <linux/rcupdate.h>
38 #include <linux/moduleparam.h>
39 #include <linux/kallsyms.h>
40 #include <linux/writeback.h>
41 #include <linux/cpu.h>
42 #include <linux/cpuset.h>
43 #include <linux/cgroup.h>
44 #include <linux/efi.h>
45 #include <linux/tick.h>
46 #include <linux/interrupt.h>
47 #include <linux/taskstats_kern.h>
48 #include <linux/delayacct.h>
49 #include <linux/unistd.h>
50 #include <linux/rmap.h>
51 #include <linux/mempolicy.h>
52 #include <linux/key.h>
53 #include <linux/buffer_head.h>
54 #include <linux/page_cgroup.h>
55 #include <linux/debug_locks.h>
56 #include <linux/debugobjects.h>
57 #include <linux/lockdep.h>
58 #include <linux/kmemleak.h>
59 #include <linux/pid_namespace.h>
60 #include <linux/device.h>
61 #include <linux/kthread.h>
62 #include <linux/sched.h>
63 #include <linux/signal.h>
64 #include <linux/idr.h>
65 #include <linux/kgdb.h>
66 #include <linux/ftrace.h>
67 #include <linux/async.h>
68 #include <linux/kmemcheck.h>
69 #include <linux/sfi.h>
70 #include <linux/shmem_fs.h>
71 #include <linux/slab.h>
72 #include <linux/perf_event.h>
73 #include <linux/file.h>
74 #include <linux/ptrace.h>
75 #include <linux/blkdev.h>
76 #include <linux/elevator.h>
77 #include <linux/sched_clock.h>
81 #include <asm/setup.h>
82 #include <asm/sections.h>
83 #include <asm/cacheflush.h>
85 #ifdef CONFIG_X86_LOCAL_APIC
89 static int kernel_init(void *);
91 extern void init_IRQ(void);
92 extern void fork_init(unsigned long);
93 extern void mca_init(void);
94 extern void sbus_init(void);
95 extern void radix_tree_init(void);
96 #ifndef CONFIG_DEBUG_RODATA
97 static inline void mark_rodata_ro(void) { }
101 extern void tc_init(void);
105 * Debug helper: via this flag we know that we are in 'early bootup code'
106 * where only the boot processor is running with IRQ disabled. This means
107 * two things - IRQ must not be enabled before the flag is cleared and some
108 * operations which are not allowed with IRQ disabled are allowed while the
111 bool early_boot_irqs_disabled __read_mostly;
113 enum system_states system_state __read_mostly;
114 EXPORT_SYMBOL(system_state);
117 * Boot command-line arguments
119 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
120 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
122 extern void time_init(void);
123 /* Default late time init is NULL. archs can override this later. */
124 void (*__initdata late_time_init)(void);
125 extern void softirq_init(void);
127 /* Untouched command line saved by arch-specific code. */
128 char __initdata boot_command_line[COMMAND_LINE_SIZE];
129 /* Untouched saved command line (eg. for /proc) */
130 char *saved_command_line;
131 /* Command line for parameter parsing */
132 static char *static_command_line;
134 static char *execute_command;
135 static char *ramdisk_execute_command;
138 * If set, this is an indication to the drivers that reset the underlying
139 * device before going ahead with the initialization otherwise driver might
140 * rely on the BIOS and skip the reset operation.
142 * This is useful if kernel is booting in an unreliable environment.
143 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
144 * skipped and devices will be in unknown state.
146 unsigned int reset_devices;
147 EXPORT_SYMBOL(reset_devices);
149 static int __init set_reset_devices(char *str)
155 __setup("reset_devices", set_reset_devices);
157 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
158 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
159 static const char *panic_later, *panic_param;
161 extern const struct obs_kernel_param __setup_start[], __setup_end[];
163 static int __init obsolete_checksetup(char *line)
165 const struct obs_kernel_param *p;
166 int had_early_param = 0;
170 int n = strlen(p->str);
171 if (parameqn(line, p->str, n)) {
173 /* Already done in parse_early_param?
174 * (Needs exact match on param part).
175 * Keep iterating, as we can have early
176 * params and __setups of same names 8( */
177 if (line[n] == '\0' || line[n] == '=')
179 } else if (!p->setup_func) {
180 pr_warn("Parameter %s is obsolete, ignored\n",
183 } else if (p->setup_func(line + n))
187 } while (p < __setup_end);
189 return had_early_param;
193 * This should be approx 2 Bo*oMips to start (note initial shift), and will
194 * still work even if initially too large, it will just take slightly longer
196 unsigned long loops_per_jiffy = (1<<12);
198 EXPORT_SYMBOL(loops_per_jiffy);
200 static int __init debug_kernel(char *str)
202 console_loglevel = 10;
206 static int __init quiet_kernel(char *str)
208 console_loglevel = 4;
212 early_param("debug", debug_kernel);
213 early_param("quiet", quiet_kernel);
215 static int __init loglevel(char *str)
220 * Only update loglevel value when a correct setting was passed,
221 * to prevent blind crashes (when loglevel being set to 0) that
222 * are quite hard to debug
224 if (get_option(&str, &newlevel)) {
225 console_loglevel = newlevel;
232 early_param("loglevel", loglevel);
234 /* Change NUL term back to "=", to make "param" the whole string. */
235 static int __init repair_env_string(char *param, char *val, const char *unused)
238 /* param=val or param="val"? */
239 if (val == param+strlen(param)+1)
241 else if (val == param+strlen(param)+2) {
243 memmove(val-1, val, strlen(val)+1);
252 * Unknown boot options get handed to init, unless they look like
253 * unused parameters (modprobe will find them in /proc/cmdline).
255 static int __init unknown_bootoption(char *param, char *val, const char *unused)
257 repair_env_string(param, val, unused);
259 /* Handle obsolete-style parameters */
260 if (obsolete_checksetup(param))
263 /* Unused module parameter. */
264 if (strchr(param, '.') && (!val || strchr(param, '.') < val))
271 /* Environment option */
273 for (i = 0; envp_init[i]; i++) {
274 if (i == MAX_INIT_ENVS) {
275 panic_later = "Too many boot env vars at `%s'";
278 if (!strncmp(param, envp_init[i], val - param))
281 envp_init[i] = param;
283 /* Command line option */
285 for (i = 0; argv_init[i]; i++) {
286 if (i == MAX_INIT_ARGS) {
287 panic_later = "Too many boot init vars at `%s'";
291 argv_init[i] = param;
296 static int __init init_setup(char *str)
300 execute_command = str;
302 * In case LILO is going to boot us with default command line,
303 * it prepends "auto" before the whole cmdline which makes
304 * the shell think it should execute a script with such name.
305 * So we ignore all arguments entered _before_ init=... [MJ]
307 for (i = 1; i < MAX_INIT_ARGS; i++)
311 __setup("init=", init_setup);
313 static int __init rdinit_setup(char *str)
317 ramdisk_execute_command = str;
318 /* See "auto" comment in init_setup */
319 for (i = 1; i < MAX_INIT_ARGS; i++)
323 __setup("rdinit=", rdinit_setup);
326 static const unsigned int setup_max_cpus = NR_CPUS;
327 #ifdef CONFIG_X86_LOCAL_APIC
328 static void __init smp_init(void)
330 APIC_init_uniprocessor();
333 #define smp_init() do { } while (0)
336 static inline void setup_nr_cpu_ids(void) { }
337 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
341 * We need to store the untouched command line for future reference.
342 * We also need to store the touched command line since the parameter
343 * parsing is performed in place, and we should allow a component to
344 * store reference of name/value for future reference.
346 static void __init setup_command_line(char *command_line)
348 saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
349 static_command_line = alloc_bootmem(strlen (command_line)+1);
350 strcpy (saved_command_line, boot_command_line);
351 strcpy (static_command_line, command_line);
355 * We need to finalize in a non-__init function or else race conditions
356 * between the root thread and the init thread may cause start_kernel to
357 * be reaped by free_initmem before the root thread has proceeded to
360 * gcc-3.4 accidentally inlines this function, so use noinline.
363 static __initdata DECLARE_COMPLETION(kthreadd_done);
365 static noinline void __init_refok rest_init(void)
369 rcu_scheduler_starting();
371 * We need to spawn init first so that it obtains pid 1, however
372 * the init task will end up wanting to create kthreads, which, if
373 * we schedule it before we create kthreadd, will OOPS.
375 kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
376 numa_default_policy();
377 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
379 kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
381 complete(&kthreadd_done);
384 * The boot idle thread must execute schedule()
385 * at least once to get things moving:
387 init_idle_bootup_task(current);
388 schedule_preempt_disabled();
389 /* Call into cpu_idle with preempt disabled */
390 cpu_startup_entry(CPUHP_ONLINE);
393 /* Check for early params. */
394 static int __init do_early_param(char *param, char *val, const char *unused)
396 const struct obs_kernel_param *p;
398 for (p = __setup_start; p < __setup_end; p++) {
399 if ((p->early && parameq(param, p->str)) ||
400 (strcmp(param, "console") == 0 &&
401 strcmp(p->str, "earlycon") == 0)
403 if (p->setup_func(val) != 0)
404 pr_warn("Malformed early option '%s'\n", param);
407 /* We accept everything at this stage. */
411 void __init parse_early_options(char *cmdline)
413 parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
416 /* Arch code calls this early on, or if not, just before other parsing. */
417 void __init parse_early_param(void)
419 static __initdata int done = 0;
420 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
425 /* All fall through to do_early_param. */
426 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
427 parse_early_options(tmp_cmdline);
432 * Activate the first processor.
435 static void __init boot_cpu_init(void)
437 int cpu = smp_processor_id();
438 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
439 set_cpu_online(cpu, true);
440 set_cpu_active(cpu, true);
441 set_cpu_present(cpu, true);
442 set_cpu_possible(cpu, true);
445 void __init __weak smp_setup_processor_id(void)
449 # if THREAD_SIZE >= PAGE_SIZE
450 void __init __weak thread_info_cache_init(void)
456 * Set up kernel memory allocators
458 static void __init mm_init(void)
461 * page_cgroup requires contiguous pages,
462 * bigger than MAX_ORDER unless SPARSEMEM.
464 page_cgroup_init_flatmem();
468 pgtable_cache_init();
472 asmlinkage void __init start_kernel(void)
475 extern const struct kernel_param __start___param[], __stop___param[];
478 * Need to run as early as possible, to initialize the
482 smp_setup_processor_id();
483 debug_objects_early_init();
486 * Set up the the initial canary ASAP:
488 boot_init_stack_canary();
493 early_boot_irqs_disabled = true;
496 * Interrupts are still disabled. Do necessary setups, then
501 pr_notice("%s", linux_banner);
502 setup_arch(&command_line);
503 mm_init_owner(&init_mm, &init_task);
504 mm_init_cpumask(&init_mm);
505 setup_command_line(command_line);
507 setup_per_cpu_areas();
508 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
510 build_all_zonelists(NULL, NULL);
513 pr_notice("Kernel command line: %s\n", boot_command_line);
515 parse_args("Booting kernel", static_command_line, __start___param,
516 __stop___param - __start___param,
517 -1, -1, &unknown_bootoption);
522 * These use large bootmem allocations and must precede
527 vfs_caches_init_early();
533 * Set up the scheduler prior starting any interrupts (such as the
534 * timer interrupt). Full topology setup happens at smp_init()
535 * time - but meanwhile we still have a functioning scheduler.
539 * Disable preemption - early bootup scheduling is extremely
540 * fragile until we cpu_idle() for the first time.
543 if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
549 /* init some links before init_ISA_irqs() */
558 sched_clock_postinit();
561 call_function_init();
562 WARN(!irqs_disabled(), "Interrupts were enabled early\n");
563 early_boot_irqs_disabled = false;
566 kmem_cache_init_late();
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.
575 panic(panic_later, panic_param);
580 * Need to run this when irqs are enabled, because it wants
581 * to self-test [hard/soft]-irqs on/off lock inversion bugs
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 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
590 page_to_pfn(virt_to_page((void *)initrd_start)),
596 debug_objects_mem_init();
598 setup_per_cpu_pageset();
607 if (efi_enabled(EFI_RUNTIME_SERVICES))
608 efi_enter_virtual_mode();
610 thread_info_cache_init();
612 fork_init(totalram_pages);
618 vfs_caches_init(totalram_pages);
620 /* rootfs populating might need page-writeback */
621 page_writeback_init();
622 #ifdef CONFIG_PROC_FS
627 taskstats_init_early();
632 acpi_early_init(); /* before LAPIC and SMP init */
635 if (efi_enabled(EFI_RUNTIME_SERVICES)) {
637 efi_free_boot_services();
642 /* Do the rest non-__init'ed, we're now alive */
646 /* Call all constructor functions linked into the kernel. */
647 static void __init do_ctors(void)
649 #ifdef CONFIG_CONSTRUCTORS
650 ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
652 for (; fn < (ctor_fn_t *) __ctors_end; fn++)
658 core_param(initcall_debug, initcall_debug, bool, 0644);
660 static int __init_or_module do_one_initcall_debug(initcall_t fn)
662 ktime_t calltime, delta, rettime;
663 unsigned long long duration;
666 pr_debug("calling %pF @ %i\n", fn, task_pid_nr(current));
667 calltime = ktime_get();
669 rettime = ktime_get();
670 delta = ktime_sub(rettime, calltime);
671 duration = (unsigned long long) ktime_to_ns(delta) >> 10;
672 pr_debug("initcall %pF returned %d after %lld usecs\n",
678 int __init_or_module do_one_initcall(initcall_t fn)
680 int count = preempt_count();
685 ret = do_one_initcall_debug(fn);
691 if (preempt_count() != count) {
692 sprintf(msgbuf, "preemption imbalance ");
693 preempt_count() = count;
695 if (irqs_disabled()) {
696 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
699 WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
705 extern initcall_t __initcall_start[];
706 extern initcall_t __initcall0_start[];
707 extern initcall_t __initcall1_start[];
708 extern initcall_t __initcall2_start[];
709 extern initcall_t __initcall3_start[];
710 extern initcall_t __initcall4_start[];
711 extern initcall_t __initcall5_start[];
712 extern initcall_t __initcall6_start[];
713 extern initcall_t __initcall7_start[];
714 extern initcall_t __initcall_end[];
716 static initcall_t *initcall_levels[] __initdata = {
728 /* Keep these in sync with initcalls in include/linux/init.h */
729 static char *initcall_level_names[] __initdata = {
740 static void __init do_initcall_level(int level)
742 extern const struct kernel_param __start___param[], __stop___param[];
745 strcpy(static_command_line, saved_command_line);
746 parse_args(initcall_level_names[level],
747 static_command_line, __start___param,
748 __stop___param - __start___param,
752 for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
753 do_one_initcall(*fn);
756 static void __init do_initcalls(void)
760 for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
761 do_initcall_level(level);
765 * Ok, the machine is now initialized. None of the devices
766 * have been touched yet, but the CPU subsystem is up and
767 * running, and memory and process management works.
769 * Now we can finally start doing some real work..
771 static void __init do_basic_setup(void)
774 usermodehelper_init();
779 usermodehelper_enable();
783 static void __init do_pre_smp_initcalls(void)
787 for (fn = __initcall_start; fn < __initcall0_start; fn++)
788 do_one_initcall(*fn);
792 * This function requests modules which should be loaded by default and is
793 * called twice right after initrd is mounted and right before init is
794 * exec'd. If such modules are on either initrd or rootfs, they will be
795 * loaded before control is passed to userland.
797 void __init load_default_modules(void)
799 load_default_elevator_module();
802 static int run_init_process(const char *init_filename)
804 argv_init[0] = init_filename;
805 return do_execve(init_filename,
806 (const char __user *const __user *)argv_init,
807 (const char __user *const __user *)envp_init);
810 static noinline void __init kernel_init_freeable(void);
812 static int __ref kernel_init(void *unused)
814 kernel_init_freeable();
815 /* need to finish all async __init code before freeing the memory */
816 async_synchronize_full();
819 system_state = SYSTEM_RUNNING;
820 numa_default_policy();
822 flush_delayed_fput();
824 if (ramdisk_execute_command) {
825 if (!run_init_process(ramdisk_execute_command))
827 pr_err("Failed to execute %s\n", ramdisk_execute_command);
831 * We try each of these until one succeeds.
833 * The Bourne shell can be used instead of init if we are
834 * trying to recover a really broken machine.
836 if (execute_command) {
837 if (!run_init_process(execute_command))
839 pr_err("Failed to execute %s. Attempting defaults...\n",
842 if (!run_init_process("/sbin/init") ||
843 !run_init_process("/etc/init") ||
844 !run_init_process("/bin/init") ||
845 !run_init_process("/bin/sh"))
848 panic("No init found. Try passing init= option to kernel. "
849 "See Linux Documentation/init.txt for guidance.");
852 static noinline void __init kernel_init_freeable(void)
855 * Wait until kthreadd is all set-up.
857 wait_for_completion(&kthreadd_done);
859 /* Now the scheduler is fully set up and can do blocking allocations */
860 gfp_allowed_mask = __GFP_BITS_MASK;
863 * init can allocate pages on any node
865 set_mems_allowed(node_states[N_MEMORY]);
867 * init can run on any cpu.
869 set_cpus_allowed_ptr(current, cpu_all_mask);
871 cad_pid = task_pid(current);
873 smp_prepare_cpus(setup_max_cpus);
875 do_pre_smp_initcalls();
876 lockup_detector_init();
883 /* Open the /dev/console on the rootfs, this should never fail */
884 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
885 pr_err("Warning: unable to open an initial console.\n");
890 * check if there is an early userspace init. If yes, let it do all
894 if (!ramdisk_execute_command)
895 ramdisk_execute_command = "/init";
897 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
898 ramdisk_execute_command = NULL;
903 * Ok, we have completed the initial bootup, and
904 * we're essentially up and running. Get rid of the
905 * initmem segments and start the user-mode stuff..
908 /* rootfs is available now, try loading default modules */
909 load_default_modules();