arch/um/kernel/um_arch.c

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