// SPDX-License-Identifier: GPL-2.0-only/* * Adapted from arm64 version. * * Copyright (C) 2012 ARM Limited * Copyright (C) 2015 Mentor Graphics Corporation. */ #include <linux/cache.h>#include <linux/vdso_datastore.h>#include <linux/elf.h>#include <linux/err.h>#include <linux/kernel.h>#include <linux/mm.h>#include <linux/of.h>#include <linux/printk.h>#include <linux/slab.h>#include <linux/vmalloc.h>#include <asm/arch_timer.h>#include <asm/barrier.h>#include <asm/cacheflush.h>#include <asm/page.h>#include <asm/vdso.h>#include <clocksource/arm_arch_timer.h>#include <vdso/helpers.h>#include <vdso/vsyscall.h> #define MAX_SYMNAME	64 static struct page **vdso_text_pagelist; extern char vdso_start[], vdso_end[]; /* Total number of pages needed for the data and text portions of the VDSO. */unsigned int vdso_total_pages __ro_after_init; static int vdso_mremap(const struct vm_special_mapping *sm,		struct vm_area_struct *new_vma){	current->mm->context.vdso = new_vma->vm_start; 	return 0;} static struct vm_special_mapping vdso_text_mapping __ro_after_init = {	.name = "[vdso]",	.mremap = vdso_mremap,}; struct elfinfo {	Elf32_Ehdr	*hdr;		/* ptr to ELF */	Elf32_Sym	*dynsym;	/* ptr to .dynsym section */	unsigned long	dynsymsize;	/* size of .dynsym section */	char		*dynstr;	/* ptr to .dynstr section */}; /* Boot-time check for whether the arch timer exists, and if so, * whether the virtual counter is usable. */static bool __init cntvct_functional(void){	struct device_node *np;	bool ret = false; 	if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))		goto out; 	/* The arm_arch_timer core should export	 * arch_timer_use_virtual or similar so we don't have to do	 * this.	 */	np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");	if (!np)		np = of_find_compatible_node(NULL, NULL, "arm,armv8-timer");	if (!np)		goto out_put; 	if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))		goto out_put; 	ret = true; out_put:	of_node_put(np);out:	return ret;} static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,				  unsigned long *size){	Elf32_Shdr *sechdrs;	unsigned int i;	char *secnames; 	/* Grab section headers and strings so we can tell who is who */	sechdrs = (void *)ehdr + ehdr->e_shoff;	secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset; 	/* Find the section they want */	for (i = 1; i < ehdr->e_shnum; i++) {		if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {			if (size)				*size = sechdrs[i].sh_size;			return (void *)ehdr + sechdrs[i].sh_offset;		}	} 	if (size)		*size = 0;	return NULL;} static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname){	unsigned int i; 	for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {		char name[MAX_SYMNAME], *c; 		if (lib->dynsym[i].st_name == 0)			continue;		strscpy(name, lib->dynstr + lib->dynsym[i].st_name,			MAX_SYMNAME);		c = strchr(name, '@');		if (c)			*c = 0;		if (strcmp(symname, name) == 0)			return &lib->dynsym[i];	}	return NULL;} static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname){	Elf32_Sym *sym; 	sym = find_symbol(lib, symname);	if (!sym)		return; 	sym->st_name = 0;} static void __init patch_vdso(void *ehdr){	struct elfinfo einfo; 	einfo = (struct elfinfo) {		.hdr = ehdr,	}; 	einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);	einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL); 	/* If the virtual counter is absent or non-functional we don't	 * want programs to incur the slight additional overhead of	 * dispatching through the VDSO only to fall back to syscalls.	 */	if (!cntvct_functional()) {		vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");		vdso_nullpatch_one(&einfo, "__vdso_clock_getres");		vdso_nullpatch_one(&einfo, "__vdso_clock_getres_time64");	}} static int __init vdso_init(void){	unsigned int text_pages;	int i; 	if (memcmp(vdso_start, "\177ELF", 4)) {		pr_err("VDSO is not a valid ELF object!\n");		return -ENOEXEC;	} 	text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; 	/* Allocate the VDSO text pagelist */	vdso_text_pagelist = kzalloc_objs(struct page *, text_pages);	if (vdso_text_pagelist == NULL)		return -ENOMEM; 	/* Grab the VDSO text pages. */	for (i = 0; i < text_pages; i++) {		struct page *page; 		page = virt_to_page(vdso_start + i * PAGE_SIZE);		vdso_text_pagelist[i] = page;	} 	vdso_text_mapping.pages = vdso_text_pagelist; 	vdso_total_pages = VDSO_NR_PAGES; /* for the data/vvar pages */	vdso_total_pages += text_pages; 	patch_vdso(vdso_start); 	return 0;}arch_initcall(vdso_init); static_assert(__VDSO_PAGES == VDSO_NR_PAGES); /* assumes mmap_lock is write-locked */void arm_install_vdso(struct mm_struct *mm, unsigned long addr){	struct vm_area_struct *vma;	unsigned long len; 	mm->context.vdso = 0; 	if (vdso_text_pagelist == NULL)		return; 	if (IS_ERR(vdso_install_vvar_mapping(mm, addr)))		return; 	/* Account for vvar pages. */	addr += VDSO_NR_PAGES * PAGE_SIZE;	len = (vdso_total_pages - VDSO_NR_PAGES) << PAGE_SHIFT; 	vma = _install_special_mapping(mm, addr, len,		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,		&vdso_text_mapping); 	if (!IS_ERR(vma))		mm->context.vdso = addr;}