// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include <asm/page.h>

extern char vdso_start[], vdso_end[];

static unsigned int vdso_pages;
static struct page **vdso_pagelist;

static int __init vdso_init(void)
{
        unsigned int i;

        vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
        vdso_pagelist =
                kzalloc_objs(struct page *, vdso_pages);
        if (unlikely(vdso_pagelist == NULL)) {
                pr_err("vdso: pagelist allocation failed\n");
                return -ENOMEM;
        }

        for (i = 0; i < vdso_pages; i++) {
                struct page *pg;

                pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
                vdso_pagelist[i] = pg;
        }

        return 0;
}
arch_initcall(vdso_init);

int arch_setup_additional_pages(struct linux_binprm *bprm,
        int uses_interp)
{
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
        unsigned long vdso_base, vdso_len;
        int ret;
        static struct vm_special_mapping vdso_mapping = {
                .name = "[vdso]",
        };

        vdso_len = vdso_pages << PAGE_SHIFT;

        mmap_write_lock(mm);
        vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
        if (IS_ERR_VALUE(vdso_base)) {
                ret = vdso_base;
                goto end;
        }

        /*
         * Put vDSO base into mm struct. We need to do this before calling
         * install_special_mapping or the perf counter mmap tracking code
         * will fail to recognise it as a vDSO (since arch_vma_name fails).
         */
        mm->context.vdso = (void *)vdso_base;

        vdso_mapping.pages = vdso_pagelist;
        vma =
           _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
                (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
                &vdso_mapping);

        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                mm->context.vdso = NULL;
                goto end;
        }

        vdso_base += (vdso_pages << PAGE_SHIFT);
        ret = 0;
end:
        mmap_write_unlock(mm);
        return ret;
}