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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/linkage.h>
#include <linux/mmap_lock.h>
#include <linux/mm.h>
#include <linux/time_namespace.h>
#include <linux/types.h>
#include <linux/vdso_datastore.h>
#include <vdso/datapage.h>
/*
* The vDSO data page.
*/
#ifdef CONFIG_HAVE_GENERIC_VDSO
static union {
struct vdso_time_data data;
u8 page[PAGE_SIZE];
} vdso_time_data_store __page_aligned_data;
struct vdso_time_data *vdso_k_time_data = &vdso_time_data_store.data;
static_assert(sizeof(vdso_time_data_store) == PAGE_SIZE);
#endif /* CONFIG_HAVE_GENERIC_VDSO */
#ifdef CONFIG_VDSO_GETRANDOM
static union {
struct vdso_rng_data data;
u8 page[PAGE_SIZE];
} vdso_rng_data_store __page_aligned_data;
struct vdso_rng_data *vdso_k_rng_data = &vdso_rng_data_store.data;
static_assert(sizeof(vdso_rng_data_store) == PAGE_SIZE);
#endif /* CONFIG_VDSO_GETRANDOM */
#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA
static union {
struct vdso_arch_data data;
u8 page[VDSO_ARCH_DATA_SIZE];
} vdso_arch_data_store __page_aligned_data;
struct vdso_arch_data *vdso_k_arch_data = &vdso_arch_data_store.data;
#endif /* CONFIG_ARCH_HAS_VDSO_ARCH_DATA */
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 VDSO_TIME_PAGE_OFFSET:
if (!IS_ENABLED(CONFIG_HAVE_GENERIC_VDSO))
return VM_FAULT_SIGBUS;
pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data));
if (timens_page) {
/*
* Fault in VVAR page too, since it will be accessed
* to get clock data anyway.
*/
addr = vmf->address + VDSO_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;
case VDSO_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 (!IS_ENABLED(CONFIG_TIME_NS) || !timens_page)
return VM_FAULT_SIGBUS;
pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data));
break;
case VDSO_RNG_PAGE_OFFSET:
if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
return VM_FAULT_SIGBUS;
pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data));
break;
case VDSO_ARCH_PAGES_START ... VDSO_ARCH_PAGES_END:
if (!IS_ENABLED(CONFIG_ARCH_HAS_VDSO_ARCH_DATA))
return VM_FAULT_SIGBUS;
pfn = __phys_to_pfn(__pa_symbol(vdso_k_arch_data)) +
vmf->pgoff - VDSO_ARCH_PAGES_START;
break;
default:
return VM_FAULT_SIGBUS;
}
return vmf_insert_pfn(vma, vmf->address, pfn);
}
const struct vm_special_mapping vdso_vvar_mapping = {
.name = "[vvar]",
.fault = vvar_fault,
};
struct vm_area_struct *vdso_install_vvar_mapping(struct mm_struct *mm, unsigned long addr)
{
return _install_special_mapping(mm, addr, VDSO_NR_PAGES * PAGE_SIZE,
VM_READ | VM_MAYREAD | VM_IO | VM_DONTDUMP |
VM_PFNMAP | VM_SEALED_SYSMAP,
&vdso_vvar_mapping);
}
#ifdef CONFIG_TIME_NS
/*
* 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_clock_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;
VMA_ITERATOR(vmi, mm, 0);
mmap_read_lock(mm);
for_each_vma(vmi, vma) {
if (vma_is_special_mapping(vma, &vdso_vvar_mapping))
zap_vma_pages(vma);
}
mmap_read_unlock(mm);
return 0;
}
#endif
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