Free Electrons

Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
/*
 *  linux/init/main.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  GK 2/5/95  -  Changed to support mounting root fs via NFS
 *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
 *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
 *  Simplified starting of init:  Michael A. Griffith <grif@acm.org> 
 */

#define __KERNEL_SYSCALLS__

#include <linux/config.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/utsname.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/initrd.h>
#include <linux/hdreg.h>
#include <linux/bootmem.h>
#include <linux/tty.h>
#include <linux/gfp.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
#include <linux/kernel_stat.h>
#include <linux/security.h>
#include <linux/workqueue.h>
#include <linux/profile.h>
#include <linux/rcupdate.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/efi.h>
#include <linux/unistd.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>

#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>

#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/smp.h>
#endif

/*
 * This is one of the first .c files built. Error out early if we have compiler
 * trouble.
 *
 * Versions of gcc older than that listed below may actually compile and link
 * okay, but the end product can have subtle run time bugs.  To avoid associated
 * bogus bug reports, we flatly refuse to compile with a gcc that is known to be
 * too old from the very beginning.
 */
#if (__GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 2)
#error Sorry, your GCC is too old. It builds incorrect kernels.
#endif

#if __GNUC__ == 4 && __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ == 0
#error gcc-4.1.0 is known to miscompile the kernel.  A different compiler version is recommended.
#endif

static int init(void *);

extern void init_IRQ(void);
extern void fork_init(unsigned long);
extern void mca_init(void);
extern void sbus_init(void);
extern void sysctl_init(void);
extern void signals_init(void);
extern void buffer_init(void);
extern void pidhash_init(void);
extern void pidmap_init(void);
extern void prio_tree_init(void);
extern void radix_tree_init(void);
extern void free_initmem(void);
extern void populate_rootfs(void);
extern void driver_init(void);
extern void prepare_namespace(void);
#ifdef	CONFIG_ACPI
extern void acpi_early_init(void);
#else
static inline void acpi_early_init(void) { }
#endif
#ifndef CONFIG_DEBUG_RODATA
static inline void mark_rodata_ro(void) { }
#endif

#ifdef CONFIG_TC
extern void tc_init(void);
#endif

enum system_states system_state;
EXPORT_SYMBOL(system_state);

/*
 * Boot command-line arguments
 */
#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT

extern void time_init(void);
/* Default late time init is NULL. archs can override this later. */
void (*late_time_init)(void);
extern void softirq_init(void);

/* Untouched command line (eg. for /proc) saved by arch-specific code. */
char saved_command_line[COMMAND_LINE_SIZE];

static char *execute_command;
static char *ramdisk_execute_command;

/* Setup configured maximum number of CPUs to activate */
static unsigned int max_cpus = NR_CPUS;

/*
 * Setup routine for controlling SMP activation
 *
 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 * activation entirely (the MPS table probe still happens, though).
 *
 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 * greater than 0, limits the maximum number of CPUs activated in
 * SMP mode to <NUM>.
 */
static int __init nosmp(char *str)
{
	max_cpus = 0;
	return 1;
}

__setup("nosmp", nosmp);

static int __init maxcpus(char *str)
{
	get_option(&str, &max_cpus);
	return 1;
}

__setup("maxcpus=", maxcpus);

static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
static const char *panic_later, *panic_param;

extern struct obs_kernel_param __setup_start[], __setup_end[];

static int __init obsolete_checksetup(char *line)
{
	struct obs_kernel_param *p;

	p = __setup_start;
	do {
		int n = strlen(p->str);
		if (!strncmp(line, p->str, n)) {
			if (p->early) {
				/* Already done in parse_early_param?  (Needs
				 * exact match on param part) */
				if (line[n] == '\0' || line[n] == '=')
					return 1;
			} else if (!p->setup_func) {
				printk(KERN_WARNING "Parameter %s is obsolete,"
				       " ignored\n", p->str);
				return 1;
			} else if (p->setup_func(line + n))
				return 1;
		}
		p++;
	} while (p < __setup_end);
	return 0;
}

/*
 * This should be approx 2 Bo*oMips to start (note initial shift), and will
 * still work even if initially too large, it will just take slightly longer
 */
unsigned long loops_per_jiffy = (1<<12);

EXPORT_SYMBOL(loops_per_jiffy);

static int __init debug_kernel(char *str)
{
	if (*str)
		return 0;
	console_loglevel = 10;
	return 1;
}

static int __init quiet_kernel(char *str)
{
	if (*str)
		return 0;
	console_loglevel = 4;
	return 1;
}

__setup("debug", debug_kernel);
__setup("quiet", quiet_kernel);

static int __init loglevel(char *str)
{
	get_option(&str, &console_loglevel);
	return 1;
}

__setup("loglevel=", loglevel);

/*
 * Unknown boot options get handed to init, unless they look like
 * failed parameters
 */
static int __init unknown_bootoption(char *param, char *val)
{
	/* Change NUL term back to "=", to make "param" the whole string. */
	if (val) {
		/* param=val or param="val"? */
		if (val == param+strlen(param)+1)
			val[-1] = '=';
		else if (val == param+strlen(param)+2) {
			val[-2] = '=';
			memmove(val-1, val, strlen(val)+1);
			val--;
		} else
			BUG();
	}

	/* Handle obsolete-style parameters */
	if (obsolete_checksetup(param))
		return 0;

	/*
	 * Preemptive maintenance for "why didn't my mispelled command
	 * line work?"
	 */
	if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
		printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
		return 0;
	}

	if (panic_later)
		return 0;

	if (val) {
		/* Environment option */
		unsigned int i;
		for (i = 0; envp_init[i]; i++) {
			if (i == MAX_INIT_ENVS) {
				panic_later = "Too many boot env vars at `%s'";
				panic_param = param;
			}
			if (!strncmp(param, envp_init[i], val - param))
				break;
		}
		envp_init[i] = param;
	} else {
		/* Command line option */
		unsigned int i;
		for (i = 0; argv_init[i]; i++) {
			if (i == MAX_INIT_ARGS) {
				panic_later = "Too many boot init vars at `%s'";
				panic_param = param;
			}
		}
		argv_init[i] = param;
	}
	return 0;
}

static int __init init_setup(char *str)
{
	unsigned int i;

	execute_command = str;
	/*
	 * In case LILO is going to boot us with default command line,
	 * it prepends "auto" before the whole cmdline which makes
	 * the shell think it should execute a script with such name.
	 * So we ignore all arguments entered _before_ init=... [MJ]
	 */
	for (i = 1; i < MAX_INIT_ARGS; i++)
		argv_init[i] = NULL;
	return 1;
}
__setup("init=", init_setup);

static int __init rdinit_setup(char *str)
{
	unsigned int i;

	ramdisk_execute_command = str;
	/* See "auto" comment in init_setup */
	for (i = 1; i < MAX_INIT_ARGS; i++)
		argv_init[i] = NULL;
	return 1;
}
__setup("rdinit=", rdinit_setup);

extern void setup_arch(char **);

#ifndef CONFIG_SMP

#ifdef CONFIG_X86_LOCAL_APIC
static void __init smp_init(void)
{
	APIC_init_uniprocessor();
}
#else
#define smp_init()	do { } while (0)
#endif

static inline void setup_per_cpu_areas(void) { }
static inline void smp_prepare_cpus(unsigned int maxcpus) { }

#else

#ifdef __GENERIC_PER_CPU
unsigned long __per_cpu_offset[NR_CPUS];

EXPORT_SYMBOL(__per_cpu_offset);

static void __init setup_per_cpu_areas(void)
{
	unsigned long size, i;
	char *ptr;

	/* Copy section for each CPU (we discard the original) */
	size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES);
#ifdef CONFIG_MODULES
	if (size < PERCPU_ENOUGH_ROOM)
		size = PERCPU_ENOUGH_ROOM;
#endif

	ptr = alloc_bootmem(size * NR_CPUS);

	for (i = 0; i < NR_CPUS; i++, ptr += size) {
		__per_cpu_offset[i] = ptr - __per_cpu_start;
		memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
	}
}
#endif /* !__GENERIC_PER_CPU */

/* Called by boot processor to activate the rest. */
static void __init smp_init(void)
{
	unsigned int i;

	/* FIXME: This should be done in userspace --RR */
	for_each_present_cpu(i) {
		if (num_online_cpus() >= max_cpus)
			break;
		if (!cpu_online(i))
			cpu_up(i);
	}

	/* Any cleanup work */
	printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
	smp_cpus_done(max_cpus);
#if 0
	/* Get other processors into their bootup holding patterns. */

	smp_commence();
#endif
}

#endif

/*
 * We need to finalize in a non-__init function or else race conditions
 * between the root thread and the init thread may cause start_kernel to
 * be reaped by free_initmem before the root thread has proceeded to
 * cpu_idle.
 *
 * gcc-3.4 accidentally inlines this function, so use noinline.
 */

static void noinline rest_init(void)
	__releases(kernel_lock)
{
	kernel_thread(init, NULL, CLONE_FS | CLONE_SIGHAND);
	numa_default_policy();
	unlock_kernel();

	/*
	 * The boot idle thread must execute schedule()
	 * at least one to get things moving:
	 */
	preempt_enable_no_resched();
	schedule();
	preempt_disable();

	/* Call into cpu_idle with preempt disabled */
	cpu_idle();
} 

/* Check for early params. */
static int __init do_early_param(char *param, char *val)
{
	struct obs_kernel_param *p;

	for (p = __setup_start; p < __setup_end; p++) {
		if (p->early && strcmp(param, p->str) == 0) {
			if (p->setup_func(val) != 0)
				printk(KERN_WARNING
				       "Malformed early option '%s'\n", param);
		}
	}
	/* We accept everything at this stage. */
	return 0;
}

/* Arch code calls this early on, or if not, just before other parsing. */
void __init parse_early_param(void)
{
	static __initdata int done = 0;
	static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];

	if (done)
		return;

	/* All fall through to do_early_param. */
	strlcpy(tmp_cmdline, saved_command_line, COMMAND_LINE_SIZE);
	parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);
	done = 1;
}

/*
 *	Activate the first processor.
 */

asmlinkage void __init start_kernel(void)
{
	char * command_line;
	extern struct kernel_param __start___param[], __stop___param[];
/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
	lock_kernel();
	page_address_init();
	printk(KERN_NOTICE);
	printk(linux_banner);
	setup_arch(&command_line);
	setup_per_cpu_areas();

	/*
	 * Mark the boot cpu "online" so that it can call console drivers in
	 * printk() and can access its per-cpu storage.
	 */
	smp_prepare_boot_cpu();

	/*
	 * Set up the scheduler prior starting any interrupts (such as the
	 * timer interrupt). Full topology setup happens at smp_init()
	 * time - but meanwhile we still have a functioning scheduler.
	 */
	sched_init();
	/*
	 * Disable preemption - early bootup scheduling is extremely
	 * fragile until we cpu_idle() for the first time.
	 */
	preempt_disable();
	build_all_zonelists();
	page_alloc_init();
	printk(KERN_NOTICE "Kernel command line: %s\n", saved_command_line);
	parse_early_param();
	parse_args("Booting kernel", command_line, __start___param,
		   __stop___param - __start___param,
		   &unknown_bootoption);
	if (!irqs_disabled()) {
		printk(KERN_WARNING "start_kernel(): bug: interrupts were "
				"enabled *very* early, fixing it\n");
		local_irq_disable();
	}
	sort_main_extable();
	trap_init();
	rcu_init();
	init_IRQ();
	pidhash_init();
	init_timers();
	hrtimers_init();
	softirq_init();
	time_init();

	/*
	 * HACK ALERT! This is early. We're enabling the console before
	 * we've done PCI setups etc, and console_init() must be aware of
	 * this. But we do want output early, in case something goes wrong.
	 */
	console_init();
	if (panic_later)
		panic(panic_later, panic_param);
	profile_init();
	local_irq_enable();
#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_start && !initrd_below_start_ok &&
			initrd_start < min_low_pfn << PAGE_SHIFT) {
		printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
		    "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
		initrd_start = 0;
	}
#endif
	vfs_caches_init_early();
	cpuset_init_early();
	mem_init();
	kmem_cache_init();
	setup_per_cpu_pageset();
	numa_policy_init();
	if (late_time_init)
		late_time_init();
	calibrate_delay();
	pidmap_init();
	pgtable_cache_init();
	prio_tree_init();
	anon_vma_init();
#ifdef CONFIG_X86
	if (efi_enabled)
		efi_enter_virtual_mode();
#endif
	fork_init(num_physpages);
	proc_caches_init();
	buffer_init();
	unnamed_dev_init();
	key_init();
	security_init();
	vfs_caches_init(num_physpages);
	radix_tree_init();
	signals_init();
	/* rootfs populating might need page-writeback */
	page_writeback_init();
#ifdef CONFIG_PROC_FS
	proc_root_init();
#endif
	cpuset_init();

	check_bugs();

	acpi_early_init(); /* before LAPIC and SMP init */

	/* Do the rest non-__init'ed, we're now alive */
	rest_init();
}

static int __initdata initcall_debug;

static int __init initcall_debug_setup(char *str)
{
	initcall_debug = 1;
	return 1;
}
__setup("initcall_debug", initcall_debug_setup);

struct task_struct *child_reaper = &init_task;

extern initcall_t __initcall_start[], __initcall_end[];

static void __init do_initcalls(void)
{
	initcall_t *call;
	int count = preempt_count();

	for (call = __initcall_start; call < __initcall_end; call++) {
		char *msg;

		if (initcall_debug) {
			printk(KERN_DEBUG "Calling initcall 0x%p", *call);
			print_fn_descriptor_symbol(": %s()", (unsigned long) *call);
			printk("\n");
		}

		(*call)();

		msg = NULL;
		if (preempt_count() != count) {
			msg = "preemption imbalance";
			preempt_count() = count;
		}
		if (irqs_disabled()) {
			msg = "disabled interrupts";
			local_irq_enable();
		}
		if (msg) {
			printk(KERN_WARNING "error in initcall at 0x%p: "
				"returned with %s\n", *call, msg);
		}
	}

	/* Make sure there is no pending stuff from the initcall sequence */
	flush_scheduled_work();
}

/*
 * Ok, the machine is now initialized. None of the devices
 * have been touched yet, but the CPU subsystem is up and
 * running, and memory and process management works.
 *
 * Now we can finally start doing some real work..
 */
static void __init do_basic_setup(void)
{
	/* drivers will send hotplug events */
	init_workqueues();
	usermodehelper_init();
	driver_init();

#ifdef CONFIG_SYSCTL
	sysctl_init();
#endif

	do_initcalls();
}

static void do_pre_smp_initcalls(void)
{
	extern int spawn_ksoftirqd(void);
#ifdef CONFIG_SMP
	extern int migration_init(void);

	migration_init();
#endif
	spawn_ksoftirqd();
	spawn_softlockup_task();
}

static void run_init_process(char *init_filename)
{
	argv_init[0] = init_filename;
	execve(init_filename, argv_init, envp_init);
}

static inline void fixup_cpu_present_map(void)
{
#ifdef CONFIG_SMP
	int i;

	/*
	 * If arch is not hotplug ready and did not populate
	 * cpu_present_map, just make cpu_present_map same as cpu_possible_map
	 * for other cpu bringup code to function as normal. e.g smp_init() etc.
	 */
	if (cpus_empty(cpu_present_map)) {
		for_each_cpu(i) {
			cpu_set(i, cpu_present_map);
		}
	}
#endif
}

static int init(void * unused)
{
	lock_kernel();
	/*
	 * init can run on any cpu.
	 */
	set_cpus_allowed(current, CPU_MASK_ALL);
	/*
	 * Tell the world that we're going to be the grim
	 * reaper of innocent orphaned children.
	 *
	 * We don't want people to have to make incorrect
	 * assumptions about where in the task array this
	 * can be found.
	 */
	child_reaper = current;

	smp_prepare_cpus(max_cpus);

	do_pre_smp_initcalls();

	fixup_cpu_present_map();
	smp_init();
	sched_init_smp();

	cpuset_init_smp();

	/*
	 * Do this before initcalls, because some drivers want to access
	 * firmware files.
	 */
	populate_rootfs();

	do_basic_setup();

	/*
	 * check if there is an early userspace init.  If yes, let it do all
	 * the work
	 */

	if (!ramdisk_execute_command)
		ramdisk_execute_command = "/init";

	if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
		ramdisk_execute_command = NULL;
		prepare_namespace();
	}

	/*
	 * Ok, we have completed the initial bootup, and
	 * we're essentially up and running. Get rid of the
	 * initmem segments and start the user-mode stuff..
	 */
	free_initmem();
	unlock_kernel();
	mark_rodata_ro();
	system_state = SYSTEM_RUNNING;
	numa_default_policy();

	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
		printk(KERN_WARNING "Warning: unable to open an initial console.\n");

	(void) sys_dup(0);
	(void) sys_dup(0);

	if (ramdisk_execute_command) {
		run_init_process(ramdisk_execute_command);
		printk(KERN_WARNING "Failed to execute %s\n",
				ramdisk_execute_command);
	}

	/*
	 * We try each of these until one succeeds.
	 *
	 * The Bourne shell can be used instead of init if we are 
	 * trying to recover a really broken machine.
	 */
	if (execute_command) {
		run_init_process(execute_command);
		printk(KERN_WARNING "Failed to execute %s.  Attempting "
					"defaults...\n", execute_command);
	}
	run_init_process("/sbin/init");
	run_init_process("/etc/init");
	run_init_process("/bin/init");
	run_init_process("/bin/sh");

	panic("No init found.  Try passing init= option to kernel.");
}