// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 */

#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/panic_notifier.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <linux/utsname.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/kmsg_dump.h>
#include <linux/suspend.h>
#include <linux/random.h>
#include <linux/smp-internal.h>

#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/text-patching.h>
#include <as-layout.h>
#include <arch.h>
#include <init.h>
#include <kern.h>
#include <kern_util.h>
#include <mem_user.h>
#include <os.h>

#include "um_arch.h"

#define DEFAULT_COMMAND_LINE_ROOT "root=98:0"
#define DEFAULT_COMMAND_LINE_CONSOLE "console=tty0"

/* Changed in add_arg and setup_arch, which run before SMP is started */
static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };

static void __init add_arg(char *arg)
{
        if (strlen(command_line) + strlen(arg) + 1 > COMMAND_LINE_SIZE) {
                os_warn("add_arg: Too many command line arguments!\n");
                exit(1);
        }
        if (strlen(command_line) > 0)
                strcat(command_line, " ");
        strcat(command_line, arg);
}

/*
 * These fields are initialized at boot time and not changed.
 */
struct cpuinfo_um boot_cpu_data = {
        .loops_per_jiffy        = 0,
        .cache_alignment        = L1_CACHE_BYTES,
        .x86_capability         = { 0 }
};

EXPORT_SYMBOL(boot_cpu_data);


/* Changed in setup_arch, which is called in early boot */
static char host_info[(__NEW_UTS_LEN + 1) * 5];

static int show_cpuinfo(struct seq_file *m, void *v)
{
        int i = 0;

#if IS_ENABLED(CONFIG_SMP)
        i = (uintptr_t) v - 1;
        if (!cpu_online(i))
                return 0;
#endif

        seq_printf(m, "processor\t: %d\n", i);
        seq_printf(m, "vendor_id\t: User Mode Linux\n");
        seq_printf(m, "model name\t: UML\n");
        seq_printf(m, "mode\t\t: skas\n");
        seq_printf(m, "host\t\t: %s\n", host_info);
        seq_printf(m, "fpu\t\t: %s\n", str_yes_no(cpu_has(&boot_cpu_data, X86_FEATURE_FPU)));
        seq_printf(m, "flags\t\t:");
        for (i = 0; i < 32*NCAPINTS; i++)
                if (cpu_has(&boot_cpu_data, i) && (x86_cap_flags[i] != NULL))
                        seq_printf(m, " %s", x86_cap_flags[i]);
        seq_printf(m, "\n");
        seq_printf(m, "cache_alignment\t: %d\n", boot_cpu_data.cache_alignment);
        seq_printf(m, "bogomips\t: %lu.%02lu\n",
                   loops_per_jiffy/(500000/HZ),
                   (loops_per_jiffy/(5000/HZ)) % 100);

        return 0;
}

static void *c_start(struct seq_file *m, loff_t *pos)
{
        if (*pos < nr_cpu_ids)
                return (void *)(uintptr_t)(*pos + 1);
        return NULL;
}

static void *c_next(struct seq_file *m, void *v, loff_t *pos)
{
        ++*pos;
        return c_start(m, pos);
}

static void c_stop(struct seq_file *m, void *v)
{
}

const struct seq_operations cpuinfo_op = {
        .start  = c_start,
        .next   = c_next,
        .stop   = c_stop,
        .show   = show_cpuinfo,
};

/* Set in linux_main */
unsigned long uml_physmem;
EXPORT_SYMBOL(uml_physmem);

unsigned long uml_reserved; /* Also modified in mem_init */
unsigned long start_vm;
unsigned long end_vm;

/* Set in early boot */
static int have_root __initdata;
static int have_console __initdata;

/* Set in uml_mem_setup and modified in linux_main */
unsigned long long physmem_size = 64 * 1024 * 1024;
EXPORT_SYMBOL(physmem_size);

static const char *usage_string =
"User Mode Linux v%s\n"
"       available at http://user-mode-linux.sourceforge.net/\n\n";

static int __init uml_version_setup(char *line, int *add)
{
        /* Explicitly use printf() to show version in stdout */
        printf("%s\n", init_utsname()->release);
        exit(0);

        return 0;
}

__uml_setup("--version", uml_version_setup,
"--version\n"
"    Prints the version number of the kernel.\n\n"
);

static int __init uml_root_setup(char *line, int *add)
{
        have_root = 1;
        return 0;
}

__uml_setup("root=", uml_root_setup,
"root=<file containing the root fs>\n"
"    This is actually used by the generic kernel in exactly the same\n"
"    way as in any other kernel. If you configure a number of block\n"
"    devices and want to boot off something other than ubd0, you \n"
"    would use something like:\n"
"        root=/dev/ubd5\n\n"
);

static int __init uml_console_setup(char *line, int *add)
{
        have_console = 1;
        return 0;
}

__uml_setup("console=", uml_console_setup,
"console=<preferred console>\n"
"    Specify the preferred console output driver\n\n"
);

static int __init Usage(char *line, int *add)
{
        const char **p;

        printf(usage_string, init_utsname()->release);
        p = &__uml_help_start;
        /* Explicitly use printf() to show help in stdout */
        while (p < &__uml_help_end) {
                printf("%s", *p);
                p++;
        }
        exit(0);
        return 0;
}

__uml_setup("--help", Usage,
"--help\n"
"    Prints this message.\n\n"
);

static void __init uml_checksetup(char *line, int *add)
{
        struct uml_param *p;

        p = &__uml_setup_start;
        while (p < &__uml_setup_end) {
                size_t n;

                n = strlen(p->str);
                if (!strncmp(line, p->str, n) && p->setup_func(line + n, add))
                        return;
                p++;
        }
}

static void __init uml_postsetup(void)
{
        initcall_t *p;

        p = &__uml_postsetup_start;
        while (p < &__uml_postsetup_end) {
                (*p)();
                p++;
        }
        return;
}

static int panic_exit(struct notifier_block *self, unsigned long unused1,
                      void *unused2)
{
        kmsg_dump(KMSG_DUMP_PANIC);
        bust_spinlocks(1);
        bust_spinlocks(0);
        uml_exitcode = 1;
        os_dump_core();

        return NOTIFY_DONE;
}

static struct notifier_block panic_exit_notifier = {
        .notifier_call  = panic_exit,
        .priority       = INT_MAX - 1, /* run as 2nd notifier, won't return */
};

void uml_finishsetup(void)
{
        atomic_notifier_chain_register(&panic_notifier_list,
                                       &panic_exit_notifier);

        uml_postsetup();

        new_thread_handler();
}

/* Set during early boot */
unsigned long stub_start;
unsigned long task_size;
EXPORT_SYMBOL(task_size);

unsigned long brk_start;

#define MIN_VMALLOC (32 * 1024 * 1024)

static void __init parse_host_cpu_flags(char *line)
{
        int i;
        for (i = 0; i < 32*NCAPINTS; i++) {
                if ((x86_cap_flags[i] != NULL) && strstr(line, x86_cap_flags[i]))
                        set_cpu_cap(&boot_cpu_data, i);
        }
}

static void __init parse_cache_line(char *line)
{
        long res;
        char *to_parse = strstr(line, ":");
        if (to_parse) {
                to_parse++;
                while (*to_parse != 0 && isspace(*to_parse)) {
                        to_parse++;
                }
                if (kstrtoul(to_parse, 10, &res) == 0 && is_power_of_2(res))
                        boot_cpu_data.cache_alignment = res;
                else
                        boot_cpu_data.cache_alignment = L1_CACHE_BYTES;
        }
}

static unsigned long __init get_top_address(char **envp)
{
        unsigned long top_addr = (unsigned long) &top_addr;
        int i;

        /* The earliest variable should be after the program name in ELF */
        for (i = 0; envp[i]; i++) {
                if ((unsigned long) envp[i] > top_addr)
                        top_addr = (unsigned long) envp[i];
        }

        return PAGE_ALIGN(top_addr + 1);
}

int __init linux_main(int argc, char **argv, char **envp)
{
        unsigned long avail, diff;
        unsigned long virtmem_size, max_physmem;
        unsigned long host_task_size;
        unsigned long stack;
        unsigned int i;
        int add;

        for (i = 1; i < argc; i++) {
                if ((i == 1) && (argv[i][0] == ' '))
                        continue;
                add = 1;
                uml_checksetup(argv[i], &add);
                if (add)
                        add_arg(argv[i]);
        }
        if (have_root == 0)
                add_arg(DEFAULT_COMMAND_LINE_ROOT);

        if (have_console == 0)
                add_arg(DEFAULT_COMMAND_LINE_CONSOLE);

        host_task_size = get_top_address(envp);
        /* reserve a few pages for the stubs */
        stub_start = host_task_size - STUB_SIZE;
        host_task_size = stub_start;

        /* Limit TASK_SIZE to what is addressable by the page table */
        task_size = host_task_size;
        if (task_size > (unsigned long long) PTRS_PER_PGD * PGDIR_SIZE)
                task_size = PTRS_PER_PGD * PGDIR_SIZE;

        /*
         * TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
         * out
         */
        task_size = task_size & PGDIR_MASK;

        /* OS sanity checks that need to happen before the kernel runs */
        os_early_checks();

        get_host_cpu_features(parse_host_cpu_flags, parse_cache_line);

        brk_start = (unsigned long) sbrk(0);

        /*
         * Increase physical memory size for exec-shield users
         * so they actually get what they asked for. This should
         * add zero for non-exec shield users
         */
        diff = PAGE_ALIGN(brk_start) - PAGE_ALIGN((unsigned long) &_end);
        if (diff > 1024 * 1024) {
                os_info("Adding %ld bytes to physical memory to account for "
                        "exec-shield gap\n", diff);
                physmem_size += diff;
        }

        uml_physmem = (unsigned long) __binary_start & PAGE_MASK;

        /* Reserve up to 4M after the current brk */
        uml_reserved = ROUND_4M(brk_start) + (1 << 22);

        setup_machinename(init_utsname()->machine);

        physmem_size = PAGE_ALIGN(physmem_size);
        max_physmem = TASK_SIZE - uml_physmem - MIN_VMALLOC;
        if (physmem_size > max_physmem) {
                physmem_size = max_physmem;
                os_info("Physical memory size shrunk to %llu bytes\n",
                        physmem_size);
        }

        high_physmem = uml_physmem + physmem_size;

        start_vm = VMALLOC_START;

        virtmem_size = physmem_size;
        stack = (unsigned long) argv;
        stack &= ~(1024 * 1024 - 1);
        avail = stack - start_vm;
        if (physmem_size > avail)
                virtmem_size = avail;
        end_vm = start_vm + virtmem_size;

        if (virtmem_size < physmem_size)
                os_info("Kernel virtual memory size shrunk to %lu bytes\n",
                        virtmem_size);

        arch_task_struct_size = sizeof(struct task_struct) + host_fp_size;

        os_flush_stdout();

        return start_uml();
}

int __init __weak read_initrd(void)
{
        return 0;
}

void __init setup_arch(char **cmdline_p)
{
        u8 rng_seed[32];

        stack_protections((unsigned long) init_task.stack);
        setup_physmem(uml_physmem, uml_reserved, physmem_size);
        uml_dtb_init();
        read_initrd();

        paging_init();
        strscpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
        *cmdline_p = command_line;
        setup_hostinfo(host_info, sizeof host_info);
        prefill_possible_map();

        if (os_getrandom(rng_seed, sizeof(rng_seed), 0) == sizeof(rng_seed)) {
                add_bootloader_randomness(rng_seed, sizeof(rng_seed));
                memzero_explicit(rng_seed, sizeof(rng_seed));
        }
}

void __init arch_cpu_finalize_init(void)
{
        arch_check_bugs();
        os_check_bugs();
}

void apply_seal_endbr(s32 *start, s32 *end)
{
}

void apply_retpolines(s32 *start, s32 *end)
{
}

void apply_returns(s32 *start, s32 *end)
{
}

void apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
                   s32 *start_cfi, s32 *end_cfi)
{
}

void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
{
}

#if IS_ENABLED(CONFIG_SMP)
void alternatives_smp_module_add(struct module *mod, char *name,
                                 void *locks, void *locks_end,
                                 void *text,  void *text_end)
{
}

void alternatives_smp_module_del(struct module *mod)
{
}
#endif

void *text_poke(void *addr, const void *opcode, size_t len)
{
        /*
         * In UML, the only reference to this function is in
         * apply_relocate_add(), which shouldn't ever actually call this
         * because UML doesn't have live patching.
         */
        WARN_ON(1);

        return memcpy(addr, opcode, len);
}

void *text_poke_copy(void *addr, const void *opcode, size_t len)
{
        return text_poke(addr, opcode, len);
}

void smp_text_poke_sync_each_cpu(void)
{
}

void uml_pm_wake(void)
{
        pm_system_wakeup();
}

#ifdef CONFIG_PM_SLEEP
static int um_suspend_valid(suspend_state_t state)
{
        return state == PM_SUSPEND_MEM;
}

static int um_suspend_prepare(void)
{
        um_irqs_suspend();
        return 0;
}

static int um_suspend_enter(suspend_state_t state)
{
        if (WARN_ON(state != PM_SUSPEND_MEM))
                return -EINVAL;

        /*
         * This is identical to the idle sleep, but we've just
         * (during suspend) turned off all interrupt sources
         * except for the ones we want, so now we can only wake
         * up on something we actually want to wake up on. All
         * timing has also been suspended.
         */
        um_idle_sleep();
        return 0;
}

static void um_suspend_finish(void)
{
        um_irqs_resume();
}

const struct platform_suspend_ops um_suspend_ops = {
        .valid = um_suspend_valid,
        .prepare = um_suspend_prepare,
        .enter = um_suspend_enter,
        .finish = um_suspend_finish,
};

static int init_pm_wake_signal(void)
{
        /*
         * In external time-travel mode we can't use signals to wake up
         * since that would mess with the scheduling. We'll have to do
         * some additional work to support wakeup on virtio devices or
         * similar, perhaps implementing a fake RTC controller that can
         * trigger wakeup (and request the appropriate scheduling from
         * the external scheduler when going to suspend.)
         */
        if (time_travel_mode != TT_MODE_EXTERNAL)
                register_pm_wake_signal();

        suspend_set_ops(&um_suspend_ops);

        return 0;
}

late_initcall(init_pm_wake_signal);
#endif