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s390/vdso: implement generic vdso time namespace support
Implement generic vdso time namespace support which also enables time namespaces for s390. This is quite similar to what arm64 has. Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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@ -129,6 +129,7 @@ config S390
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select GENERIC_PTDUMP
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select GENERIC_SMP_IDLE_THREAD
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select GENERIC_TIME_VSYSCALL
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select GENERIC_VDSO_TIME_NS
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select HAVE_ALIGNED_STRUCT_PAGE if SLUB
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select HAVE_ARCH_AUDITSYSCALL
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select HAVE_ARCH_JUMP_LABEL
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@ -3,6 +3,7 @@ CONFIG_NO_HZ_IDLE=y
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CONFIG_HIGH_RES_TIMERS=y
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# CONFIG_CPU_ISOLATION is not set
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# CONFIG_UTS_NS is not set
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# CONFIG_TIME_NS is not set
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# CONFIG_PID_NS is not set
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# CONFIG_NET_NS is not set
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CONFIG_BLK_DEV_INITRD=y
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@ -7,6 +7,8 @@
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/* Default link address for the vDSO */
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#define VDSO64_LBASE 0
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#define __VVAR_PAGES 2
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#define VDSO_VERSION_STRING LINUX_2.6.29
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#ifndef __ASSEMBLY__
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@ -67,4 +67,11 @@ long clock_getres_fallback(clockid_t clkid, struct __kernel_timespec *ts)
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return r2;
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}
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#ifdef CONFIG_TIME_NS
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static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
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{
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return _timens_data;
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}
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#endif
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#endif
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@ -15,12 +15,15 @@
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/smp.h>
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#include <linux/time_namespace.h>
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#include <vdso/datapage.h>
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#include <asm/vdso.h>
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extern char vdso64_start[], vdso64_end[];
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static unsigned int vdso_pages;
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static struct vm_special_mapping vvar_mapping;
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static union {
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struct vdso_data data[CS_BASES];
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u8 page[PAGE_SIZE];
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@ -28,6 +31,12 @@ static union {
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struct vdso_data *vdso_data = vdso_data_store.data;
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enum vvar_pages {
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VVAR_DATA_PAGE_OFFSET,
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VVAR_TIMENS_PAGE_OFFSET,
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VVAR_NR_PAGES,
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};
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unsigned int __read_mostly vdso_enabled = 1;
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static int __init vdso_setup(char *str)
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@ -40,12 +49,89 @@ static int __init vdso_setup(char *str)
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}
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__setup("vdso=", vdso_setup);
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#ifdef CONFIG_TIME_NS
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struct vdso_data *arch_get_vdso_data(void *vvar_page)
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{
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return (struct vdso_data *)(vvar_page);
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}
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static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
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{
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if (likely(vma->vm_mm == current->mm))
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return current->nsproxy->time_ns->vvar_page;
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/*
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* VM_PFNMAP | VM_IO protect .fault() handler from being called
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* through interfaces like /proc/$pid/mem or
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* process_vm_{readv,writev}() as long as there's no .access()
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* in special_mapping_vmops().
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* For more details check_vma_flags() and __access_remote_vm()
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*/
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WARN(1, "vvar_page accessed remotely");
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return NULL;
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}
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/*
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* The VVAR page layout depends on whether a task belongs to the root or
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* non-root time namespace. Whenever a task changes its namespace, the VVAR
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* page tables are cleared and then they will be re-faulted with a
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* corresponding layout.
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* See also the comment near timens_setup_vdso_data() for details.
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*/
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int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
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{
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struct mm_struct *mm = task->mm;
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struct vm_area_struct *vma;
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mmap_read_lock(mm);
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for (vma = mm->mmap; vma; vma = vma->vm_next) {
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unsigned long size = vma->vm_end - vma->vm_start;
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if (!vma_is_special_mapping(vma, &vvar_mapping))
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continue;
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zap_page_range(vma, vma->vm_start, size);
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break;
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}
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mmap_read_unlock(mm);
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return 0;
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}
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#else
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static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
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{
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return NULL;
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}
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#endif
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static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
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struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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if (vmf->pgoff == 0)
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return vmf_insert_pfn(vma, vmf->address, virt_to_pfn(vdso_data));
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return VM_FAULT_SIGBUS;
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struct page *timens_page = find_timens_vvar_page(vma);
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unsigned long pfn;
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switch (vmf->pgoff) {
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case VVAR_DATA_PAGE_OFFSET:
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if (timens_page)
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pfn = page_to_pfn(timens_page);
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else
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pfn = virt_to_pfn(vdso_data);
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break;
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#ifdef CONFIG_TIME_NS
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case VVAR_TIMENS_PAGE_OFFSET:
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/*
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* If a task belongs to a time namespace then a namespace
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* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
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* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
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* offset.
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* See also the comment near timens_setup_vdso_data().
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*/
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if (!timens_page)
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return VM_FAULT_SIGBUS;
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pfn = virt_to_pfn(vdso_data);
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break;
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#endif /* CONFIG_TIME_NS */
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default:
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return VM_FAULT_SIGBUS;
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}
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return vmf_insert_pfn(vma, vmf->address, pfn);
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}
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static int vdso_mremap(const struct vm_special_mapping *sm,
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@ -80,23 +166,25 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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struct vm_area_struct *vma;
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int rc;
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BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
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if (!vdso_enabled || is_compat_task())
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return 0;
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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vdso_text_len = vdso_pages << PAGE_SHIFT;
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vdso_mapping_len = vdso_text_len + PAGE_SIZE;
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vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE;
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vvar_start = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
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rc = vvar_start;
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if (IS_ERR_VALUE(vvar_start))
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goto out;
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vma = _install_special_mapping(mm, vvar_start, PAGE_SIZE,
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VM_READ|VM_MAYREAD|VM_PFNMAP,
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vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE,
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VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
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VM_PFNMAP,
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&vvar_mapping);
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rc = PTR_ERR(vma);
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if (IS_ERR(vma))
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goto out;
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vdso_text_start = vvar_start + PAGE_SIZE;
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vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE;
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/* VM_MAYWRITE for COW so gdb can set breakpoints */
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vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
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VM_READ|VM_EXEC|
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@ -13,7 +13,10 @@ ENTRY(_start)
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SECTIONS
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{
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PROVIDE(_vdso_data = . - PAGE_SIZE);
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PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
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#ifdef CONFIG_TIME_NS
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PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
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#endif
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. = VDSO64_LBASE + SIZEOF_HEADERS;
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.hash : { *(.hash) } :text
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