linux/arch/arm/kernel/vdso.c
Anna-Maria Behnsen a0d2fcd62a vdso/ARM: Make union vdso_data_store available for all architectures
The vDSO data page "union vdso_data_store" is defined in an ARM specific
header file and also defined in several other places.

Move the definition from the ARM header file into the generic vdso datapage
header to make it also usable for others and to prevent code duplication.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240219153939.75719-5-anna-maria@linutronix.de
2024-02-20 20:56:00 +01:00

257 lines
5.8 KiB
C

// 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/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/timekeeper_internal.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 union vdso_data_store vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = vdso_data_store.data;
static struct page *vdso_data_page __ro_after_init;
static const struct vm_special_mapping vdso_data_mapping = {
.name = "[vvar]",
.pages = &vdso_data_page,
};
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 */
};
/* Cached result of boot-time check for whether the arch timer exists,
* and if so, whether the virtual counter is useable.
*/
bool cntvct_ok __ro_after_init;
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_ok) {
vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
}
}
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 = kcalloc(text_pages, sizeof(struct page *),
GFP_KERNEL);
if (vdso_text_pagelist == NULL)
return -ENOMEM;
/* Grab the VDSO data page. */
vdso_data_page = virt_to_page(vdso_data);
/* 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 = 1; /* for the data/vvar page */
vdso_total_pages += text_pages;
cntvct_ok = cntvct_functional();
patch_vdso(vdso_start);
return 0;
}
arch_initcall(vdso_init);
static int install_vvar(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma;
vma = _install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_MAYREAD,
&vdso_data_mapping);
return PTR_ERR_OR_ZERO(vma);
}
/* 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 (install_vvar(mm, addr))
return;
/* Account for vvar page. */
addr += PAGE_SIZE;
len = (vdso_total_pages - 1) << 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;
}