// SPDX-License-Identifier: GPL-2.0
/*  Copyright(c) 2016-20 Intel Corporation. */

#include <linux/acpi.h>
#include <linux/miscdevice.h>
#include <linux/mman.h>
#include <linux/security.h>
#include <linux/suspend.h>
#include <asm/traps.h>
#include "driver.h"
#include "encl.h"

u64 sgx_attributes_reserved_mask;
u64 sgx_xfrm_reserved_mask = ~0x3;
u32 sgx_misc_reserved_mask;

static int __sgx_open(struct inode *inode, struct file *file)
{
        struct sgx_encl *encl;
        int ret;

        encl = kzalloc_obj(*encl);
        if (!encl)
                return -ENOMEM;

        kref_init(&encl->refcount);
        xa_init(&encl->page_array);
        mutex_init(&encl->lock);
        INIT_LIST_HEAD(&encl->va_pages);
        INIT_LIST_HEAD(&encl->mm_list);
        spin_lock_init(&encl->mm_lock);

        ret = init_srcu_struct(&encl->srcu);
        if (ret) {
                kfree(encl);
                return ret;
        }

        file->private_data = encl;

        return 0;
}

static int sgx_open(struct inode *inode, struct file *file)
{
        int ret;

        ret = sgx_inc_usage_count();
        if (ret)
                return ret;

        ret = __sgx_open(inode, file);
        if (ret) {
                sgx_dec_usage_count();
                return ret;
        }

        return 0;
}

static int sgx_release(struct inode *inode, struct file *file)
{
        struct sgx_encl *encl = file->private_data;
        struct sgx_encl_mm *encl_mm;

        /*
         * Drain the remaining mm_list entries. At this point the list contains
         * entries for processes, which have closed the enclave file but have
         * not exited yet. The processes, which have exited, are gone from the
         * list by sgx_mmu_notifier_release().
         */
        for ( ; ; )  {
                spin_lock(&encl->mm_lock);

                if (list_empty(&encl->mm_list)) {
                        encl_mm = NULL;
                } else {
                        encl_mm = list_first_entry(&encl->mm_list,
                                                   struct sgx_encl_mm, list);
                        list_del_rcu(&encl_mm->list);
                }

                spin_unlock(&encl->mm_lock);

                /* The enclave is no longer mapped by any mm. */
                if (!encl_mm)
                        break;

                synchronize_srcu(&encl->srcu);
                mmu_notifier_unregister(&encl_mm->mmu_notifier, encl_mm->mm);
                kfree(encl_mm);

                /* 'encl_mm' is gone, put encl_mm->encl reference: */
                kref_put(&encl->refcount, sgx_encl_release);
        }

        kref_put(&encl->refcount, sgx_encl_release);
        return 0;
}

static int sgx_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct sgx_encl *encl = file->private_data;
        int ret;

        ret = sgx_encl_may_map(encl, vma->vm_start, vma->vm_end, vma->vm_flags);
        if (ret)
                return ret;

        ret = sgx_encl_mm_add(encl, vma->vm_mm);
        if (ret)
                return ret;

        vma->vm_ops = &sgx_vm_ops;
        vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO);
        vma->vm_private_data = encl;

        return 0;
}

static unsigned long sgx_get_unmapped_area(struct file *file,
                                           unsigned long addr,
                                           unsigned long len,
                                           unsigned long pgoff,
                                           unsigned long flags)
{
        if ((flags & MAP_TYPE) == MAP_PRIVATE)
                return -EINVAL;

        if (flags & MAP_FIXED)
                return addr;

        return mm_get_unmapped_area(file, addr, len, pgoff, flags);
}

#ifdef CONFIG_COMPAT
static long sgx_compat_ioctl(struct file *filep, unsigned int cmd,
                              unsigned long arg)
{
        return sgx_ioctl(filep, cmd, arg);
}
#endif

static const struct file_operations sgx_encl_fops = {
        .owner                  = THIS_MODULE,
        .open                   = sgx_open,
        .release                = sgx_release,
        .unlocked_ioctl         = sgx_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl           = sgx_compat_ioctl,
#endif
        .mmap                   = sgx_mmap,
        .get_unmapped_area      = sgx_get_unmapped_area,
};

static struct miscdevice sgx_dev_enclave = {
        .minor = MISC_DYNAMIC_MINOR,
        .name = "sgx_enclave",
        .nodename = "sgx_enclave",
        .fops = &sgx_encl_fops,
};

int __init sgx_drv_init(void)
{
        unsigned int eax, ebx, ecx, edx;
        u64 attr_mask;
        u64 xfrm_mask;
        int ret;

        if (!cpu_feature_enabled(X86_FEATURE_SGX_LC)) {
                pr_info("SGX disabled: SGX launch control CPU feature is not available, /dev/sgx_enclave disabled.\n");
                return -ENODEV;
        }

        cpuid_count(SGX_CPUID, 0, &eax, &ebx, &ecx, &edx);

        if (!(eax & 1))  {
                pr_info("SGX disabled: SGX1 instruction support not available, /dev/sgx_enclave disabled.\n");
                return -ENODEV;
        }

        sgx_misc_reserved_mask = ~ebx | SGX_MISC_RESERVED_MASK;

        cpuid_count(SGX_CPUID, 1, &eax, &ebx, &ecx, &edx);

        attr_mask = (((u64)ebx) << 32) + (u64)eax;
        sgx_attributes_reserved_mask = ~attr_mask | SGX_ATTR_RESERVED_MASK;

        if (cpu_feature_enabled(X86_FEATURE_OSXSAVE)) {
                xfrm_mask = (((u64)edx) << 32) + (u64)ecx;
                sgx_xfrm_reserved_mask = ~xfrm_mask;
        }

        ret = misc_register(&sgx_dev_enclave);
        if (ret) {
                pr_info("SGX disabled: Unable to register the /dev/sgx_enclave driver (%d).\n", ret);
                return ret;
        }

        return 0;
}