linux/arch/um/kernel/um_arch.c
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   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
  17#include <asm/pgtable.h>
  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 */
  32static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };
  33
  34static 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 */
  50struct cpuinfo_um boot_cpu_data = {
  51        .loops_per_jiffy        = 0,
  52        .ipi_pipe               = { -1, -1 }
  53};
  54
  55union thread_union cpu0_irqstack
  56        __attribute__((__section__(".data..init_irqstack"))) =
  57                { .thread_info = INIT_THREAD_INFO(init_task) };
  58
  59/* Changed in setup_arch, which is called in early boot */
  60static char host_info[(__NEW_UTS_LEN + 1) * 5];
  61
  62static 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
  78static void *c_start(struct seq_file *m, loff_t *pos)
  79{
  80        return *pos < NR_CPUS ? cpu_data + *pos : NULL;
  81}
  82
  83static void *c_next(struct seq_file *m, void *v, loff_t *pos)
  84{
  85        ++*pos;
  86        return c_start(m, pos);
  87}
  88
  89static void c_stop(struct seq_file *m, void *v)
  90{
  91}
  92
  93const 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 */
 101unsigned long uml_physmem;
 102EXPORT_SYMBOL(uml_physmem);
 103
 104unsigned long uml_reserved; /* Also modified in mem_init */
 105unsigned long start_vm;
 106unsigned long end_vm;
 107
 108/* Set in uml_ncpus_setup */
 109int ncpus = 1;
 110
 111/* Set in early boot */
 112static int have_root __initdata = 0;
 113
 114/* Set in uml_mem_setup and modified in linux_main */
 115long long physmem_size = 32 * 1024 * 1024;
 116EXPORT_SYMBOL(physmem_size);
 117
 118static const char *usage_string =
 119"User Mode Linux v%s\n"
 120"       available at http://user-mode-linux.sourceforge.net/\n\n";
 121
 122static 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
 136static 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
 151static 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
 164static 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
 184static 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
 199static 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
 211static 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
 222static struct notifier_block panic_exit_notifier = {
 223        .notifier_call          = panic_exit,
 224        .next                   = NULL,
 225        .priority               = 0
 226};
 227
 228void 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 */
 239unsigned long task_size;
 240EXPORT_SYMBOL(task_size);
 241
 242unsigned long host_task_size;
 243
 244unsigned long brk_start;
 245unsigned long end_iomem;
 246EXPORT_SYMBOL(end_iomem);
 247
 248#define MIN_VMALLOC (32 * 1024 * 1024)
 249
 250int __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
 338int __init __weak read_initrd(void)
 339{
 340        return 0;
 341}
 342
 343void __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
 356void __init check_bugs(void)
 357{
 358        arch_check_bugs();
 359        os_check_bugs();
 360}
 361
 362void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
 363{
 364}
 365