#include <linux/security.h>
#include <linux/memblock.h>
#include <linux/syscalls.h>
+#include <linux/time_namespace.h>
#include <vdso/datapage.h>
#include <asm/syscall.h>
} vdso_data_store __page_aligned_data;
struct vdso_arch_data *vdso_data = &vdso_data_store.data;
+enum vvar_pages {
+ VVAR_DATA_PAGE_OFFSET,
+ VVAR_TIMENS_PAGE_OFFSET,
+ VVAR_NR_PAGES,
+};
+
static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma,
unsigned long text_size)
{
return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start);
}
+static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
+ struct vm_area_struct *vma, struct vm_fault *vmf);
+
static struct vm_special_mapping vvar_spec __ro_after_init = {
.name = "[vvar]",
+ .fault = vvar_fault,
};
static struct vm_special_mapping vdso32_spec __ro_after_init = {
.mremap = vdso64_mremap,
};
+#ifdef CONFIG_TIME_NS
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+ return ((struct vdso_arch_data *)vvar_page)->data;
+}
+
+/*
+ * The vvar mapping contains data for a specific time namespace, so when a task
+ * changes namespace we must unmap its vvar data for the old namespace.
+ * Subsequent faults will map in data for the new namespace.
+ *
+ * For more details see timens_setup_vdso_data().
+ */
+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_spec))
+ zap_page_range(vma, vma->vm_start, size);
+ }
+
+ mmap_read_unlock(mm);
+ return 0;
+}
+
+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;
+}
+#else
+static 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 pfn;
+
+ switch (vmf->pgoff) {
+ case VVAR_DATA_PAGE_OFFSET:
+ if (timens_page)
+ pfn = page_to_pfn(timens_page);
+ else
+ pfn = virt_to_pfn(vdso_data);
+ 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);
+}
+
/*
* This is called from binfmt_elf, we create the special vma for the
* vDSO and insert it into the mm struct tree
{
unsigned long vdso_size, vdso_base, mappings_size;
struct vm_special_mapping *vdso_spec;
- unsigned long vvar_size = PAGE_SIZE;
+ unsigned long vvar_size = VVAR_NR_PAGES * PAGE_SIZE;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
return pagelist;
}
-static struct page ** __init vvar_setup_pages(void)
-{
- struct page **pagelist;
-
- /* .pages is NULL-terminated */
- pagelist = kcalloc(2, sizeof(struct page *), GFP_KERNEL);
- if (!pagelist)
- panic("%s: Cannot allocate page list for VVAR", __func__);
-
- pagelist[0] = virt_to_page(vdso_data);
- return pagelist;
-}
-
static int __init vdso_init(void)
{
#ifdef CONFIG_PPC64
if (IS_ENABLED(CONFIG_PPC64))
vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end);
- vvar_spec.pages = vvar_setup_pages();
-
smp_wmb();
return 0;
projects / platform / kernel / linux-starfive.git / commitdiff