xref: /openbmc/linux/arch/um/kernel/um_arch.c (revision c900529f3d9161bfde5cca0754f83b4d3c3e0220)
1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4   */
5  
6  #include <linux/cpu.h>
7  #include <linux/delay.h>
8  #include <linux/init.h>
9  #include <linux/mm.h>
10  #include <linux/ctype.h>
11  #include <linux/module.h>
12  #include <linux/panic_notifier.h>
13  #include <linux/seq_file.h>
14  #include <linux/string.h>
15  #include <linux/utsname.h>
16  #include <linux/sched.h>
17  #include <linux/sched/task.h>
18  #include <linux/kmsg_dump.h>
19  #include <linux/suspend.h>
20  #include <linux/random.h>
21  
22  #include <asm/processor.h>
23  #include <asm/cpufeature.h>
24  #include <asm/sections.h>
25  #include <asm/setup.h>
26  #include <as-layout.h>
27  #include <arch.h>
28  #include <init.h>
29  #include <kern.h>
30  #include <kern_util.h>
31  #include <mem_user.h>
32  #include <os.h>
33  
34  #include "um_arch.h"
35  
36  #define DEFAULT_COMMAND_LINE_ROOT "root=98:0"
37  #define DEFAULT_COMMAND_LINE_CONSOLE "console=tty0"
38  
39  /* Changed in add_arg and setup_arch, which run before SMP is started */
40  static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };
41  
add_arg(char * arg)42  static void __init add_arg(char *arg)
43  {
44  	if (strlen(command_line) + strlen(arg) + 1 > COMMAND_LINE_SIZE) {
45  		os_warn("add_arg: Too many command line arguments!\n");
46  		exit(1);
47  	}
48  	if (strlen(command_line) > 0)
49  		strcat(command_line, " ");
50  	strcat(command_line, arg);
51  }
52  
53  /*
54   * These fields are initialized at boot time and not changed.
55   * XXX This structure is used only in the non-SMP case.  Maybe this
56   * should be moved to smp.c.
57   */
58  struct cpuinfo_um boot_cpu_data = {
59  	.loops_per_jiffy	= 0,
60  	.ipi_pipe		= { -1, -1 },
61  	.cache_alignment	= L1_CACHE_BYTES,
62  	.x86_capability		= { 0 }
63  };
64  
65  EXPORT_SYMBOL(boot_cpu_data);
66  
67  union thread_union cpu0_irqstack
68  	__section(".data..init_irqstack") =
69  		{ .thread_info = INIT_THREAD_INFO(init_task) };
70  
71  /* Changed in setup_arch, which is called in early boot */
72  static char host_info[(__NEW_UTS_LEN + 1) * 5];
73  
show_cpuinfo(struct seq_file * m,void * v)74  static int show_cpuinfo(struct seq_file *m, void *v)
75  {
76  	int i = 0;
77  
78  	seq_printf(m, "processor\t: %d\n", i);
79  	seq_printf(m, "vendor_id\t: User Mode Linux\n");
80  	seq_printf(m, "model name\t: UML\n");
81  	seq_printf(m, "mode\t\t: skas\n");
82  	seq_printf(m, "host\t\t: %s\n", host_info);
83  	seq_printf(m, "fpu\t\t: %s\n", cpu_has(&boot_cpu_data, X86_FEATURE_FPU) ? "yes" : "no");
84  	seq_printf(m, "flags\t\t:");
85  	for (i = 0; i < 32*NCAPINTS; i++)
86  		if (cpu_has(&boot_cpu_data, i) && (x86_cap_flags[i] != NULL))
87  			seq_printf(m, " %s", x86_cap_flags[i]);
88  	seq_printf(m, "\n");
89  	seq_printf(m, "cache_alignment\t: %d\n", boot_cpu_data.cache_alignment);
90  	seq_printf(m, "bogomips\t: %lu.%02lu\n",
91  		   loops_per_jiffy/(500000/HZ),
92  		   (loops_per_jiffy/(5000/HZ)) % 100);
93  
94  
95  	return 0;
96  }
97  
c_start(struct seq_file * m,loff_t * pos)98  static void *c_start(struct seq_file *m, loff_t *pos)
99  {
100  	return *pos < nr_cpu_ids ? &boot_cpu_data + *pos : NULL;
101  }
102  
c_next(struct seq_file * m,void * v,loff_t * pos)103  static void *c_next(struct seq_file *m, void *v, loff_t *pos)
104  {
105  	++*pos;
106  	return c_start(m, pos);
107  }
108  
c_stop(struct seq_file * m,void * v)109  static void c_stop(struct seq_file *m, void *v)
110  {
111  }
112  
113  const struct seq_operations cpuinfo_op = {
114  	.start	= c_start,
115  	.next	= c_next,
116  	.stop	= c_stop,
117  	.show	= show_cpuinfo,
118  };
119  
120  /* Set in linux_main */
121  unsigned long uml_physmem;
122  EXPORT_SYMBOL(uml_physmem);
123  
124  unsigned long uml_reserved; /* Also modified in mem_init */
125  unsigned long start_vm;
126  unsigned long end_vm;
127  
128  /* Set in uml_ncpus_setup */
129  int ncpus = 1;
130  
131  /* Set in early boot */
132  static int have_root __initdata;
133  static int have_console __initdata;
134  
135  /* Set in uml_mem_setup and modified in linux_main */
136  long long physmem_size = 64 * 1024 * 1024;
137  EXPORT_SYMBOL(physmem_size);
138  
139  static const char *usage_string =
140  "User Mode Linux v%s\n"
141  "	available at http://user-mode-linux.sourceforge.net/\n\n";
142  
uml_version_setup(char * line,int * add)143  static int __init uml_version_setup(char *line, int *add)
144  {
145  	/* Explicitly use printf() to show version in stdout */
146  	printf("%s\n", init_utsname()->release);
147  	exit(0);
148  
149  	return 0;
150  }
151  
152  __uml_setup("--version", uml_version_setup,
153  "--version\n"
154  "    Prints the version number of the kernel.\n\n"
155  );
156  
uml_root_setup(char * line,int * add)157  static int __init uml_root_setup(char *line, int *add)
158  {
159  	have_root = 1;
160  	return 0;
161  }
162  
163  __uml_setup("root=", uml_root_setup,
164  "root=<file containing the root fs>\n"
165  "    This is actually used by the generic kernel in exactly the same\n"
166  "    way as in any other kernel. If you configure a number of block\n"
167  "    devices and want to boot off something other than ubd0, you \n"
168  "    would use something like:\n"
169  "        root=/dev/ubd5\n\n"
170  );
171  
no_skas_debug_setup(char * line,int * add)172  static int __init no_skas_debug_setup(char *line, int *add)
173  {
174  	os_warn("'debug' is not necessary to gdb UML in skas mode - run\n");
175  	os_warn("'gdb linux'\n");
176  
177  	return 0;
178  }
179  
180  __uml_setup("debug", no_skas_debug_setup,
181  "debug\n"
182  "    this flag is not needed to run gdb on UML in skas mode\n\n"
183  );
184  
uml_console_setup(char * line,int * add)185  static int __init uml_console_setup(char *line, int *add)
186  {
187  	have_console = 1;
188  	return 0;
189  }
190  
191  __uml_setup("console=", uml_console_setup,
192  "console=<preferred console>\n"
193  "    Specify the preferred console output driver\n\n"
194  );
195  
Usage(char * line,int * add)196  static int __init Usage(char *line, int *add)
197  {
198  	const char **p;
199  
200  	printf(usage_string, init_utsname()->release);
201  	p = &__uml_help_start;
202  	/* Explicitly use printf() to show help in stdout */
203  	while (p < &__uml_help_end) {
204  		printf("%s", *p);
205  		p++;
206  	}
207  	exit(0);
208  	return 0;
209  }
210  
211  __uml_setup("--help", Usage,
212  "--help\n"
213  "    Prints this message.\n\n"
214  );
215  
uml_checksetup(char * line,int * add)216  static void __init uml_checksetup(char *line, int *add)
217  {
218  	struct uml_param *p;
219  
220  	p = &__uml_setup_start;
221  	while (p < &__uml_setup_end) {
222  		size_t n;
223  
224  		n = strlen(p->str);
225  		if (!strncmp(line, p->str, n) && p->setup_func(line + n, add))
226  			return;
227  		p++;
228  	}
229  }
230  
uml_postsetup(void)231  static void __init uml_postsetup(void)
232  {
233  	initcall_t *p;
234  
235  	p = &__uml_postsetup_start;
236  	while (p < &__uml_postsetup_end) {
237  		(*p)();
238  		p++;
239  	}
240  	return;
241  }
242  
panic_exit(struct notifier_block * self,unsigned long unused1,void * unused2)243  static int panic_exit(struct notifier_block *self, unsigned long unused1,
244  		      void *unused2)
245  {
246  	kmsg_dump(KMSG_DUMP_PANIC);
247  	bust_spinlocks(1);
248  	bust_spinlocks(0);
249  	uml_exitcode = 1;
250  	os_dump_core();
251  
252  	return NOTIFY_DONE;
253  }
254  
255  static struct notifier_block panic_exit_notifier = {
256  	.notifier_call	= panic_exit,
257  	.priority	= INT_MAX - 1, /* run as 2nd notifier, won't return */
258  };
259  
uml_finishsetup(void)260  void uml_finishsetup(void)
261  {
262  	atomic_notifier_chain_register(&panic_notifier_list,
263  				       &panic_exit_notifier);
264  
265  	uml_postsetup();
266  
267  	new_thread_handler();
268  }
269  
270  /* Set during early boot */
271  unsigned long stub_start;
272  unsigned long task_size;
273  EXPORT_SYMBOL(task_size);
274  
275  unsigned long host_task_size;
276  
277  unsigned long brk_start;
278  unsigned long end_iomem;
279  EXPORT_SYMBOL(end_iomem);
280  
281  #define MIN_VMALLOC (32 * 1024 * 1024)
282  
parse_host_cpu_flags(char * line)283  static void parse_host_cpu_flags(char *line)
284  {
285  	int i;
286  	for (i = 0; i < 32*NCAPINTS; i++) {
287  		if ((x86_cap_flags[i] != NULL) && strstr(line, x86_cap_flags[i]))
288  			set_cpu_cap(&boot_cpu_data, i);
289  	}
290  }
parse_cache_line(char * line)291  static void parse_cache_line(char *line)
292  {
293  	long res;
294  	char *to_parse = strstr(line, ":");
295  	if (to_parse) {
296  		to_parse++;
297  		while (*to_parse != 0 && isspace(*to_parse)) {
298  			to_parse++;
299  		}
300  		if (kstrtoul(to_parse, 10, &res) == 0 && is_power_of_2(res))
301  			boot_cpu_data.cache_alignment = res;
302  		else
303  			boot_cpu_data.cache_alignment = L1_CACHE_BYTES;
304  	}
305  }
306  
linux_main(int argc,char ** argv)307  int __init linux_main(int argc, char **argv)
308  {
309  	unsigned long avail, diff;
310  	unsigned long virtmem_size, max_physmem;
311  	unsigned long stack;
312  	unsigned int i;
313  	int add;
314  
315  	for (i = 1; i < argc; i++) {
316  		if ((i == 1) && (argv[i][0] == ' '))
317  			continue;
318  		add = 1;
319  		uml_checksetup(argv[i], &add);
320  		if (add)
321  			add_arg(argv[i]);
322  	}
323  	if (have_root == 0)
324  		add_arg(DEFAULT_COMMAND_LINE_ROOT);
325  
326  	if (have_console == 0)
327  		add_arg(DEFAULT_COMMAND_LINE_CONSOLE);
328  
329  	host_task_size = os_get_top_address();
330  	/* reserve a few pages for the stubs (taking care of data alignment) */
331  	/* align the data portion */
332  	BUILD_BUG_ON(!is_power_of_2(STUB_DATA_PAGES));
333  	stub_start = (host_task_size - 1) & ~(STUB_DATA_PAGES * PAGE_SIZE - 1);
334  	/* another page for the code portion */
335  	stub_start -= PAGE_SIZE;
336  	host_task_size = stub_start;
337  
338  	/*
339  	 * TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
340  	 * out
341  	 */
342  	task_size = host_task_size & PGDIR_MASK;
343  
344  	/* OS sanity checks that need to happen before the kernel runs */
345  	os_early_checks();
346  
347  	get_host_cpu_features(parse_host_cpu_flags, parse_cache_line);
348  
349  	brk_start = (unsigned long) sbrk(0);
350  
351  	/*
352  	 * Increase physical memory size for exec-shield users
353  	 * so they actually get what they asked for. This should
354  	 * add zero for non-exec shield users
355  	 */
356  
357  	diff = UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
358  	if (diff > 1024 * 1024) {
359  		os_info("Adding %ld bytes to physical memory to account for "
360  			"exec-shield gap\n", diff);
361  		physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
362  	}
363  
364  	uml_physmem = (unsigned long) __binary_start & PAGE_MASK;
365  
366  	/* Reserve up to 4M after the current brk */
367  	uml_reserved = ROUND_4M(brk_start) + (1 << 22);
368  
369  	setup_machinename(init_utsname()->machine);
370  
371  	highmem = 0;
372  	iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
373  	max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
374  
375  	/*
376  	 * Zones have to begin on a 1 << MAX_ORDER page boundary,
377  	 * so this makes sure that's true for highmem
378  	 */
379  	max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
380  	if (physmem_size + iomem_size > max_physmem) {
381  		highmem = physmem_size + iomem_size - max_physmem;
382  		physmem_size -= highmem;
383  	}
384  
385  	high_physmem = uml_physmem + physmem_size;
386  	end_iomem = high_physmem + iomem_size;
387  	high_memory = (void *) end_iomem;
388  
389  	start_vm = VMALLOC_START;
390  
391  	virtmem_size = physmem_size;
392  	stack = (unsigned long) argv;
393  	stack &= ~(1024 * 1024 - 1);
394  	avail = stack - start_vm;
395  	if (physmem_size > avail)
396  		virtmem_size = avail;
397  	end_vm = start_vm + virtmem_size;
398  
399  	if (virtmem_size < physmem_size)
400  		os_info("Kernel virtual memory size shrunk to %lu bytes\n",
401  			virtmem_size);
402  
403  	os_flush_stdout();
404  
405  	return start_uml();
406  }
407  
read_initrd(void)408  int __init __weak read_initrd(void)
409  {
410  	return 0;
411  }
412  
setup_arch(char ** cmdline_p)413  void __init setup_arch(char **cmdline_p)
414  {
415  	u8 rng_seed[32];
416  
417  	stack_protections((unsigned long) &init_thread_info);
418  	setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
419  	mem_total_pages(physmem_size, iomem_size, highmem);
420  	uml_dtb_init();
421  	read_initrd();
422  
423  	paging_init();
424  	strscpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
425  	*cmdline_p = command_line;
426  	setup_hostinfo(host_info, sizeof host_info);
427  
428  	if (os_getrandom(rng_seed, sizeof(rng_seed), 0) == sizeof(rng_seed)) {
429  		add_bootloader_randomness(rng_seed, sizeof(rng_seed));
430  		memzero_explicit(rng_seed, sizeof(rng_seed));
431  	}
432  }
433  
arch_cpu_finalize_init(void)434  void __init arch_cpu_finalize_init(void)
435  {
436  	arch_check_bugs();
437  	os_check_bugs();
438  }
439  
apply_seal_endbr(s32 * start,s32 * end)440  void apply_seal_endbr(s32 *start, s32 *end)
441  {
442  }
443  
apply_retpolines(s32 * start,s32 * end)444  void apply_retpolines(s32 *start, s32 *end)
445  {
446  }
447  
apply_returns(s32 * start,s32 * end)448  void apply_returns(s32 *start, s32 *end)
449  {
450  }
451  
apply_fineibt(s32 * start_retpoline,s32 * end_retpoline,s32 * start_cfi,s32 * end_cfi)452  void apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
453  		   s32 *start_cfi, s32 *end_cfi)
454  {
455  }
456  
apply_alternatives(struct alt_instr * start,struct alt_instr * end)457  void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
458  {
459  }
460  
text_poke(void * addr,const void * opcode,size_t len)461  void *text_poke(void *addr, const void *opcode, size_t len)
462  {
463  	/*
464  	 * In UML, the only reference to this function is in
465  	 * apply_relocate_add(), which shouldn't ever actually call this
466  	 * because UML doesn't have live patching.
467  	 */
468  	WARN_ON(1);
469  
470  	return memcpy(addr, opcode, len);
471  }
472  
text_poke_sync(void)473  void text_poke_sync(void)
474  {
475  }
476  
uml_pm_wake(void)477  void uml_pm_wake(void)
478  {
479  	pm_system_wakeup();
480  }
481  
482  #ifdef CONFIG_PM_SLEEP
um_suspend_valid(suspend_state_t state)483  static int um_suspend_valid(suspend_state_t state)
484  {
485  	return state == PM_SUSPEND_MEM;
486  }
487  
um_suspend_prepare(void)488  static int um_suspend_prepare(void)
489  {
490  	um_irqs_suspend();
491  	return 0;
492  }
493  
um_suspend_enter(suspend_state_t state)494  static int um_suspend_enter(suspend_state_t state)
495  {
496  	if (WARN_ON(state != PM_SUSPEND_MEM))
497  		return -EINVAL;
498  
499  	/*
500  	 * This is identical to the idle sleep, but we've just
501  	 * (during suspend) turned off all interrupt sources
502  	 * except for the ones we want, so now we can only wake
503  	 * up on something we actually want to wake up on. All
504  	 * timing has also been suspended.
505  	 */
506  	um_idle_sleep();
507  	return 0;
508  }
509  
um_suspend_finish(void)510  static void um_suspend_finish(void)
511  {
512  	um_irqs_resume();
513  }
514  
515  const struct platform_suspend_ops um_suspend_ops = {
516  	.valid = um_suspend_valid,
517  	.prepare = um_suspend_prepare,
518  	.enter = um_suspend_enter,
519  	.finish = um_suspend_finish,
520  };
521  
init_pm_wake_signal(void)522  static int init_pm_wake_signal(void)
523  {
524  	/*
525  	 * In external time-travel mode we can't use signals to wake up
526  	 * since that would mess with the scheduling. We'll have to do
527  	 * some additional work to support wakeup on virtio devices or
528  	 * similar, perhaps implementing a fake RTC controller that can
529  	 * trigger wakeup (and request the appropriate scheduling from
530  	 * the external scheduler when going to suspend.)
531  	 */
532  	if (time_travel_mode != TT_MODE_EXTERNAL)
533  		register_pm_wake_signal();
534  
535  	suspend_set_ops(&um_suspend_ops);
536  
537  	return 0;
538  }
539  
540  late_initcall(init_pm_wake_signal);
541  #endif
542