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>
78 #include <linux/context_tracking.h>
79 #include <linux/random.h>
80 #include <linux/list.h>
84 #include <asm/setup.h>
85 #include <asm/sections.h>
86 #include <asm/cacheflush.h>
88 #ifdef CONFIG_X86_LOCAL_APIC
92 static int kernel_init(void *);
94 extern void init_IRQ(void);
95 extern void fork_init(unsigned long);
96 extern void radix_tree_init(void);
97 #ifndef CONFIG_DEBUG_RODATA
98 static inline void mark_rodata_ro(void) { }
102 * Debug helper: via this flag we know that we are in 'early bootup code'
103 * where only the boot processor is running with IRQ disabled. This means
104 * two things - IRQ must not be enabled before the flag is cleared and some
105 * operations which are not allowed with IRQ disabled are allowed while the
108 bool early_boot_irqs_disabled __read_mostly;
110 enum system_states system_state __read_mostly;
111 EXPORT_SYMBOL(system_state);
114 * Boot command-line arguments
116 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
117 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
119 extern void time_init(void);
120 /* Default late time init is NULL. archs can override this later. */
121 void (*__initdata late_time_init)(void);
123 /* Untouched command line saved by arch-specific code. */
124 char __initdata boot_command_line[COMMAND_LINE_SIZE];
125 /* Untouched saved command line (eg. for /proc) */
126 char *saved_command_line;
127 /* Command line for parameter parsing */
128 static char *static_command_line;
129 /* Command line for per-initcall parameter parsing */
130 static char *initcall_command_line;
132 static char *execute_command;
133 static char *ramdisk_execute_command;
136 * Used to generate warnings if static_key manipulation functions are used
137 * before jump_label_init is called.
139 bool static_key_initialized __read_mostly = false;
140 EXPORT_SYMBOL_GPL(static_key_initialized);
143 * If set, this is an indication to the drivers that reset the underlying
144 * device before going ahead with the initialization otherwise driver might
145 * rely on the BIOS and skip the reset operation.
147 * This is useful if kernel is booting in an unreliable environment.
148 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
149 * skipped and devices will be in unknown state.
151 unsigned int reset_devices;
152 EXPORT_SYMBOL(reset_devices);
154 static int __init set_reset_devices(char *str)
160 __setup("reset_devices", set_reset_devices);
162 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
163 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
164 static const char *panic_later, *panic_param;
166 extern const struct obs_kernel_param __setup_start[], __setup_end[];
168 static int __init obsolete_checksetup(char *line)
170 const struct obs_kernel_param *p;
171 int had_early_param = 0;
175 int n = strlen(p->str);
176 if (parameqn(line, p->str, n)) {
178 /* Already done in parse_early_param?
179 * (Needs exact match on param part).
180 * Keep iterating, as we can have early
181 * params and __setups of same names 8( */
182 if (line[n] == '\0' || line[n] == '=')
184 } else if (!p->setup_func) {
185 pr_warn("Parameter %s is obsolete, ignored\n",
188 } else if (p->setup_func(line + n))
192 } while (p < __setup_end);
194 return had_early_param;
198 * This should be approx 2 Bo*oMips to start (note initial shift), and will
199 * still work even if initially too large, it will just take slightly longer
201 unsigned long loops_per_jiffy = (1<<12);
203 EXPORT_SYMBOL(loops_per_jiffy);
205 static int __init debug_kernel(char *str)
207 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
211 static int __init quiet_kernel(char *str)
213 console_loglevel = CONSOLE_LOGLEVEL_QUIET;
217 early_param("debug", debug_kernel);
218 early_param("quiet", quiet_kernel);
220 static int __init loglevel(char *str)
225 * Only update loglevel value when a correct setting was passed,
226 * to prevent blind crashes (when loglevel being set to 0) that
227 * are quite hard to debug
229 if (get_option(&str, &newlevel)) {
230 console_loglevel = newlevel;
237 early_param("loglevel", loglevel);
239 /* Change NUL term back to "=", to make "param" the whole string. */
240 static int __init repair_env_string(char *param, char *val, const char *unused)
243 /* param=val or param="val"? */
244 if (val == param+strlen(param)+1)
246 else if (val == param+strlen(param)+2) {
248 memmove(val-1, val, strlen(val)+1);
257 * Unknown boot options get handed to init, unless they look like
258 * unused parameters (modprobe will find them in /proc/cmdline).
260 static int __init unknown_bootoption(char *param, char *val, const char *unused)
262 repair_env_string(param, val, unused);
264 /* Handle obsolete-style parameters */
265 if (obsolete_checksetup(param))
268 /* Unused module parameter. */
269 if (strchr(param, '.') && (!val || strchr(param, '.') < val))
276 /* Environment option */
278 for (i = 0; envp_init[i]; i++) {
279 if (i == MAX_INIT_ENVS) {
283 if (!strncmp(param, envp_init[i], val - param))
286 envp_init[i] = param;
288 /* Command line option */
290 for (i = 0; argv_init[i]; i++) {
291 if (i == MAX_INIT_ARGS) {
292 panic_later = "init";
296 argv_init[i] = param;
301 static int __init init_setup(char *str)
305 execute_command = str;
307 * In case LILO is going to boot us with default command line,
308 * it prepends "auto" before the whole cmdline which makes
309 * the shell think it should execute a script with such name.
310 * So we ignore all arguments entered _before_ init=... [MJ]
312 for (i = 1; i < MAX_INIT_ARGS; i++)
316 __setup("init=", init_setup);
318 static int __init rdinit_setup(char *str)
322 ramdisk_execute_command = str;
323 /* See "auto" comment in init_setup */
324 for (i = 1; i < MAX_INIT_ARGS; i++)
328 __setup("rdinit=", rdinit_setup);
331 static const unsigned int setup_max_cpus = NR_CPUS;
332 #ifdef CONFIG_X86_LOCAL_APIC
333 static void __init smp_init(void)
335 APIC_init_uniprocessor();
338 #define smp_init() do { } while (0)
341 static inline void setup_nr_cpu_ids(void) { }
342 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
346 * We need to store the untouched command line for future reference.
347 * We also need to store the touched command line since the parameter
348 * parsing is performed in place, and we should allow a component to
349 * store reference of name/value for future reference.
351 static void __init setup_command_line(char *command_line)
354 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
355 initcall_command_line =
356 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
357 static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
358 strcpy (saved_command_line, boot_command_line);
359 strcpy (static_command_line, command_line);
363 * We need to finalize in a non-__init function or else race conditions
364 * between the root thread and the init thread may cause start_kernel to
365 * be reaped by free_initmem before the root thread has proceeded to
368 * gcc-3.4 accidentally inlines this function, so use noinline.
371 static __initdata DECLARE_COMPLETION(kthreadd_done);
373 static noinline void __init_refok rest_init(void)
377 rcu_scheduler_starting();
379 * We need to spawn init first so that it obtains pid 1, however
380 * the init task will end up wanting to create kthreads, which, if
381 * we schedule it before we create kthreadd, will OOPS.
383 kernel_thread(kernel_init, NULL, CLONE_FS);
384 numa_default_policy();
385 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
387 kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
389 complete(&kthreadd_done);
392 * The boot idle thread must execute schedule()
393 * at least once to get things moving:
395 init_idle_bootup_task(current);
396 schedule_preempt_disabled();
397 /* Call into cpu_idle with preempt disabled */
398 cpu_startup_entry(CPUHP_ONLINE);
401 /* Check for early params. */
402 static int __init do_early_param(char *param, char *val, const char *unused)
404 const struct obs_kernel_param *p;
406 for (p = __setup_start; p < __setup_end; p++) {
407 if ((p->early && parameq(param, p->str)) ||
408 (strcmp(param, "console") == 0 &&
409 strcmp(p->str, "earlycon") == 0)
411 if (p->setup_func(val) != 0)
412 pr_warn("Malformed early option '%s'\n", param);
415 /* We accept everything at this stage. */
419 void __init parse_early_options(char *cmdline)
421 parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
424 /* Arch code calls this early on, or if not, just before other parsing. */
425 void __init parse_early_param(void)
427 static __initdata int done = 0;
428 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
433 /* All fall through to do_early_param. */
434 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
435 parse_early_options(tmp_cmdline);
440 * Activate the first processor.
443 static void __init boot_cpu_init(void)
445 int cpu = smp_processor_id();
446 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
447 set_cpu_online(cpu, true);
448 set_cpu_active(cpu, true);
449 set_cpu_present(cpu, true);
450 set_cpu_possible(cpu, true);
453 void __init __weak smp_setup_processor_id(void)
457 # if THREAD_SIZE >= PAGE_SIZE
458 void __init __weak thread_info_cache_init(void)
464 * Set up kernel memory allocators
466 static void __init mm_init(void)
469 * page_cgroup requires contiguous pages,
470 * bigger than MAX_ORDER unless SPARSEMEM.
472 page_cgroup_init_flatmem();
480 asmlinkage __visible void __init start_kernel(void)
483 extern const struct kernel_param __start___param[], __stop___param[];
486 * Need to run as early as possible, to initialize the
490 smp_setup_processor_id();
491 debug_objects_early_init();
494 * Set up the the initial canary ASAP:
496 boot_init_stack_canary();
501 early_boot_irqs_disabled = true;
504 * Interrupts are still disabled. Do necessary setups, then
509 pr_notice("%s", linux_banner);
510 setup_arch(&command_line);
511 mm_init_cpumask(&init_mm);
512 setup_command_line(command_line);
514 setup_per_cpu_areas();
515 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
517 build_all_zonelists(NULL, NULL);
520 pr_notice("Kernel command line: %s\n", boot_command_line);
522 parse_args("Booting kernel", static_command_line, __start___param,
523 __stop___param - __start___param,
524 -1, -1, &unknown_bootoption);
529 * These use large bootmem allocations and must precede
534 vfs_caches_init_early();
540 * Set up the scheduler prior starting any interrupts (such as the
541 * timer interrupt). Full topology setup happens at smp_init()
542 * time - but meanwhile we still have a functioning scheduler.
546 * Disable preemption - early bootup scheduling is extremely
547 * fragile until we cpu_idle() for the first time.
550 if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
555 context_tracking_init();
557 /* init some links before init_ISA_irqs() */
566 sched_clock_postinit();
569 call_function_init();
570 WARN(!irqs_disabled(), "Interrupts were enabled early\n");
571 early_boot_irqs_disabled = false;
574 kmem_cache_init_late();
577 * HACK ALERT! This is early. We're enabling the console before
578 * we've done PCI setups etc, and console_init() must be aware of
579 * this. But we do want output early, in case something goes wrong.
583 panic("Too many boot %s vars at `%s'", panic_later,
589 * Need to run this when irqs are enabled, because it wants
590 * to self-test [hard/soft]-irqs on/off lock inversion bugs
595 #ifdef CONFIG_BLK_DEV_INITRD
596 if (initrd_start && !initrd_below_start_ok &&
597 page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
598 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
599 page_to_pfn(virt_to_page((void *)initrd_start)),
605 debug_objects_mem_init();
607 setup_per_cpu_pageset();
617 if (efi_enabled(EFI_RUNTIME_SERVICES))
618 efi_enter_virtual_mode();
620 thread_info_cache_init();
622 fork_init(totalram_pages);
628 vfs_caches_init(totalram_pages);
630 /* rootfs populating might need page-writeback */
631 page_writeback_init();
632 #ifdef CONFIG_PROC_FS
637 taskstats_init_early();
644 if (efi_enabled(EFI_RUNTIME_SERVICES)) {
646 efi_free_boot_services();
651 /* Do the rest non-__init'ed, we're now alive */
655 /* Call all constructor functions linked into the kernel. */
656 static void __init do_ctors(void)
658 #ifdef CONFIG_CONSTRUCTORS
659 ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
661 for (; fn < (ctor_fn_t *) __ctors_end; fn++)
667 core_param(initcall_debug, initcall_debug, bool, 0644);
669 #ifdef CONFIG_KALLSYMS
670 struct blacklist_entry {
671 struct list_head next;
675 static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
677 static int __init initcall_blacklist(char *str)
680 struct blacklist_entry *entry;
682 /* str argument is a comma-separated list of functions */
684 str_entry = strsep(&str, ",");
686 pr_debug("blacklisting initcall %s\n", str_entry);
687 entry = alloc_bootmem(sizeof(*entry));
688 entry->buf = alloc_bootmem(strlen(str_entry) + 1);
689 strcpy(entry->buf, str_entry);
690 list_add(&entry->next, &blacklisted_initcalls);
697 static bool __init_or_module initcall_blacklisted(initcall_t fn)
699 struct list_head *tmp;
700 struct blacklist_entry *entry;
703 fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
707 list_for_each(tmp, &blacklisted_initcalls) {
708 entry = list_entry(tmp, struct blacklist_entry, next);
709 if (!strcmp(fn_name, entry->buf)) {
710 pr_debug("initcall %s blacklisted\n", fn_name);
720 static int __init initcall_blacklist(char *str)
722 pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
726 static bool __init_or_module initcall_blacklisted(initcall_t fn)
731 __setup("initcall_blacklist=", initcall_blacklist);
733 static int __init_or_module do_one_initcall_debug(initcall_t fn)
735 ktime_t calltime, delta, rettime;
736 unsigned long long duration;
739 printk(KERN_DEBUG "calling %pF @ %i\n", fn, task_pid_nr(current));
740 calltime = ktime_get();
742 rettime = ktime_get();
743 delta = ktime_sub(rettime, calltime);
744 duration = (unsigned long long) ktime_to_ns(delta) >> 10;
745 printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n",
751 int __init_or_module do_one_initcall(initcall_t fn)
753 int count = preempt_count();
757 if (initcall_blacklisted(fn))
761 ret = do_one_initcall_debug(fn);
767 if (preempt_count() != count) {
768 sprintf(msgbuf, "preemption imbalance ");
769 preempt_count_set(count);
771 if (irqs_disabled()) {
772 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
775 WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
781 extern initcall_t __initcall_start[];
782 extern initcall_t __initcall0_start[];
783 extern initcall_t __initcall1_start[];
784 extern initcall_t __initcall2_start[];
785 extern initcall_t __initcall3_start[];
786 extern initcall_t __initcall4_start[];
787 extern initcall_t __initcall5_start[];
788 extern initcall_t __initcall6_start[];
789 extern initcall_t __initcall7_start[];
790 extern initcall_t __initcall_end[];
792 static initcall_t *initcall_levels[] __initdata = {
804 /* Keep these in sync with initcalls in include/linux/init.h */
805 static char *initcall_level_names[] __initdata = {
816 static void __init do_initcall_level(int level)
818 extern const struct kernel_param __start___param[], __stop___param[];
821 strcpy(initcall_command_line, saved_command_line);
822 parse_args(initcall_level_names[level],
823 initcall_command_line, __start___param,
824 __stop___param - __start___param,
828 for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
829 do_one_initcall(*fn);
832 static void __init do_initcalls(void)
836 for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
837 do_initcall_level(level);
841 * Ok, the machine is now initialized. None of the devices
842 * have been touched yet, but the CPU subsystem is up and
843 * running, and memory and process management works.
845 * Now we can finally start doing some real work..
847 static void __init do_basic_setup(void)
850 usermodehelper_init();
855 usermodehelper_enable();
857 random_int_secret_init();
860 static void __init do_pre_smp_initcalls(void)
864 for (fn = __initcall_start; fn < __initcall0_start; fn++)
865 do_one_initcall(*fn);
869 * This function requests modules which should be loaded by default and is
870 * called twice right after initrd is mounted and right before init is
871 * exec'd. If such modules are on either initrd or rootfs, they will be
872 * loaded before control is passed to userland.
874 void __init load_default_modules(void)
876 load_default_elevator_module();
879 static int run_init_process(const char *init_filename)
881 argv_init[0] = init_filename;
882 return do_execve(getname_kernel(init_filename),
883 (const char __user *const __user *)argv_init,
884 (const char __user *const __user *)envp_init);
887 static int try_to_run_init_process(const char *init_filename)
891 ret = run_init_process(init_filename);
893 if (ret && ret != -ENOENT) {
894 pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
901 static noinline void __init kernel_init_freeable(void);
903 static int __ref kernel_init(void *unused)
907 kernel_init_freeable();
908 /* need to finish all async __init code before freeing the memory */
909 async_synchronize_full();
912 system_state = SYSTEM_RUNNING;
913 numa_default_policy();
915 flush_delayed_fput();
917 if (ramdisk_execute_command) {
918 ret = run_init_process(ramdisk_execute_command);
921 pr_err("Failed to execute %s (error %d)\n",
922 ramdisk_execute_command, ret);
926 * We try each of these until one succeeds.
928 * The Bourne shell can be used instead of init if we are
929 * trying to recover a really broken machine.
931 if (execute_command) {
932 ret = run_init_process(execute_command);
935 pr_err("Failed to execute %s (error %d). Attempting defaults...\n",
936 execute_command, ret);
938 if (!try_to_run_init_process("/sbin/init") ||
939 !try_to_run_init_process("/etc/init") ||
940 !try_to_run_init_process("/bin/init") ||
941 !try_to_run_init_process("/bin/sh"))
944 panic("No working init found. Try passing init= option to kernel. "
945 "See Linux Documentation/init.txt for guidance.");
948 static noinline void __init kernel_init_freeable(void)
951 * Wait until kthreadd is all set-up.
953 wait_for_completion(&kthreadd_done);
955 /* Now the scheduler is fully set up and can do blocking allocations */
956 gfp_allowed_mask = __GFP_BITS_MASK;
959 * init can allocate pages on any node
961 set_mems_allowed(node_states[N_MEMORY]);
963 * init can run on any cpu.
965 set_cpus_allowed_ptr(current, cpu_all_mask);
967 cad_pid = task_pid(current);
969 smp_prepare_cpus(setup_max_cpus);
971 do_pre_smp_initcalls();
972 lockup_detector_init();
979 /* Open the /dev/console on the rootfs, this should never fail */
980 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
981 pr_err("Warning: unable to open an initial console.\n");
986 * check if there is an early userspace init. If yes, let it do all
990 if (!ramdisk_execute_command)
991 ramdisk_execute_command = "/init";
993 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
994 ramdisk_execute_command = NULL;
999 * Ok, we have completed the initial bootup, and
1000 * we're essentially up and running. Get rid of the
1001 * initmem segments and start the user-mode stuff..
1004 /* rootfs is available now, try loading default modules */
1005 load_default_modules();