linux/arch/arm64/kernel/vdso.c

433 lines
9.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* VDSO implementations.
*
* Copyright (C) 2012 ARM Limited
*
* Author: Will Deacon <will.deacon@arm.com>
*/
#include <linux/cache.h>
#include <linux/clocksource.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>
#include <linux/vmalloc.h>
#include <vdso/datapage.h>
#include <vdso/helpers.h>
#include <vdso/vsyscall.h>
#include <asm/cacheflush.h>
#include <asm/signal32.h>
#include <asm/vdso.h>
extern char vdso_start[], vdso_end[];
#ifdef CONFIG_COMPAT_VDSO
extern char vdso32_start[], vdso32_end[];
#endif /* CONFIG_COMPAT_VDSO */
/* vdso_lookup arch_index */
enum arch_vdso_type {
ARM64_VDSO = 0,
#ifdef CONFIG_COMPAT_VDSO
ARM64_VDSO32 = 1,
#endif /* CONFIG_COMPAT_VDSO */
};
#ifdef CONFIG_COMPAT_VDSO
#define VDSO_TYPES (ARM64_VDSO32 + 1)
#else
#define VDSO_TYPES (ARM64_VDSO + 1)
#endif /* CONFIG_COMPAT_VDSO */
struct __vdso_abi {
const char *name;
const char *vdso_code_start;
const char *vdso_code_end;
unsigned long vdso_pages;
/* Data Mapping */
struct vm_special_mapping *dm;
/* Code Mapping */
struct vm_special_mapping *cm;
};
static struct __vdso_abi vdso_lookup[VDSO_TYPES] __ro_after_init = {
{
.name = "vdso",
.vdso_code_start = vdso_start,
.vdso_code_end = vdso_end,
},
#ifdef CONFIG_COMPAT_VDSO
{
.name = "vdso32",
.vdso_code_start = vdso32_start,
.vdso_code_end = vdso32_end,
},
#endif /* CONFIG_COMPAT_VDSO */
};
/*
* The vDSO data page.
*/
static union {
struct vdso_data data[CS_BASES];
u8 page[PAGE_SIZE];
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = vdso_data_store.data;
static int __vdso_remap(enum arch_vdso_type arch_index,
const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
unsigned long vdso_size = vdso_lookup[arch_index].vdso_code_end -
vdso_lookup[arch_index].vdso_code_start;
if (vdso_size != new_size)
return -EINVAL;
current->mm->context.vdso = (void *)new_vma->vm_start;
return 0;
}
static int __vdso_init(enum arch_vdso_type arch_index)
{
int i;
struct page **vdso_pagelist;
unsigned long pfn;
if (memcmp(vdso_lookup[arch_index].vdso_code_start, "\177ELF", 4)) {
pr_err("vDSO is not a valid ELF object!\n");
return -EINVAL;
}
vdso_lookup[arch_index].vdso_pages = (
vdso_lookup[arch_index].vdso_code_end -
vdso_lookup[arch_index].vdso_code_start) >>
PAGE_SHIFT;
/* Allocate the vDSO pagelist, plus a page for the data. */
vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages + 1,
sizeof(struct page *),
GFP_KERNEL);
if (vdso_pagelist == NULL)
return -ENOMEM;
/* Grab the vDSO data page. */
vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
/* Grab the vDSO code pages. */
pfn = sym_to_pfn(vdso_lookup[arch_index].vdso_code_start);
for (i = 0; i < vdso_lookup[arch_index].vdso_pages; i++)
vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
vdso_lookup[arch_index].dm->pages = &vdso_pagelist[0];
vdso_lookup[arch_index].cm->pages = &vdso_pagelist[1];
return 0;
}
static int __setup_additional_pages(enum arch_vdso_type arch_index,
struct mm_struct *mm,
struct linux_binprm *bprm,
int uses_interp)
{
unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
void *ret;
vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT;
/* Be sure to map the data page */
vdso_mapping_len = vdso_text_len + PAGE_SIZE;
vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
ret = ERR_PTR(vdso_base);
goto up_fail;
}
ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_MAYREAD,
vdso_lookup[arch_index].dm);
if (IS_ERR(ret))
goto up_fail;
vdso_base += PAGE_SIZE;
mm->context.vdso = (void *)vdso_base;
ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_lookup[arch_index].cm);
if (IS_ERR(ret))
goto up_fail;
return 0;
up_fail:
mm->context.vdso = NULL;
return PTR_ERR(ret);
}
#ifdef CONFIG_COMPAT
/*
* Create and map the vectors page for AArch32 tasks.
*/
#ifdef CONFIG_COMPAT_VDSO
static int aarch32_vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
return __vdso_remap(ARM64_VDSO32, sm, new_vma);
}
#endif /* CONFIG_COMPAT_VDSO */
/*
* aarch32_vdso_pages:
* 0 - kuser helpers
* 1 - sigreturn code
* or (CONFIG_COMPAT_VDSO):
* 0 - kuser helpers
* 1 - vdso data
* 2 - vdso code
*/
#define C_VECTORS 0
#ifdef CONFIG_COMPAT_VDSO
#define C_VVAR 1
#define C_VDSO 2
#define C_PAGES (C_VDSO + 1)
#else
#define C_SIGPAGE 1
#define C_PAGES (C_SIGPAGE + 1)
#endif /* CONFIG_COMPAT_VDSO */
static struct page *aarch32_vdso_pages[C_PAGES] __ro_after_init;
static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
{
.name = "[vectors]", /* ABI */
.pages = &aarch32_vdso_pages[C_VECTORS],
},
#ifdef CONFIG_COMPAT_VDSO
{
.name = "[vvar]",
},
{
.name = "[vdso]",
.mremap = aarch32_vdso_mremap,
},
#else
{
.name = "[sigpage]", /* ABI */
.pages = &aarch32_vdso_pages[C_SIGPAGE],
},
#endif /* CONFIG_COMPAT_VDSO */
};
static int aarch32_alloc_kuser_vdso_page(void)
{
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
unsigned long vdso_page;
if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
return 0;
vdso_page = get_zeroed_page(GFP_ATOMIC);
if (!vdso_page)
return -ENOMEM;
memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start,
kuser_sz);
aarch32_vdso_pages[C_VECTORS] = virt_to_page(vdso_page);
flush_dcache_page(aarch32_vdso_pages[C_VECTORS]);
return 0;
}
#ifdef CONFIG_COMPAT_VDSO
static int __aarch32_alloc_vdso_pages(void)
{
int ret;
vdso_lookup[ARM64_VDSO32].dm = &aarch32_vdso_spec[C_VVAR];
vdso_lookup[ARM64_VDSO32].cm = &aarch32_vdso_spec[C_VDSO];
ret = __vdso_init(ARM64_VDSO32);
if (ret)
return ret;
ret = aarch32_alloc_kuser_vdso_page();
if (ret) {
unsigned long c_vvar =
(unsigned long)page_to_virt(aarch32_vdso_pages[C_VVAR]);
unsigned long c_vdso =
(unsigned long)page_to_virt(aarch32_vdso_pages[C_VDSO]);
free_page(c_vvar);
free_page(c_vdso);
}
return ret;
}
#else
static int __aarch32_alloc_vdso_pages(void)
{
extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
unsigned long sigpage;
int ret;
sigpage = get_zeroed_page(GFP_ATOMIC);
if (!sigpage)
return -ENOMEM;
memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz);
aarch32_vdso_pages[C_SIGPAGE] = virt_to_page(sigpage);
flush_dcache_page(aarch32_vdso_pages[C_SIGPAGE]);
ret = aarch32_alloc_kuser_vdso_page();
if (ret)
free_page(sigpage);
return ret;
}
#endif /* CONFIG_COMPAT_VDSO */
static int __init aarch32_alloc_vdso_pages(void)
{
return __aarch32_alloc_vdso_pages();
}
arch_initcall(aarch32_alloc_vdso_pages);
static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
{
void *ret;
if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
return 0;
/*
* Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's
* not safe to CoW the page containing the CPU exception vectors.
*/
ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE,
VM_READ | VM_EXEC |
VM_MAYREAD | VM_MAYEXEC,
&aarch32_vdso_spec[C_VECTORS]);
return PTR_ERR_OR_ZERO(ret);
}
#ifndef CONFIG_COMPAT_VDSO
static int aarch32_sigreturn_setup(struct mm_struct *mm)
{
unsigned long addr;
void *ret;
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = ERR_PTR(addr);
goto out;
}
/*
* VM_MAYWRITE is required to allow gdb to Copy-on-Write and
* set breakpoints.
*/
ret = _install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC | VM_MAYREAD |
VM_MAYWRITE | VM_MAYEXEC,
&aarch32_vdso_spec[C_SIGPAGE]);
if (IS_ERR(ret))
goto out;
mm->context.vdso = (void *)addr;
out:
return PTR_ERR_OR_ZERO(ret);
}
#endif /* !CONFIG_COMPAT_VDSO */
int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
int ret;
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
ret = aarch32_kuser_helpers_setup(mm);
if (ret)
goto out;
#ifdef CONFIG_COMPAT_VDSO
ret = __setup_additional_pages(ARM64_VDSO32,
mm,
bprm,
uses_interp);
#else
ret = aarch32_sigreturn_setup(mm);
#endif /* CONFIG_COMPAT_VDSO */
out:
up_write(&mm->mmap_sem);
return ret;
}
#endif /* CONFIG_COMPAT */
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
return __vdso_remap(ARM64_VDSO, sm, new_vma);
}
/*
* aarch64_vdso_pages:
* 0 - vvar
* 1 - vdso
*/
#define A_VVAR 0
#define A_VDSO 1
#define A_PAGES (A_VDSO + 1)
static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = {
{
.name = "[vvar]",
},
{
.name = "[vdso]",
.mremap = vdso_mremap,
},
};
static int __init vdso_init(void)
{
vdso_lookup[ARM64_VDSO].dm = &vdso_spec[A_VVAR];
vdso_lookup[ARM64_VDSO].cm = &vdso_spec[A_VDSO];
return __vdso_init(ARM64_VDSO);
}
arch_initcall(vdso_init);
int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
int ret;
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
ret = __setup_additional_pages(ARM64_VDSO,
mm,
bprm,
uses_interp);
up_write(&mm->mmap_sem);
return ret;
}