/* * Copyright 2012 Tilera Corporation. All Rights Reserved. * *   This program is free software; you can redistribute it and/or *   modify it under the terms of the GNU General Public License *   as published by the Free Software Foundation, version 2. * *   This program is distributed in the hope that it will be useful, but *   WITHOUT ANY WARRANTY; without even the implied warranty of *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or *   NON INFRINGEMENT.  See the GNU General Public License for *   more details. */ #include <linux/binfmts.h>#include <linux/compat.h>#include <linux/elf.h>#include <linux/mm.h>#include <linux/pagemap.h> #include <asm/vdso.h>#include <asm/mman.h>#include <asm/sections.h> #include <arch/sim.h> /* The alignment of the vDSO. */#define VDSO_ALIGNMENT  PAGE_SIZE  static unsigned int vdso_pages;static struct page **vdso_pagelist; #ifdef CONFIG_COMPATstatic unsigned int vdso32_pages;static struct page **vdso32_pagelist;#endifstatic int vdso_ready; /* * The vdso data page. */static union {	struct vdso_data	data;	u8			page[PAGE_SIZE];} vdso_data_store __page_aligned_data; struct vdso_data *vdso_data = &vdso_data_store.data; static unsigned int __read_mostly vdso_enabled = 1; static struct page **vdso_setup(void *vdso_kbase, unsigned int pages){	int i;	struct page **pagelist; 	pagelist = kzalloc(sizeof(struct page *) * (pages + 1), GFP_KERNEL);	BUG_ON(pagelist == NULL);	for (i = 0; i < pages - 1; i++) {		struct page *pg = virt_to_page(vdso_kbase + i*PAGE_SIZE);		ClearPageReserved(pg);		pagelist[i] = pg;	}	pagelist[pages - 1] = virt_to_page(vdso_data);	pagelist[pages] = NULL; 	return pagelist;} static int __init vdso_init(void){	int data_pages = sizeof(vdso_data_store) >> PAGE_SHIFT; 	/*	 * We can disable vDSO support generally, but we need to retain	 * one page to support the two-bundle (16-byte) rt_sigreturn path.	 */	if (!vdso_enabled) {		size_t offset = (unsigned long)&__vdso_rt_sigreturn;		static struct page *sigret_page;		sigret_page = alloc_page(GFP_KERNEL | __GFP_ZERO);		BUG_ON(sigret_page == NULL);		vdso_pagelist = &sigret_page;		vdso_pages = 1;		BUG_ON(offset >= PAGE_SIZE);		memcpy(page_address(sigret_page) + offset,		       vdso_start + offset, 16);#ifdef CONFIG_COMPAT		vdso32_pages = vdso_pages;		vdso32_pagelist = vdso_pagelist;#endif		vdso_ready = 1;		return 0;	} 	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;	vdso_pages += data_pages;	vdso_pagelist = vdso_setup(vdso_start, vdso_pages); #ifdef CONFIG_COMPAT	vdso32_pages = (vdso32_end - vdso32_start) >> PAGE_SHIFT;	vdso32_pages += data_pages;	vdso32_pagelist = vdso_setup(vdso32_start, vdso32_pages);#endif 	smp_wmb();	vdso_ready = 1; 	return 0;}arch_initcall(vdso_init); const char *arch_vma_name(struct vm_area_struct *vma){	if (vma->vm_mm && vma->vm_start == VDSO_BASE)		return "[vdso]";#ifndef __tilegx__	if (vma->vm_start == MEM_USER_INTRPT)		return "[intrpt]";#endif	return NULL;} int setup_vdso_pages(void){	struct page **pagelist;	unsigned long pages;	struct mm_struct *mm = current->mm;	unsigned long vdso_base = 0;	int retval = 0; 	if (!vdso_ready)		return 0; 	mm->context.vdso_base = 0; 	pagelist = vdso_pagelist;	pages = vdso_pages;#ifdef CONFIG_COMPAT	if (is_compat_task()) {		pagelist = vdso32_pagelist;		pages = vdso32_pages;	}#endif 	/*	 * vDSO has a problem and was disabled, just don't "enable" it for the	 * process.	 */	if (pages == 0)		return 0; 	vdso_base = get_unmapped_area(NULL, vdso_base,				      (pages << PAGE_SHIFT) +				      ((VDSO_ALIGNMENT - 1) & PAGE_MASK),				      0, 0);	if (IS_ERR_VALUE(vdso_base)) {		retval = vdso_base;		return retval;	} 	/* Add required alignment. */	vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT); 	/*	 * 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_base = vdso_base; 	/*	 * our vma flags don't have VM_WRITE so by default, the process isn't	 * allowed to write those pages.	 * gdb can break that with ptrace interface, and thus trigger COW on	 * those pages but it's then your responsibility to never do that on	 * the "data" page of the vDSO or you'll stop getting kernel updates	 * and your nice userland gettimeofday will be totally dead.	 * It's fine to use that for setting breakpoints in the vDSO code	 * pages though	 */	retval = install_special_mapping(mm, vdso_base,					 pages << PAGE_SHIFT,					 VM_READ|VM_EXEC |					 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,					 pagelist);	if (retval)		mm->context.vdso_base = 0; 	return retval;} static __init int vdso_func(char *s){	return kstrtouint(s, 0, &vdso_enabled);}__setup("vdso=", vdso_func);