1 /* 2 * linux/init/main.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * 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> 10 */ 11 12 #define DEBUG /* Enable initcall_debug */ 13 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 78 #include <asm/io.h> 79 #include <asm/bugs.h> 80 #include <asm/setup.h> 81 #include <asm/sections.h> 82 #include <asm/cacheflush.h> 83 84 #ifdef CONFIG_X86_LOCAL_APIC 85 #include <asm/smp.h> 86 #endif 87 88 static int kernel_init(void *); 89 90 extern void init_IRQ(void); 91 extern void fork_init(unsigned long); 92 extern void mca_init(void); 93 extern void sbus_init(void); 94 extern void radix_tree_init(void); 95 #ifndef CONFIG_DEBUG_RODATA 96 static inline void mark_rodata_ro(void) { } 97 #endif 98 99 #ifdef CONFIG_TC 100 extern void tc_init(void); 101 #endif 102 103 /* 104 * Debug helper: via this flag we know that we are in 'early bootup code' 105 * where only the boot processor is running with IRQ disabled. This means 106 * two things - IRQ must not be enabled before the flag is cleared and some 107 * operations which are not allowed with IRQ disabled are allowed while the 108 * flag is set. 109 */ 110 bool early_boot_irqs_disabled __read_mostly; 111 112 enum system_states system_state __read_mostly; 113 EXPORT_SYMBOL(system_state); 114 115 /* 116 * Boot command-line arguments 117 */ 118 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT 119 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT 120 121 extern void time_init(void); 122 /* Default late time init is NULL. archs can override this later. */ 123 void (*__initdata late_time_init)(void); 124 extern void softirq_init(void); 125 126 /* Untouched command line saved by arch-specific code. */ 127 char __initdata boot_command_line[COMMAND_LINE_SIZE]; 128 /* Untouched saved command line (eg. for /proc) */ 129 char *saved_command_line; 130 /* Command line for parameter parsing */ 131 static char *static_command_line; 132 133 static char *execute_command; 134 static char *ramdisk_execute_command; 135 136 /* 137 * If set, this is an indication to the drivers that reset the underlying 138 * device before going ahead with the initialization otherwise driver might 139 * rely on the BIOS and skip the reset operation. 140 * 141 * This is useful if kernel is booting in an unreliable environment. 142 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been 143 * skipped and devices will be in unknown state. 144 */ 145 unsigned int reset_devices; 146 EXPORT_SYMBOL(reset_devices); 147 148 static int __init set_reset_devices(char *str) 149 { 150 reset_devices = 1; 151 return 1; 152 } 153 154 __setup("reset_devices", set_reset_devices); 155 156 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, }; 157 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, }; 158 static const char *panic_later, *panic_param; 159 160 extern const struct obs_kernel_param __setup_start[], __setup_end[]; 161 162 static int __init obsolete_checksetup(char *line) 163 { 164 const struct obs_kernel_param *p; 165 int had_early_param = 0; 166 167 p = __setup_start; 168 do { 169 int n = strlen(p->str); 170 if (parameqn(line, p->str, n)) { 171 if (p->early) { 172 /* Already done in parse_early_param? 173 * (Needs exact match on param part). 174 * Keep iterating, as we can have early 175 * params and __setups of same names 8( */ 176 if (line[n] == '\0' || line[n] == '=') 177 had_early_param = 1; 178 } else if (!p->setup_func) { 179 pr_warn("Parameter %s is obsolete, ignored\n", 180 p->str); 181 return 1; 182 } else if (p->setup_func(line + n)) 183 return 1; 184 } 185 p++; 186 } while (p < __setup_end); 187 188 return had_early_param; 189 } 190 191 /* 192 * This should be approx 2 Bo*oMips to start (note initial shift), and will 193 * still work even if initially too large, it will just take slightly longer 194 */ 195 unsigned long loops_per_jiffy = (1<<12); 196 197 EXPORT_SYMBOL(loops_per_jiffy); 198 199 static int __init debug_kernel(char *str) 200 { 201 console_loglevel = 10; 202 return 0; 203 } 204 205 static int __init quiet_kernel(char *str) 206 { 207 console_loglevel = 4; 208 return 0; 209 } 210 211 early_param("debug", debug_kernel); 212 early_param("quiet", quiet_kernel); 213 214 static int __init loglevel(char *str) 215 { 216 int newlevel; 217 218 /* 219 * Only update loglevel value when a correct setting was passed, 220 * to prevent blind crashes (when loglevel being set to 0) that 221 * are quite hard to debug 222 */ 223 if (get_option(&str, &newlevel)) { 224 console_loglevel = newlevel; 225 return 0; 226 } 227 228 return -EINVAL; 229 } 230 231 early_param("loglevel", loglevel); 232 233 /* Change NUL term back to "=", to make "param" the whole string. */ 234 static int __init repair_env_string(char *param, char *val, const char *unused) 235 { 236 if (val) { 237 /* param=val or param="val"? */ 238 if (val == param+strlen(param)+1) 239 val[-1] = '='; 240 else if (val == param+strlen(param)+2) { 241 val[-2] = '='; 242 memmove(val-1, val, strlen(val)+1); 243 val--; 244 } else 245 BUG(); 246 } 247 return 0; 248 } 249 250 /* 251 * Unknown boot options get handed to init, unless they look like 252 * unused parameters (modprobe will find them in /proc/cmdline). 253 */ 254 static int __init unknown_bootoption(char *param, char *val, const char *unused) 255 { 256 repair_env_string(param, val, unused); 257 258 /* Handle obsolete-style parameters */ 259 if (obsolete_checksetup(param)) 260 return 0; 261 262 /* Unused module parameter. */ 263 if (strchr(param, '.') && (!val || strchr(param, '.') < val)) 264 return 0; 265 266 if (panic_later) 267 return 0; 268 269 if (val) { 270 /* Environment option */ 271 unsigned int i; 272 for (i = 0; envp_init[i]; i++) { 273 if (i == MAX_INIT_ENVS) { 274 panic_later = "Too many boot env vars at `%s'"; 275 panic_param = param; 276 } 277 if (!strncmp(param, envp_init[i], val - param)) 278 break; 279 } 280 envp_init[i] = param; 281 } else { 282 /* Command line option */ 283 unsigned int i; 284 for (i = 0; argv_init[i]; i++) { 285 if (i == MAX_INIT_ARGS) { 286 panic_later = "Too many boot init vars at `%s'"; 287 panic_param = param; 288 } 289 } 290 argv_init[i] = param; 291 } 292 return 0; 293 } 294 295 static int __init init_setup(char *str) 296 { 297 unsigned int i; 298 299 execute_command = str; 300 /* 301 * In case LILO is going to boot us with default command line, 302 * it prepends "auto" before the whole cmdline which makes 303 * the shell think it should execute a script with such name. 304 * So we ignore all arguments entered _before_ init=... [MJ] 305 */ 306 for (i = 1; i < MAX_INIT_ARGS; i++) 307 argv_init[i] = NULL; 308 return 1; 309 } 310 __setup("init=", init_setup); 311 312 static int __init rdinit_setup(char *str) 313 { 314 unsigned int i; 315 316 ramdisk_execute_command = str; 317 /* See "auto" comment in init_setup */ 318 for (i = 1; i < MAX_INIT_ARGS; i++) 319 argv_init[i] = NULL; 320 return 1; 321 } 322 __setup("rdinit=", rdinit_setup); 323 324 #ifndef CONFIG_SMP 325 static const unsigned int setup_max_cpus = NR_CPUS; 326 #ifdef CONFIG_X86_LOCAL_APIC 327 static void __init smp_init(void) 328 { 329 APIC_init_uniprocessor(); 330 } 331 #else 332 #define smp_init() do { } while (0) 333 #endif 334 335 static inline void setup_nr_cpu_ids(void) { } 336 static inline void smp_prepare_cpus(unsigned int maxcpus) { } 337 #endif 338 339 /* 340 * We need to store the untouched command line for future reference. 341 * We also need to store the touched command line since the parameter 342 * parsing is performed in place, and we should allow a component to 343 * store reference of name/value for future reference. 344 */ 345 static void __init setup_command_line(char *command_line) 346 { 347 saved_command_line = alloc_bootmem(strlen (boot_command_line)+1); 348 static_command_line = alloc_bootmem(strlen (command_line)+1); 349 strcpy (saved_command_line, boot_command_line); 350 strcpy (static_command_line, command_line); 351 } 352 353 /* 354 * We need to finalize in a non-__init function or else race conditions 355 * between the root thread and the init thread may cause start_kernel to 356 * be reaped by free_initmem before the root thread has proceeded to 357 * cpu_idle. 358 * 359 * gcc-3.4 accidentally inlines this function, so use noinline. 360 */ 361 362 static __initdata DECLARE_COMPLETION(kthreadd_done); 363 364 static noinline void __init_refok rest_init(void) 365 { 366 int pid; 367 368 rcu_scheduler_starting(); 369 /* 370 * We need to spawn init first so that it obtains pid 1, however 371 * the init task will end up wanting to create kthreads, which, if 372 * we schedule it before we create kthreadd, will OOPS. 373 */ 374 kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND); 375 numa_default_policy(); 376 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); 377 rcu_read_lock(); 378 kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns); 379 rcu_read_unlock(); 380 complete(&kthreadd_done); 381 382 /* 383 * The boot idle thread must execute schedule() 384 * at least once to get things moving: 385 */ 386 init_idle_bootup_task(current); 387 schedule_preempt_disabled(); 388 /* Call into cpu_idle with preempt disabled */ 389 cpu_startup_entry(CPUHP_ONLINE); 390 } 391 392 /* Check for early params. */ 393 static int __init do_early_param(char *param, char *val, const char *unused) 394 { 395 const struct obs_kernel_param *p; 396 397 for (p = __setup_start; p < __setup_end; p++) { 398 if ((p->early && parameq(param, p->str)) || 399 (strcmp(param, "console") == 0 && 400 strcmp(p->str, "earlycon") == 0) 401 ) { 402 if (p->setup_func(val) != 0) 403 pr_warn("Malformed early option '%s'\n", param); 404 } 405 } 406 /* We accept everything at this stage. */ 407 return 0; 408 } 409 410 void __init parse_early_options(char *cmdline) 411 { 412 parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param); 413 } 414 415 /* Arch code calls this early on, or if not, just before other parsing. */ 416 void __init parse_early_param(void) 417 { 418 static __initdata int done = 0; 419 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE]; 420 421 if (done) 422 return; 423 424 /* All fall through to do_early_param. */ 425 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE); 426 parse_early_options(tmp_cmdline); 427 done = 1; 428 } 429 430 /* 431 * Activate the first processor. 432 */ 433 434 static void __init boot_cpu_init(void) 435 { 436 int cpu = smp_processor_id(); 437 /* Mark the boot cpu "present", "online" etc for SMP and UP case */ 438 set_cpu_online(cpu, true); 439 set_cpu_active(cpu, true); 440 set_cpu_present(cpu, true); 441 set_cpu_possible(cpu, true); 442 } 443 444 void __init __weak smp_setup_processor_id(void) 445 { 446 } 447 448 # if THREAD_SIZE >= PAGE_SIZE 449 void __init __weak thread_info_cache_init(void) 450 { 451 } 452 #endif 453 454 /* 455 * Set up kernel memory allocators 456 */ 457 static void __init mm_init(void) 458 { 459 /* 460 * page_cgroup requires contiguous pages, 461 * bigger than MAX_ORDER unless SPARSEMEM. 462 */ 463 page_cgroup_init_flatmem(); 464 mem_init(); 465 kmem_cache_init(); 466 percpu_init_late(); 467 pgtable_cache_init(); 468 vmalloc_init(); 469 } 470 471 asmlinkage void __init start_kernel(void) 472 { 473 char * command_line; 474 extern const struct kernel_param __start___param[], __stop___param[]; 475 476 /* 477 * Need to run as early as possible, to initialize the 478 * lockdep hash: 479 */ 480 lockdep_init(); 481 smp_setup_processor_id(); 482 debug_objects_early_init(); 483 484 /* 485 * Set up the the initial canary ASAP: 486 */ 487 boot_init_stack_canary(); 488 489 cgroup_init_early(); 490 491 local_irq_disable(); 492 early_boot_irqs_disabled = true; 493 494 /* 495 * Interrupts are still disabled. Do necessary setups, then 496 * enable them 497 */ 498 boot_cpu_init(); 499 page_address_init(); 500 pr_notice("%s", linux_banner); 501 setup_arch(&command_line); 502 mm_init_owner(&init_mm, &init_task); 503 mm_init_cpumask(&init_mm); 504 setup_command_line(command_line); 505 setup_nr_cpu_ids(); 506 setup_per_cpu_areas(); 507 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */ 508 509 build_all_zonelists(NULL, NULL); 510 page_alloc_init(); 511 512 pr_notice("Kernel command line: %s\n", boot_command_line); 513 parse_early_param(); 514 parse_args("Booting kernel", static_command_line, __start___param, 515 __stop___param - __start___param, 516 -1, -1, &unknown_bootoption); 517 518 jump_label_init(); 519 520 /* 521 * These use large bootmem allocations and must precede 522 * kmem_cache_init() 523 */ 524 setup_log_buf(0); 525 pidhash_init(); 526 vfs_caches_init_early(); 527 sort_main_extable(); 528 trap_init(); 529 mm_init(); 530 531 /* 532 * Set up the scheduler prior starting any interrupts (such as the 533 * timer interrupt). Full topology setup happens at smp_init() 534 * time - but meanwhile we still have a functioning scheduler. 535 */ 536 sched_init(); 537 /* 538 * Disable preemption - early bootup scheduling is extremely 539 * fragile until we cpu_idle() for the first time. 540 */ 541 preempt_disable(); 542 if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n")) 543 local_irq_disable(); 544 idr_init_cache(); 545 perf_event_init(); 546 rcu_init(); 547 tick_nohz_init(); 548 radix_tree_init(); 549 /* init some links before init_ISA_irqs() */ 550 early_irq_init(); 551 init_IRQ(); 552 tick_init(); 553 init_timers(); 554 hrtimers_init(); 555 softirq_init(); 556 timekeeping_init(); 557 time_init(); 558 profile_init(); 559 call_function_init(); 560 WARN(!irqs_disabled(), "Interrupts were enabled early\n"); 561 early_boot_irqs_disabled = false; 562 local_irq_enable(); 563 564 kmem_cache_init_late(); 565 566 /* 567 * HACK ALERT! This is early. We're enabling the console before 568 * we've done PCI setups etc, and console_init() must be aware of 569 * this. But we do want output early, in case something goes wrong. 570 */ 571 console_init(); 572 if (panic_later) 573 panic(panic_later, panic_param); 574 575 lockdep_info(); 576 577 /* 578 * Need to run this when irqs are enabled, because it wants 579 * to self-test [hard/soft]-irqs on/off lock inversion bugs 580 * too: 581 */ 582 locking_selftest(); 583 584 #ifdef CONFIG_BLK_DEV_INITRD 585 if (initrd_start && !initrd_below_start_ok && 586 page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) { 587 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n", 588 page_to_pfn(virt_to_page((void *)initrd_start)), 589 min_low_pfn); 590 initrd_start = 0; 591 } 592 #endif 593 page_cgroup_init(); 594 debug_objects_mem_init(); 595 kmemleak_init(); 596 setup_per_cpu_pageset(); 597 numa_policy_init(); 598 if (late_time_init) 599 late_time_init(); 600 sched_clock_init(); 601 calibrate_delay(); 602 pidmap_init(); 603 anon_vma_init(); 604 #ifdef CONFIG_X86 605 if (efi_enabled(EFI_RUNTIME_SERVICES)) 606 efi_enter_virtual_mode(); 607 #endif 608 thread_info_cache_init(); 609 cred_init(); 610 fork_init(totalram_pages); 611 proc_caches_init(); 612 buffer_init(); 613 key_init(); 614 security_init(); 615 dbg_late_init(); 616 vfs_caches_init(totalram_pages); 617 signals_init(); 618 /* rootfs populating might need page-writeback */ 619 page_writeback_init(); 620 #ifdef CONFIG_PROC_FS 621 proc_root_init(); 622 #endif 623 cgroup_init(); 624 cpuset_init(); 625 taskstats_init_early(); 626 delayacct_init(); 627 628 check_bugs(); 629 630 acpi_early_init(); /* before LAPIC and SMP init */ 631 sfi_init_late(); 632 633 if (efi_enabled(EFI_RUNTIME_SERVICES)) { 634 efi_late_init(); 635 efi_free_boot_services(); 636 } 637 638 ftrace_init(); 639 640 /* Do the rest non-__init'ed, we're now alive */ 641 rest_init(); 642 } 643 644 /* Call all constructor functions linked into the kernel. */ 645 static void __init do_ctors(void) 646 { 647 #ifdef CONFIG_CONSTRUCTORS 648 ctor_fn_t *fn = (ctor_fn_t *) __ctors_start; 649 650 for (; fn < (ctor_fn_t *) __ctors_end; fn++) 651 (*fn)(); 652 #endif 653 } 654 655 bool initcall_debug; 656 core_param(initcall_debug, initcall_debug, bool, 0644); 657 658 static char msgbuf[64]; 659 660 static int __init_or_module do_one_initcall_debug(initcall_t fn) 661 { 662 ktime_t calltime, delta, rettime; 663 unsigned long long duration; 664 int ret; 665 666 pr_debug("calling %pF @ %i\n", fn, task_pid_nr(current)); 667 calltime = ktime_get(); 668 ret = fn(); 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", 673 fn, ret, duration); 674 675 return ret; 676 } 677 678 int __init_or_module do_one_initcall(initcall_t fn) 679 { 680 int count = preempt_count(); 681 int ret; 682 683 if (initcall_debug) 684 ret = do_one_initcall_debug(fn); 685 else 686 ret = fn(); 687 688 msgbuf[0] = 0; 689 690 if (preempt_count() != count) { 691 sprintf(msgbuf, "preemption imbalance "); 692 preempt_count() = count; 693 } 694 if (irqs_disabled()) { 695 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf)); 696 local_irq_enable(); 697 } 698 WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf); 699 700 return ret; 701 } 702 703 704 extern initcall_t __initcall_start[]; 705 extern initcall_t __initcall0_start[]; 706 extern initcall_t __initcall1_start[]; 707 extern initcall_t __initcall2_start[]; 708 extern initcall_t __initcall3_start[]; 709 extern initcall_t __initcall4_start[]; 710 extern initcall_t __initcall5_start[]; 711 extern initcall_t __initcall6_start[]; 712 extern initcall_t __initcall7_start[]; 713 extern initcall_t __initcall_end[]; 714 715 static initcall_t *initcall_levels[] __initdata = { 716 __initcall0_start, 717 __initcall1_start, 718 __initcall2_start, 719 __initcall3_start, 720 __initcall4_start, 721 __initcall5_start, 722 __initcall6_start, 723 __initcall7_start, 724 __initcall_end, 725 }; 726 727 /* Keep these in sync with initcalls in include/linux/init.h */ 728 static char *initcall_level_names[] __initdata = { 729 "early", 730 "core", 731 "postcore", 732 "arch", 733 "subsys", 734 "fs", 735 "device", 736 "late", 737 }; 738 739 static void __init do_initcall_level(int level) 740 { 741 extern const struct kernel_param __start___param[], __stop___param[]; 742 initcall_t *fn; 743 744 strcpy(static_command_line, saved_command_line); 745 parse_args(initcall_level_names[level], 746 static_command_line, __start___param, 747 __stop___param - __start___param, 748 level, level, 749 &repair_env_string); 750 751 for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++) 752 do_one_initcall(*fn); 753 } 754 755 static void __init do_initcalls(void) 756 { 757 int level; 758 759 for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++) 760 do_initcall_level(level); 761 } 762 763 /* 764 * Ok, the machine is now initialized. None of the devices 765 * have been touched yet, but the CPU subsystem is up and 766 * running, and memory and process management works. 767 * 768 * Now we can finally start doing some real work.. 769 */ 770 static void __init do_basic_setup(void) 771 { 772 cpuset_init_smp(); 773 usermodehelper_init(); 774 shmem_init(); 775 driver_init(); 776 init_irq_proc(); 777 do_ctors(); 778 usermodehelper_enable(); 779 do_initcalls(); 780 } 781 782 static void __init do_pre_smp_initcalls(void) 783 { 784 initcall_t *fn; 785 786 for (fn = __initcall_start; fn < __initcall0_start; fn++) 787 do_one_initcall(*fn); 788 } 789 790 /* 791 * This function requests modules which should be loaded by default and is 792 * called twice right after initrd is mounted and right before init is 793 * exec'd. If such modules are on either initrd or rootfs, they will be 794 * loaded before control is passed to userland. 795 */ 796 void __init load_default_modules(void) 797 { 798 load_default_elevator_module(); 799 } 800 801 static int run_init_process(const char *init_filename) 802 { 803 argv_init[0] = init_filename; 804 return do_execve(init_filename, 805 (const char __user *const __user *)argv_init, 806 (const char __user *const __user *)envp_init); 807 } 808 809 static noinline void __init kernel_init_freeable(void); 810 811 static int __ref kernel_init(void *unused) 812 { 813 kernel_init_freeable(); 814 /* need to finish all async __init code before freeing the memory */ 815 async_synchronize_full(); 816 free_initmem(); 817 mark_rodata_ro(); 818 system_state = SYSTEM_RUNNING; 819 numa_default_policy(); 820 821 flush_delayed_fput(); 822 823 if (ramdisk_execute_command) { 824 if (!run_init_process(ramdisk_execute_command)) 825 return 0; 826 pr_err("Failed to execute %s\n", ramdisk_execute_command); 827 } 828 829 /* 830 * We try each of these until one succeeds. 831 * 832 * The Bourne shell can be used instead of init if we are 833 * trying to recover a really broken machine. 834 */ 835 if (execute_command) { 836 if (!run_init_process(execute_command)) 837 return 0; 838 pr_err("Failed to execute %s. Attempting defaults...\n", 839 execute_command); 840 } 841 if (!run_init_process("/sbin/init") || 842 !run_init_process("/etc/init") || 843 !run_init_process("/bin/init") || 844 !run_init_process("/bin/sh")) 845 return 0; 846 847 panic("No init found. Try passing init= option to kernel. " 848 "See Linux Documentation/init.txt for guidance."); 849 } 850 851 static noinline void __init kernel_init_freeable(void) 852 { 853 /* 854 * Wait until kthreadd is all set-up. 855 */ 856 wait_for_completion(&kthreadd_done); 857 858 /* Now the scheduler is fully set up and can do blocking allocations */ 859 gfp_allowed_mask = __GFP_BITS_MASK; 860 861 /* 862 * init can allocate pages on any node 863 */ 864 set_mems_allowed(node_states[N_MEMORY]); 865 /* 866 * init can run on any cpu. 867 */ 868 set_cpus_allowed_ptr(current, cpu_all_mask); 869 870 cad_pid = task_pid(current); 871 872 smp_prepare_cpus(setup_max_cpus); 873 874 do_pre_smp_initcalls(); 875 lockup_detector_init(); 876 877 smp_init(); 878 sched_init_smp(); 879 880 do_basic_setup(); 881 882 /* Open the /dev/console on the rootfs, this should never fail */ 883 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) 884 pr_err("Warning: unable to open an initial console.\n"); 885 886 (void) sys_dup(0); 887 (void) sys_dup(0); 888 /* 889 * check if there is an early userspace init. If yes, let it do all 890 * the work 891 */ 892 893 if (!ramdisk_execute_command) 894 ramdisk_execute_command = "/init"; 895 896 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) { 897 ramdisk_execute_command = NULL; 898 prepare_namespace(); 899 } 900 901 /* 902 * Ok, we have completed the initial bootup, and 903 * we're essentially up and running. Get rid of the 904 * initmem segments and start the user-mode stuff.. 905 */ 906 907 /* rootfs is available now, try loading default modules */ 908 load_default_modules(); 909 } 910