Commit eeab78b0 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
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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: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 1ba2d6c0

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -129,6 +129,7 @@ config S390 
	select GENERIC_PTDUMP

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_TIME_VSYSCALL

	select GENERIC_VDSO_TIME_NS

	select HAVE_ALIGNED_STRUCT_PAGE if SLUB

	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_JUMP_LABEL

arch/s390/configs/zfcpdump_defconfig

+1 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ CONFIG_NO_HZ_IDLE=y 
CONFIG_HIGH_RES_TIMERS=y

# CONFIG_CPU_ISOLATION is not set

# CONFIG_UTS_NS is not set

# CONFIG_TIME_NS is not set

# CONFIG_PID_NS is not set

# CONFIG_NET_NS is not set

CONFIG_BLK_DEV_INITRD=y

arch/s390/include/asm/vdso.h

+2 −0
Original line number Diff line number Diff line
@@ -7,6 +7,8 @@ 
/* Default link address for the vDSO */

#define VDSO64_LBASE	0



#define __VVAR_PAGES	2



#define VDSO_VERSION_STRING	LINUX_2.6.29



#ifndef __ASSEMBLY__

arch/s390/include/asm/vdso/gettimeofday.h

+7 −0
Original line number Diff line number Diff line
@@ -67,4 +67,11 @@ long clock_getres_fallback(clockid_t clkid, struct __kernel_timespec *ts) 
	return r2;

}



#ifdef CONFIG_TIME_NS

static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)

{

	return _timens_data;

}

#endif



#endif

arch/s390/kernel/vdso.c

+95 −7
Original line number Diff line number Diff line
@@ -15,12 +15,15 @@ 
#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];
@@ -28,6 +31,12 @@ static union { 


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)
@@ -40,13 +49,90 @@ static int __init vdso_setup(char *str) 
}

__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)

{

	if (vmf->pgoff == 0)

		return vmf_insert_pfn(vma, vmf->address, virt_to_pfn(vdso_data));

	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);

}



static int vdso_mremap(const struct vm_special_mapping *sm,

		       struct vm_area_struct *vma)
@@ -80,23 +166,25 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
	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 + PAGE_SIZE;

	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, PAGE_SIZE,

				       VM_READ|VM_MAYREAD|VM_PFNMAP,

	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 + PAGE_SIZE;

	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|