1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
7 * GK 2/5/95 - Changed to support mounting root fs via NFS
8 * Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
9 * Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
10 * Simplified starting of init: Michael A. Griffith <grif@acm.org>
13 #define DEBUG /* Enable initcall_debug */
15 #include <linux/types.h>
16 #include <linux/extable.h>
17 #include <linux/module.h>
18 #include <linux/proc_fs.h>
19 #include <linux/binfmts.h>
20 #include <linux/kernel.h>
21 #include <linux/syscalls.h>
22 #include <linux/stackprotector.h>
23 #include <linux/string.h>
24 #include <linux/ctype.h>
25 #include <linux/delay.h>
26 #include <linux/ioport.h>
27 #include <linux/init.h>
28 #include <linux/initrd.h>
29 #include <linux/memblock.h>
30 #include <linux/acpi.h>
31 #include <linux/bootconfig.h>
32 #include <linux/console.h>
33 #include <linux/nmi.h>
34 #include <linux/percpu.h>
35 #include <linux/kmod.h>
36 #include <linux/kprobes.h>
37 #include <linux/vmalloc.h>
38 #include <linux/kernel_stat.h>
39 #include <linux/start_kernel.h>
40 #include <linux/security.h>
41 #include <linux/smp.h>
42 #include <linux/profile.h>
43 #include <linux/kfence.h>
44 #include <linux/rcupdate.h>
45 #include <linux/moduleparam.h>
46 #include <linux/kallsyms.h>
47 #include <linux/writeback.h>
48 #include <linux/cpu.h>
49 #include <linux/cpuset.h>
50 #include <linux/cgroup.h>
51 #include <linux/efi.h>
52 #include <linux/tick.h>
53 #include <linux/sched/isolation.h>
54 #include <linux/interrupt.h>
55 #include <linux/taskstats_kern.h>
56 #include <linux/delayacct.h>
57 #include <linux/unistd.h>
58 #include <linux/utsname.h>
59 #include <linux/rmap.h>
60 #include <linux/mempolicy.h>
61 #include <linux/key.h>
62 #include <linux/page_ext.h>
63 #include <linux/debug_locks.h>
64 #include <linux/debugobjects.h>
65 #include <linux/lockdep.h>
66 #include <linux/kmemleak.h>
67 #include <linux/padata.h>
68 #include <linux/pid_namespace.h>
69 #include <linux/device/driver.h>
70 #include <linux/kthread.h>
71 #include <linux/sched.h>
72 #include <linux/sched/init.h>
73 #include <linux/signal.h>
74 #include <linux/idr.h>
75 #include <linux/kgdb.h>
76 #include <linux/ftrace.h>
77 #include <linux/async.h>
78 #include <linux/shmem_fs.h>
79 #include <linux/slab.h>
80 #include <linux/perf_event.h>
81 #include <linux/ptrace.h>
82 #include <linux/pti.h>
83 #include <linux/blkdev.h>
84 #include <linux/elevator.h>
85 #include <linux/sched/clock.h>
86 #include <linux/sched/task.h>
87 #include <linux/sched/task_stack.h>
88 #include <linux/context_tracking.h>
89 #include <linux/random.h>
90 #include <linux/list.h>
91 #include <linux/integrity.h>
92 #include <linux/proc_ns.h>
94 #include <linux/cache.h>
95 #include <linux/rodata_test.h>
96 #include <linux/jump_label.h>
97 #include <linux/mem_encrypt.h>
98 #include <linux/kcsan.h>
99 #include <linux/init_syscalls.h>
100 #include <linux/stackdepot.h>
103 #include <asm/bugs.h>
104 #include <asm/setup.h>
105 #include <asm/sections.h>
106 #include <asm/cacheflush.h>
108 #define CREATE_TRACE_POINTS
109 #include <trace/events/initcall.h>
111 #include <kunit/test.h>
113 static int kernel_init(void *);
115 extern void init_IRQ(void);
116 extern void radix_tree_init(void);
119 * Debug helper: via this flag we know that we are in 'early bootup code'
120 * where only the boot processor is running with IRQ disabled. This means
121 * two things - IRQ must not be enabled before the flag is cleared and some
122 * operations which are not allowed with IRQ disabled are allowed while the
125 bool early_boot_irqs_disabled __read_mostly
;
127 enum system_states system_state __read_mostly
;
128 EXPORT_SYMBOL(system_state
);
131 * Boot command-line arguments
133 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
134 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
136 extern void time_init(void);
137 /* Default late time init is NULL. archs can override this later. */
138 void (*__initdata late_time_init
)(void);
140 /* Untouched command line saved by arch-specific code. */
141 char __initdata boot_command_line
[COMMAND_LINE_SIZE
];
142 /* Untouched saved command line (eg. for /proc) */
143 char *saved_command_line
;
144 /* Command line for parameter parsing */
145 static char *static_command_line
;
146 /* Untouched extra command line */
147 static char *extra_command_line
;
148 /* Extra init arguments */
149 static char *extra_init_args
;
151 #ifdef CONFIG_BOOT_CONFIG
152 /* Is bootconfig on command line? */
153 static bool bootconfig_found
;
154 static bool initargs_found
;
156 # define bootconfig_found false
157 # define initargs_found false
160 static char *execute_command
;
161 static char *ramdisk_execute_command
= "/init";
164 * Used to generate warnings if static_key manipulation functions are used
165 * before jump_label_init is called.
167 bool static_key_initialized __read_mostly
;
168 EXPORT_SYMBOL_GPL(static_key_initialized
);
171 * If set, this is an indication to the drivers that reset the underlying
172 * device before going ahead with the initialization otherwise driver might
173 * rely on the BIOS and skip the reset operation.
175 * This is useful if kernel is booting in an unreliable environment.
176 * For ex. kdump situation where previous kernel has crashed, BIOS has been
177 * skipped and devices will be in unknown state.
179 unsigned int reset_devices
;
180 EXPORT_SYMBOL(reset_devices
);
182 static int __init
set_reset_devices(char *str
)
188 __setup("reset_devices", set_reset_devices
);
190 static const char *argv_init
[MAX_INIT_ARGS
+2] = { "init", NULL
, };
191 const char *envp_init
[MAX_INIT_ENVS
+2] = { "HOME=/", "TERM=linux", NULL
, };
192 static const char *panic_later
, *panic_param
;
194 extern const struct obs_kernel_param __setup_start
[], __setup_end
[];
196 static bool __init
obsolete_checksetup(char *line
)
198 const struct obs_kernel_param
*p
;
199 bool had_early_param
= false;
203 int n
= strlen(p
->str
);
204 if (parameqn(line
, p
->str
, n
)) {
206 /* Already done in parse_early_param?
207 * (Needs exact match on param part).
208 * Keep iterating, as we can have early
209 * params and __setups of same names 8( */
210 if (line
[n
] == '\0' || line
[n
] == '=')
211 had_early_param
= true;
212 } else if (!p
->setup_func
) {
213 pr_warn("Parameter %s is obsolete, ignored\n",
216 } else if (p
->setup_func(line
+ n
))
220 } while (p
< __setup_end
);
222 return had_early_param
;
226 * This should be approx 2 Bo*oMips to start (note initial shift), and will
227 * still work even if initially too large, it will just take slightly longer
229 unsigned long loops_per_jiffy
= (1<<12);
230 EXPORT_SYMBOL(loops_per_jiffy
);
232 static int __init
debug_kernel(char *str
)
234 console_loglevel
= CONSOLE_LOGLEVEL_DEBUG
;
238 static int __init
quiet_kernel(char *str
)
240 console_loglevel
= CONSOLE_LOGLEVEL_QUIET
;
244 early_param("debug", debug_kernel
);
245 early_param("quiet", quiet_kernel
);
247 static int __init
loglevel(char *str
)
252 * Only update loglevel value when a correct setting was passed,
253 * to prevent blind crashes (when loglevel being set to 0) that
254 * are quite hard to debug
256 if (get_option(&str
, &newlevel
)) {
257 console_loglevel
= newlevel
;
264 early_param("loglevel", loglevel
);
266 #ifdef CONFIG_BLK_DEV_INITRD
267 static void * __init
get_boot_config_from_initrd(u32
*_size
, u32
*_csum
)
277 data
= (char *)initrd_end
- BOOTCONFIG_MAGIC_LEN
;
279 * Since Grub may align the size of initrd to 4, we must
280 * check the preceding 3 bytes as well.
282 for (i
= 0; i
< 4; i
++) {
283 if (!memcmp(data
, BOOTCONFIG_MAGIC
, BOOTCONFIG_MAGIC_LEN
))
290 hdr
= (u32
*)(data
- 8);
291 size
= le32_to_cpu(hdr
[0]);
292 csum
= le32_to_cpu(hdr
[1]);
294 data
= ((void *)hdr
) - size
;
295 if ((unsigned long)data
< initrd_start
) {
296 pr_err("bootconfig size %d is greater than initrd size %ld\n",
297 size
, initrd_end
- initrd_start
);
301 /* Remove bootconfig from initramfs/initrd */
302 initrd_end
= (unsigned long)data
;
311 static void * __init
get_boot_config_from_initrd(u32
*_size
, u32
*_csum
)
317 #ifdef CONFIG_BOOT_CONFIG
319 static char xbc_namebuf
[XBC_KEYLEN_MAX
] __initdata
;
321 #define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
323 static int __init
xbc_snprint_cmdline(char *buf
, size_t size
,
324 struct xbc_node
*root
)
326 struct xbc_node
*knode
, *vnode
;
327 char *end
= buf
+ size
;
331 xbc_node_for_each_key_value(root
, knode
, val
) {
332 ret
= xbc_node_compose_key_after(root
, knode
,
333 xbc_namebuf
, XBC_KEYLEN_MAX
);
337 vnode
= xbc_node_get_child(knode
);
339 ret
= snprintf(buf
, rest(buf
, end
), "%s ", xbc_namebuf
);
345 xbc_array_for_each_value(vnode
, val
) {
346 ret
= snprintf(buf
, rest(buf
, end
), "%s=\"%s\" ",
354 return buf
- (end
- size
);
358 /* Make an extra command line under given key word */
359 static char * __init
xbc_make_cmdline(const char *key
)
361 struct xbc_node
*root
;
365 root
= xbc_find_node(key
);
369 /* Count required buffer size */
370 len
= xbc_snprint_cmdline(NULL
, 0, root
);
374 new_cmdline
= memblock_alloc(len
+ 1, SMP_CACHE_BYTES
);
376 pr_err("Failed to allocate memory for extra kernel cmdline.\n");
380 ret
= xbc_snprint_cmdline(new_cmdline
, len
+ 1, root
);
381 if (ret
< 0 || ret
> len
) {
382 pr_err("Failed to print extra kernel cmdline.\n");
389 static u32
boot_config_checksum(unsigned char *p
, u32 size
)
399 static int __init
bootconfig_params(char *param
, char *val
,
400 const char *unused
, void *arg
)
402 if (strcmp(param
, "bootconfig") == 0) {
403 bootconfig_found
= true;
408 static void __init
setup_boot_config(void)
410 static char tmp_cmdline
[COMMAND_LINE_SIZE
] __initdata
;
414 char *data
, *copy
, *err
;
417 /* Cut out the bootconfig data even if we have no bootconfig option */
418 data
= get_boot_config_from_initrd(&size
, &csum
);
420 strlcpy(tmp_cmdline
, boot_command_line
, COMMAND_LINE_SIZE
);
421 err
= parse_args("bootconfig", tmp_cmdline
, NULL
, 0, 0, 0, NULL
,
424 if (IS_ERR(err
) || !bootconfig_found
)
427 /* parse_args() stops at '--' and returns an address */
429 initargs_found
= true;
432 pr_err("'bootconfig' found on command line, but no bootconfig found\n");
436 if (size
>= XBC_DATA_MAX
) {
437 pr_err("bootconfig size %d greater than max size %d\n",
442 if (boot_config_checksum((unsigned char *)data
, size
) != csum
) {
443 pr_err("bootconfig checksum failed\n");
447 copy
= memblock_alloc(size
+ 1, SMP_CACHE_BYTES
);
449 pr_err("Failed to allocate memory for bootconfig\n");
453 memcpy(copy
, data
, size
);
456 ret
= xbc_init(copy
, &msg
, &pos
);
459 pr_err("Failed to init bootconfig: %s.\n", msg
);
461 pr_err("Failed to parse bootconfig: %s at %d.\n",
464 pr_info("Load bootconfig: %d bytes %d nodes\n", size
, ret
);
465 /* keys starting with "kernel." are passed via cmdline */
466 extra_command_line
= xbc_make_cmdline("kernel");
467 /* Also, "init." keys are init arguments */
468 extra_init_args
= xbc_make_cmdline("init");
475 static void __init
setup_boot_config(void)
477 /* Remove bootconfig data from initrd */
478 get_boot_config_from_initrd(NULL
, NULL
);
481 static int __init
warn_bootconfig(char *str
)
483 pr_warn("WARNING: 'bootconfig' found on the kernel command line but CONFIG_BOOT_CONFIG is not set.\n");
486 early_param("bootconfig", warn_bootconfig
);
490 /* Change NUL term back to "=", to make "param" the whole string. */
491 static void __init
repair_env_string(char *param
, char *val
)
494 /* param=val or param="val"? */
495 if (val
== param
+strlen(param
)+1)
497 else if (val
== param
+strlen(param
)+2) {
499 memmove(val
-1, val
, strlen(val
)+1);
505 /* Anything after -- gets handed straight to init. */
506 static int __init
set_init_arg(char *param
, char *val
,
507 const char *unused
, void *arg
)
514 repair_env_string(param
, val
);
516 for (i
= 0; argv_init
[i
]; i
++) {
517 if (i
== MAX_INIT_ARGS
) {
518 panic_later
= "init";
523 argv_init
[i
] = param
;
528 * Unknown boot options get handed to init, unless they look like
529 * unused parameters (modprobe will find them in /proc/cmdline).
531 static int __init
unknown_bootoption(char *param
, char *val
,
532 const char *unused
, void *arg
)
534 size_t len
= strlen(param
);
536 repair_env_string(param
, val
);
538 /* Handle obsolete-style parameters */
539 if (obsolete_checksetup(param
))
542 /* Unused module parameter. */
543 if (strnchr(param
, len
, '.'))
550 /* Environment option */
552 for (i
= 0; envp_init
[i
]; i
++) {
553 if (i
== MAX_INIT_ENVS
) {
557 if (!strncmp(param
, envp_init
[i
], len
+1))
560 envp_init
[i
] = param
;
562 /* Command line option */
564 for (i
= 0; argv_init
[i
]; i
++) {
565 if (i
== MAX_INIT_ARGS
) {
566 panic_later
= "init";
570 argv_init
[i
] = param
;
575 static int __init
init_setup(char *str
)
579 execute_command
= str
;
581 * In case LILO is going to boot us with default command line,
582 * it prepends "auto" before the whole cmdline which makes
583 * the shell think it should execute a script with such name.
584 * So we ignore all arguments entered _before_ init=... [MJ]
586 for (i
= 1; i
< MAX_INIT_ARGS
; i
++)
590 __setup("init=", init_setup
);
592 static int __init
rdinit_setup(char *str
)
596 ramdisk_execute_command
= str
;
597 /* See "auto" comment in init_setup */
598 for (i
= 1; i
< MAX_INIT_ARGS
; i
++)
602 __setup("rdinit=", rdinit_setup
);
605 static const unsigned int setup_max_cpus
= NR_CPUS
;
606 static inline void setup_nr_cpu_ids(void) { }
607 static inline void smp_prepare_cpus(unsigned int maxcpus
) { }
611 * We need to store the untouched command line for future reference.
612 * We also need to store the touched command line since the parameter
613 * parsing is performed in place, and we should allow a component to
614 * store reference of name/value for future reference.
616 static void __init
setup_command_line(char *command_line
)
618 size_t len
, xlen
= 0, ilen
= 0;
620 if (extra_command_line
)
621 xlen
= strlen(extra_command_line
);
623 ilen
= strlen(extra_init_args
) + 4; /* for " -- " */
625 len
= xlen
+ strlen(boot_command_line
) + 1;
627 saved_command_line
= memblock_alloc(len
+ ilen
, SMP_CACHE_BYTES
);
628 if (!saved_command_line
)
629 panic("%s: Failed to allocate %zu bytes\n", __func__
, len
+ ilen
);
631 static_command_line
= memblock_alloc(len
, SMP_CACHE_BYTES
);
632 if (!static_command_line
)
633 panic("%s: Failed to allocate %zu bytes\n", __func__
, len
);
637 * We have to put extra_command_line before boot command
638 * lines because there could be dashes (separator of init
639 * command line) in the command lines.
641 strcpy(saved_command_line
, extra_command_line
);
642 strcpy(static_command_line
, extra_command_line
);
644 strcpy(saved_command_line
+ xlen
, boot_command_line
);
645 strcpy(static_command_line
+ xlen
, command_line
);
649 * Append supplemental init boot args to saved_command_line
650 * so that user can check what command line options passed
653 len
= strlen(saved_command_line
);
654 if (initargs_found
) {
655 saved_command_line
[len
++] = ' ';
657 strcpy(saved_command_line
+ len
, " -- ");
661 strcpy(saved_command_line
+ len
, extra_init_args
);
666 * We need to finalize in a non-__init function or else race conditions
667 * between the root thread and the init thread may cause start_kernel to
668 * be reaped by free_initmem before the root thread has proceeded to
671 * gcc-3.4 accidentally inlines this function, so use noinline.
674 static __initdata
DECLARE_COMPLETION(kthreadd_done
);
676 noinline
void __ref
rest_init(void)
678 struct task_struct
*tsk
;
681 rcu_scheduler_starting();
683 * We need to spawn init first so that it obtains pid 1, however
684 * the init task will end up wanting to create kthreads, which, if
685 * we schedule it before we create kthreadd, will OOPS.
687 pid
= kernel_thread(kernel_init
, NULL
, CLONE_FS
);
689 * Pin init on the boot CPU. Task migration is not properly working
690 * until sched_init_smp() has been run. It will set the allowed
691 * CPUs for init to the non isolated CPUs.
694 tsk
= find_task_by_pid_ns(pid
, &init_pid_ns
);
695 tsk
->flags
|= PF_NO_SETAFFINITY
;
696 set_cpus_allowed_ptr(tsk
, cpumask_of(smp_processor_id()));
699 numa_default_policy();
700 pid
= kernel_thread(kthreadd
, NULL
, CLONE_FS
| CLONE_FILES
);
702 kthreadd_task
= find_task_by_pid_ns(pid
, &init_pid_ns
);
706 * Enable might_sleep() and smp_processor_id() checks.
707 * They cannot be enabled earlier because with CONFIG_PREEMPTION=y
708 * kernel_thread() would trigger might_sleep() splats. With
709 * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
710 * already, but it's stuck on the kthreadd_done completion.
712 system_state
= SYSTEM_SCHEDULING
;
714 complete(&kthreadd_done
);
717 * The boot idle thread must execute schedule()
718 * at least once to get things moving:
720 schedule_preempt_disabled();
721 /* Call into cpu_idle with preempt disabled */
722 cpu_startup_entry(CPUHP_ONLINE
);
725 /* Check for early params. */
726 static int __init
do_early_param(char *param
, char *val
,
727 const char *unused
, void *arg
)
729 const struct obs_kernel_param
*p
;
731 for (p
= __setup_start
; p
< __setup_end
; p
++) {
732 if ((p
->early
&& parameq(param
, p
->str
)) ||
733 (strcmp(param
, "console") == 0 &&
734 strcmp(p
->str
, "earlycon") == 0)
736 if (p
->setup_func(val
) != 0)
737 pr_warn("Malformed early option '%s'\n", param
);
740 /* We accept everything at this stage. */
744 void __init
parse_early_options(char *cmdline
)
746 parse_args("early options", cmdline
, NULL
, 0, 0, 0, NULL
,
750 /* Arch code calls this early on, or if not, just before other parsing. */
751 void __init
parse_early_param(void)
753 static int done __initdata
;
754 static char tmp_cmdline
[COMMAND_LINE_SIZE
] __initdata
;
759 /* All fall through to do_early_param. */
760 strlcpy(tmp_cmdline
, boot_command_line
, COMMAND_LINE_SIZE
);
761 parse_early_options(tmp_cmdline
);
765 void __init __weak
arch_post_acpi_subsys_init(void) { }
767 void __init __weak
smp_setup_processor_id(void)
771 # if THREAD_SIZE >= PAGE_SIZE
772 void __init __weak
thread_stack_cache_init(void)
777 void __init __weak
mem_encrypt_init(void) { }
779 void __init __weak
poking_init(void) { }
781 void __init __weak
pgtable_cache_init(void) { }
784 core_param(initcall_debug
, initcall_debug
, bool, 0644);
786 #ifdef TRACEPOINTS_ENABLED
787 static void __init
initcall_debug_enable(void);
789 static inline void initcall_debug_enable(void)
794 /* Report memory auto-initialization states for this boot. */
795 static void __init
report_meminit(void)
799 if (IS_ENABLED(CONFIG_INIT_STACK_ALL_PATTERN
))
800 stack
= "all(pattern)";
801 else if (IS_ENABLED(CONFIG_INIT_STACK_ALL_ZERO
))
803 else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
))
804 stack
= "byref_all(zero)";
805 else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF
))
806 stack
= "byref(zero)";
807 else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER
))
808 stack
= "__user(zero)";
812 pr_info("mem auto-init: stack:%s, heap alloc:%s, heap free:%s\n",
813 stack
, want_init_on_alloc(GFP_KERNEL
) ? "on" : "off",
814 want_init_on_free() ? "on" : "off");
815 if (want_init_on_free())
816 pr_info("mem auto-init: clearing system memory may take some time...\n");
820 * Set up kernel memory allocators
822 static void __init
mm_init(void)
825 * page_ext requires contiguous pages,
826 * bigger than MAX_ORDER unless SPARSEMEM.
828 page_ext_init_flatmem();
829 init_mem_debugging_and_hardening();
834 mem_init_print_info();
835 /* page_owner must be initialized after buddy is ready */
836 page_ext_init_flatmem_late();
840 debug_objects_mem_init();
842 /* Should be run before the first non-init thread is created */
844 /* Should be run after espfix64 is set up. */
848 #ifdef CONFIG_HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
849 DEFINE_STATIC_KEY_MAYBE_RO(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT
,
850 randomize_kstack_offset
);
851 DEFINE_PER_CPU(u32
, kstack_offset
);
853 static int __init
early_randomize_kstack_offset(char *buf
)
858 ret
= kstrtobool(buf
, &bool_result
);
863 static_branch_enable(&randomize_kstack_offset
);
865 static_branch_disable(&randomize_kstack_offset
);
868 early_param("randomize_kstack_offset", early_randomize_kstack_offset
);
871 void __init __weak
arch_call_rest_init(void)
876 static void __init
print_unknown_bootoptions(void)
878 char *unknown_options
;
880 const char *const *p
;
883 if (panic_later
|| (!argv_init
[1] && !envp_init
[2]))
887 * Determine how many options we have to print out, plus a space
890 len
= 1; /* null terminator */
891 for (p
= &argv_init
[1]; *p
; p
++) {
895 for (p
= &envp_init
[2]; *p
; p
++) {
900 unknown_options
= memblock_alloc(len
, SMP_CACHE_BYTES
);
901 if (!unknown_options
) {
902 pr_err("%s: Failed to allocate %zu bytes\n",
906 end
= unknown_options
;
908 for (p
= &argv_init
[1]; *p
; p
++)
909 end
+= sprintf(end
, " %s", *p
);
910 for (p
= &envp_init
[2]; *p
; p
++)
911 end
+= sprintf(end
, " %s", *p
);
913 pr_notice("Unknown command line parameters:%s\n", unknown_options
);
914 memblock_free(__pa(unknown_options
), len
);
917 asmlinkage __visible
void __init __no_sanitize_address
start_kernel(void)
922 set_task_stack_end_magic(&init_task
);
923 smp_setup_processor_id();
924 debug_objects_early_init();
929 early_boot_irqs_disabled
= true;
932 * Interrupts are still disabled. Do necessary setups, then
937 pr_notice("%s", linux_banner
);
938 early_security_init();
939 setup_arch(&command_line
);
941 setup_command_line(command_line
);
943 setup_per_cpu_areas();
944 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
945 boot_cpu_hotplug_init();
947 build_all_zonelists(NULL
);
950 pr_notice("Kernel command line: %s\n", saved_command_line
);
951 /* parameters may set static keys */
954 after_dashes
= parse_args("Booting kernel",
955 static_command_line
, __start___param
,
956 __stop___param
- __start___param
,
957 -1, -1, NULL
, &unknown_bootoption
);
958 print_unknown_bootoptions();
959 if (!IS_ERR_OR_NULL(after_dashes
))
960 parse_args("Setting init args", after_dashes
, NULL
, 0, -1, -1,
963 parse_args("Setting extra init args", extra_init_args
,
964 NULL
, 0, -1, -1, NULL
, set_init_arg
);
967 * These use large bootmem allocations and must precede
971 vfs_caches_init_early();
978 /* trace_printk can be enabled here */
982 * Set up the scheduler prior starting any interrupts (such as the
983 * timer interrupt). Full topology setup happens at smp_init()
984 * time - but meanwhile we still have a functioning scheduler.
988 if (WARN(!irqs_disabled(),
989 "Interrupts were enabled *very* early, fixing it\n"))
994 * Set up housekeeping before setting up workqueues to allow the unbound
995 * workqueue to take non-housekeeping into account.
1000 * Allow workqueue creation and work item queueing/cancelling
1001 * early. Work item execution depends on kthreads and starts after
1004 workqueue_init_early();
1008 /* Trace events are available after this */
1012 initcall_debug_enable();
1014 context_tracking_init();
1015 /* init some links before init_ISA_irqs() */
1027 * For best initial stack canary entropy, prepare it after:
1028 * - setup_arch() for any UEFI RNG entropy and boot cmdline access
1029 * - timekeeping_init() for ktime entropy used in rand_initialize()
1030 * - rand_initialize() to get any arch-specific entropy like RDRAND
1031 * - add_latent_entropy() to get any latent entropy
1032 * - adding command line entropy
1035 add_latent_entropy();
1036 add_device_randomness(command_line
, strlen(command_line
));
1037 boot_init_stack_canary();
1042 call_function_init();
1043 WARN(!irqs_disabled(), "Interrupts were enabled early\n");
1045 early_boot_irqs_disabled
= false;
1048 kmem_cache_init_late();
1051 * HACK ALERT! This is early. We're enabling the console before
1052 * we've done PCI setups etc, and console_init() must be aware of
1053 * this. But we do want output early, in case something goes wrong.
1057 panic("Too many boot %s vars at `%s'", panic_later
,
1063 * Need to run this when irqs are enabled, because it wants
1064 * to self-test [hard/soft]-irqs on/off lock inversion bugs
1070 * This needs to be called before any devices perform DMA
1071 * operations that might use the SWIOTLB bounce buffers. It will
1072 * mark the bounce buffers as decrypted so that their usage will
1073 * not cause "plain-text" data to be decrypted when accessed.
1077 #ifdef CONFIG_BLK_DEV_INITRD
1078 if (initrd_start
&& !initrd_below_start_ok
&&
1079 page_to_pfn(virt_to_page((void *)initrd_start
)) < min_low_pfn
) {
1080 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
1081 page_to_pfn(virt_to_page((void *)initrd_start
)),
1086 setup_per_cpu_pageset();
1096 if (efi_enabled(EFI_RUNTIME_SERVICES
))
1097 efi_enter_virtual_mode();
1099 thread_stack_cache_init();
1115 taskstats_init_early();
1121 acpi_subsystem_init();
1122 arch_post_acpi_subsys_init();
1125 /* Do the rest non-__init'ed, we're now alive */
1126 arch_call_rest_init();
1128 prevent_tail_call_optimization();
1131 /* Call all constructor functions linked into the kernel. */
1132 static void __init
do_ctors(void)
1135 * For UML, the constructors have already been called by the
1136 * normal setup code as it's just a normal ELF binary, so we
1137 * cannot do it again - but we do need CONFIG_CONSTRUCTORS
1138 * even on UML for modules.
1140 #if defined(CONFIG_CONSTRUCTORS) && !defined(CONFIG_UML)
1141 ctor_fn_t
*fn
= (ctor_fn_t
*) __ctors_start
;
1143 for (; fn
< (ctor_fn_t
*) __ctors_end
; fn
++)
1148 #ifdef CONFIG_KALLSYMS
1149 struct blacklist_entry
{
1150 struct list_head next
;
1154 static __initdata_or_module
LIST_HEAD(blacklisted_initcalls
);
1156 static int __init
initcall_blacklist(char *str
)
1159 struct blacklist_entry
*entry
;
1161 /* str argument is a comma-separated list of functions */
1163 str_entry
= strsep(&str
, ",");
1165 pr_debug("blacklisting initcall %s\n", str_entry
);
1166 entry
= memblock_alloc(sizeof(*entry
),
1169 panic("%s: Failed to allocate %zu bytes\n",
1170 __func__
, sizeof(*entry
));
1171 entry
->buf
= memblock_alloc(strlen(str_entry
) + 1,
1174 panic("%s: Failed to allocate %zu bytes\n",
1175 __func__
, strlen(str_entry
) + 1);
1176 strcpy(entry
->buf
, str_entry
);
1177 list_add(&entry
->next
, &blacklisted_initcalls
);
1179 } while (str_entry
);
1184 static bool __init_or_module
initcall_blacklisted(initcall_t fn
)
1186 struct blacklist_entry
*entry
;
1187 char fn_name
[KSYM_SYMBOL_LEN
];
1190 if (list_empty(&blacklisted_initcalls
))
1193 addr
= (unsigned long) dereference_function_descriptor(fn
);
1194 sprint_symbol_no_offset(fn_name
, addr
);
1197 * fn will be "function_name [module_name]" where [module_name] is not
1198 * displayed for built-in init functions. Strip off the [module_name].
1200 strreplace(fn_name
, ' ', '\0');
1202 list_for_each_entry(entry
, &blacklisted_initcalls
, next
) {
1203 if (!strcmp(fn_name
, entry
->buf
)) {
1204 pr_debug("initcall %s blacklisted\n", fn_name
);
1212 static int __init
initcall_blacklist(char *str
)
1214 pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
1218 static bool __init_or_module
initcall_blacklisted(initcall_t fn
)
1223 __setup("initcall_blacklist=", initcall_blacklist
);
1225 static __init_or_module
void
1226 trace_initcall_start_cb(void *data
, initcall_t fn
)
1228 ktime_t
*calltime
= (ktime_t
*)data
;
1230 printk(KERN_DEBUG
"calling %pS @ %i\n", fn
, task_pid_nr(current
));
1231 *calltime
= ktime_get();
1234 static __init_or_module
void
1235 trace_initcall_finish_cb(void *data
, initcall_t fn
, int ret
)
1237 ktime_t
*calltime
= (ktime_t
*)data
;
1238 ktime_t delta
, rettime
;
1239 unsigned long long duration
;
1241 rettime
= ktime_get();
1242 delta
= ktime_sub(rettime
, *calltime
);
1243 duration
= (unsigned long long) ktime_to_ns(delta
) >> 10;
1244 printk(KERN_DEBUG
"initcall %pS returned %d after %lld usecs\n",
1248 static ktime_t initcall_calltime
;
1250 #ifdef TRACEPOINTS_ENABLED
1251 static void __init
initcall_debug_enable(void)
1255 ret
= register_trace_initcall_start(trace_initcall_start_cb
,
1256 &initcall_calltime
);
1257 ret
|= register_trace_initcall_finish(trace_initcall_finish_cb
,
1258 &initcall_calltime
);
1259 WARN(ret
, "Failed to register initcall tracepoints\n");
1261 # define do_trace_initcall_start trace_initcall_start
1262 # define do_trace_initcall_finish trace_initcall_finish
1264 static inline void do_trace_initcall_start(initcall_t fn
)
1266 if (!initcall_debug
)
1268 trace_initcall_start_cb(&initcall_calltime
, fn
);
1270 static inline void do_trace_initcall_finish(initcall_t fn
, int ret
)
1272 if (!initcall_debug
)
1274 trace_initcall_finish_cb(&initcall_calltime
, fn
, ret
);
1276 #endif /* !TRACEPOINTS_ENABLED */
1278 int __init_or_module
do_one_initcall(initcall_t fn
)
1280 int count
= preempt_count();
1284 if (initcall_blacklisted(fn
))
1287 do_trace_initcall_start(fn
);
1289 do_trace_initcall_finish(fn
, ret
);
1293 if (preempt_count() != count
) {
1294 sprintf(msgbuf
, "preemption imbalance ");
1295 preempt_count_set(count
);
1297 if (irqs_disabled()) {
1298 strlcat(msgbuf
, "disabled interrupts ", sizeof(msgbuf
));
1301 WARN(msgbuf
[0], "initcall %pS returned with %s\n", fn
, msgbuf
);
1303 add_latent_entropy();
1308 extern initcall_entry_t __initcall_start
[];
1309 extern initcall_entry_t __initcall0_start
[];
1310 extern initcall_entry_t __initcall1_start
[];
1311 extern initcall_entry_t __initcall2_start
[];
1312 extern initcall_entry_t __initcall3_start
[];
1313 extern initcall_entry_t __initcall4_start
[];
1314 extern initcall_entry_t __initcall5_start
[];
1315 extern initcall_entry_t __initcall6_start
[];
1316 extern initcall_entry_t __initcall7_start
[];
1317 extern initcall_entry_t __initcall_end
[];
1319 static initcall_entry_t
*initcall_levels
[] __initdata
= {
1331 /* Keep these in sync with initcalls in include/linux/init.h */
1332 static const char *initcall_level_names
[] __initdata
= {
1343 static int __init
ignore_unknown_bootoption(char *param
, char *val
,
1344 const char *unused
, void *arg
)
1349 static void __init
do_initcall_level(int level
, char *command_line
)
1351 initcall_entry_t
*fn
;
1353 parse_args(initcall_level_names
[level
],
1354 command_line
, __start___param
,
1355 __stop___param
- __start___param
,
1357 NULL
, ignore_unknown_bootoption
);
1359 trace_initcall_level(initcall_level_names
[level
]);
1360 for (fn
= initcall_levels
[level
]; fn
< initcall_levels
[level
+1]; fn
++)
1361 do_one_initcall(initcall_from_entry(fn
));
1364 static void __init
do_initcalls(void)
1367 size_t len
= strlen(saved_command_line
) + 1;
1370 command_line
= kzalloc(len
, GFP_KERNEL
);
1372 panic("%s: Failed to allocate %zu bytes\n", __func__
, len
);
1374 for (level
= 0; level
< ARRAY_SIZE(initcall_levels
) - 1; level
++) {
1375 /* Parser modifies command_line, restore it each time */
1376 strcpy(command_line
, saved_command_line
);
1377 do_initcall_level(level
, command_line
);
1380 kfree(command_line
);
1384 * Ok, the machine is now initialized. None of the devices
1385 * have been touched yet, but the CPU subsystem is up and
1386 * running, and memory and process management works.
1388 * Now we can finally start doing some real work..
1390 static void __init
do_basic_setup(void)
1396 usermodehelper_enable();
1400 static void __init
do_pre_smp_initcalls(void)
1402 initcall_entry_t
*fn
;
1404 trace_initcall_level("early");
1405 for (fn
= __initcall_start
; fn
< __initcall0_start
; fn
++)
1406 do_one_initcall(initcall_from_entry(fn
));
1409 static int run_init_process(const char *init_filename
)
1411 const char *const *p
;
1413 argv_init
[0] = init_filename
;
1414 pr_info("Run %s as init process\n", init_filename
);
1415 pr_debug(" with arguments:\n");
1416 for (p
= argv_init
; *p
; p
++)
1417 pr_debug(" %s\n", *p
);
1418 pr_debug(" with environment:\n");
1419 for (p
= envp_init
; *p
; p
++)
1420 pr_debug(" %s\n", *p
);
1421 return kernel_execve(init_filename
, argv_init
, envp_init
);
1424 static int try_to_run_init_process(const char *init_filename
)
1428 ret
= run_init_process(init_filename
);
1430 if (ret
&& ret
!= -ENOENT
) {
1431 pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
1432 init_filename
, ret
);
1438 static noinline
void __init
kernel_init_freeable(void);
1440 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
1441 bool rodata_enabled __ro_after_init
= true;
1442 static int __init
set_debug_rodata(char *str
)
1444 return strtobool(str
, &rodata_enabled
);
1446 __setup("rodata=", set_debug_rodata
);
1449 #ifdef CONFIG_STRICT_KERNEL_RWX
1450 static void mark_readonly(void)
1452 if (rodata_enabled
) {
1454 * load_module() results in W+X mappings, which are cleaned
1455 * up with call_rcu(). Let's make sure that queued work is
1456 * flushed so that we don't hit false positives looking for
1457 * insecure pages which are W+X.
1463 pr_info("Kernel memory protection disabled.\n");
1465 #elif defined(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)
1466 static inline void mark_readonly(void)
1468 pr_warn("Kernel memory protection not selected by kernel config.\n");
1471 static inline void mark_readonly(void)
1473 pr_warn("This architecture does not have kernel memory protection.\n");
1477 void __weak
free_initmem(void)
1479 free_initmem_default(POISON_FREE_INITMEM
);
1482 static int __ref
kernel_init(void *unused
)
1487 * Wait until kthreadd is all set-up.
1489 wait_for_completion(&kthreadd_done
);
1491 kernel_init_freeable();
1492 /* need to finish all async __init code before freeing the memory */
1493 async_synchronize_full();
1494 kprobe_free_init_mem();
1495 ftrace_free_init_mem();
1496 kgdb_free_init_mem();
1501 * Kernel mappings are now finalized - update the userspace page-table
1506 system_state
= SYSTEM_RUNNING
;
1507 numa_default_policy();
1509 rcu_end_inkernel_boot();
1513 if (ramdisk_execute_command
) {
1514 ret
= run_init_process(ramdisk_execute_command
);
1517 pr_err("Failed to execute %s (error %d)\n",
1518 ramdisk_execute_command
, ret
);
1522 * We try each of these until one succeeds.
1524 * The Bourne shell can be used instead of init if we are
1525 * trying to recover a really broken machine.
1527 if (execute_command
) {
1528 ret
= run_init_process(execute_command
);
1531 panic("Requested init %s failed (error %d).",
1532 execute_command
, ret
);
1535 if (CONFIG_DEFAULT_INIT
[0] != '\0') {
1536 ret
= run_init_process(CONFIG_DEFAULT_INIT
);
1538 pr_err("Default init %s failed (error %d)\n",
1539 CONFIG_DEFAULT_INIT
, ret
);
1544 if (!try_to_run_init_process("/sbin/init") ||
1545 !try_to_run_init_process("/etc/init") ||
1546 !try_to_run_init_process("/bin/init") ||
1547 !try_to_run_init_process("/bin/sh"))
1550 panic("No working init found. Try passing init= option to kernel. "
1551 "See Linux Documentation/admin-guide/init.rst for guidance.");
1554 /* Open /dev/console, for stdin/stdout/stderr, this should never fail */
1555 void __init
console_on_rootfs(void)
1557 struct file
*file
= filp_open("/dev/console", O_RDWR
, 0);
1560 pr_err("Warning: unable to open an initial console.\n");
1569 static noinline
void __init
kernel_init_freeable(void)
1571 /* Now the scheduler is fully set up and can do blocking allocations */
1572 gfp_allowed_mask
= __GFP_BITS_MASK
;
1575 * init can allocate pages on any node
1577 set_mems_allowed(node_states
[N_MEMORY
]);
1579 cad_pid
= get_pid(task_pid(current
));
1581 smp_prepare_cpus(setup_max_cpus
);
1585 init_mm_internals();
1587 rcu_init_tasks_generic();
1588 do_pre_smp_initcalls();
1589 lockup_detector_init();
1595 page_alloc_init_late();
1596 /* Initialize page ext after all struct pages are initialized. */
1601 kunit_run_all_tests();
1603 wait_for_initramfs();
1604 console_on_rootfs();
1607 * check if there is an early userspace init. If yes, let it do all
1610 if (init_eaccess(ramdisk_execute_command
) != 0) {
1611 ramdisk_execute_command
= NULL
;
1612 prepare_namespace();
1616 * Ok, we have completed the initial bootup, and
1617 * we're essentially up and running. Get rid of the
1618 * initmem segments and start the user-mode stuff..
1620 * rootfs is available now, try loading the public keys
1621 * and default modules
1624 integrity_load_keys();