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// SPDX-License-Identifier: GPL-2.0
/*
* vdso setup for s390
*
* Copyright IBM Corp. 2008
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#include <linux/binfmts.h>
#include <linux/compat.h>
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/time_namespace.h>
#include <vdso/datapage.h>
#include <asm/vdso.h>
extern char vdso64_start[], vdso64_end[];
static unsigned int vdso_pages;
static struct vm_special_mapping vvar_mapping;
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;
enum vvar_pages {
VVAR_DATA_PAGE_OFFSET,
VVAR_TIMENS_PAGE_OFFSET,
VVAR_NR_PAGES,
};
unsigned int __read_mostly vdso_enabled = 1;
static int __init vdso_setup(char *str)
{
bool enabled;
if (!kstrtobool(str, &enabled))
vdso_enabled = enabled;
return 1;
}
__setup("vdso=", vdso_setup);
#ifdef CONFIG_TIME_NS
struct vdso_data *arch_get_vdso_data(void *vvar_page)
{
return (struct vdso_data *)(vvar_page);
}
static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
{
if (likely(vma->vm_mm == current->mm))
return current->nsproxy->time_ns->vvar_page;
/*
* VM_PFNMAP | VM_IO protect .fault() handler from being called
* through interfaces like /proc/$pid/mem or
* process_vm_{readv,writev}() as long as there's no .access()
* in special_mapping_vmops().
* For more details check_vma_flags() and __access_remote_vm()
*/
WARN(1, "vvar_page accessed remotely");
return NULL;
}
/*
* The VVAR page layout depends on whether a task belongs to the root or
* non-root time namespace. Whenever a task changes its namespace, the VVAR
* page tables are cleared and then they will be re-faulted with a
* corresponding layout.
* See also the comment near timens_setup_vdso_data() for details.
*/
int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
{
struct mm_struct *mm = task->mm;
struct vm_area_struct *vma;
mmap_read_lock(mm);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
unsigned long size = vma->vm_end - vma->vm_start;
if (!vma_is_special_mapping(vma, &vvar_mapping))
continue;
zap_page_range(vma, vma->vm_start, size);
break;
}
mmap_read_unlock(mm);
return 0;
}
#else
static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
{
return NULL;
}
#endif
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *timens_page = find_timens_vvar_page(vma);
unsigned long addr, pfn;
vm_fault_t err;
switch (vmf->pgoff) {
case VVAR_DATA_PAGE_OFFSET:
pfn = virt_to_pfn(vdso_data);
if (timens_page) {
/*
* Fault in VVAR page too, since it will be accessed
* to get clock data anyway.
*/
addr = vmf->address + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE;
err = vmf_insert_pfn(vma, addr, pfn);
if (unlikely(err & VM_FAULT_ERROR))
return err;
pfn = page_to_pfn(timens_page);
}
break;
#ifdef CONFIG_TIME_NS
case VVAR_TIMENS_PAGE_OFFSET:
/*
* If a task belongs to a time namespace then a namespace
* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
* offset.
* See also the comment near timens_setup_vdso_data().
*/
if (!timens_page)
return VM_FAULT_SIGBUS;
pfn = virt_to_pfn(vdso_data);
break;
#endif /* CONFIG_TIME_NS */
default:
return VM_FAULT_SIGBUS;
}
return vmf_insert_pfn(vma, vmf->address, pfn);
}
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *vma)
{
current->mm->context.vdso_base = vma->vm_start;
return 0;
}
static struct vm_special_mapping vvar_mapping = {
.name = "[vvar]",
.fault = vvar_fault,
};
static struct vm_special_mapping vdso_mapping = {
.name = "[vdso]",
.mremap = vdso_mremap,
};
int vdso_getcpu_init(void)
{
set_tod_programmable_field(smp_processor_id());
return 0;
}
early_initcall(vdso_getcpu_init); /* Must be called before SMP init */
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
unsigned long vdso_text_len, vdso_mapping_len;
unsigned long vvar_start, vdso_text_start;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int rc;
BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
if (!vdso_enabled || is_compat_task())
return 0;
if (mmap_write_lock_killable(mm))
return -EINTR;
vdso_text_len = vdso_pages << PAGE_SHIFT;
vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE;
vvar_start = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
rc = vvar_start;
if (IS_ERR_VALUE(vvar_start))
goto out;
vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE,
VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
VM_PFNMAP,
&vvar_mapping);
rc = PTR_ERR(vma);
if (IS_ERR(vma))
goto out;
vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE;
/* VM_MAYWRITE for COW so gdb can set breakpoints */
vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&vdso_mapping);
if (IS_ERR(vma)) {
do_munmap(mm, vvar_start, PAGE_SIZE, NULL);
rc = PTR_ERR(vma);
} else {
current->mm->context.vdso_base = vdso_text_start;
rc = 0;
}
out:
mmap_write_unlock(mm);
return rc;
}
static int __init vdso_init(void)
{
struct page **pages;
int i;
vdso_pages = (vdso64_end - vdso64_start) >> PAGE_SHIFT;
pages = kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
if (!pages) {
vdso_enabled = 0;
return -ENOMEM;
}
for (i = 0; i < vdso_pages; i++)
pages[i] = virt_to_page(vdso64_start + i * PAGE_SIZE);
pages[vdso_pages] = NULL;
vdso_mapping.pages = pages;
return 0;
}
arch_initcall(vdso_init);
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