// SPDX-License-Identifier: GPL-2.0/* *  Copyright (c) 2022 Helge Deller <deller@gmx.de> * *  based on arch/s390/kernel/vdso.c which is *  Copyright IBM Corp. 2008 *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) */ #include <linux/kernel.h>#include <linux/mm.h>#include <linux/slab.h>#include <linux/elf.h>#include <linux/timekeeper_internal.h>#include <linux/compat.h>#include <linux/nsproxy.h>#include <linux/time_namespace.h>#include <linux/random.h> #include <asm/pgtable.h>#include <asm/page.h>#include <asm/sections.h>#include <asm/vdso.h>#include <asm/cacheflush.h> extern char vdso32_start, vdso32_end;extern char vdso64_start, vdso64_end; static int vdso_mremap(const struct vm_special_mapping *sm,		       struct vm_area_struct *vma){	current->mm->context.vdso_base = vma->vm_start;	return 0;} #ifdef CONFIG_64BITstatic struct vm_special_mapping vdso64_mapping = {	.name = "[vdso]",	.mremap = vdso_mremap,};#endif static struct vm_special_mapping vdso32_mapping = {	.name = "[vdso]",	.mremap = vdso_mremap,}; /* * This is called from binfmt_elf, we create the special vma for the * vDSO and insert it into the mm struct tree */int arch_setup_additional_pages(struct linux_binprm *bprm,				int executable_stack){ 	unsigned long vdso_text_start, vdso_text_len, map_base;	struct vm_special_mapping *vdso_mapping;	struct mm_struct *mm = current->mm;	struct vm_area_struct *vma;	int rc; 	if (mmap_write_lock_killable(mm))		return -EINTR; #ifdef CONFIG_64BIT	if (!is_compat_task()) {		vdso_text_len = &vdso64_end - &vdso64_start;		vdso_mapping = &vdso64_mapping;	} else#endif	{		vdso_text_len = &vdso32_end - &vdso32_start;		vdso_mapping = &vdso32_mapping;	} 	map_base = mm->mmap_base;	if (current->flags & PF_RANDOMIZE)		map_base -= get_random_u32_below(0x20) * PAGE_SIZE; 	vdso_text_start = get_unmapped_area(NULL, map_base, vdso_text_len, 0, 0); 	/* VM_MAYWRITE for COW so gdb can set breakpoints */	vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,				       VM_READ|VM_EXEC|				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,				       vdso_mapping);	if (IS_ERR(vma)) {		do_munmap(mm, vdso_text_start, PAGE_SIZE, NULL);		rc = PTR_ERR(vma);	} else {		current->mm->context.vdso_base = vdso_text_start;		rc = 0;	} 	mmap_write_unlock(mm);	return rc;} static struct page ** __init vdso_setup_pages(void *start, void *end){	int pages = (end - start) >> PAGE_SHIFT;	struct page **pagelist;	int i; 	pagelist = kzalloc_objs(struct page *, pages + 1);	if (!pagelist)		panic("%s: Cannot allocate page list for VDSO", __func__);	for (i = 0; i < pages; i++)		pagelist[i] = virt_to_page(start + i * PAGE_SIZE);	return pagelist;} static int __init vdso_init(void){#ifdef CONFIG_64BIT	vdso64_mapping.pages = vdso_setup_pages(&vdso64_start, &vdso64_end);#endif	if (IS_ENABLED(CONFIG_COMPAT) || !IS_ENABLED(CONFIG_64BIT))		vdso32_mapping.pages = vdso_setup_pages(&vdso32_start, &vdso32_end);	return 0;}arch_initcall(vdso_init);