// 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;}