15 files changed, 207 insertions, 84 deletions

diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 67a60016bab..fa9905ce7d0 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -27,6 +27,8 @@ int main(void)
 	DEFINE(__TI_flags, offsetof(struct thread_info, flags));
 	DEFINE(__TI_cpu, offsetof(struct thread_info, cpu));
 	DEFINE(__TI_precount, offsetof(struct thread_info, preempt_count));
+	DEFINE(__TI_user_timer, offsetof(struct thread_info, user_timer));
+	DEFINE(__TI_system_timer, offsetof(struct thread_info, system_timer));
 	BLANK();
 	DEFINE(__PT_ARGS, offsetof(struct pt_regs, args));
 	DEFINE(__PT_PSW, offsetof(struct pt_regs, psw));
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 6cc87d8c868..002c70d3cb7 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -702,20 +702,12 @@ asmlinkage long sys32_fstatat64(unsigned int dfd, char __user *filename,
 				struct stat64_emu31 __user* statbuf, int flag)
 {
 	struct kstat stat;
-	int error = -EINVAL;
-
-	if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
-		goto out;
-
-	if (flag & AT_SYMLINK_NOFOLLOW)
-		error = vfs_lstat_fd(dfd, filename, &stat);
-	else
-		error = vfs_stat_fd(dfd, filename, &stat);
+	int error;
 
-	if (!error)
-		error = cp_stat64(statbuf, &stat);
-out:
-	return error;
+	error = vfs_fstatat(dfd, filename, &stat, flag);
+	if (error)
+		return error;
+	return cp_stat64(statbuf, &stat);
 }
 
 /*
diff --git a/arch/s390/kernel/compat_wrapper.S b/arch/s390/kernel/compat_wrapper.S
index 87cf5a79a35..fb38af6316b 100644
--- a/arch/s390/kernel/compat_wrapper.S
+++ b/arch/s390/kernel/compat_wrapper.S
@@ -1805,3 +1805,21 @@ compat_sys_keyctl_wrapper:
 	llgfr	%r5,%r5			# u32
 	llgfr	%r6,%r6			# u32
 	jg	compat_sys_keyctl	# branch to system call
+
+	.globl	compat_sys_preadv_wrapper
+compat_sys_preadv_wrapper:
+	llgfr	%r2,%r2			# unsigned long
+	llgtr	%r3,%r3			# compat_iovec *
+	llgfr	%r4,%r4			# unsigned long
+	llgfr	%r5,%r5			# u32
+	llgfr	%r6,%r6			# u32
+	jg	compat_sys_preadv	# branch to system call
+
+	.globl	compat_sys_pwritev_wrapper
+compat_sys_pwritev_wrapper:
+	llgfr	%r2,%r2			# unsigned long
+	llgtr	%r3,%r3			# compat_iovec *
+	llgfr	%r4,%r4			# unsigned long
+	llgfr	%r5,%r5			# u32
+	llgfr	%r6,%r6			# u32
+	jg	compat_sys_pwritev	# branch to system call
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 4d221c81c84..cf09948faad 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -34,8 +34,25 @@
 
 char kernel_nss_name[NSS_NAME_SIZE + 1];
 
+static unsigned long machine_flags;
+
 static void __init setup_boot_command_line(void);
 
+/*
+ * Get the TOD clock running.
+ */
+static void __init reset_tod_clock(void)
+{
+	u64 time;
+
+	if (store_clock(&time) == 0)
+		return;
+	/* TOD clock not running. Set the clock to Unix Epoch. */
+	if (set_clock(TOD_UNIX_EPOCH) != 0 || store_clock(&time) != 0)
+		disabled_wait(0);
+
+	sched_clock_base_cc = TOD_UNIX_EPOCH;
+}
 
 #ifdef CONFIG_SHARED_KERNEL
 int __init savesys_ipl_nss(char *cmd, const int cmdlen);
@@ -370,6 +387,7 @@ static void __init setup_boot_command_line(void)
  */
 void __init startup_init(void)
 {
+	reset_tod_clock();
 	ipl_save_parameters();
 	rescue_initrd();
 	clear_bss_section();
@@ -391,5 +409,6 @@ void __init startup_init(void)
 	setup_hpage();
 	sclp_facilities_detect();
 	detect_memory_layout(memory_chunk);
+	S390_lowcore.machine_flags = machine_flags;
 	lockdep_on();
 }
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 1268aa2991b..f3e27593421 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -837,16 +837,29 @@ mcck_return:
 	__CPUINIT
 	.globl restart_int_handler
 restart_int_handler:
+	basr	%r1,0
+restart_base:
+	spt	restart_vtime-restart_base(%r1)
+	stck	__LC_LAST_UPDATE_CLOCK
+	mvc	__LC_LAST_UPDATE_TIMER(8),restart_vtime-restart_base(%r1)
+	mvc	__LC_EXIT_TIMER(8),restart_vtime-restart_base(%r1)
 	l	%r15,__LC_SAVE_AREA+60	# load ksp
 	lctl	%c0,%c15,__LC_CREGS_SAVE_AREA # get new ctl regs
 	lam	%a0,%a15,__LC_AREGS_SAVE_AREA
 	lm	%r6,%r15,__SF_GPRS(%r15) # load registers from clone
+	l	%r1,__LC_THREAD_INFO
+	mvc	__LC_USER_TIMER(8),__TI_user_timer(%r1)
+	mvc	__LC_SYSTEM_TIMER(8),__TI_system_timer(%r1)
+	xc	__LC_STEAL_TIMER(8),__LC_STEAL_TIMER
 	stosm	__SF_EMPTY(%r15),0x04	# now we can turn dat on
 	basr	%r14,0
 	l	%r14,restart_addr-.(%r14)
 	br	%r14			# branch to start_secondary
 restart_addr:
 	.long	start_secondary
+	.align	8
+restart_vtime:
+	.long	0x7fffffff,0xffffffff
 	.previous
 #else
 /*
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index c6fbde13971..84a105838e0 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -831,14 +831,27 @@ mcck_return:
 	__CPUINIT
 	.globl restart_int_handler
 restart_int_handler:
+	basr	%r1,0
+restart_base:
+	spt	restart_vtime-restart_base(%r1)
+	stck	__LC_LAST_UPDATE_CLOCK
+	mvc	__LC_LAST_UPDATE_TIMER(8),restart_vtime-restart_base(%r1)
+	mvc	__LC_EXIT_TIMER(8),restart_vtime-restart_base(%r1)
 	lg	%r15,__LC_SAVE_AREA+120 # load ksp
 	lghi	%r10,__LC_CREGS_SAVE_AREA
 	lctlg	%c0,%c15,0(%r10) # get new ctl regs
 	lghi	%r10,__LC_AREGS_SAVE_AREA
 	lam	%a0,%a15,0(%r10)
 	lmg	%r6,%r15,__SF_GPRS(%r15) # load registers from clone
+	lg	%r1,__LC_THREAD_INFO
+	mvc	__LC_USER_TIMER(8),__TI_user_timer(%r1)
+	mvc	__LC_SYSTEM_TIMER(8),__TI_system_timer(%r1)
+	xc	__LC_STEAL_TIMER(8),__LC_STEAL_TIMER
 	stosm	__SF_EMPTY(%r15),0x04	# now we can turn dat on
 	jg	start_secondary
+	.align	8
+restart_vtime:
+	.long	0x7fffffff,0xffffffff
 	.previous
 #else
 /*
diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index 1046c2c9f8d..22596d70fc2 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -23,6 +23,7 @@
  *
  */
 
+#include <linux/init.h>
 #include <asm/setup.h>
 #include <asm/lowcore.h>
 #include <asm/asm-offsets.h>
@@ -35,7 +36,7 @@
 #define ARCH_OFFSET	0
 #endif
 
-.section ".text.head","ax"
+__HEAD
 #ifndef CONFIG_IPL
 	.org   0
 	.long  0x00080000,0x80000000+startup	# Just a restart PSW
@@ -471,7 +472,12 @@ startup:basr	%r13,0			# get base
 .LPG0:
 	xc	0x200(256),0x200	# partially clear lowcore
 	xc	0x300(256),0x300
-
+	l	%r1,5f-.LPG0(%r13)
+	stck	0(%r1)
+	spt	6f-.LPG0(%r13)
+	mvc	__LC_LAST_UPDATE_CLOCK(8),0(%r1)
+	mvc	__LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
+	mvc	__LC_EXIT_TIMER(8),5f-.LPG0(%r13)
 #ifndef CONFIG_MARCH_G5
 	# check processor version against MARCH_{G5,Z900,Z990,Z9_109,Z10}
 	stidp	__LC_CPUID		# store cpuid
@@ -496,9 +502,13 @@ startup:basr	%r13,0			# get base
 	brct	%r0,0b
 #endif
 
-	l	%r13,0f-.LPG0(%r13)
+	l	%r13,4f-.LPG0(%r13)
 	b	0(%r13)
-0:	.long	startup_continue
+	.align	4
+4:	.long	startup_continue
+5:	.long	sched_clock_base_cc
+	.align	8
+6:	.long	0x7fffffff,0xffffffff
 
 #
 # params at 10400 (setup.h)
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 6f3711a0eaa..b8bf4b14006 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -23,6 +23,7 @@
 #include <asm/ebcdic.h>
 #include <asm/reset.h>
 #include <asm/sclp.h>
+#include <asm/sigp.h>
 #include <asm/checksum.h>
 
 #define IPL_PARM_BLOCK_VERSION 0
diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 4bfdc421d7e..28cf196ba77 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -10,6 +10,7 @@
 
 #include <linux/init.h>
 #include <linux/errno.h>
+#include <linux/hardirq.h>
 #include <linux/time.h>
 #include <linux/module.h>
 #include <asm/lowcore.h>
@@ -253,7 +254,7 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 	struct mci *mci;
 	int umode;
 
-	lockdep_off();
+	nmi_enter();
 	s390_idle_check();
 
 	mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
@@ -363,7 +364,7 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 		mcck->warning = 1;
 		set_thread_flag(TIF_MCCK_PENDING);
 	}
-	lockdep_on();
+	nmi_exit();
 }
 
 static int __init machine_check_init(void)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 06201b93cbb..7402b6a39ea 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -82,9 +82,6 @@ EXPORT_SYMBOL(console_devno);
 unsigned int console_irq = -1;
 EXPORT_SYMBOL(console_irq);
 
-unsigned long machine_flags;
-EXPORT_SYMBOL(machine_flags);
-
 unsigned long elf_hwcap = 0;
 char elf_platform[ELF_PLATFORM_SIZE];
 
@@ -426,6 +423,7 @@ setup_lowcore(void)
 		__alloc_bootmem(PAGE_SIZE, PAGE_SIZE, 0) + PAGE_SIZE;
 	lc->current_task = (unsigned long) init_thread_union.thread_info.task;
 	lc->thread_info = (unsigned long) &init_thread_union;
+	lc->machine_flags = S390_lowcore.machine_flags;
 #ifndef CONFIG_64BIT
 	if (MACHINE_HAS_IEEE) {
 		lc->extended_save_area_addr = (__u32)
@@ -436,6 +434,14 @@ setup_lowcore(void)
 #else
 	lc->vdso_per_cpu_data = (unsigned long) &lc->paste[0];
 #endif
+	lc->sync_enter_timer = S390_lowcore.sync_enter_timer;
+	lc->async_enter_timer = S390_lowcore.async_enter_timer;
+	lc->exit_timer = S390_lowcore.exit_timer;
+	lc->user_timer = S390_lowcore.user_timer;
+	lc->system_timer = S390_lowcore.system_timer;
+	lc->steal_timer = S390_lowcore.steal_timer;
+	lc->last_update_timer = S390_lowcore.last_update_timer;
+	lc->last_update_clock = S390_lowcore.last_update_clock;
 	set_prefix((u32)(unsigned long) lc);
 	lowcore_ptr[0] = lc;
 }
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 006ed5016eb..a985a3ba440 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -571,6 +571,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
 	cpu_lowcore->current_task = (unsigned long) idle;
 	cpu_lowcore->cpu_nr = cpu;
 	cpu_lowcore->kernel_asce = S390_lowcore.kernel_asce;
+	cpu_lowcore->machine_flags = S390_lowcore.machine_flags;
 	eieio();
 
 	while (signal_processor(cpu, sigp_restart) == sigp_busy)
@@ -590,7 +591,8 @@ static int __init setup_possible_cpus(char *s)
 	int pcpus, cpu;
 
 	pcpus = simple_strtoul(s, NULL, 0);
-	for (cpu = 0; cpu < pcpus && cpu < nr_cpu_ids; cpu++)
+	init_cpu_possible(cpumask_of(0));
+	for (cpu = 1; cpu < pcpus && cpu < nr_cpu_ids; cpu++)
 		set_cpu_possible(cpu, true);
 	return 0;
 }
diff --git a/arch/s390/kernel/syscalls.S b/arch/s390/kernel/syscalls.S
index fe5b25a988a..2c7739fe70b 100644
--- a/arch/s390/kernel/syscalls.S
+++ b/arch/s390/kernel/syscalls.S
@@ -336,3 +336,5 @@ SYSCALL(sys_inotify_init1,sys_inotify_init1,sys_inotify_init1_wrapper)
 SYSCALL(sys_pipe2,sys_pipe2,sys_pipe2_wrapper) /* 325 */
 SYSCALL(sys_dup3,sys_dup3,sys_dup3_wrapper)
 SYSCALL(sys_epoll_create1,sys_epoll_create1,sys_epoll_create1_wrapper)
+SYSCALL(sys_preadv,sys_preadv,compat_sys_preadv_wrapper)
+SYSCALL(sys_pwritev,sys_pwritev,compat_sys_pwritev_wrapper)
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index f72d41068dc..ef596d02057 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -52,9 +52,6 @@
 #define USECS_PER_JIFFY     ((unsigned long) 1000000/HZ)
 #define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
 
-/* The value of the TOD clock for 1.1.1970. */
-#define TOD_UNIX_EPOCH 0x7d91048bca000000ULL
-
 /*
  * Create a small time difference between the timer interrupts
  * on the different cpus to avoid lock contention.
@@ -63,9 +60,10 @@
 
 #define TICK_SIZE tick
 
+u64 sched_clock_base_cc = -1;	/* Force to data section. */
+
 static ext_int_info_t ext_int_info_cc;
 static ext_int_info_t ext_int_etr_cc;
-static u64 sched_clock_base_cc;
 
 static DEFINE_PER_CPU(struct clock_event_device, comparators);
 
@@ -195,25 +193,15 @@ static void timing_alert_interrupt(__u16 code)
 static void etr_reset(void);
 static void stp_reset(void);
 
-/*
- * Get the TOD clock running.
- */
-static u64 __init reset_tod_clock(void)
+unsigned long read_persistent_clock(void)
 {
-	u64 time;
-
-	etr_reset();
-	stp_reset();
-	if (store_clock(&time) == 0)
-		return time;
-	/* TOD clock not running. Set the clock to Unix Epoch. */
-	if (set_clock(TOD_UNIX_EPOCH) != 0 || store_clock(&time) != 0)
-		panic("TOD clock not operational.");
+	struct timespec ts;
 
-	return TOD_UNIX_EPOCH;
+	tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, &ts);
+	return ts.tv_sec;
 }
 
-static cycle_t read_tod_clock(void)
+static cycle_t read_tod_clock(struct clocksource *cs)
 {
 	return get_clock();
 }
@@ -265,12 +253,13 @@ void update_vsyscall_tz(void)
  */
 void __init time_init(void)
 {
-	sched_clock_base_cc = reset_tod_clock();
+	struct timespec ts;
+	unsigned long flags;
+	cycle_t now;
 
-	/* set xtime */
-	tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &xtime);
-        set_normalized_timespec(&wall_to_monotonic,
-                                -xtime.tv_sec, -xtime.tv_nsec);
+	/* Reset time synchronization interfaces. */
+	etr_reset();
+	stp_reset();
 
 	/* request the clock comparator external interrupt */
 	if (register_early_external_interrupt(0x1004,
@@ -278,17 +267,38 @@ void __init time_init(void)
 					      &ext_int_info_cc) != 0)
                 panic("Couldn't request external interrupt 0x1004");
 
-	if (clocksource_register(&clocksource_tod) != 0)
-		panic("Could not register TOD clock source");
-
 	/* request the timing alert external interrupt */
 	if (register_early_external_interrupt(0x1406,
 					      timing_alert_interrupt,
 					      &ext_int_etr_cc) != 0)
 		panic("Couldn't request external interrupt 0x1406");
 
+	if (clocksource_register(&clocksource_tod) != 0)
+		panic("Could not register TOD clock source");
+
+	/*
+	 * The TOD clock is an accurate clock. The xtime should be
+	 * initialized in a way that the difference between TOD and
+	 * xtime is reasonably small. Too bad that timekeeping_init
+	 * sets xtime.tv_nsec to zero. In addition the clock source
+	 * change from the jiffies clock source to the TOD clock
+	 * source add another error of up to 1/HZ second. The same
+	 * function sets wall_to_monotonic to a value that is too
+	 * small for /proc/uptime to be accurate.
+	 * Reset xtime and wall_to_monotonic to sane values.
+	 */
+	write_seqlock_irqsave(&xtime_lock, flags);
+	now = get_clock();
+	tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);
+	clocksource_tod.cycle_last = now;
+	clocksource_tod.raw_time = xtime;
+	tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);
+	set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);
+	write_sequnlock_irqrestore(&xtime_lock, flags);
+
 	/* Enable TOD clock interrupts on the boot cpu. */
 	init_cpu_timer();
+
 	/* Enable cpu timer interrupts on the boot cpu. */
 	vtime_init();
 }
@@ -1423,6 +1433,7 @@ static void *stp_page;
 static void stp_work_fn(struct work_struct *work);
 static DEFINE_MUTEX(stp_work_mutex);
 static DECLARE_WORK(stp_work, stp_work_fn);
+static struct timer_list stp_timer;
 
 static int __init early_parse_stp(char *p)
 {
@@ -1454,10 +1465,16 @@ static void __init stp_reset(void)
 	}
 }
 
+static void stp_timeout(unsigned long dummy)
+{
+	queue_work(time_sync_wq, &stp_work);
+}
+
 static int __init stp_init(void)
 {
 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
 		return 0;
+	setup_timer(&stp_timer, stp_timeout, 0UL);
 	time_init_wq();
 	if (!stp_online)
 		return 0;
@@ -1565,6 +1582,7 @@ static void stp_work_fn(struct work_struct *work)
 
 	if (!stp_online) {
 		chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000);
+		del_timer_sync(&stp_timer);
 		goto out_unlock;
 	}
 
@@ -1586,6 +1604,13 @@ static void stp_work_fn(struct work_struct *work)
 	stop_machine(stp_sync_clock, &stp_sync, &cpu_online_map);
 	put_online_cpus();
 
+	if (!check_sync_clock())
+		/*
+		 * There is a usable clock but the synchonization failed.
+		 * Retry after a second.
+		 */
+		mod_timer(&stp_timer, jiffies + HZ);
+
 out_unlock:
 	mutex_unlock(&stp_work_mutex);
 }
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 7a2063eb88f..89399b8756c 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -29,8 +29,8 @@ SECTIONS
 	. = 0x00000000;
 	.text : {
 	_text = .;		/* Text and read-only data */
-		*(.text.head)
-	TEXT_TEXT
+		HEAD_TEXT
+		TEXT_TEXT
 		SCHED_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index ecf0304e61c..c87f59bd824 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -134,6 +134,8 @@ void vtime_start_cpu(void)
 	/* Account time spent with enabled wait psw loaded as idle time. */
 	idle_time = S390_lowcore.int_clock - idle->idle_enter;
 	account_idle_time(idle_time);
+	S390_lowcore.steal_timer +=
+		idle->idle_enter - S390_lowcore.last_update_clock;
 	S390_lowcore.last_update_clock = S390_lowcore.int_clock;
 
 	/* Account system time spent going idle. */
@@ -238,6 +240,22 @@ void vtime_stop_cpu(void)
 	}
 }
 
+cputime64_t s390_get_idle_time(int cpu)
+{
+	struct s390_idle_data *idle;
+	unsigned long long now, idle_time, idle_enter;
+
+	idle = &per_cpu(s390_idle, cpu);
+	spin_lock(&idle->lock);
+	now = get_clock();
+	idle_time = 0;
+	idle_enter = idle->idle_enter;
+	if (idle_enter != 0ULL && idle_enter < now)
+		idle_time = now - idle_enter;
+	spin_unlock(&idle->lock);
+	return idle_time;
+}
+
 /*
  * Sorted add to a list. List is linear searched until first bigger
  * element is found.
@@ -425,17 +443,7 @@ void add_virt_timer_periodic(void *new)
 }
 EXPORT_SYMBOL(add_virt_timer_periodic);
 
-/*
- * If we change a pending timer the function must be called on the CPU
- * where the timer is running on, e.g. by smp_call_function_single()
- *
- * The original mod_timer adds the timer if it is not pending. For
- * compatibility we do the same. The timer will be added on the current
- * CPU as a oneshot timer.
- *
- * returns whether it has modified a pending timer (1) or not (0)
- */
-int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
+int __mod_vtimer(struct vtimer_list *timer, __u64 expires, int periodic)
 {
 	struct vtimer_queue *vq;
 	unsigned long flags;
@@ -444,39 +452,35 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
 	BUG_ON(!timer->function);
 	BUG_ON(!expires || expires > VTIMER_MAX_SLICE);
 
-	/*
-	 * This is a common optimization triggered by the
-	 * networking code - if the timer is re-modified
-	 * to be the same thing then just return:
-	 */
 	if (timer->expires == expires && vtimer_pending(timer))
 		return 1;
 
 	cpu = get_cpu();
 	vq = &per_cpu(virt_cpu_timer, cpu);
 
-	/* check if we run on the right CPU */
-	BUG_ON(timer->cpu != cpu);
-
 	/* disable interrupts before test if timer is pending */
 	spin_lock_irqsave(&vq->lock, flags);
 
 	/* if timer isn't pending add it on the current CPU */
 	if (!vtimer_pending(timer)) {
 		spin_unlock_irqrestore(&vq->lock, flags);
-		/* we do not activate an interval timer with mod_virt_timer */
-		timer->interval = 0;
+
+		if (periodic)
+			timer->interval = expires;
+		else
+			timer->interval = 0;
 		timer->expires = expires;
 		timer->cpu = cpu;
 		internal_add_vtimer(timer);
 		return 0;
 	}
 
+	/* check if we run on the right CPU */
+	BUG_ON(timer->cpu != cpu);
+
 	list_del_init(&timer->entry);
 	timer->expires = expires;
-
-	/* also change the interval if we have an interval timer */
-	if (timer->interval)
+	if (periodic)
 		timer->interval = expires;
 
 	/* the timer can't expire anymore so we can release the lock */
@@ -484,9 +488,32 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
 	internal_add_vtimer(timer);
 	return 1;
 }
+
+/*
+ * If we change a pending timer the function must be called on the CPU
+ * where the timer is running on.
+ *
+ * returns whether it has modified a pending timer (1) or not (0)
+ */
+int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
+{
+	return __mod_vtimer(timer, expires, 0);
+}
 EXPORT_SYMBOL(mod_virt_timer);
 
 /*
+ * If we change a pending timer the function must be called on the CPU
+ * where the timer is running on.
+ *
+ * returns whether it has modified a pending timer (1) or not (0)
+ */
+int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires)
+{
+	return __mod_vtimer(timer, expires, 1);
+}
+EXPORT_SYMBOL(mod_virt_timer_periodic);
+
+/*
  * delete a virtual timer
  *
  * returns whether the deleted timer was pending (1) or not (0)
@@ -516,16 +543,8 @@ EXPORT_SYMBOL(del_virt_timer);
  */
 void init_cpu_vtimer(void)
 {
-	struct thread_info *ti = current_thread_info();
 	struct vtimer_queue *vq;
 
-	S390_lowcore.user_timer = ti->user_timer;
-	S390_lowcore.system_timer = ti->system_timer;
-
-	/* kick the virtual timer */
-	asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));
-	asm volatile ("STPT %0" : "=m" (S390_lowcore.last_update_timer));
-
 	/* initialize per cpu vtimer structure */
 	vq = &__get_cpu_var(virt_cpu_timer);
 	INIT_LIST_HEAD(&vq->list);