// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
 */

#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <asm/elf.h>
#include <linux/init.h>

unsigned long um_vdso_addr;
static struct page *um_vdso;

extern unsigned long task_size;
extern char vdso_start[], vdso_end[];

static int __init init_vdso(void)
{
        BUG_ON(vdso_end - vdso_start > PAGE_SIZE);

        um_vdso_addr = task_size - PAGE_SIZE;

        um_vdso = alloc_page(GFP_KERNEL);
        if (!um_vdso)
                panic("Cannot allocate vdso\n");

        copy_page(page_address(um_vdso), vdso_start);

        return 0;
}
subsys_initcall(init_vdso);

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
        static struct vm_special_mapping vdso_mapping = {
                .name = "[vdso]",
                .pages = &um_vdso,
        };

        if (mmap_write_lock_killable(mm))
                return -EINTR;

        vma = _install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
                VM_READ|VM_EXEC|
                VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
                &vdso_mapping);

        mmap_write_unlock(mm);

        return IS_ERR(vma) ? PTR_ERR(vma) : 0;
}