// SPDX-License-Identifier: GPL-2.0-only
/*
 * vDSO implementation for Hexagon
 *
 * Copyright (c) 2011, The Linux Foundation. All rights reserved.
 */

#include <linux/err.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/binfmts.h>

#include <asm/elf.h>
#include <asm/vdso.h>

static struct page *vdso_page;

/* Create a vDSO page holding the signal trampoline.
 * We want this for a non-executable stack.
 */
static int __init vdso_init(void)
{
        struct hexagon_vdso *vdso;

        vdso_page = alloc_page(GFP_KERNEL);
        if (!vdso_page)
                panic("Cannot allocate vdso");

        vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
        if (!vdso)
                panic("Cannot map vdso");
        clear_page(vdso);

        /* Install the signal trampoline; currently looks like this:
         *      r6 = #__NR_rt_sigreturn;
         *      trap0(#1);
         */
        vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0];
        vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1];

        vunmap(vdso);

        return 0;
}
arch_initcall(vdso_init);

/*
 * Called from binfmt_elf.  Create a VMA for the vDSO page.
 */
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
        int ret;
        unsigned long vdso_base;
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
        static struct vm_special_mapping vdso_mapping = {
                .name = "[vdso]",
        };

        if (mmap_write_lock_killable(mm))
                return -EINTR;

        /* Try to get it loaded right near ld.so/glibc. */
        vdso_base = STACK_TOP;

        vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0);
        if (IS_ERR_VALUE(vdso_base)) {
                ret = vdso_base;
                goto up_fail;
        }

        /* MAYWRITE to allow gdb to COW and set breakpoints. */
        vdso_mapping.pages = &vdso_page;
        vma = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
                                      VM_READ|VM_EXEC|
                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
                                      &vdso_mapping);

        ret = PTR_ERR(vma);
        if (IS_ERR(vma))
                goto up_fail;

        mm->context.vdso = (void *)vdso_base;
        ret = 0;
up_fail:
        mmap_write_unlock(mm);
        return ret;
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
        if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
                return "[vdso]";
        return NULL;
}