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linux/arch/arm64/kernel/vdso.c
Mark Rutland 1d09094aa6 arm64: vdso: use consistent 'map' nomenclature 
The current code doesn't use a consistent naming scheme for structures,
enums, or variables, making it harder than necessary to determine the
relationship between these.

Let's make this easier by consistently using 'map' nomenclature for
mappings created in userspace, minimizing redundant comments, and
using designated array initializers to tie indices to their respective
elements.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200428164921.41641-5-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2020-04-29 10:52:53 +01:00

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// 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 */
enum vdso_abi {
VDSO_ABI_AA64,
#ifdef CONFIG_COMPAT_VDSO
VDSO_ABI_AA32,
#endif /* CONFIG_COMPAT_VDSO */
};
struct vdso_abi_info {
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_info vdso_info[] __ro_after_init = {
[VDSO_ABI_AA64] = {
.name = "vdso",
.vdso_code_start = vdso_start,
.vdso_code_end = vdso_end,
},
#ifdef CONFIG_COMPAT_VDSO
[VDSO_ABI_AA32] = {
.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 vdso_abi abi,
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_info[abi].vdso_code_end -
vdso_info[abi].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 vdso_abi abi)
{
int i;
struct page **vdso_pagelist;
unsigned long pfn;
if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) {
pr_err("vDSO is not a valid ELF object!\n");
return -EINVAL;
}
vdso_info[abi].vdso_pages = (
vdso_info[abi].vdso_code_end -
vdso_info[abi].vdso_code_start) >>
PAGE_SHIFT;
/* Allocate the vDSO pagelist, plus a page for the data. */
vdso_pagelist = kcalloc(vdso_info[abi].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_info[abi].vdso_code_start);
for (i = 0; i < vdso_info[abi].vdso_pages; i++)
vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
vdso_info[abi].dm->pages = &vdso_pagelist[0];
vdso_info[abi].cm->pages = &vdso_pagelist[1];
return 0;
}
static int __setup_additional_pages(enum vdso_abi abi,
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_info[abi].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_info[abi].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_info[abi].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(VDSO_ABI_AA32, sm, new_vma);
}
#endif /* CONFIG_COMPAT_VDSO */
enum aarch32_map {
AA32_MAP_VECTORS, /* kuser helpers */
#ifdef CONFIG_COMPAT_VDSO
AA32_MAP_VVAR,
AA32_MAP_VDSO,
#else
AA32_MAP_SIGPAGE
#endif
};
static struct page *aarch32_vectors_page __ro_after_init;
#ifndef CONFIG_COMPAT_VDSO
static struct page *aarch32_sig_page __ro_after_init;
#endif
static struct vm_special_mapping aarch32_vdso_maps[] = {
[AA32_MAP_VECTORS] = {
.name = "[vectors]", /* ABI */
.pages = &aarch32_vectors_page,
},
#ifdef CONFIG_COMPAT_VDSO
[AA32_MAP_VVAR] = {
.name = "[vvar]",
},
[AA32_MAP_VDSO] = {
.name = "[vdso]",
.mremap = aarch32_vdso_mremap,
},
#else
[AA32_MAP_SIGPAGE] = {
.name = "[sigpage]", /* ABI */
.pages = &aarch32_sig_page,
},
#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_vectors_page = virt_to_page(vdso_page);
flush_dcache_page(aarch32_vectors_page);
return 0;
}
#ifdef CONFIG_COMPAT_VDSO
static int __aarch32_alloc_vdso_pages(void)
{
int ret;
vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR];
vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO];
ret = __vdso_init(VDSO_ABI_AA32);
if (ret)
return ret;
return aarch32_alloc_kuser_vdso_page();
}
#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_sig_page = virt_to_page(sigpage);
flush_dcache_page(aarch32_sig_page);
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_maps[AA32_MAP_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_maps[AA32_MAP_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(VDSO_ABI_AA32,
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(VDSO_ABI_AA64, sm, new_vma);
}
enum aarch64_map {
AA64_MAP_VVAR,
AA64_MAP_VDSO,
};
static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = {
[AA64_MAP_VVAR] = {
.name = "[vvar]",
},
[AA64_MAP_VDSO] = {
.name = "[vdso]",
.mremap = vdso_mremap,
},
};
static int __init vdso_init(void)
{
vdso_info[VDSO_ABI_AA64].dm = &aarch64_vdso_maps[AA64_MAP_VVAR];
vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_maps[AA64_MAP_VDSO];
return __vdso_init(VDSO_ABI_AA64);
}
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(VDSO_ABI_AA64,
mm,
bprm,
uses_interp);
up_write(&mm->mmap_sem);
return ret;
}
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