[thirdparty/linux.git] / init / main.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  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 DEBUG           /* Enable initcall_debug */

#include <linux/types.h>
#include <linux/extable.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/binfmts.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/stackprotector.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/memblock.h>
#include <linux/acpi.h>
#include <linux/bootconfig.h>
#include <linux/console.h>
#include <linux/nmi.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
#include <linux/kprobes.h>
#include <linux/kmsan.h>
#include <linux/vmalloc.h>
#include <linux/kernel_stat.h>
#include <linux/start_kernel.h>
#include <linux/security.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <linux/kfence.h>
#include <linux/rcupdate.h>
#include <linux/srcu.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/buildid.h>
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cgroup.h>
#include <linux/efi.h>
#include <linux/tick.h>
#include <linux/sched/isolation.h>
#include <linux/interrupt.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/utsname.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
#include <linux/debug_locks.h>
#include <linux/debugobjects.h>
#include <linux/lockdep.h>
#include <linux/kmemleak.h>
#include <linux/padata.h>
#include <linux/pid_namespace.h>
#include <linux/device/driver.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/sched/init.h>
#include <linux/signal.h>
#include <linux/idr.h>
#include <linux/kgdb.h>
#include <linux/ftrace.h>
#include <linux/async.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/pti.h>
#include <linux/blkdev.h>
#include <linux/sched/clock.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/context_tracking.h>
#include <linux/random.h>
#include <linux/moduleloader.h>
#include <linux/list.h>
#include <linux/integrity.h>
#include <linux/proc_ns.h>
#include <linux/io.h>
#include <linux/cache.h>
#include <linux/rodata_test.h>
#include <linux/jump_label.h>
#include <linux/kcsan.h>
#include <linux/init_syscalls.h>
#include <linux/stackdepot.h>
#include <linux/randomize_kstack.h>
#include <linux/pidfs.h>
#include <linux/ptdump.h>
#include <net/net_namespace.h>

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

#define CREATE_TRACE_POINTS
#include <trace/events/initcall.h>

#include <kunit/test.h>

static int kernel_init(void *);

/*
 * Debug helper: via this flag we know that we are in 'early bootup code'
 * where only the boot processor is running with IRQ disabled.  This means
 * two things - IRQ must not be enabled before the flag is cleared and some
 * operations which are not allowed with IRQ disabled are allowed while the
 * flag is set.
 */
bool early_boot_irqs_disabled __read_mostly;

enum system_states system_state __read_mostly;
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

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

/* Untouched command line saved by arch-specific code. */
char __initdata boot_command_line[COMMAND_LINE_SIZE];
/* Untouched saved command line (eg. for /proc) */
char *saved_command_line __ro_after_init;
unsigned int saved_command_line_len __ro_after_init;
/* Command line for parameter parsing */
static char *static_command_line;
/* Untouched extra command line */
static char *extra_command_line;
/* Extra init arguments */
static char *extra_init_args;

#ifdef CONFIG_BOOT_CONFIG
/* Is bootconfig on command line? */
static bool bootconfig_found;
static size_t initargs_offs;
#else
# define bootconfig_found false
# define initargs_offs 0
#endif

static char *execute_command;
static char *ramdisk_execute_command = "/init";

/*
 * Used to generate warnings if static_key manipulation functions are used
 * before jump_label_init is called.
 */
bool static_key_initialized __read_mostly;
EXPORT_SYMBOL_GPL(static_key_initialized);

/*
 * If set, this is an indication to the drivers that reset the underlying
 * device before going ahead with the initialization otherwise driver might
 * rely on the BIOS and skip the reset operation.
 *
 * This is useful if kernel is booting in an unreliable environment.
 * For ex. kdump situation where previous kernel has crashed, BIOS has been
 * skipped and devices will be in unknown state.
 */
unsigned int reset_devices;
EXPORT_SYMBOL(reset_devices);

static int __init set_reset_devices(char *str)
{
        reset_devices = 1;
        return 1;
}

__setup("reset_devices", set_reset_devices);

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

static bool __init obsolete_checksetup(char *line)
{
        const struct obs_kernel_param *p;
        bool had_early_param = false;

        p = __setup_start;
        do {
                int n = strlen(p->str);
                if (parameqn(line, p->str, n)) {
                        if (p->early) {
                                /* Already done in parse_early_param?
                                 * (Needs exact match on param part).
                                 * Keep iterating, as we can have early
                                 * params and __setups of same names 8( */
                                if (line[n] == '\0' || line[n] == '=')
                                        had_early_param = true;
                        } else if (!p->setup_func) {
                                pr_warn("Parameter %s is obsolete, ignored\n",
                                        p->str);
                                return true;
                        } else if (p->setup_func(line + n))
                                return true;
                }
                p++;
        } while (p < __setup_end);

        return had_early_param;
}

/*
 * 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)
{
        console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
        return 0;
}

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

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

static int __init loglevel(char *str)
{
        int newlevel;

        /*
         * Only update loglevel value when a correct setting was passed,
         * to prevent blind crashes (when loglevel being set to 0) that
         * are quite hard to debug
         */
        if (get_option(&str, &newlevel)) {
                console_loglevel = newlevel;
                return 0;
        }

        return -EINVAL;
}

early_param("loglevel", loglevel);

#ifdef CONFIG_BLK_DEV_INITRD
static void * __init get_boot_config_from_initrd(size_t *_size)
{
        u32 size, csum;
        char *data;
        u32 *hdr;
        int i;

        if (!initrd_end)
                return NULL;

        data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;
        /*
         * Since Grub may align the size of initrd to 4, we must
         * check the preceding 3 bytes as well.
         */
        for (i = 0; i < 4; i++) {
                if (!memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
                        goto found;
                data--;
        }
        return NULL;

found:
        hdr = (u32 *)(data - 8);
        size = le32_to_cpu(hdr[0]);
        csum = le32_to_cpu(hdr[1]);

        data = ((void *)hdr) - size;
        if ((unsigned long)data < initrd_start) {
                pr_err("bootconfig size %d is greater than initrd size %ld\n",
                        size, initrd_end - initrd_start);
                return NULL;
        }

        if (xbc_calc_checksum(data, size) != csum) {
                pr_err("bootconfig checksum failed\n");
                return NULL;
        }

        /* Remove bootconfig from initramfs/initrd */
        initrd_end = (unsigned long)data;
        if (_size)
                *_size = size;

        return data;
}
#else
static void * __init get_boot_config_from_initrd(size_t *_size)
{
        return NULL;
}
#endif

#ifdef CONFIG_BOOT_CONFIG

static char xbc_namebuf[XBC_KEYLEN_MAX] __initdata;

#define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)

static int __init xbc_snprint_cmdline(char *buf, size_t size,
                                      struct xbc_node *root)
{
        struct xbc_node *knode, *vnode;
        char *end = buf + size;
        const char *val;
        int ret;

        xbc_node_for_each_key_value(root, knode, val) {
                ret = xbc_node_compose_key_after(root, knode,
                                        xbc_namebuf, XBC_KEYLEN_MAX);
                if (ret < 0)
                        return ret;

                vnode = xbc_node_get_child(knode);
                if (!vnode) {
                        ret = snprintf(buf, rest(buf, end), "%s ", xbc_namebuf);
                        if (ret < 0)
                                return ret;
                        buf += ret;
                        continue;
                }
                xbc_array_for_each_value(vnode, val) {
                        ret = snprintf(buf, rest(buf, end), "%s=\"%s\" ",
                                       xbc_namebuf, val);
                        if (ret < 0)
                                return ret;
                        buf += ret;
                }
        }

        return buf - (end - size);
}
#undef rest

/* Make an extra command line under given key word */
static char * __init xbc_make_cmdline(const char *key)
{
        struct xbc_node *root;
        char *new_cmdline;
        int ret, len = 0;

        root = xbc_find_node(key);
        if (!root)
                return NULL;

        /* Count required buffer size */
        len = xbc_snprint_cmdline(NULL, 0, root);
        if (len <= 0)
                return NULL;

        new_cmdline = memblock_alloc(len + 1, SMP_CACHE_BYTES);
        if (!new_cmdline) {
                pr_err("Failed to allocate memory for extra kernel cmdline.\n");
                return NULL;
        }

        ret = xbc_snprint_cmdline(new_cmdline, len + 1, root);
        if (ret < 0 || ret > len) {
                pr_err("Failed to print extra kernel cmdline.\n");
                memblock_free(new_cmdline, len + 1);
                return NULL;
        }

        return new_cmdline;
}

static int __init bootconfig_params(char *param, char *val,
                                    const char *unused, void *arg)
{
        if (strcmp(param, "bootconfig") == 0) {
                bootconfig_found = true;
        }
        return 0;
}

static int __init warn_bootconfig(char *str)
{
        /* The 'bootconfig' has been handled by bootconfig_params(). */
        return 0;
}

static void __init setup_boot_config(void)
{
        static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
        const char *msg, *data;
        int pos, ret;
        size_t size;
        char *err;

        /* Cut out the bootconfig data even if we have no bootconfig option */
        data = get_boot_config_from_initrd(&size);
        /* If there is no bootconfig in initrd, try embedded one. */
        if (!data)
                data = xbc_get_embedded_bootconfig(&size);

        strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
        err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
                         bootconfig_params);

        if (IS_ERR(err) || !(bootconfig_found || IS_ENABLED(CONFIG_BOOT_CONFIG_FORCE)))
                return;

        /* parse_args() stops at the next param of '--' and returns an address */
        if (err)
                initargs_offs = err - tmp_cmdline;

        if (!data) {
                /* If user intended to use bootconfig, show an error level message */
                if (bootconfig_found)
                        pr_err("'bootconfig' found on command line, but no bootconfig found\n");
                else
                        pr_info("No bootconfig data provided, so skipping bootconfig");
                return;
        }

        if (size >= XBC_DATA_MAX) {
                pr_err("bootconfig size %ld greater than max size %d\n",
                        (long)size, XBC_DATA_MAX);
                return;
        }

        ret = xbc_init(data, size, &msg, &pos);
        if (ret < 0) {
                if (pos < 0)
                        pr_err("Failed to init bootconfig: %s.\n", msg);
                else
                        pr_err("Failed to parse bootconfig: %s at %d.\n",
                                msg, pos);
        } else {
                xbc_get_info(&ret, NULL);
                pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
                /* keys starting with "kernel." are passed via cmdline */
                extra_command_line = xbc_make_cmdline("kernel");
                /* Also, "init." keys are init arguments */
                extra_init_args = xbc_make_cmdline("init");
        }
        return;
}

static void __init exit_boot_config(void)
{
        xbc_exit();
}

#else   /* !CONFIG_BOOT_CONFIG */

static void __init setup_boot_config(void)
{
        /* Remove bootconfig data from initrd */
        get_boot_config_from_initrd(NULL);
}

static int __init warn_bootconfig(char *str)
{
        pr_warn("WARNING: 'bootconfig' found on the kernel command line but CONFIG_BOOT_CONFIG is not set.\n");
        return 0;
}

#define exit_boot_config()      do {} while (0)

#endif  /* CONFIG_BOOT_CONFIG */

early_param("bootconfig", warn_bootconfig);

bool __init cmdline_has_extra_options(void)
{
        return extra_command_line || extra_init_args;
}

/* Change NUL term back to "=", to make "param" the whole string. */
static void __init repair_env_string(char *param, char *val)
{
        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);
                } else
                        BUG();
        }
}

/* Anything after -- gets handed straight to init. */
static int __init set_init_arg(char *param, char *val,
                               const char *unused, void *arg)
{
        unsigned int i;

        if (panic_later)
                return 0;

        repair_env_string(param, val);

        for (i = 0; argv_init[i]; i++) {
                if (i == MAX_INIT_ARGS) {
                        panic_later = "init";
                        panic_param = param;
                        return 0;
                }
        }
        argv_init[i] = param;
        return 0;
}

/*
 * Unknown boot options get handed to init, unless they look like
 * unused parameters (modprobe will find them in /proc/cmdline).
 */
static int __init unknown_bootoption(char *param, char *val,
                                     const char *unused, void *arg)
{
        size_t len = strlen(param);

        /* Handle params aliased to sysctls */
        if (sysctl_is_alias(param))
                return 0;

        repair_env_string(param, val);

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

        /* Unused module parameter. */
        if (strnchr(param, len, '.'))
                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 = "env";
                                panic_param = param;
                        }
                        if (!strncmp(param, envp_init[i], len+1))
                                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 = "init";
                                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);

#ifndef CONFIG_SMP
static inline void setup_nr_cpu_ids(void) { }
static inline void smp_prepare_cpus(unsigned int maxcpus) { }
#endif

/*
 * We need to store the untouched command line for future reference.
 * We also need to store the touched command line since the parameter
 * parsing is performed in place, and we should allow a component to
 * store reference of name/value for future reference.
 */
static void __init setup_command_line(char *command_line)
{
        size_t len, xlen = 0, ilen = 0;

        if (extra_command_line)
                xlen = strlen(extra_command_line);
        if (extra_init_args)
                ilen = strlen(extra_init_args) + 4; /* for " -- " */

        len = xlen + strlen(boot_command_line) + 1;

        saved_command_line = memblock_alloc(len + ilen, SMP_CACHE_BYTES);
        if (!saved_command_line)
                panic("%s: Failed to allocate %zu bytes\n", __func__, len + ilen);

        static_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
        if (!static_command_line)
                panic("%s: Failed to allocate %zu bytes\n", __func__, len);

        if (xlen) {
                /*
                 * We have to put extra_command_line before boot command
                 * lines because there could be dashes (separator of init
                 * command line) in the command lines.
                 */
                strcpy(saved_command_line, extra_command_line);
                strcpy(static_command_line, extra_command_line);
        }
        strcpy(saved_command_line + xlen, boot_command_line);
        strcpy(static_command_line + xlen, command_line);

        if (ilen) {
                /*
                 * Append supplemental init boot args to saved_command_line
                 * so that user can check what command line options passed
                 * to init.
                 * The order should always be
                 * " -- "[bootconfig init-param][cmdline init-param]
                 */
                if (initargs_offs) {
                        len = xlen + initargs_offs;
                        strcpy(saved_command_line + len, extra_init_args);
                        len += ilen - 4;        /* strlen(extra_init_args) */
                        strcpy(saved_command_line + len,
                                boot_command_line + initargs_offs - 1);
                } else {
                        len = strlen(saved_command_line);
                        strcpy(saved_command_line + len, " -- ");
                        len += 4;
                        strcpy(saved_command_line + len, extra_init_args);
                }
        }

        saved_command_line_len = strlen(saved_command_line);
}

/*
 * 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 __initdata DECLARE_COMPLETION(kthreadd_done);

static noinline void __ref __noreturn rest_init(void)
{
        struct task_struct *tsk;
        int pid;

        rcu_scheduler_starting();
        /*
         * We need to spawn init first so that it obtains pid 1, however
         * the init task will end up wanting to create kthreads, which, if
         * we schedule it before we create kthreadd, will OOPS.
         */
        pid = user_mode_thread(kernel_init, NULL, CLONE_FS);
        /*
         * Pin init on the boot CPU. Task migration is not properly working
         * until sched_init_smp() has been run. It will set the allowed
         * CPUs for init to the non isolated CPUs.
         */
        rcu_read_lock();
        tsk = find_task_by_pid_ns(pid, &init_pid_ns);
        tsk->flags |= PF_NO_SETAFFINITY;
        set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id()));
        rcu_read_unlock();

        numa_default_policy();
        pid = kernel_thread(kthreadd, NULL, NULL, CLONE_FS | CLONE_FILES);
        rcu_read_lock();
        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
        rcu_read_unlock();

        /*
         * Enable might_sleep() and smp_processor_id() checks.
         * They cannot be enabled earlier because with CONFIG_PREEMPTION=y
         * kernel_thread() would trigger might_sleep() splats. With
         * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
         * already, but it's stuck on the kthreadd_done completion.
         */
        system_state = SYSTEM_SCHEDULING;

        complete(&kthreadd_done);

        /*
         * The boot idle thread must execute schedule()
         * at least once to get things moving:
         */
        schedule_preempt_disabled();
        /* Call into cpu_idle with preempt disabled */
        cpu_startup_entry(CPUHP_ONLINE);
}

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

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

void __init parse_early_options(char *cmdline)
{
        parse_args("early options", cmdline, NULL, 0, 0, 0, NULL,
                   do_early_param);
}

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

        if (done)
                return;

        /* All fall through to do_early_param. */
        strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
        parse_early_options(tmp_cmdline);
        done = 1;
}

void __init __weak arch_post_acpi_subsys_init(void) { }

void __init __weak smp_setup_processor_id(void)
{
}

void __init __weak smp_prepare_boot_cpu(void)
{
}

# if THREAD_SIZE >= PAGE_SIZE
void __init __weak thread_stack_cache_init(void)
{
}
#endif

void __init __weak poking_init(void) { }

void __init __weak pgtable_cache_init(void) { }

void __init __weak trap_init(void) { }

bool initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);

#ifdef TRACEPOINTS_ENABLED
static void __init initcall_debug_enable(void);
#else
static inline void initcall_debug_enable(void)
{
}
#endif

#ifdef CONFIG_RANDOMIZE_KSTACK_OFFSET
DEFINE_STATIC_KEY_MAYBE_RO(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT,
                           randomize_kstack_offset);
DEFINE_PER_CPU(u32, kstack_offset);

static int __init early_randomize_kstack_offset(char *buf)
{
        int ret;
        bool bool_result;

        ret = kstrtobool(buf, &bool_result);
        if (ret)
                return ret;

        if (bool_result)
                static_branch_enable(&randomize_kstack_offset);
        else
                static_branch_disable(&randomize_kstack_offset);
        return 0;
}
early_param("randomize_kstack_offset", early_randomize_kstack_offset);
#endif

static void __init print_unknown_bootoptions(void)
{
        char *unknown_options;
        char *end;
        const char *const *p;
        size_t len;

        if (panic_later || (!argv_init[1] && !envp_init[2]))
                return;

        /*
         * Determine how many options we have to print out, plus a space
         * before each
         */
        len = 1; /* null terminator */
        for (p = &argv_init[1]; *p; p++) {
                len++;
                len += strlen(*p);
        }
        for (p = &envp_init[2]; *p; p++) {
                len++;
                len += strlen(*p);
        }

        unknown_options = memblock_alloc(len, SMP_CACHE_BYTES);
        if (!unknown_options) {
                pr_err("%s: Failed to allocate %zu bytes\n",
                        __func__, len);
                return;
        }
        end = unknown_options;

        for (p = &argv_init[1]; *p; p++)
                end += sprintf(end, " %s", *p);
        for (p = &envp_init[2]; *p; p++)
                end += sprintf(end, " %s", *p);

        /* Start at unknown_options[1] to skip the initial space */
        pr_notice("Unknown kernel command line parameters \"%s\", will be passed to user space.\n",
                &unknown_options[1]);
        memblock_free(unknown_options, len);
}

asmlinkage __visible __init __no_sanitize_address __noreturn __no_stack_protector
void start_kernel(void)
{
        char *command_line;
        char *after_dashes;

        set_task_stack_end_magic(&init_task);
        smp_setup_processor_id();
        debug_objects_early_init();
        init_vmlinux_build_id();

        cgroup_init_early();

        local_irq_disable();
        early_boot_irqs_disabled = true;

        /*
         * Interrupts are still disabled. Do necessary setups, then
         * enable them.
         */
        boot_cpu_init();
        page_address_init();
        pr_notice("%s", linux_banner);
        early_security_init();
        setup_arch(&command_line);
        setup_boot_config();
        setup_command_line(command_line);
        setup_nr_cpu_ids();
        setup_per_cpu_areas();
        smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
        boot_cpu_hotplug_init();

        pr_notice("Kernel command line: %s\n", saved_command_line);
        /* parameters may set static keys */
        jump_label_init();
        parse_early_param();
        after_dashes = parse_args("Booting kernel",
                                  static_command_line, __start___param,
                                  __stop___param - __start___param,
                                  -1, -1, NULL, &unknown_bootoption);
        print_unknown_bootoptions();
        if (!IS_ERR_OR_NULL(after_dashes))
                parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
                           NULL, set_init_arg);
        if (extra_init_args)
                parse_args("Setting extra init args", extra_init_args,
                           NULL, 0, -1, -1, NULL, set_init_arg);

        /* Architectural and non-timekeeping rng init, before allocator init */
        random_init_early(command_line);

        /*
         * These use large bootmem allocations and must precede
         * initalization of page allocator
         */
        setup_log_buf(0);
        vfs_caches_init_early();
        sort_main_extable();
        trap_init();
        mm_core_init();
        poking_init();
        ftrace_init();

        /* trace_printk can be enabled here */
        early_trace_init();

        /*
         * 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();

        if (WARN(!irqs_disabled(),
                 "Interrupts were enabled *very* early, fixing it\n"))
                local_irq_disable();
        radix_tree_init();
        maple_tree_init();

        /*
         * Set up housekeeping before setting up workqueues to allow the unbound
         * workqueue to take non-housekeeping into account.
         */
        housekeeping_init();

        /*
         * Allow workqueue creation and work item queueing/cancelling
         * early.  Work item execution depends on kthreads and starts after
         * workqueue_init().
         */
        workqueue_init_early();

        rcu_init();

        /* Trace events are available after this */
        trace_init();

        if (initcall_debug)
                initcall_debug_enable();

        context_tracking_init();
        /* init some links before init_ISA_irqs() */
        early_irq_init();
        init_IRQ();
        tick_init();
        rcu_init_nohz();
        init_timers();
        srcu_init();
        hrtimers_init();
        softirq_init();
        timekeeping_init();
        time_init();

        /* This must be after timekeeping is initialized */
        random_init();

        /* These make use of the fully initialized rng */
        kfence_init();
        boot_init_stack_canary();

        perf_event_init();
        profile_init();
        call_function_init();
        WARN(!irqs_disabled(), "Interrupts were enabled early\n");

        early_boot_irqs_disabled = false;
        local_irq_enable();

        kmem_cache_init_late();

        /*
         * 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("Too many boot %s vars at `%s'", panic_later,
                      panic_param);

        lockdep_init();

        /*
         * Need to run this when irqs are enabled, because it wants
         * to self-test [hard/soft]-irqs on/off lock inversion bugs
         * too:
         */
        locking_selftest();

#ifdef CONFIG_BLK_DEV_INITRD
        if (initrd_start && !initrd_below_start_ok &&
            page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
                pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
                    page_to_pfn(virt_to_page((void *)initrd_start)),
                    min_low_pfn);
                initrd_start = 0;
        }
#endif
        setup_per_cpu_pageset();
        numa_policy_init();
        acpi_early_init();
        if (late_time_init)
                late_time_init();
        sched_clock_init();
        calibrate_delay();

        arch_cpu_finalize_init();

        pid_idr_init();
        anon_vma_init();
#ifdef CONFIG_X86
        if (efi_enabled(EFI_RUNTIME_SERVICES))
                efi_enter_virtual_mode();
#endif
        thread_stack_cache_init();
        cred_init();
        fork_init();
        proc_caches_init();
        uts_ns_init();
        key_init();
        security_init();
        dbg_late_init();
        net_ns_init();
        vfs_caches_init();
        pagecache_init();
        signals_init();
        seq_file_init();
        proc_root_init();
        nsfs_init();
        pidfs_init();
        cpuset_init();
        cgroup_init();
        taskstats_init_early();
        delayacct_init();

        acpi_subsystem_init();
        arch_post_acpi_subsys_init();
        kcsan_init();

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

        /*
         * Avoid stack canaries in callers of boot_init_stack_canary for gcc-10
         * and older.
         */
#if !__has_attribute(__no_stack_protector__)
        prevent_tail_call_optimization();
#endif
}

/* Call all constructor functions linked into the kernel. */
static void __init do_ctors(void)
{
/*
 * For UML, the constructors have already been called by the
 * normal setup code as it's just a normal ELF binary, so we
 * cannot do it again - but we do need CONFIG_CONSTRUCTORS
 * even on UML for modules.
 */
#if defined(CONFIG_CONSTRUCTORS) && !defined(CONFIG_UML)
        ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;

        for (; fn < (ctor_fn_t *) __ctors_end; fn++)
                (*fn)();
#endif
}

#ifdef CONFIG_KALLSYMS
struct blacklist_entry {
        struct list_head next;
        char *buf;
};

static __initdata_or_module LIST_HEAD(blacklisted_initcalls);

static int __init initcall_blacklist(char *str)
{
        char *str_entry;
        struct blacklist_entry *entry;

        /* str argument is a comma-separated list of functions */
        do {
                str_entry = strsep(&str, ",");
                if (str_entry) {
                        pr_debug("blacklisting initcall %s\n", str_entry);
                        entry = memblock_alloc(sizeof(*entry),
                                               SMP_CACHE_BYTES);
                        if (!entry)
                                panic("%s: Failed to allocate %zu bytes\n",
                                      __func__, sizeof(*entry));
                        entry->buf = memblock_alloc(strlen(str_entry) + 1,
                                                    SMP_CACHE_BYTES);
                        if (!entry->buf)
                                panic("%s: Failed to allocate %zu bytes\n",
                                      __func__, strlen(str_entry) + 1);
                        strcpy(entry->buf, str_entry);
                        list_add(&entry->next, &blacklisted_initcalls);
                }
        } while (str_entry);

        return 1;
}

static bool __init_or_module initcall_blacklisted(initcall_t fn)
{
        struct blacklist_entry *entry;
        char fn_name[KSYM_SYMBOL_LEN];
        unsigned long addr;

        if (list_empty(&blacklisted_initcalls))
                return false;

        addr = (unsigned long) dereference_function_descriptor(fn);
        sprint_symbol_no_offset(fn_name, addr);

        /*
         * fn will be "function_name [module_name]" where [module_name] is not
         * displayed for built-in init functions.  Strip off the [module_name].
         */
        strreplace(fn_name, ' ', '\0');

        list_for_each_entry(entry, &blacklisted_initcalls, next) {
                if (!strcmp(fn_name, entry->buf)) {
                        pr_debug("initcall %s blacklisted\n", fn_name);
                        return true;
                }
        }

        return false;
}
#else
static int __init initcall_blacklist(char *str)
{
        pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
        return 0;
}

static bool __init_or_module initcall_blacklisted(initcall_t fn)
{
        return false;
}
#endif
__setup("initcall_blacklist=", initcall_blacklist);

static __init_or_module void
trace_initcall_start_cb(void *data, initcall_t fn)
{
        ktime_t *calltime = data;

        printk(KERN_DEBUG "calling  %pS @ %i\n", fn, task_pid_nr(current));
        *calltime = ktime_get();
}

static __init_or_module void
trace_initcall_finish_cb(void *data, initcall_t fn, int ret)
{
        ktime_t rettime, *calltime = data;

        rettime = ktime_get();
        printk(KERN_DEBUG "initcall %pS returned %d after %lld usecs\n",
                 fn, ret, (unsigned long long)ktime_us_delta(rettime, *calltime));
}

static ktime_t initcall_calltime;

#ifdef TRACEPOINTS_ENABLED
static void __init initcall_debug_enable(void)
{
        int ret;

        ret = register_trace_initcall_start(trace_initcall_start_cb,
                                            &initcall_calltime);
        ret |= register_trace_initcall_finish(trace_initcall_finish_cb,
                                              &initcall_calltime);
        WARN(ret, "Failed to register initcall tracepoints\n");
}
# define do_trace_initcall_start        trace_initcall_start
# define do_trace_initcall_finish       trace_initcall_finish
#else
static inline void do_trace_initcall_start(initcall_t fn)
{
        if (!initcall_debug)
                return;
        trace_initcall_start_cb(&initcall_calltime, fn);
}
static inline void do_trace_initcall_finish(initcall_t fn, int ret)
{
        if (!initcall_debug)
                return;
        trace_initcall_finish_cb(&initcall_calltime, fn, ret);
}
#endif /* !TRACEPOINTS_ENABLED */

int __init_or_module do_one_initcall(initcall_t fn)
{
        int count = preempt_count();
        char msgbuf[64];
        int ret;

        if (initcall_blacklisted(fn))
                return -EPERM;

        do_trace_initcall_start(fn);
        ret = fn();
        do_trace_initcall_finish(fn, ret);

        msgbuf[0] = 0;

        if (preempt_count() != count) {
                sprintf(msgbuf, "preemption imbalance ");
                preempt_count_set(count);
        }
        if (irqs_disabled()) {
                strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
                local_irq_enable();
        }
        WARN(msgbuf[0], "initcall %pS returned with %s\n", fn, msgbuf);

        add_latent_entropy();
        return ret;
}


static initcall_entry_t *initcall_levels[] __initdata = {
        __initcall0_start,
        __initcall1_start,
        __initcall2_start,
        __initcall3_start,
        __initcall4_start,
        __initcall5_start,
        __initcall6_start,
        __initcall7_start,
        __initcall_end,
};

/* Keep these in sync with initcalls in include/linux/init.h */
static const char *initcall_level_names[] __initdata = {
        "pure",
        "core",
        "postcore",
        "arch",
        "subsys",
        "fs",
        "device",
        "late",
};

static int __init ignore_unknown_bootoption(char *param, char *val,
                               const char *unused, void *arg)
{
        return 0;
}

static void __init do_initcall_level(int level, char *command_line)
{
        initcall_entry_t *fn;

        parse_args(initcall_level_names[level],
                   command_line, __start___param,
                   __stop___param - __start___param,
                   level, level,
                   NULL, ignore_unknown_bootoption);

        trace_initcall_level(initcall_level_names[level]);
        for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
                do_one_initcall(initcall_from_entry(fn));
}

static void __init do_initcalls(void)
{
        int level;
        size_t len = saved_command_line_len + 1;
        char *command_line;

        command_line = kzalloc(len, GFP_KERNEL);
        if (!command_line)
                panic("%s: Failed to allocate %zu bytes\n", __func__, len);

        for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++) {
                /* Parser modifies command_line, restore it each time */
                strcpy(command_line, saved_command_line);
                do_initcall_level(level, command_line);
        }

        kfree(command_line);
}

/*
 * 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)
{
        cpuset_init_smp();
        driver_init();
        init_irq_proc();
        do_ctors();
        do_initcalls();
}

static void __init do_pre_smp_initcalls(void)
{
        initcall_entry_t *fn;

        trace_initcall_level("early");
        for (fn = __initcall_start; fn < __initcall0_start; fn++)
                do_one_initcall(initcall_from_entry(fn));
}

static int run_init_process(const char *init_filename)
{
        const char *const *p;

        argv_init[0] = init_filename;
        pr_info("Run %s as init process\n", init_filename);
        pr_debug("  with arguments:\n");
        for (p = argv_init; *p; p++)
                pr_debug("    %s\n", *p);
        pr_debug("  with environment:\n");
        for (p = envp_init; *p; p++)
                pr_debug("    %s\n", *p);
        return kernel_execve(init_filename, argv_init, envp_init);
}

static int try_to_run_init_process(const char *init_filename)
{
        int ret;

        ret = run_init_process(init_filename);

        if (ret && ret != -ENOENT) {
                pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
                       init_filename, ret);
        }

        return ret;
}

static noinline void __init kernel_init_freeable(void);

#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
bool rodata_enabled __ro_after_init = true;

#ifndef arch_parse_debug_rodata
static inline bool arch_parse_debug_rodata(char *str) { return false; }
#endif

static int __init set_debug_rodata(char *str)
{
        if (arch_parse_debug_rodata(str))
                return 0;

        if (str && !strcmp(str, "on"))
                rodata_enabled = true;
        else if (str && !strcmp(str, "off"))
                rodata_enabled = false;
        else
                pr_warn("Invalid option string for rodata: '%s'\n", str);
        return 0;
}
early_param("rodata", set_debug_rodata);
#endif

static void mark_readonly(void)
{
        if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) && rodata_enabled) {
                /*
                 * load_module() results in W+X mappings, which are cleaned
                 * up with init_free_wq. Let's make sure that queued work is
                 * flushed so that we don't hit false positives looking for
                 * insecure pages which are W+X.
                 */
                flush_module_init_free_work();
                mark_rodata_ro();
                debug_checkwx();
                rodata_test();
        } else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
                pr_info("Kernel memory protection disabled.\n");
        } else if (IS_ENABLED(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)) {
                pr_warn("Kernel memory protection not selected by kernel config.\n");
        } else {
                pr_warn("This architecture does not have kernel memory protection.\n");
        }
}

void __weak free_initmem(void)
{
        free_initmem_default(POISON_FREE_INITMEM);
}

static int __ref kernel_init(void *unused)
{
        int ret;

        /*
         * Wait until kthreadd is all set-up.
         */
        wait_for_completion(&kthreadd_done);

        kernel_init_freeable();
        /* need to finish all async __init code before freeing the memory */
        async_synchronize_full();

        system_state = SYSTEM_FREEING_INITMEM;
        kprobe_free_init_mem();
        ftrace_free_init_mem();
        kgdb_free_init_mem();
        exit_boot_config();
        free_initmem();
        mark_readonly();

        /*
         * Kernel mappings are now finalized - update the userspace page-table
         * to finalize PTI.
         */
        pti_finalize();

        system_state = SYSTEM_RUNNING;
        numa_default_policy();

        rcu_end_inkernel_boot();

        do_sysctl_args();

        if (ramdisk_execute_command) {
                ret = run_init_process(ramdisk_execute_command);
                if (!ret)
                        return 0;
                pr_err("Failed to execute %s (error %d)\n",
                       ramdisk_execute_command, ret);
        }

        /*
         * 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) {
                ret = run_init_process(execute_command);
                if (!ret)
                        return 0;
                panic("Requested init %s failed (error %d).",
                      execute_command, ret);
        }

        if (CONFIG_DEFAULT_INIT[0] != '\0') {
                ret = run_init_process(CONFIG_DEFAULT_INIT);
                if (ret)
                        pr_err("Default init %s failed (error %d)\n",
                               CONFIG_DEFAULT_INIT, ret);
                else
                        return 0;
        }

        if (!try_to_run_init_process("/sbin/init") ||
            !try_to_run_init_process("/etc/init") ||
            !try_to_run_init_process("/bin/init") ||
            !try_to_run_init_process("/bin/sh"))
                return 0;

        panic("No working init found.  Try passing init= option to kernel. "
              "See Linux Documentation/admin-guide/init.rst for guidance.");
}

/* Open /dev/console, for stdin/stdout/stderr, this should never fail */
void __init console_on_rootfs(void)
{
        struct file *file = filp_open("/dev/console", O_RDWR, 0);

        if (IS_ERR(file)) {
                pr_err("Warning: unable to open an initial console.\n");
                return;
        }
        init_dup(file);
        init_dup(file);
        init_dup(file);
        fput(file);
}

static noinline void __init kernel_init_freeable(void)
{
        /* Now the scheduler is fully set up and can do blocking allocations */
        gfp_allowed_mask = __GFP_BITS_MASK;

        /*
         * init can allocate pages on any node
         */
        set_mems_allowed(node_states[N_MEMORY]);

        cad_pid = get_pid(task_pid(current));

        smp_prepare_cpus(setup_max_cpus);

        workqueue_init();

        init_mm_internals();

        rcu_init_tasks_generic();
        do_pre_smp_initcalls();
        lockup_detector_init();

        smp_init();
        sched_init_smp();

        workqueue_init_topology();
        async_init();
        padata_init();
        page_alloc_init_late();

        do_basic_setup();

        kunit_run_all_tests();

        wait_for_initramfs();
        console_on_rootfs();

        /*
         * check if there is an early userspace init.  If yes, let it do all
         * the work
         */
        if (init_eaccess(ramdisk_execute_command) != 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..
         *
         * rootfs is available now, try loading the public keys
         * and default modules
         */

        integrity_load_keys();
}