// SPDX-License-Identifier: GPL-2.0
#include <linux/capability.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/proc_fs.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/init.h>

#define LINE_SIZE 80

#include <asm/mtrr.h>

#include "mtrr.h"

#define FILE_FCOUNT(f) (((struct seq_file *)((f)->private_data))->private)

static const char *const mtrr_strings[MTRR_NUM_TYPES] =
{
        "uncachable",           /* 0 */
        "write-combining",      /* 1 */
        "?",                    /* 2 */
        "?",                    /* 3 */
        "write-through",        /* 4 */
        "write-protect",        /* 5 */
        "write-back",           /* 6 */
};

const char *mtrr_attrib_to_str(int x)
{
        return (x <= 6) ? mtrr_strings[x] : "?";
}

#ifdef CONFIG_PROC_FS

static int
mtrr_file_add(unsigned long base, unsigned long size,
              unsigned int type, bool increment, struct file *file, int page)
{
        unsigned int *fcount = FILE_FCOUNT(file);
        int reg, max;

        max = num_var_ranges;
        if (fcount == NULL) {
                fcount = kcalloc(max, sizeof(*fcount), GFP_KERNEL);
                if (!fcount)
                        return -ENOMEM;
                FILE_FCOUNT(file) = fcount;
        }
        if (!page) {
                if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1)))
                        return -EINVAL;
                base >>= PAGE_SHIFT;
                size >>= PAGE_SHIFT;
        }
        reg = mtrr_add_page(base, size, type, true);
        if (reg >= 0)
                ++fcount[reg];
        return reg;
}

static int
mtrr_file_del(unsigned long base, unsigned long size,
              struct file *file, int page)
{
        unsigned int *fcount = FILE_FCOUNT(file);
        int reg;

        if (!page) {
                if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1)))
                        return -EINVAL;
                base >>= PAGE_SHIFT;
                size >>= PAGE_SHIFT;
        }
        reg = mtrr_del_page(-1, base, size);
        if (reg < 0)
                return reg;
        if (fcount == NULL)
                return reg;
        if (fcount[reg] < 1)
                return -EINVAL;
        --fcount[reg];
        return reg;
}

/*
 * seq_file can seek but we ignore it.
 *
 * Format of control line:
 *    "base=%Lx size=%Lx type=%s" or "disable=%d"
 */
static ssize_t
mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
{
        int i, err;
        unsigned long reg;
        unsigned long long base, size;
        char *ptr;
        char line[LINE_SIZE];
        int length;

        memset(line, 0, LINE_SIZE);

        len = min_t(size_t, len, LINE_SIZE - 1);
        length = strncpy_from_user(line, buf, len);
        if (length < 0)
                return length;

        ptr = line + length - 1;
        if (length && *ptr == '\n')
                *ptr = '\0';

        if (!strncmp(line, "disable=", 8)) {
                reg = simple_strtoul(line + 8, &ptr, 0);
                err = mtrr_del_page(reg, 0, 0);
                if (err < 0)
                        return err;
                return len;
        }

        if (strncmp(line, "base=", 5))
                return -EINVAL;

        base = simple_strtoull(line + 5, &ptr, 0);
        ptr = skip_spaces(ptr);

        if (strncmp(ptr, "size=", 5))
                return -EINVAL;

        size = simple_strtoull(ptr + 5, &ptr, 0);
        if ((base & 0xfff) || (size & 0xfff))
                return -EINVAL;
        ptr = skip_spaces(ptr);

        if (strncmp(ptr, "type=", 5))
                return -EINVAL;
        ptr = skip_spaces(ptr + 5);

        i = match_string(mtrr_strings, MTRR_NUM_TYPES, ptr);
        if (i < 0)
                return i;

        base >>= PAGE_SHIFT;
        size >>= PAGE_SHIFT;
        err = mtrr_add_page((unsigned long)base, (unsigned long)size, i, true);
        if (err < 0)
                return err;
        return len;
}

static long
mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
{
        int err = 0;
        mtrr_type type;
        unsigned long base;
        unsigned long size;
        struct mtrr_sentry sentry;
        struct mtrr_gentry gentry;
        void __user *arg = (void __user *) __arg;

        memset(&gentry, 0, sizeof(gentry));

        switch (cmd) {
        case MTRRIOC_ADD_ENTRY:
        case MTRRIOC_SET_ENTRY:
        case MTRRIOC_DEL_ENTRY:
        case MTRRIOC_KILL_ENTRY:
        case MTRRIOC_ADD_PAGE_ENTRY:
        case MTRRIOC_SET_PAGE_ENTRY:
        case MTRRIOC_DEL_PAGE_ENTRY:
        case MTRRIOC_KILL_PAGE_ENTRY:
                if (copy_from_user(&sentry, arg, sizeof(sentry)))
                        return -EFAULT;
                break;
        case MTRRIOC_GET_ENTRY:
        case MTRRIOC_GET_PAGE_ENTRY:
                if (copy_from_user(&gentry, arg, sizeof(gentry)))
                        return -EFAULT;
                break;
#ifdef CONFIG_COMPAT
        case MTRRIOC32_ADD_ENTRY:
        case MTRRIOC32_SET_ENTRY:
        case MTRRIOC32_DEL_ENTRY:
        case MTRRIOC32_KILL_ENTRY:
        case MTRRIOC32_ADD_PAGE_ENTRY:
        case MTRRIOC32_SET_PAGE_ENTRY:
        case MTRRIOC32_DEL_PAGE_ENTRY:
        case MTRRIOC32_KILL_PAGE_ENTRY: {
                struct mtrr_sentry32 __user *s32;

                s32 = (struct mtrr_sentry32 __user *)__arg;
                err = get_user(sentry.base, &s32->base);
                err |= get_user(sentry.size, &s32->size);
                err |= get_user(sentry.type, &s32->type);
                if (err)
                        return err;
                break;
        }
        case MTRRIOC32_GET_ENTRY:
        case MTRRIOC32_GET_PAGE_ENTRY: {
                struct mtrr_gentry32 __user *g32;

                g32 = (struct mtrr_gentry32 __user *)__arg;
                err = get_user(gentry.regnum, &g32->regnum);
                err |= get_user(gentry.base, &g32->base);
                err |= get_user(gentry.size, &g32->size);
                err |= get_user(gentry.type, &g32->type);
                if (err)
                        return err;
                break;
        }
#endif
        }

        switch (cmd) {
        default:
                return -ENOTTY;
        case MTRRIOC_ADD_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_ADD_ENTRY:
#endif
                err =
                    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
                                  file, 0);
                break;
        case MTRRIOC_SET_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_SET_ENTRY:
#endif
                err = mtrr_add(sentry.base, sentry.size, sentry.type, false);
                break;
        case MTRRIOC_DEL_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_DEL_ENTRY:
#endif
                err = mtrr_file_del(sentry.base, sentry.size, file, 0);
                break;
        case MTRRIOC_KILL_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_KILL_ENTRY:
#endif
                err = mtrr_del(-1, sentry.base, sentry.size);
                break;
        case MTRRIOC_GET_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_GET_ENTRY:
#endif
                if (gentry.regnum >= num_var_ranges)
                        return -EINVAL;
                mtrr_if->get(gentry.regnum, &base, &size, &type);

                /* Hide entries that go above 4GB */
                if (base + size - 1 >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT))
                    || size >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT)))
                        gentry.base = gentry.size = gentry.type = 0;
                else {
                        gentry.base = base << PAGE_SHIFT;
                        gentry.size = size << PAGE_SHIFT;
                        gentry.type = type;
                }

                break;
        case MTRRIOC_ADD_PAGE_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_ADD_PAGE_ENTRY:
#endif
                err =
                    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
                                  file, 1);
                break;
        case MTRRIOC_SET_PAGE_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_SET_PAGE_ENTRY:
#endif
                err =
                    mtrr_add_page(sentry.base, sentry.size, sentry.type, false);
                break;
        case MTRRIOC_DEL_PAGE_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_DEL_PAGE_ENTRY:
#endif
                err = mtrr_file_del(sentry.base, sentry.size, file, 1);
                break;
        case MTRRIOC_KILL_PAGE_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_KILL_PAGE_ENTRY:
#endif
                err = mtrr_del_page(-1, sentry.base, sentry.size);
                break;
        case MTRRIOC_GET_PAGE_ENTRY:
#ifdef CONFIG_COMPAT
        case MTRRIOC32_GET_PAGE_ENTRY:
#endif
                if (gentry.regnum >= num_var_ranges)
                        return -EINVAL;
                mtrr_if->get(gentry.regnum, &base, &size, &type);
                /* Hide entries that would overflow */
                if (size != (__typeof__(gentry.size))size)
                        gentry.base = gentry.size = gentry.type = 0;
                else {
                        gentry.base = base;
                        gentry.size = size;
                        gentry.type = type;
                }
                break;
        }

        if (err)
                return err;

        switch (cmd) {
        case MTRRIOC_GET_ENTRY:
        case MTRRIOC_GET_PAGE_ENTRY:
                if (copy_to_user(arg, &gentry, sizeof(gentry)))
                        err = -EFAULT;
                break;
#ifdef CONFIG_COMPAT
        case MTRRIOC32_GET_ENTRY:
        case MTRRIOC32_GET_PAGE_ENTRY: {
                struct mtrr_gentry32 __user *g32;

                g32 = (struct mtrr_gentry32 __user *)__arg;
                err = put_user(gentry.base, &g32->base);
                err |= put_user(gentry.size, &g32->size);
                err |= put_user(gentry.regnum, &g32->regnum);
                err |= put_user(gentry.type, &g32->type);
                break;
        }
#endif
        }
        return err;
}

static int mtrr_close(struct inode *ino, struct file *file)
{
        unsigned int *fcount = FILE_FCOUNT(file);
        int i, max;

        if (fcount != NULL) {
                max = num_var_ranges;
                for (i = 0; i < max; ++i) {
                        while (fcount[i] > 0) {
                                mtrr_del(i, 0, 0);
                                --fcount[i];
                        }
                }
                kfree(fcount);
                FILE_FCOUNT(file) = NULL;
        }
        return single_release(ino, file);
}

static int mtrr_seq_show(struct seq_file *seq, void *offset)
{
        char factor;
        int i, max;
        mtrr_type type;
        unsigned long base, size;

        max = num_var_ranges;
        for (i = 0; i < max; i++) {
                mtrr_if->get(i, &base, &size, &type);
                if (size == 0) {
                        mtrr_usage_table[i] = 0;
                        continue;
                }
                if (size < (0x100000 >> PAGE_SHIFT)) {
                        /* less than 1MB */
                        factor = 'K';
                        size <<= PAGE_SHIFT - 10;
                } else {
                        factor = 'M';
                        size >>= 20 - PAGE_SHIFT;
                }
                /* Base can be > 32bit */
                seq_printf(seq, "reg%02i: base=0x%06lx000 (%5luMB), size=%5lu%cB, count=%d: %s\n",
                           i, base, base >> (20 - PAGE_SHIFT),
                           size, factor,
                           mtrr_usage_table[i], mtrr_attrib_to_str(type));
        }
        return 0;
}

static int mtrr_open(struct inode *inode, struct file *file)
{
        if (!mtrr_if)
                return -EIO;
        if (!mtrr_if->get)
                return -ENXIO;
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        return single_open(file, mtrr_seq_show, NULL);
}

static const struct proc_ops mtrr_proc_ops = {
        .proc_open              = mtrr_open,
        .proc_read              = seq_read,
        .proc_lseek             = seq_lseek,
        .proc_write             = mtrr_write,
        .proc_ioctl             = mtrr_ioctl,
#ifdef CONFIG_COMPAT
        .proc_compat_ioctl      = mtrr_ioctl,
#endif
        .proc_release           = mtrr_close,
};

static int __init mtrr_if_init(void)
{
        struct cpuinfo_x86 *c = &boot_cpu_data;

        if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
            (!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
            (!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
            (!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
                return -ENODEV;

        proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_proc_ops);
        return 0;
}
arch_initcall(mtrr_if_init);
#endif                  /*  CONFIG_PROC_FS  */