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/extable.h>
16 #include <linux/module.h>
17 #include <linux/proc_fs.h>
18 #include <linux/binfmts.h>
19 #include <linux/kernel.h>
20 #include <linux/syscalls.h>
21 #include <linux/stackprotector.h>
22 #include <linux/string.h>
23 #include <linux/ctype.h>
24 #include <linux/delay.h>
25 #include <linux/ioport.h>
26 #include <linux/init.h>
27 #include <linux/initrd.h>
28 #include <linux/memblock.h>
29 #include <linux/acpi.h>
30 #include <linux/console.h>
31 #include <linux/nmi.h>
32 #include <linux/percpu.h>
33 #include <linux/kmod.h>
34 #include <linux/vmalloc.h>
35 #include <linux/kernel_stat.h>
36 #include <linux/start_kernel.h>
37 #include <linux/security.h>
38 #include <linux/smp.h>
39 #include <linux/profile.h>
40 #include <linux/rcupdate.h>
41 #include <linux/moduleparam.h>
42 #include <linux/kallsyms.h>
43 #include <linux/writeback.h>
44 #include <linux/cpu.h>
45 #include <linux/cpuset.h>
46 #include <linux/cgroup.h>
47 #include <linux/efi.h>
48 #include <linux/tick.h>
49 #include <linux/sched/isolation.h>
50 #include <linux/interrupt.h>
51 #include <linux/taskstats_kern.h>
52 #include <linux/delayacct.h>
53 #include <linux/unistd.h>
54 #include <linux/utsname.h>
55 #include <linux/rmap.h>
56 #include <linux/mempolicy.h>
57 #include <linux/key.h>
58 #include <linux/buffer_head.h>
59 #include <linux/page_ext.h>
60 #include <linux/debug_locks.h>
61 #include <linux/debugobjects.h>
62 #include <linux/lockdep.h>
63 #include <linux/kmemleak.h>
64 #include <linux/pid_namespace.h>
65 #include <linux/device.h>
66 #include <linux/kthread.h>
67 #include <linux/sched.h>
68 #include <linux/sched/init.h>
69 #include <linux/signal.h>
70 #include <linux/idr.h>
71 #include <linux/kgdb.h>
72 #include <linux/ftrace.h>
73 #include <linux/async.h>
74 #include <linux/sfi.h>
75 #include <linux/shmem_fs.h>
76 #include <linux/slab.h>
77 #include <linux/perf_event.h>
78 #include <linux/ptrace.h>
79 #include <linux/pti.h>
80 #include <linux/blkdev.h>
81 #include <linux/elevator.h>
82 #include <linux/sched/clock.h>
83 #include <linux/sched/task.h>
84 #include <linux/sched/task_stack.h>
85 #include <linux/context_tracking.h>
86 #include <linux/random.h>
87 #include <linux/list.h>
88 #include <linux/integrity.h>
89 #include <linux/proc_ns.h>
91 #include <linux/cache.h>
92 #include <linux/rodata_test.h>
93 #include <linux/jump_label.h>
94 #include <linux/mem_encrypt.h>
98 #include <asm/setup.h>
99 #include <asm/sections.h>
100 #include <asm/cacheflush.h>
102 #define CREATE_TRACE_POINTS
103 #include <trace/events/initcall.h>
105 static int kernel_init(void *);
107 extern void init_IRQ(void);
108 extern void radix_tree_init(void);
111 * Debug helper: via this flag we know that we are in 'early bootup code'
112 * where only the boot processor is running with IRQ disabled. This means
113 * two things - IRQ must not be enabled before the flag is cleared and some
114 * operations which are not allowed with IRQ disabled are allowed while the
117 bool early_boot_irqs_disabled __read_mostly;
119 enum system_states system_state __read_mostly;
120 EXPORT_SYMBOL(system_state);
123 * Boot command-line arguments
125 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
126 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
128 extern void time_init(void);
129 /* Default late time init is NULL. archs can override this later. */
130 void (*__initdata late_time_init)(void);
132 /* Untouched command line saved by arch-specific code. */
133 char __initdata boot_command_line[COMMAND_LINE_SIZE];
134 /* Untouched saved command line (eg. for /proc) */
135 char *saved_command_line;
136 /* Command line for parameter parsing */
137 static char *static_command_line;
138 /* Command line for per-initcall parameter parsing */
139 static char *initcall_command_line;
141 static char *execute_command;
142 static char *ramdisk_execute_command;
145 * Used to generate warnings if static_key manipulation functions are used
146 * before jump_label_init is called.
148 bool static_key_initialized __read_mostly;
149 EXPORT_SYMBOL_GPL(static_key_initialized);
152 * If set, this is an indication to the drivers that reset the underlying
153 * device before going ahead with the initialization otherwise driver might
154 * rely on the BIOS and skip the reset operation.
156 * This is useful if kernel is booting in an unreliable environment.
157 * For ex. kdump situation where previous kernel has crashed, BIOS has been
158 * skipped and devices will be in unknown state.
160 unsigned int reset_devices;
161 EXPORT_SYMBOL(reset_devices);
163 static int __init set_reset_devices(char *str)
169 __setup("reset_devices", set_reset_devices);
171 static const char *argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
172 const char *envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
173 static const char *panic_later, *panic_param;
175 extern const struct obs_kernel_param __setup_start[], __setup_end[];
177 static bool __init obsolete_checksetup(char *line)
179 const struct obs_kernel_param *p;
180 bool had_early_param = false;
184 int n = strlen(p->str);
185 if (parameqn(line, p->str, n)) {
187 /* Already done in parse_early_param?
188 * (Needs exact match on param part).
189 * Keep iterating, as we can have early
190 * params and __setups of same names 8( */
191 if (line[n] == '\0' || line[n] == '=')
192 had_early_param = true;
193 } else if (!p->setup_func) {
194 pr_warn("Parameter %s is obsolete, ignored\n",
197 } else if (p->setup_func(line + n))
201 } while (p < __setup_end);
203 return had_early_param;
207 * This should be approx 2 Bo*oMips to start (note initial shift), and will
208 * still work even if initially too large, it will just take slightly longer
210 unsigned long loops_per_jiffy = (1<<12);
211 EXPORT_SYMBOL(loops_per_jiffy);
213 static int __init debug_kernel(char *str)
215 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
219 static int __init quiet_kernel(char *str)
221 console_loglevel = CONSOLE_LOGLEVEL_QUIET;
225 early_param("debug", debug_kernel);
226 early_param("quiet", quiet_kernel);
228 static int __init loglevel(char *str)
233 * Only update loglevel value when a correct setting was passed,
234 * to prevent blind crashes (when loglevel being set to 0) that
235 * are quite hard to debug
237 if (get_option(&str, &newlevel)) {
238 console_loglevel = newlevel;
245 early_param("loglevel", loglevel);
247 /* Change NUL term back to "=", to make "param" the whole string. */
248 static int __init repair_env_string(char *param, char *val,
249 const char *unused, void *arg)
252 /* param=val or param="val"? */
253 if (val == param+strlen(param)+1)
255 else if (val == param+strlen(param)+2) {
257 memmove(val-1, val, strlen(val)+1);
265 /* Anything after -- gets handed straight to init. */
266 static int __init set_init_arg(char *param, char *val,
267 const char *unused, void *arg)
274 repair_env_string(param, val, unused, NULL);
276 for (i = 0; argv_init[i]; i++) {
277 if (i == MAX_INIT_ARGS) {
278 panic_later = "init";
283 argv_init[i] = param;
288 * Unknown boot options get handed to init, unless they look like
289 * unused parameters (modprobe will find them in /proc/cmdline).
291 static int __init unknown_bootoption(char *param, char *val,
292 const char *unused, void *arg)
294 repair_env_string(param, val, unused, NULL);
296 /* Handle obsolete-style parameters */
297 if (obsolete_checksetup(param))
300 /* Unused module parameter. */
301 if (strchr(param, '.') && (!val || strchr(param, '.') < val))
308 /* Environment option */
310 for (i = 0; envp_init[i]; i++) {
311 if (i == MAX_INIT_ENVS) {
315 if (!strncmp(param, envp_init[i], val - param))
318 envp_init[i] = param;
320 /* Command line option */
322 for (i = 0; argv_init[i]; i++) {
323 if (i == MAX_INIT_ARGS) {
324 panic_later = "init";
328 argv_init[i] = param;
333 static int __init init_setup(char *str)
337 execute_command = str;
339 * In case LILO is going to boot us with default command line,
340 * it prepends "auto" before the whole cmdline which makes
341 * the shell think it should execute a script with such name.
342 * So we ignore all arguments entered _before_ init=... [MJ]
344 for (i = 1; i < MAX_INIT_ARGS; i++)
348 __setup("init=", init_setup);
350 static int __init rdinit_setup(char *str)
354 ramdisk_execute_command = str;
355 /* See "auto" comment in init_setup */
356 for (i = 1; i < MAX_INIT_ARGS; i++)
360 __setup("rdinit=", rdinit_setup);
363 static const unsigned int setup_max_cpus = NR_CPUS;
364 static inline void setup_nr_cpu_ids(void) { }
365 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
369 * We need to store the untouched command line for future reference.
370 * We also need to store the touched command line since the parameter
371 * parsing is performed in place, and we should allow a component to
372 * store reference of name/value for future reference.
374 static void __init setup_command_line(char *command_line)
376 size_t len = strlen(boot_command_line) + 1;
378 saved_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
379 if (!saved_command_line)
380 panic("%s: Failed to allocate %zu bytes\n", __func__, len);
382 initcall_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
383 if (!initcall_command_line)
384 panic("%s: Failed to allocate %zu bytes\n", __func__, len);
386 static_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
387 if (!static_command_line)
388 panic("%s: Failed to allocate %zu bytes\n", __func__, len);
390 strcpy(saved_command_line, boot_command_line);
391 strcpy(static_command_line, command_line);
395 * We need to finalize in a non-__init function or else race conditions
396 * between the root thread and the init thread may cause start_kernel to
397 * be reaped by free_initmem before the root thread has proceeded to
400 * gcc-3.4 accidentally inlines this function, so use noinline.
403 static __initdata DECLARE_COMPLETION(kthreadd_done);
405 noinline void __ref rest_init(void)
407 struct task_struct *tsk;
410 rcu_scheduler_starting();
412 * We need to spawn init first so that it obtains pid 1, however
413 * the init task will end up wanting to create kthreads, which, if
414 * we schedule it before we create kthreadd, will OOPS.
416 pid = kernel_thread(kernel_init, NULL, CLONE_FS);
418 * Pin init on the boot CPU. Task migration is not properly working
419 * until sched_init_smp() has been run. It will set the allowed
420 * CPUs for init to the non isolated CPUs.
423 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
424 set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id()));
427 numa_default_policy();
428 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
430 kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
434 * Enable might_sleep() and smp_processor_id() checks.
435 * They cannot be enabled earlier because with CONFIG_PREEMPT=y
436 * kernel_thread() would trigger might_sleep() splats. With
437 * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
438 * already, but it's stuck on the kthreadd_done completion.
440 system_state = SYSTEM_SCHEDULING;
442 complete(&kthreadd_done);
445 * The boot idle thread must execute schedule()
446 * at least once to get things moving:
448 schedule_preempt_disabled();
449 /* Call into cpu_idle with preempt disabled */
450 cpu_startup_entry(CPUHP_ONLINE);
453 /* Check for early params. */
454 static int __init do_early_param(char *param, char *val,
455 const char *unused, void *arg)
457 const struct obs_kernel_param *p;
459 for (p = __setup_start; p < __setup_end; p++) {
460 if ((p->early && parameq(param, p->str)) ||
461 (strcmp(param, "console") == 0 &&
462 strcmp(p->str, "earlycon") == 0)
464 if (p->setup_func(val) != 0)
465 pr_warn("Malformed early option '%s'\n", param);
468 /* We accept everything at this stage. */
472 void __init parse_early_options(char *cmdline)
474 parse_args("early options", cmdline, NULL, 0, 0, 0, NULL,
478 /* Arch code calls this early on, or if not, just before other parsing. */
479 void __init parse_early_param(void)
481 static int done __initdata;
482 static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
487 /* All fall through to do_early_param. */
488 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
489 parse_early_options(tmp_cmdline);
493 void __init __weak arch_post_acpi_subsys_init(void) { }
495 void __init __weak smp_setup_processor_id(void)
499 # if THREAD_SIZE >= PAGE_SIZE
500 void __init __weak thread_stack_cache_init(void)
505 void __init __weak mem_encrypt_init(void) { }
507 void __init __weak poking_init(void) { }
509 void __init __weak pgd_cache_init(void) { }
512 core_param(initcall_debug, initcall_debug, bool, 0644);
514 #ifdef TRACEPOINTS_ENABLED
515 static void __init initcall_debug_enable(void);
517 static inline void initcall_debug_enable(void)
523 * Set up kernel memory allocators
525 static void __init mm_init(void)
528 * page_ext requires contiguous pages,
529 * bigger than MAX_ORDER unless SPARSEMEM.
531 page_ext_init_flatmem();
535 debug_objects_mem_init();
538 /* Should be run before the first non-init thread is created */
540 /* Should be run after espfix64 is set up. */
545 void __init __weak arch_call_rest_init(void)
550 asmlinkage __visible void __init start_kernel(void)
555 set_task_stack_end_magic(&init_task);
556 smp_setup_processor_id();
557 debug_objects_early_init();
562 early_boot_irqs_disabled = true;
565 * Interrupts are still disabled. Do necessary setups, then
570 pr_notice("%s", linux_banner);
571 setup_arch(&command_line);
573 * Set up the the initial canary and entropy after arch
574 * and after adding latent and command line entropy.
576 add_latent_entropy();
577 add_device_randomness(command_line, strlen(command_line));
578 boot_init_stack_canary();
579 mm_init_cpumask(&init_mm);
580 setup_command_line(command_line);
582 setup_per_cpu_areas();
583 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
584 boot_cpu_hotplug_init();
586 build_all_zonelists(NULL);
589 pr_notice("Kernel command line: %s\n", boot_command_line);
590 /* parameters may set static keys */
593 after_dashes = parse_args("Booting kernel",
594 static_command_line, __start___param,
595 __stop___param - __start___param,
596 -1, -1, NULL, &unknown_bootoption);
597 if (!IS_ERR_OR_NULL(after_dashes))
598 parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
602 * These use large bootmem allocations and must precede
606 vfs_caches_init_early();
613 /* trace_printk can be enabled here */
617 * Set up the scheduler prior starting any interrupts (such as the
618 * timer interrupt). Full topology setup happens at smp_init()
619 * time - but meanwhile we still have a functioning scheduler.
623 * Disable preemption - early bootup scheduling is extremely
624 * fragile until we cpu_idle() for the first time.
627 if (WARN(!irqs_disabled(),
628 "Interrupts were enabled *very* early, fixing it\n"))
633 * Set up housekeeping before setting up workqueues to allow the unbound
634 * workqueue to take non-housekeeping into account.
639 * Allow workqueue creation and work item queueing/cancelling
640 * early. Work item execution depends on kthreads and starts after
643 workqueue_init_early();
647 /* Trace events are available after this */
651 initcall_debug_enable();
653 context_tracking_init();
654 /* init some links before init_ISA_irqs() */
667 call_function_init();
668 WARN(!irqs_disabled(), "Interrupts were enabled early\n");
670 early_boot_irqs_disabled = false;
673 kmem_cache_init_late();
676 * HACK ALERT! This is early. We're enabling the console before
677 * we've done PCI setups etc, and console_init() must be aware of
678 * this. But we do want output early, in case something goes wrong.
682 panic("Too many boot %s vars at `%s'", panic_later,
688 * Need to run this when irqs are enabled, because it wants
689 * to self-test [hard/soft]-irqs on/off lock inversion bugs
695 * This needs to be called before any devices perform DMA
696 * operations that might use the SWIOTLB bounce buffers. It will
697 * mark the bounce buffers as decrypted so that their usage will
698 * not cause "plain-text" data to be decrypted when accessed.
702 #ifdef CONFIG_BLK_DEV_INITRD
703 if (initrd_start && !initrd_below_start_ok &&
704 page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
705 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
706 page_to_pfn(virt_to_page((void *)initrd_start)),
712 setup_per_cpu_pageset();
722 if (efi_enabled(EFI_RUNTIME_SERVICES))
723 efi_enter_virtual_mode();
725 thread_stack_cache_init();
742 taskstats_init_early();
748 acpi_subsystem_init();
749 arch_post_acpi_subsys_init();
752 /* Do the rest non-__init'ed, we're now alive */
753 arch_call_rest_init();
756 /* Call all constructor functions linked into the kernel. */
757 static void __init do_ctors(void)
759 #ifdef CONFIG_CONSTRUCTORS
760 ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
762 for (; fn < (ctor_fn_t *) __ctors_end; fn++)
767 #ifdef CONFIG_KALLSYMS
768 struct blacklist_entry {
769 struct list_head next;
773 static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
775 static int __init initcall_blacklist(char *str)
778 struct blacklist_entry *entry;
780 /* str argument is a comma-separated list of functions */
782 str_entry = strsep(&str, ",");
784 pr_debug("blacklisting initcall %s\n", str_entry);
785 entry = memblock_alloc(sizeof(*entry),
788 panic("%s: Failed to allocate %zu bytes\n",
789 __func__, sizeof(*entry));
790 entry->buf = memblock_alloc(strlen(str_entry) + 1,
793 panic("%s: Failed to allocate %zu bytes\n",
794 __func__, strlen(str_entry) + 1);
795 strcpy(entry->buf, str_entry);
796 list_add(&entry->next, &blacklisted_initcalls);
803 static bool __init_or_module initcall_blacklisted(initcall_t fn)
805 struct blacklist_entry *entry;
806 char fn_name[KSYM_SYMBOL_LEN];
809 if (list_empty(&blacklisted_initcalls))
812 addr = (unsigned long) dereference_function_descriptor(fn);
813 sprint_symbol_no_offset(fn_name, addr);
816 * fn will be "function_name [module_name]" where [module_name] is not
817 * displayed for built-in init functions. Strip off the [module_name].
819 strreplace(fn_name, ' ', '\0');
821 list_for_each_entry(entry, &blacklisted_initcalls, next) {
822 if (!strcmp(fn_name, entry->buf)) {
823 pr_debug("initcall %s blacklisted\n", fn_name);
831 static int __init initcall_blacklist(char *str)
833 pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
837 static bool __init_or_module initcall_blacklisted(initcall_t fn)
842 __setup("initcall_blacklist=", initcall_blacklist);
844 static __init_or_module void
845 trace_initcall_start_cb(void *data, initcall_t fn)
847 ktime_t *calltime = (ktime_t *)data;
849 printk(KERN_DEBUG "calling %pS @ %i\n", fn, task_pid_nr(current));
850 *calltime = ktime_get();
853 static __init_or_module void
854 trace_initcall_finish_cb(void *data, initcall_t fn, int ret)
856 ktime_t *calltime = (ktime_t *)data;
857 ktime_t delta, rettime;
858 unsigned long long duration;
860 rettime = ktime_get();
861 delta = ktime_sub(rettime, *calltime);
862 duration = (unsigned long long) ktime_to_ns(delta) >> 10;
863 printk(KERN_DEBUG "initcall %pS returned %d after %lld usecs\n",
867 static ktime_t initcall_calltime;
869 #ifdef TRACEPOINTS_ENABLED
870 static void __init initcall_debug_enable(void)
874 ret = register_trace_initcall_start(trace_initcall_start_cb,
876 ret |= register_trace_initcall_finish(trace_initcall_finish_cb,
878 WARN(ret, "Failed to register initcall tracepoints\n");
880 # define do_trace_initcall_start trace_initcall_start
881 # define do_trace_initcall_finish trace_initcall_finish
883 static inline void do_trace_initcall_start(initcall_t fn)
887 trace_initcall_start_cb(&initcall_calltime, fn);
889 static inline void do_trace_initcall_finish(initcall_t fn, int ret)
893 trace_initcall_finish_cb(&initcall_calltime, fn, ret);
895 #endif /* !TRACEPOINTS_ENABLED */
897 int __init_or_module do_one_initcall(initcall_t fn)
899 int count = preempt_count();
903 if (initcall_blacklisted(fn))
906 do_trace_initcall_start(fn);
908 do_trace_initcall_finish(fn, ret);
912 if (preempt_count() != count) {
913 sprintf(msgbuf, "preemption imbalance ");
914 preempt_count_set(count);
916 if (irqs_disabled()) {
917 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
920 WARN(msgbuf[0], "initcall %pS returned with %s\n", fn, msgbuf);
922 add_latent_entropy();
927 extern initcall_entry_t __initcall_start[];
928 extern initcall_entry_t __initcall0_start[];
929 extern initcall_entry_t __initcall1_start[];
930 extern initcall_entry_t __initcall2_start[];
931 extern initcall_entry_t __initcall3_start[];
932 extern initcall_entry_t __initcall4_start[];
933 extern initcall_entry_t __initcall5_start[];
934 extern initcall_entry_t __initcall6_start[];
935 extern initcall_entry_t __initcall7_start[];
936 extern initcall_entry_t __initcall_end[];
938 static initcall_entry_t *initcall_levels[] __initdata = {
950 /* Keep these in sync with initcalls in include/linux/init.h */
951 static const char *initcall_level_names[] __initdata = {
962 static void __init do_initcall_level(int level)
964 initcall_entry_t *fn;
966 strcpy(initcall_command_line, saved_command_line);
967 parse_args(initcall_level_names[level],
968 initcall_command_line, __start___param,
969 __stop___param - __start___param,
971 NULL, &repair_env_string);
973 trace_initcall_level(initcall_level_names[level]);
974 for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
975 do_one_initcall(initcall_from_entry(fn));
978 static void __init do_initcalls(void)
982 for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
983 do_initcall_level(level);
987 * Ok, the machine is now initialized. None of the devices
988 * have been touched yet, but the CPU subsystem is up and
989 * running, and memory and process management works.
991 * Now we can finally start doing some real work..
993 static void __init do_basic_setup(void)
1000 usermodehelper_enable();
1004 static void __init do_pre_smp_initcalls(void)
1006 initcall_entry_t *fn;
1008 trace_initcall_level("early");
1009 for (fn = __initcall_start; fn < __initcall0_start; fn++)
1010 do_one_initcall(initcall_from_entry(fn));
1013 static int run_init_process(const char *init_filename)
1015 argv_init[0] = init_filename;
1016 pr_info("Run %s as init process\n", init_filename);
1017 return do_execve(getname_kernel(init_filename),
1018 (const char __user *const __user *)argv_init,
1019 (const char __user *const __user *)envp_init);
1022 static int try_to_run_init_process(const char *init_filename)
1026 ret = run_init_process(init_filename);
1028 if (ret && ret != -ENOENT) {
1029 pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
1030 init_filename, ret);
1036 static noinline void __init kernel_init_freeable(void);
1038 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
1039 bool rodata_enabled __ro_after_init = true;
1040 static int __init set_debug_rodata(char *str)
1042 return strtobool(str, &rodata_enabled);
1044 __setup("rodata=", set_debug_rodata);
1047 #ifdef CONFIG_STRICT_KERNEL_RWX
1048 static void mark_readonly(void)
1050 if (rodata_enabled) {
1052 * load_module() results in W+X mappings, which are cleaned
1053 * up with call_rcu(). Let's make sure that queued work is
1054 * flushed so that we don't hit false positives looking for
1055 * insecure pages which are W+X.
1061 pr_info("Kernel memory protection disabled.\n");
1064 static inline void mark_readonly(void)
1066 pr_warn("This architecture does not have kernel memory protection.\n");
1070 static int __ref kernel_init(void *unused)
1074 kernel_init_freeable();
1075 /* need to finish all async __init code before freeing the memory */
1076 async_synchronize_full();
1077 ftrace_free_init_mem();
1082 * Kernel mappings are now finalized - update the userspace page-table
1087 system_state = SYSTEM_RUNNING;
1088 numa_default_policy();
1090 rcu_end_inkernel_boot();
1092 if (ramdisk_execute_command) {
1093 ret = run_init_process(ramdisk_execute_command);
1096 pr_err("Failed to execute %s (error %d)\n",
1097 ramdisk_execute_command, ret);
1101 * We try each of these until one succeeds.
1103 * The Bourne shell can be used instead of init if we are
1104 * trying to recover a really broken machine.
1106 if (execute_command) {
1107 ret = run_init_process(execute_command);
1110 panic("Requested init %s failed (error %d).",
1111 execute_command, ret);
1113 if (!try_to_run_init_process("/sbin/init") ||
1114 !try_to_run_init_process("/etc/init") ||
1115 !try_to_run_init_process("/bin/init") ||
1116 !try_to_run_init_process("/bin/sh"))
1119 panic("No working init found. Try passing init= option to kernel. "
1120 "See Linux Documentation/admin-guide/init.rst for guidance.");
1123 static noinline void __init kernel_init_freeable(void)
1126 * Wait until kthreadd is all set-up.
1128 wait_for_completion(&kthreadd_done);
1130 /* Now the scheduler is fully set up and can do blocking allocations */
1131 gfp_allowed_mask = __GFP_BITS_MASK;
1134 * init can allocate pages on any node
1136 set_mems_allowed(node_states[N_MEMORY]);
1138 cad_pid = task_pid(current);
1140 smp_prepare_cpus(setup_max_cpus);
1144 init_mm_internals();
1146 do_pre_smp_initcalls();
1147 lockup_detector_init();
1152 page_alloc_init_late();
1153 /* Initialize page ext after all struct pages are initialized. */
1158 /* Open the /dev/console on the rootfs, this should never fail */
1159 if (ksys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
1160 pr_err("Warning: unable to open an initial console.\n");
1165 * check if there is an early userspace init. If yes, let it do all
1169 if (!ramdisk_execute_command)
1170 ramdisk_execute_command = "/init";
1172 if (ksys_access((const char __user *)
1173 ramdisk_execute_command, 0) != 0) {
1174 ramdisk_execute_command = NULL;
1175 prepare_namespace();
1179 * Ok, we have completed the initial bootup, and
1180 * we're essentially up and running. Get rid of the
1181 * initmem segments and start the user-mode stuff..
1183 * rootfs is available now, try loading the public keys
1184 * and default modules
1187 integrity_load_keys();