Merge branch 'cputime' of git://git390.osdl.marist.edu/pub/scm/linux-2.6

* 'cputime' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
  [PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID
  [PATCH] improve idle cputime accounting
  [PATCH] improve precision of idle time detection.
  [PATCH] improve precision of process accounting.
  [PATCH] idle cputime accounting
  [PATCH] fix scaled & unscaled cputime accounting

19 files changed, 563 insertions, 368 deletions

diff --git a/arch/s390/include/asm/cpu.h b/arch/s390/include/asm/cpu.h
index e5a6a9ba3adf..d60a2eefb17b 100644
--- a/arch/s390/include/asm/cpu.h
+++ b/arch/s390/include/asm/cpu.h
@@ -14,7 +14,6 @@
 
 struct s390_idle_data {
         spinlock_t lock;
-        unsigned int in_idle;
         unsigned long long idle_count;
         unsigned long long idle_enter;
         unsigned long long idle_time;
@@ -22,12 +21,12 @@ struct s390_idle_data {
 
 DECLARE_PER_CPU(struct s390_idle_data, s390_idle);
 
-void s390_idle_leave(void);
+void vtime_start_cpu(void);
 
 static inline void s390_idle_check(void)
 {
-        if ((&__get_cpu_var(s390_idle))->in_idle)
-                s390_idle_leave();
+        if ((&__get_cpu_var(s390_idle))->idle_enter != 0ULL)
+                vtime_start_cpu();
 }
 
 #endif /* _ASM_S390_CPU_H_ */
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 133ce054fc89..521726430afa 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -11,7 +11,7 @@
 
 #include <asm/div64.h>
 
-/* We want to use micro-second resolution. */
+/* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
 
 typedef unsigned long long cputime_t;
 typedef unsigned long long cputime64_t;
@@ -53,9 +53,9 @@ __div(unsigned long long n, unsigned int base)
 #define cputime_ge(__a, __b)            ((__a) >= (__b))
 #define cputime_lt(__a, __b)            ((__a) <  (__b))
 #define cputime_le(__a, __b)            ((__a) <= (__b))
-#define cputime_to_jiffies(__ct)        (__div((__ct), 1000000 / HZ))
+#define cputime_to_jiffies(__ct)        (__div((__ct), 4096000000ULL / HZ))
 #define cputime_to_scaled(__ct)         (__ct)
-#define jiffies_to_cputime(__hz)        ((cputime_t)(__hz) * (1000000 / HZ))
+#define jiffies_to_cputime(__hz)        ((cputime_t)(__hz) * (4096000000ULL / HZ))
 
 #define cputime64_zero                  (0ULL)
 #define cputime64_add(__a, __b)         ((__a) + (__b))
@@ -64,7 +64,7 @@ __div(unsigned long long n, unsigned int base)
 static inline u64
 cputime64_to_jiffies64(cputime64_t cputime)
 {
-        do_div(cputime, 1000000 / HZ);
+        do_div(cputime, 4096000000ULL / HZ);
         return cputime;
 }
 
@@ -74,13 +74,13 @@ cputime64_to_jiffies64(cputime64_t cputime)
 static inline unsigned int
 cputime_to_msecs(const cputime_t cputime)
 {
-        return __div(cputime, 1000);
+        return __div(cputime, 4096000);
 }
 
 static inline cputime_t
 msecs_to_cputime(const unsigned int m)
 {
-        return (cputime_t) m * 1000;
+        return (cputime_t) m * 4096000;
 }
 
 /*
@@ -89,13 +89,13 @@ msecs_to_cputime(const unsigned int m)
 static inline unsigned int
 cputime_to_secs(const cputime_t cputime)
 {
-        return __div(cputime, 1000000);
+        return __div(cputime, 2048000000) >> 1;
 }
 
 static inline cputime_t
 secs_to_cputime(const unsigned int s)
 {
-        return (cputime_t) s * 1000000;
+        return (cputime_t) s * 4096000000ULL;
 }
 
 /*
@@ -104,7 +104,7 @@ secs_to_cputime(const unsigned int s)
 static inline cputime_t
 timespec_to_cputime(const struct timespec *value)
 {
-        return value->tv_nsec / 1000 + (u64) value->tv_sec * 1000000;
+        return value->tv_nsec * 4096 / 1000 + (u64) value->tv_sec * 4096000000ULL;
 }
 
 static inline void
@@ -114,12 +114,12 @@ cputime_to_timespec(const cputime_t cputime, struct timespec *value)
         register_pair rp;
 
         rp.pair = cputime >> 1;
-        asm ("dr %0,%1" : "+d" (rp) : "d" (1000000 >> 1));
-        value->tv_nsec = rp.subreg.even * 1000;
+        asm ("dr %0,%1" : "+d" (rp) : "d" (2048000000UL));
+        value->tv_nsec = rp.subreg.even * 1000 / 4096;
         value->tv_sec = rp.subreg.odd;
 #else
-        value->tv_nsec = (cputime % 1000000) * 1000;
-        value->tv_sec = cputime / 1000000;
+        value->tv_nsec = (cputime % 4096000000ULL) * 1000 / 4096;
+        value->tv_sec = cputime / 4096000000ULL;
 #endif
 }
 
@@ -131,7 +131,7 @@ cputime_to_timespec(const cputime_t cputime, struct timespec *value)
 static inline cputime_t
 timeval_to_cputime(const struct timeval *value)
 {
-        return value->tv_usec + (u64) value->tv_sec * 1000000;
+        return value->tv_usec * 4096 + (u64) value->tv_sec * 4096000000ULL;
 }
 
 static inline void
@@ -141,12 +141,12 @@ cputime_to_timeval(const cputime_t cputime, struct timeval *value)
         register_pair rp;
 
         rp.pair = cputime >> 1;
-        asm ("dr %0,%1" : "+d" (rp) : "d" (1000000 >> 1));
-        value->tv_usec = rp.subreg.even;
+        asm ("dr %0,%1" : "+d" (rp) : "d" (2048000000UL));
+        value->tv_usec = rp.subreg.even / 4096;
         value->tv_sec = rp.subreg.odd;
 #else
-        value->tv_usec = cputime % 1000000;
-        value->tv_sec = cputime / 1000000;
+        value->tv_usec = cputime % 4096000000ULL;
+        value->tv_sec = cputime / 4096000000ULL;
 #endif
 }
 
@@ -156,13 +156,13 @@ cputime_to_timeval(const cputime_t cputime, struct timeval *value)
 static inline clock_t
 cputime_to_clock_t(cputime_t cputime)
 {
-        return __div(cputime, 1000000 / USER_HZ);
+        return __div(cputime, 4096000000ULL / USER_HZ);
 }
 
 static inline cputime_t
 clock_t_to_cputime(unsigned long x)
 {
-        return (cputime_t) x * (1000000 / USER_HZ);
+        return (cputime_t) x * (4096000000ULL / USER_HZ);
 }
 
 /*
@@ -171,7 +171,7 @@ clock_t_to_cputime(unsigned long x)
 static inline clock_t
 cputime64_to_clock_t(cputime64_t cputime)
 {
-       return __div(cputime, 1000000 / USER_HZ);
+       return __div(cputime, 4096000000ULL / USER_HZ);
 }
 
 #endif /* _S390_CPUTIME_H */
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index 0bc51d52a899..ffdef5fe8587 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -67,11 +67,11 @@
 #define __LC_SYNC_ENTER_TIMER           0x248
 #define __LC_ASYNC_ENTER_TIMER          0x250
 #define __LC_EXIT_TIMER                 0x258
-#define __LC_LAST_UPDATE_TIMER          0x260
-#define __LC_USER_TIMER                 0x268
-#define __LC_SYSTEM_TIMER               0x270
-#define __LC_LAST_UPDATE_CLOCK          0x278
-#define __LC_STEAL_CLOCK                0x280
+#define __LC_USER_TIMER                 0x260
+#define __LC_SYSTEM_TIMER               0x268
+#define __LC_STEAL_TIMER                0x270
+#define __LC_LAST_UPDATE_TIMER          0x278
+#define __LC_LAST_UPDATE_CLOCK          0x280
 #define __LC_RETURN_MCCK_PSW            0x288
 #define __LC_KERNEL_STACK               0xC40
 #define __LC_THREAD_INFO                0xC44
@@ -89,11 +89,11 @@
 #define __LC_SYNC_ENTER_TIMER           0x250
 #define __LC_ASYNC_ENTER_TIMER          0x258
 #define __LC_EXIT_TIMER                 0x260
-#define __LC_LAST_UPDATE_TIMER          0x268
-#define __LC_USER_TIMER                 0x270
-#define __LC_SYSTEM_TIMER               0x278
-#define __LC_LAST_UPDATE_CLOCK          0x280
-#define __LC_STEAL_CLOCK                0x288
+#define __LC_USER_TIMER                 0x268
+#define __LC_SYSTEM_TIMER               0x270
+#define __LC_STEAL_TIMER                0x278
+#define __LC_LAST_UPDATE_TIMER          0x280
+#define __LC_LAST_UPDATE_CLOCK          0x288
 #define __LC_RETURN_MCCK_PSW            0x290
 #define __LC_KERNEL_STACK               0xD40
 #define __LC_THREAD_INFO                0xD48
@@ -106,8 +106,10 @@
 #define __LC_IPLDEV                     0xDB8
 #define __LC_CURRENT                    0xDD8
 #define __LC_INT_CLOCK                  0xDE8
+#define __LC_VDSO_PER_CPU               0xE38
 #endif /* __s390x__ */
 
+#define __LC_PASTE                      0xE40
 
 #define __LC_PANIC_MAGIC                0xE00
 #ifndef __s390x__
@@ -252,11 +254,11 @@ struct _lowcore
         __u64        sync_enter_timer;         /* 0x248 */
         __u64        async_enter_timer;        /* 0x250 */
         __u64        exit_timer;               /* 0x258 */
-        __u64        last_update_timer;        /* 0x260 */
-        __u64        user_timer;               /* 0x268 */
-        __u64        system_timer;             /* 0x270 */
-        __u64        last_update_clock;        /* 0x278 */
-        __u64        steal_clock;              /* 0x280 */
+        __u64        user_timer;               /* 0x260 */
+        __u64        system_timer;             /* 0x268 */
+        __u64        steal_timer;              /* 0x270 */
+        __u64        last_update_timer;        /* 0x278 */
+        __u64        last_update_clock;        /* 0x280 */
         psw_t        return_mcck_psw;          /* 0x288 */
         __u8         pad8[0xc00-0x290];        /* 0x290 */
 
@@ -343,11 +345,11 @@ struct _lowcore
         __u64        sync_enter_timer;         /* 0x250 */
         __u64        async_enter_timer;        /* 0x258 */
         __u64        exit_timer;               /* 0x260 */
-        __u64        last_update_timer;        /* 0x268 */
-        __u64        user_timer;               /* 0x270 */
-        __u64        system_timer;             /* 0x278 */
-        __u64        last_update_clock;        /* 0x280 */
-        __u64        steal_clock;              /* 0x288 */
+        __u64        user_timer;               /* 0x268 */
+        __u64        system_timer;             /* 0x270 */
+        __u64        steal_timer;              /* 0x278 */
+        __u64        last_update_timer;        /* 0x280 */
+        __u64        last_update_clock;        /* 0x288 */
         psw_t        return_mcck_psw;          /* 0x290 */
         __u8         pad8[0xc00-0x2a0];        /* 0x2a0 */
         /* System info area */
@@ -381,7 +383,12 @@ struct _lowcore
         /* whether the kernel died with panic() or not */
         __u32        panic_magic;              /* 0xe00 */
 
-        __u8         pad13[0x11b8-0xe04];      /* 0xe04 */
+        /* Per cpu primary space access list */
+        __u8         pad_0xe04[0xe3c-0xe04];   /* 0xe04 */
+        __u32        vdso_per_cpu_data;        /* 0xe3c */
+        __u32        paste[16];                /* 0xe40 */
+
+        __u8         pad13[0x11b8-0xe80];      /* 0xe80 */
 
         /* 64 bit extparam used for pfault, diag 250 etc  */
         __u64        ext_params2;               /* 0x11B8 */
diff --git a/arch/s390/include/asm/system.h b/arch/s390/include/asm/system.h
index 024ef42ed6d7..3a8b26eb1f2e 100644
--- a/arch/s390/include/asm/system.h
+++ b/arch/s390/include/asm/system.h
@@ -99,7 +99,7 @@ static inline void restore_access_regs(unsigned int *acrs)
         prev = __switch_to(prev,next);                                       \
 } while (0)
 
-extern void account_vtime(struct task_struct *);
+extern void account_vtime(struct task_struct *, struct task_struct *);
 extern void account_tick_vtime(struct task_struct *);
 extern void account_system_vtime(struct task_struct *);
 
@@ -121,7 +121,7 @@ static inline void cmma_init(void) { }
 
 #define finish_arch_switch(prev) do {                                        \
         set_fs(current->thread.mm_segment);                                  \
-        account_vtime(prev);                                                 \
+        account_vtime(prev, current);                                        \
 } while (0)
 
 #define nop() asm volatile("nop")
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index c1eaf9604da7..c544aa524535 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -47,6 +47,8 @@ struct thread_info {
         unsigned int            cpu;            /* current CPU */
         int                     preempt_count;  /* 0 => preemptable, <0 => BUG */
         struct restart_block    restart_block;
+        __u64                   user_timer;
+        __u64                   system_timer;
 };
 
 /*
diff --git a/arch/s390/include/asm/timer.h b/arch/s390/include/asm/timer.h
index 61705d60f995..e4bcab739c19 100644
--- a/arch/s390/include/asm/timer.h
+++ b/arch/s390/include/asm/timer.h
@@ -23,20 +23,18 @@ struct vtimer_list {
         __u64 expires;
         __u64 interval;
 
-        spinlock_t lock;
-        unsigned long magic;
-
         void (*function)(unsigned long);
         unsigned long data;
 };
 
-/* the offset value will wrap after ca. 71 years */
+/* the vtimer value will wrap after ca. 71 years */
 struct vtimer_queue {
         struct list_head list;
         spinlock_t lock;
-        __u64 to_expire;          /* current event expire time */
-        __u64 offset;             /* list offset to zero */
-        __u64 idle;               /* temp var for idle */
+        __u64 timer;            /* last programmed timer */
+        __u64 elapsed;          /* elapsed time of timer expire values */
+        __u64 idle;             /* temp var for idle */
+        int do_spt;             /* =1: reprogram cpu timer in idle */
 };
 
 extern void init_virt_timer(struct vtimer_list *timer);
@@ -48,8 +46,8 @@ extern int del_virt_timer(struct vtimer_list *timer);
 extern void init_cpu_vtimer(void);
 extern void vtime_init(void);
 
-extern void vtime_start_cpu_timer(void);
-extern void vtime_stop_cpu_timer(void);
+extern void vtime_stop_cpu(void);
+extern void vtime_start_leave(void);
 
 #endif /* __KERNEL__ */
 
diff --git a/arch/s390/include/asm/vdso.h b/arch/s390/include/asm/vdso.h
index a44f4fe16a35..7bdd7c8ebc91 100644
--- a/arch/s390/include/asm/vdso.h
+++ b/arch/s390/include/asm/vdso.h
@@ -12,9 +12,9 @@
 #ifndef __ASSEMBLY__
 
 /*
- * Note about this structure:
+ * Note about the vdso_data and vdso_per_cpu_data structures:
  *
- * NEVER USE THIS IN USERSPACE CODE DIRECTLY. The layout of this
+ * NEVER USE THEM IN USERSPACE CODE DIRECTLY. The layout of the
  * structure is supposed to be known only to the function in the vdso
  * itself and may change without notice.
  */
@@ -28,10 +28,21 @@ struct vdso_data {
         __u64 wtom_clock_nsec;          /*                              0x28 */
         __u32 tz_minuteswest;           /* Minutes west of Greenwich    0x30 */
         __u32 tz_dsttime;               /* Type of dst correction       0x34 */
+        __u32 ectg_available;
+};
+
+struct vdso_per_cpu_data {
+        __u64 ectg_timer_base;
+        __u64 ectg_user_time;
 };
 
 extern struct vdso_data *vdso_data;
 
+#ifdef CONFIG_64BIT
+int vdso_alloc_per_cpu(int cpu, struct _lowcore *lowcore);
+void vdso_free_per_cpu(int cpu, struct _lowcore *lowcore);
+#endif
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __KERNEL__ */
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index e641f60bac99..67a60016babb 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -48,6 +48,11 @@ int main(void)
         DEFINE(__VDSO_WTOM_SEC, offsetof(struct vdso_data, wtom_clock_sec));
         DEFINE(__VDSO_WTOM_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));
         DEFINE(__VDSO_TIMEZONE, offsetof(struct vdso_data, tz_minuteswest));
+        DEFINE(__VDSO_ECTG_OK, offsetof(struct vdso_data, ectg_available));
+        DEFINE(__VDSO_ECTG_BASE,
+               offsetof(struct vdso_per_cpu_data, ectg_timer_base));
+        DEFINE(__VDSO_ECTG_USER,
+               offsetof(struct vdso_per_cpu_data, ectg_user_time));
         /* constants used by the vdso */
         DEFINE(CLOCK_REALTIME, CLOCK_REALTIME);
         DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC);
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 55de521aef77..1268aa2991bf 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -583,8 +583,8 @@ kernel_per:
 
         .globl io_int_handler
 io_int_handler:
-        stpt    __LC_ASYNC_ENTER_TIMER
         stck    __LC_INT_CLOCK
+        stpt    __LC_ASYNC_ENTER_TIMER
         SAVE_ALL_BASE __LC_SAVE_AREA+16
         SAVE_ALL_ASYNC __LC_IO_OLD_PSW,__LC_SAVE_AREA+16
         CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+16
@@ -723,8 +723,8 @@ io_notify_resume:
 
         .globl  ext_int_handler
 ext_int_handler:
-        stpt    __LC_ASYNC_ENTER_TIMER
         stck    __LC_INT_CLOCK
+        stpt    __LC_ASYNC_ENTER_TIMER
         SAVE_ALL_BASE __LC_SAVE_AREA+16
         SAVE_ALL_ASYNC __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16
         CREATE_STACK_FRAME __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16
@@ -750,6 +750,7 @@ __critical_end:
 
         .globl mcck_int_handler
 mcck_int_handler:
+        stck    __LC_INT_CLOCK
         spt     __LC_CPU_TIMER_SAVE_AREA        # revalidate cpu timer
         lm      %r0,%r15,__LC_GPREGS_SAVE_AREA  # revalidate gprs
         SAVE_ALL_BASE __LC_SAVE_AREA+32
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 16bb4fd1a403..c6fbde13971a 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -177,8 +177,11 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
         .if !\sync
         ni      \psworg+1,0xfd          # clear wait state bit
         .endif
-        lmg     %r0,%r15,SP_R0(%r15)    # load gprs 0-15 of user
+        lg      %r14,__LC_VDSO_PER_CPU
+        lmg     %r0,%r13,SP_R0(%r15)    # load gprs 0-13 of user
         stpt    __LC_EXIT_TIMER
+        mvc     __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
+        lmg     %r14,%r15,SP_R14(%r15)  # load grps 14-15 of user
         lpswe   \psworg                 # back to caller
         .endm
 
@@ -559,8 +562,8 @@ kernel_per:
  */
         .globl io_int_handler
 io_int_handler:
-        stpt    __LC_ASYNC_ENTER_TIMER
         stck    __LC_INT_CLOCK
+        stpt    __LC_ASYNC_ENTER_TIMER
         SAVE_ALL_BASE __LC_SAVE_AREA+32
         SAVE_ALL_ASYNC __LC_IO_OLD_PSW,__LC_SAVE_AREA+32
         CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+32
@@ -721,8 +724,8 @@ io_notify_resume:
  */
         .globl  ext_int_handler
 ext_int_handler:
-        stpt    __LC_ASYNC_ENTER_TIMER
         stck    __LC_INT_CLOCK
+        stpt    __LC_ASYNC_ENTER_TIMER
         SAVE_ALL_BASE __LC_SAVE_AREA+32
         SAVE_ALL_ASYNC __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32
         CREATE_STACK_FRAME __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32
@@ -746,6 +749,7 @@ __critical_end:
  */
         .globl mcck_int_handler
 mcck_int_handler:
+        stck    __LC_INT_CLOCK
         la      %r1,4095                # revalidate r1
         spt     __LC_CPU_TIMER_SAVE_AREA-4095(%r1)      # revalidate cpu timer
         lmg     %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# revalidate gprs
@@ -979,23 +983,23 @@ cleanup_sysc_return:
 
 cleanup_sysc_leave:
         clc     8(8,%r12),BASED(cleanup_sysc_leave_insn)
-        je      2f
-        mvc     __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
+        je      3f
         clc     8(8,%r12),BASED(cleanup_sysc_leave_insn+8)
-        je      2f
-        mvc     __LC_RETURN_PSW(16),SP_PSW(%r15)
+        jhe     0f
+        mvc     __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
+0:      mvc     __LC_RETURN_PSW(16),SP_PSW(%r15)
         cghi    %r12,__LC_MCK_OLD_PSW
-        jne     0f
+        jne     1f
         mvc     __LC_SAVE_AREA+64(32),SP_R12(%r15)
-        j       1f
-0:      mvc     __LC_SAVE_AREA+32(32),SP_R12(%r15)
-1:      lmg     %r0,%r11,SP_R0(%r15)
+        j       2f
+1:      mvc     __LC_SAVE_AREA+32(32),SP_R12(%r15)
+2:      lmg     %r0,%r11,SP_R0(%r15)
         lg      %r15,SP_R15(%r15)
-2:      la      %r12,__LC_RETURN_PSW
+3:      la      %r12,__LC_RETURN_PSW
         br      %r14
 cleanup_sysc_leave_insn:
         .quad   sysc_done - 4
-        .quad   sysc_done - 8
+        .quad   sysc_done - 16
 
 cleanup_io_return:
         mvc     __LC_RETURN_PSW(8),0(%r12)
@@ -1005,23 +1009,23 @@ cleanup_io_return:
 
 cleanup_io_leave:
         clc     8(8,%r12),BASED(cleanup_io_leave_insn)
-        je      2f
-        mvc     __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
+        je      3f
         clc     8(8,%r12),BASED(cleanup_io_leave_insn+8)
-        je      2f
-        mvc     __LC_RETURN_PSW(16),SP_PSW(%r15)
+        jhe     0f
+        mvc     __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
+0:      mvc     __LC_RETURN_PSW(16),SP_PSW(%r15)
         cghi    %r12,__LC_MCK_OLD_PSW
-        jne     0f
+        jne     1f
         mvc     __LC_SAVE_AREA+64(32),SP_R12(%r15)
-        j       1f
-0:      mvc     __LC_SAVE_AREA+32(32),SP_R12(%r15)
-1:      lmg     %r0,%r11,SP_R0(%r15)
+        j       2f
+1:      mvc     __LC_SAVE_AREA+32(32),SP_R12(%r15)
+2:      lmg     %r0,%r11,SP_R0(%r15)
         lg      %r15,SP_R15(%r15)
-2:      la      %r12,__LC_RETURN_PSW
+3:      la      %r12,__LC_RETURN_PSW
         br      %r14
 cleanup_io_leave_insn:
         .quad   io_done - 4
-        .quad   io_done - 8
+        .quad   io_done - 16
 
 /*
  * Integer constants
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index 3ccd36b24b8f..f9f70aa15244 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -87,6 +87,8 @@ startup_continue:
         lg      %r12,.Lparmaddr-.LPG1(%r13)     # pointer to parameter area
                                         # move IPL device to lowcore
         mvc     __LC_IPLDEV(4),IPL_DEVICE+4-PARMAREA(%r12)
+        lghi    %r0,__LC_PASTE
+        stg     %r0,__LC_VDSO_PER_CPU
 #
 # Setup stack
 #
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 04f8c67a6101..b6110bdf8dc2 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -38,6 +38,7 @@
 #include <linux/utsname.h>
 #include <linux/tick.h>
 #include <linux/elfcore.h>
+#include <linux/kernel_stat.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -45,7 +46,6 @@
 #include <asm/processor.h>
 #include <asm/irq.h>
 #include <asm/timer.h>
-#include <asm/cpu.h>
 #include "entry.h"
 
 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
@@ -75,36 +75,6 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
         return sf->gprs[8];
 }
 
-DEFINE_PER_CPU(struct s390_idle_data, s390_idle) = {
-        .lock = __SPIN_LOCK_UNLOCKED(s390_idle.lock)
-};
-
-static int s390_idle_enter(void)
-{
-        struct s390_idle_data *idle;
-
-        idle = &__get_cpu_var(s390_idle);
-        spin_lock(&idle->lock);
-        idle->idle_count++;
-        idle->in_idle = 1;
-        idle->idle_enter = get_clock();
-        spin_unlock(&idle->lock);
-        vtime_stop_cpu_timer();
-        return NOTIFY_OK;
-}
-
-void s390_idle_leave(void)
-{
-        struct s390_idle_data *idle;
-
-        vtime_start_cpu_timer();
-        idle = &__get_cpu_var(s390_idle);
-        spin_lock(&idle->lock);
-        idle->idle_time += get_clock() - idle->idle_enter;
-        idle->in_idle = 0;
-        spin_unlock(&idle->lock);
-}
-
 extern void s390_handle_mcck(void);
 /*
  * The idle loop on a S390...
@@ -117,10 +87,6 @@ static void default_idle(void)
                 local_irq_enable();
                 return;
         }
-        if (s390_idle_enter() == NOTIFY_BAD) {
-                local_irq_enable();
-                return;
-        }
 #ifdef CONFIG_HOTPLUG_CPU
         if (cpu_is_offline(smp_processor_id())) {
                 preempt_enable_no_resched();
@@ -130,7 +96,6 @@ static void default_idle(void)
         local_mcck_disable();
         if (test_thread_flag(TIF_MCCK_PENDING)) {
                 local_mcck_enable();
-                s390_idle_leave();
                 local_irq_enable();
                 s390_handle_mcck();
                 return;
@@ -138,9 +103,9 @@ static void default_idle(void)
         trace_hardirqs_on();
         /* Don't trace preempt off for idle. */
         stop_critical_timings();
-        /* Wait for external, I/O or machine check interrupt. */
-        __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
-                        PSW_MASK_IO | PSW_MASK_EXT);
+        /* Stop virtual timer and halt the cpu. */
+        vtime_stop_cpu();
+        /* Reenable preemption tracer. */
         start_critical_timings();
 }
 
diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index e019b419efc6..a0d2d55d7fb3 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -119,8 +119,8 @@ void do_extint(struct pt_regs *regs, unsigned short code)
         struct pt_regs *old_regs;
 
         old_regs = set_irq_regs(regs);
-        irq_enter();
         s390_idle_check();
+        irq_enter();
         if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
                 /* Serve timer interrupts first. */
                 clock_comparator_work();
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index b7a1efd5522c..d825f4950e4e 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -427,6 +427,8 @@ setup_lowcore(void)
                 /* enable extended save area */
                 __ctl_set_bit(14, 29);
         }
+#else
+        lc->vdso_per_cpu_data = (unsigned long) &lc->paste[0];
 #endif
         set_prefix((u32)(unsigned long) lc);
 }
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 3ed5c7a83c6c..9c0ccb532a45 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -47,6 +47,7 @@
 #include <asm/lowcore.h>
 #include <asm/sclp.h>
 #include <asm/cpu.h>
+#include <asm/vdso.h>
 #include "entry.h"
 
 /*
@@ -500,6 +501,9 @@ static int __cpuinit smp_alloc_lowcore(int cpu)
                         goto out;
                 lowcore->extended_save_area_addr = (u32) save_area;
         }
+#else
+        if (vdso_alloc_per_cpu(cpu, lowcore))
+                goto out;
 #endif
         lowcore_ptr[cpu] = lowcore;
         return 0;
@@ -522,6 +526,8 @@ static void smp_free_lowcore(int cpu)
 #ifndef CONFIG_64BIT
         if (MACHINE_HAS_IEEE)
                 free_page((unsigned long) lowcore->extended_save_area_addr);
+#else
+        vdso_free_per_cpu(cpu, lowcore);
 #endif
         free_page(lowcore->panic_stack - PAGE_SIZE);
         free_pages(lowcore->async_stack - ASYNC_SIZE, ASYNC_ORDER);
@@ -664,6 +670,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
         lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, lc_order);
         panic_stack = __get_free_page(GFP_KERNEL);
         async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
+        BUG_ON(!lowcore || !panic_stack || !async_stack);
 #ifndef CONFIG_64BIT
         if (MACHINE_HAS_IEEE)
                 save_area = get_zeroed_page(GFP_KERNEL);
@@ -677,6 +684,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 #ifndef CONFIG_64BIT
         if (MACHINE_HAS_IEEE)
                 lowcore->extended_save_area_addr = (u32) save_area;
+#else
+        BUG_ON(vdso_alloc_per_cpu(smp_processor_id(), lowcore));
 #endif
         set_prefix((u32)(unsigned long) lowcore);
         local_mcck_enable();
@@ -845,9 +854,11 @@ static ssize_t show_idle_count(struct sys_device *dev,
         unsigned long long idle_count;
 
         idle = &per_cpu(s390_idle, dev->id);
-        spin_lock_irq(&idle->lock);
+        spin_lock(&idle->lock);
         idle_count = idle->idle_count;
-        spin_unlock_irq(&idle->lock);
+        if (idle->idle_enter)
+                idle_count++;
+        spin_unlock(&idle->lock);
         return sprintf(buf, "%llu\n", idle_count);
 }
 static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL);
@@ -856,18 +867,17 @@ static ssize_t show_idle_time(struct sys_device *dev,
                                 struct sysdev_attribute *attr, char *buf)
 {
         struct s390_idle_data *idle;
-        unsigned long long new_time;
+        unsigned long long now, idle_time, idle_enter;
 
         idle = &per_cpu(s390_idle, dev->id);
-        spin_lock_irq(&idle->lock);
-        if (idle->in_idle) {
-                new_time = get_clock();
-                idle->idle_time += new_time - idle->idle_enter;
-                idle->idle_enter = new_time;
-        }
-        new_time = idle->idle_time;
-        spin_unlock_irq(&idle->lock);
-        return sprintf(buf, "%llu\n", new_time >> 12);
+        spin_lock(&idle->lock);
+        now = get_clock();
+        idle_time = idle->idle_time;
+        idle_enter = idle->idle_enter;
+        if (idle_enter != 0ULL && idle_enter < now)
+                idle_time += now - idle_enter;
+        spin_unlock(&idle->lock);
+        return sprintf(buf, "%llu\n", idle_time >> 12);
 }
 static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL);
 
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 10a6ccef4412..25a6a82f1c02 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -31,9 +31,6 @@
 #include <asm/sections.h>
 #include <asm/vdso.h>
 
-/* Max supported size for symbol names */
-#define MAX_SYMNAME     64
-
 #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
 extern char vdso32_start, vdso32_end;
 static void *vdso32_kbase = &vdso32_start;
@@ -71,6 +68,119 @@ static union {
 struct vdso_data *vdso_data = &vdso_data_store.data;
 
 /*
+ * Setup vdso data page.
+ */
+static void vdso_init_data(struct vdso_data *vd)
+{
+        unsigned int facility_list;
+
+        facility_list = stfl();
+        vd->ectg_available = switch_amode && (facility_list & 1);
+}
+
+#ifdef CONFIG_64BIT
+/*
+ * Setup per cpu vdso data page.
+ */
+static void vdso_init_per_cpu_data(int cpu, struct vdso_per_cpu_data *vpcd)
+{
+}
+
+/*
+ * Allocate/free per cpu vdso data.
+ */
+#ifdef CONFIG_64BIT
+#define SEGMENT_ORDER   2
+#else
+#define SEGMENT_ORDER   1
+#endif
+
+int vdso_alloc_per_cpu(int cpu, struct _lowcore *lowcore)
+{
+        unsigned long segment_table, page_table, page_frame;
+        u32 *psal, *aste;
+        int i;
+
+        lowcore->vdso_per_cpu_data = __LC_PASTE;
+
+        if (!switch_amode || !vdso_enabled)
+                return 0;
+
+        segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
+        page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
+        page_frame = get_zeroed_page(GFP_KERNEL);
+        if (!segment_table || !page_table || !page_frame)
+                goto out;
+
+        clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
+                    PAGE_SIZE << SEGMENT_ORDER);
+        clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY,
+                    256*sizeof(unsigned long));
+
+        *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
+        *(unsigned long *) page_table = _PAGE_RO + page_frame;
+
+        psal = (u32 *) (page_table + 256*sizeof(unsigned long));
+        aste = psal + 32;
+
+        for (i = 4; i < 32; i += 4)
+                psal[i] = 0x80000000;
+
+        lowcore->paste[4] = (u32)(addr_t) psal;
+        psal[0] = 0x20000000;
+        psal[2] = (u32)(addr_t) aste;
+        *(unsigned long *) (aste + 2) = segment_table +
+                _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
+        aste[4] = (u32)(addr_t) psal;
+        lowcore->vdso_per_cpu_data = page_frame;
+
+        vdso_init_per_cpu_data(cpu, (struct vdso_per_cpu_data *) page_frame);
+        return 0;
+
+out:
+        free_page(page_frame);
+        free_page(page_table);
+        free_pages(segment_table, SEGMENT_ORDER);
+        return -ENOMEM;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+void vdso_free_per_cpu(int cpu, struct _lowcore *lowcore)
+{
+        unsigned long segment_table, page_table, page_frame;
+        u32 *psal, *aste;
+
+        if (!switch_amode || !vdso_enabled)
+                return;
+
+        psal = (u32 *)(addr_t) lowcore->paste[4];
+        aste = (u32 *)(addr_t) psal[2];
+        segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
+        page_table = *(unsigned long *) segment_table;
+        page_frame = *(unsigned long *) page_table;
+
+        free_page(page_frame);
+        free_page(page_table);
+        free_pages(segment_table, SEGMENT_ORDER);
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static void __vdso_init_cr5(void *dummy)
+{
+        unsigned long cr5;
+
+        cr5 = offsetof(struct _lowcore, paste);
+        __ctl_load(cr5, 5, 5);
+}
+
+static void vdso_init_cr5(void)
+{
+        if (switch_amode && vdso_enabled)
+                on_each_cpu(__vdso_init_cr5, NULL, 1);
+}
+#endif /* CONFIG_64BIT */
+
+/*
  * This is called from binfmt_elf, we create the special vma for the
  * vDSO and insert it into the mm struct tree
  */
@@ -172,6 +282,9 @@ static int __init vdso_init(void)
 {
         int i;
 
+        if (!vdso_enabled)
+                return 0;
+        vdso_init_data(vdso_data);
 #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
         /* Calculate the size of the 32 bit vDSO */
         vdso32_pages = ((&vdso32_end - &vdso32_start
@@ -208,6 +321,10 @@ static int __init vdso_init(void)
         }
         vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
         vdso64_pagelist[vdso64_pages] = NULL;
+#ifndef CONFIG_SMP
+        BUG_ON(vdso_alloc_per_cpu(0, S390_lowcore));
+#endif
+        vdso_init_cr5();
 #endif /* CONFIG_64BIT */
 
         get_page(virt_to_page(vdso_data));
diff --git a/arch/s390/kernel/vdso64/clock_getres.S b/arch/s390/kernel/vdso64/clock_getres.S
index 488e31a3c0e7..9ce8caafdb4e 100644
--- a/arch/s390/kernel/vdso64/clock_getres.S
+++ b/arch/s390/kernel/vdso64/clock_getres.S
@@ -22,7 +22,12 @@ __kernel_clock_getres:
         cghi    %r2,CLOCK_REALTIME
         je      0f
         cghi    %r2,CLOCK_MONOTONIC
+        je      0f
+        cghi    %r2,-2          /* CLOCK_THREAD_CPUTIME_ID for this thread */
         jne     2f
+        larl    %r5,_vdso_data
+        icm     %r0,15,__LC_ECTG_OK(%r5)
+        jz      2f
 0:      ltgr    %r3,%r3
         jz      1f                              /* res == NULL */
         larl    %r1,3f
diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S
index 738a410b7eb2..79dbfee831ec 100644
--- a/arch/s390/kernel/vdso64/clock_gettime.S
+++ b/arch/s390/kernel/vdso64/clock_gettime.S
@@ -22,8 +22,10 @@ __kernel_clock_gettime:
         larl    %r5,_vdso_data
         cghi    %r2,CLOCK_REALTIME
         je      4f
+        cghi    %r2,-2          /* CLOCK_THREAD_CPUTIME_ID for this thread */
+        je      9f
         cghi    %r2,CLOCK_MONOTONIC
-        jne     9f
+        jne     12f
 
         /* CLOCK_MONOTONIC */
         ltgr    %r3,%r3
@@ -42,7 +44,7 @@ __kernel_clock_gettime:
         alg     %r0,__VDSO_WTOM_SEC(%r5)
         clg     %r4,__VDSO_UPD_COUNT(%r5)       /* check update counter */
         jne     0b
-        larl    %r5,10f
+        larl    %r5,13f
 1:      clg     %r1,0(%r5)
         jl      2f
         slg     %r1,0(%r5)
@@ -68,7 +70,7 @@ __kernel_clock_gettime:
         lg      %r0,__VDSO_XTIME_SEC(%r5)
         clg     %r4,__VDSO_UPD_COUNT(%r5)       /* check update counter */
         jne     5b
-        larl    %r5,10f
+        larl    %r5,13f
 6:      clg     %r1,0(%r5)
         jl      7f
         slg     %r1,0(%r5)
@@ -79,11 +81,38 @@ __kernel_clock_gettime:
 8:      lghi    %r2,0
         br      %r14
 
+        /* CLOCK_THREAD_CPUTIME_ID for this thread */
+9:      icm     %r0,15,__VDSO_ECTG_OK(%r5)
+        jz      12f
+        ear     %r2,%a4
+        llilh   %r4,0x0100
+        sar     %a4,%r4
+        lghi    %r4,0
+        sacf    512                             /* Magic ectg instruction */
+        .insn   ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4
+        sacf    0
+        sar     %a4,%r2
+        algr    %r1,%r0                         /* r1 = cputime as TOD value */
+        mghi    %r1,1000                        /* convert to nanoseconds */
+        srlg    %r1,%r1,12                      /* r1 = cputime in nanosec */
+        lgr     %r4,%r1
+        larl    %r5,13f
+        srlg    %r1,%r1,9                       /* divide by 1000000000 */
+        mlg     %r0,8(%r5)
+        srlg    %r0,%r0,11                      /* r0 = tv_sec */
+        stg     %r0,0(%r3)
+        msg     %r0,0(%r5)                      /* calculate tv_nsec */
+        slgr    %r4,%r0                         /* r4 = tv_nsec */
+        stg     %r4,8(%r3)
+        lghi    %r2,0
+        br      %r14
+
         /* Fallback to system call */
-9:      lghi    %r1,__NR_clock_gettime
+12:     lghi    %r1,__NR_clock_gettime
         svc     0
         br      %r14
 
-10:     .quad   1000000000
+13:     .quad   1000000000
+14:     .quad   19342813113834067
         .cfi_endproc
         .size   __kernel_clock_gettime,.-__kernel_clock_gettime
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 75a6e62ea973..2fb36e462194 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -23,19 +23,43 @@
 #include <asm/s390_ext.h>
 #include <asm/timer.h>
 #include <asm/irq_regs.h>
+#include <asm/cpu.h>
 
 static ext_int_info_t ext_int_info_timer;
+
 static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
 
+DEFINE_PER_CPU(struct s390_idle_data, s390_idle) = {
+        .lock = __SPIN_LOCK_UNLOCKED(s390_idle.lock)
+};
+
+static inline __u64 get_vtimer(void)
+{
+        __u64 timer;
+
+        asm volatile("STPT %0" : "=m" (timer));
+        return timer;
+}
+
+static inline void set_vtimer(__u64 expires)
+{
+        __u64 timer;
+
+        asm volatile ("  STPT %0\n"  /* Store current cpu timer value */
+                      "  SPT %1"     /* Set new value immediatly afterwards */
+                      : "=m" (timer) : "m" (expires) );
+        S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
+        S390_lowcore.last_update_timer = expires;
+}
+
 /*
  * Update process times based on virtual cpu times stored by entry.S
  * to the lowcore fields user_timer, system_timer & steal_clock.
  */
-void account_process_tick(struct task_struct *tsk, int user_tick)
+static void do_account_vtime(struct task_struct *tsk, int hardirq_offset)
 {
-        cputime_t cputime;
-        __u64 timer, clock;
-        int rcu_user_flag;
+        struct thread_info *ti = task_thread_info(tsk);
+        __u64 timer, clock, user, system, steal;
 
         timer = S390_lowcore.last_update_timer;
         clock = S390_lowcore.last_update_clock;
@@ -44,50 +68,41 @@ void account_process_tick(struct task_struct *tsk, int user_tick)
                       : "=m" (S390_lowcore.last_update_timer),
                         "=m" (S390_lowcore.last_update_clock) );
         S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
-        S390_lowcore.steal_clock += S390_lowcore.last_update_clock - clock;
-
-        cputime = S390_lowcore.user_timer >> 12;
-        rcu_user_flag = cputime != 0;
-        S390_lowcore.user_timer -= cputime << 12;
-        S390_lowcore.steal_clock -= cputime << 12;
-        account_user_time(tsk, cputime);
-
-        cputime =  S390_lowcore.system_timer >> 12;
-        S390_lowcore.system_timer -= cputime << 12;
-        S390_lowcore.steal_clock -= cputime << 12;
-        account_system_time(tsk, HARDIRQ_OFFSET, cputime);
-
-        cputime = S390_lowcore.steal_clock;
-        if ((__s64) cputime > 0) {
-                cputime >>= 12;
-                S390_lowcore.steal_clock -= cputime << 12;
-                account_steal_time(tsk, cputime);
+        S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
+
+        user = S390_lowcore.user_timer - ti->user_timer;
+        S390_lowcore.steal_timer -= user;
+        ti->user_timer = S390_lowcore.user_timer;
+        account_user_time(tsk, user, user);
+
+        system = S390_lowcore.system_timer - ti->system_timer;
+        S390_lowcore.steal_timer -= system;
+        ti->system_timer = S390_lowcore.system_timer;
+        account_system_time(tsk, hardirq_offset, system, system);
+
+        steal = S390_lowcore.steal_timer;
+        if ((s64) steal > 0) {
+                S390_lowcore.steal_timer = 0;
+                account_steal_time(steal);
         }
 }
 
-/*
- * Update process times based on virtual cpu times stored by entry.S
- * to the lowcore fields user_timer, system_timer & steal_clock.
- */
-void account_vtime(struct task_struct *tsk)
+void account_vtime(struct task_struct *prev, struct task_struct *next)
 {
-        cputime_t cputime;
-        __u64 timer;
-
-        timer = S390_lowcore.last_update_timer;
-        asm volatile ("  STPT %0"    /* Store current cpu timer value */
-                      : "=m" (S390_lowcore.last_update_timer) );
-        S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
-
-        cputime = S390_lowcore.user_timer >> 12;
-        S390_lowcore.user_timer -= cputime << 12;
-        S390_lowcore.steal_clock -= cputime << 12;
-        account_user_time(tsk, cputime);
+        struct thread_info *ti;
+
+        do_account_vtime(prev, 0);
+        ti = task_thread_info(prev);
+        ti->user_timer = S390_lowcore.user_timer;
+        ti->system_timer = S390_lowcore.system_timer;
+        ti = task_thread_info(next);
+        S390_lowcore.user_timer = ti->user_timer;
+        S390_lowcore.system_timer = ti->system_timer;
+}
 
-        cputime =  S390_lowcore.system_timer >> 12;
-        S390_lowcore.system_timer -= cputime << 12;
-        S390_lowcore.steal_clock -= cputime << 12;
-        account_system_time(tsk, 0, cputime);
+void account_process_tick(struct task_struct *tsk, int user_tick)
+{
+        do_account_vtime(tsk, HARDIRQ_OFFSET);
 }
 
 /*
@@ -96,80 +111,131 @@ void account_vtime(struct task_struct *tsk)
  */
 void account_system_vtime(struct task_struct *tsk)
 {
-        cputime_t cputime;
-        __u64 timer;
+        struct thread_info *ti = task_thread_info(tsk);
+        __u64 timer, system;
 
         timer = S390_lowcore.last_update_timer;
-        asm volatile ("  STPT %0"    /* Store current cpu timer value */
-                      : "=m" (S390_lowcore.last_update_timer) );
+        S390_lowcore.last_update_timer = get_vtimer();
         S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
 
-        cputime =  S390_lowcore.system_timer >> 12;
-        S390_lowcore.system_timer -= cputime << 12;
-        S390_lowcore.steal_clock -= cputime << 12;
-        account_system_time(tsk, 0, cputime);
+        system = S390_lowcore.system_timer - ti->system_timer;
+        S390_lowcore.steal_timer -= system;
+        ti->system_timer = S390_lowcore.system_timer;
+        account_system_time(tsk, 0, system, system);
 }
 EXPORT_SYMBOL_GPL(account_system_vtime);
 
-static inline void set_vtimer(__u64 expires)
-{
-        __u64 timer;
-
-        asm volatile ("  STPT %0\n"  /* Store current cpu timer value */
-                      "  SPT %1"     /* Set new value immediatly afterwards */
-                      : "=m" (timer) : "m" (expires) );
-        S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
-        S390_lowcore.last_update_timer = expires;
-
-        /* store expire time for this CPU timer */
-        __get_cpu_var(virt_cpu_timer).to_expire = expires;
-}
-
-void vtime_start_cpu_timer(void)
+void vtime_start_cpu(void)
 {
-        struct vtimer_queue *vt_list;
-
-        vt_list = &__get_cpu_var(virt_cpu_timer);
-
-        /* CPU timer interrupt is pending, don't reprogramm it */
-        if (vt_list->idle & 1LL<<63)
-                return;
+        struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
+        struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
+        __u64 idle_time, expires;
+
+        /* 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.last_update_clock = S390_lowcore.int_clock;
+
+        /* Account system time spent going idle. */
+        S390_lowcore.system_timer += S390_lowcore.last_update_timer - vq->idle;
+        S390_lowcore.last_update_timer = S390_lowcore.async_enter_timer;
+
+        /* Restart vtime CPU timer */
+        if (vq->do_spt) {
+                /* Program old expire value but first save progress. */
+                expires = vq->idle - S390_lowcore.async_enter_timer;
+                expires += get_vtimer();
+                set_vtimer(expires);
+        } else {
+                /* Don't account the CPU timer delta while the cpu was idle. */
+                vq->elapsed -= vq->idle - S390_lowcore.async_enter_timer;
+        }
 
-        if (!list_empty(&vt_list->list))
-                set_vtimer(vt_list->idle);
+        spin_lock(&idle->lock);
+        idle->idle_time += idle_time;
+        idle->idle_enter = 0ULL;
+        idle->idle_count++;
+        spin_unlock(&idle->lock);
 }
 
-void vtime_stop_cpu_timer(void)
+void vtime_stop_cpu(void)
 {
-        struct vtimer_queue *vt_list;
-
-        vt_list = &__get_cpu_var(virt_cpu_timer);
-
-        /* nothing to do */
-        if (list_empty(&vt_list->list)) {
-                vt_list->idle = VTIMER_MAX_SLICE;
-                goto fire;
+        struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
+        struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
+        psw_t psw;
+
+        /* Wait for external, I/O or machine check interrupt. */
+        psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;
+
+        /* Check if the CPU timer needs to be reprogrammed. */
+        if (vq->do_spt) {
+                __u64 vmax = VTIMER_MAX_SLICE;
+                /*
+                 * The inline assembly is equivalent to
+                 *      vq->idle = get_cpu_timer();
+                 *      set_cpu_timer(VTIMER_MAX_SLICE);
+                 *      idle->idle_enter = get_clock();
+                 *      __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
+                 *                         PSW_MASK_IO | PSW_MASK_EXT);
+                 * The difference is that the inline assembly makes sure that
+                 * the last three instruction are stpt, stck and lpsw in that
+                 * order. This is done to increase the precision.
+                 */
+                asm volatile(
+#ifndef CONFIG_64BIT
+                        "       basr    1,0\n"
+                        "0:     ahi     1,1f-0b\n"
+                        "       st      1,4(%2)\n"
+#else /* CONFIG_64BIT */
+                        "       larl    1,1f\n"
+                        "       stg     1,8(%2)\n"
+#endif /* CONFIG_64BIT */
+                        "       stpt    0(%4)\n"
+                        "       spt     0(%5)\n"
+                        "       stck    0(%3)\n"
+#ifndef CONFIG_64BIT
+                        "       lpsw    0(%2)\n"
+#else /* CONFIG_64BIT */
+                        "       lpswe   0(%2)\n"
+#endif /* CONFIG_64BIT */
+                        "1:"
+                        : "=m" (idle->idle_enter), "=m" (vq->idle)
+                        : "a" (&psw), "a" (&idle->idle_enter),
+                          "a" (&vq->idle), "a" (&vmax), "m" (vmax), "m" (psw)
+                        : "memory", "cc", "1");
+        } else {
+                /*
+                 * The inline assembly is equivalent to
+                 *      vq->idle = get_cpu_timer();
+                 *      idle->idle_enter = get_clock();
+                 *      __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
+                 *                         PSW_MASK_IO | PSW_MASK_EXT);
+                 * The difference is that the inline assembly makes sure that
+                 * the last three instruction are stpt, stck and lpsw in that
+                 * order. This is done to increase the precision.
+                 */
+                asm volatile(
+#ifndef CONFIG_64BIT
+                        "       basr    1,0\n"
+                        "0:     ahi     1,1f-0b\n"
+                        "       st      1,4(%2)\n"
+#else /* CONFIG_64BIT */
+                        "       larl    1,1f\n"
+                        "       stg     1,8(%2)\n"
+#endif /* CONFIG_64BIT */
+                        "       stpt    0(%4)\n"
+                        "       stck    0(%3)\n"
+#ifndef CONFIG_64BIT
+                        "       lpsw    0(%2)\n"
+#else /* CONFIG_64BIT */
+                        "       lpswe   0(%2)\n"
+#endif /* CONFIG_64BIT */
+                        "1:"
+                        : "=m" (idle->idle_enter), "=m" (vq->idle)
+                        : "a" (&psw), "a" (&idle->idle_enter),
+                          "a" (&vq->idle), "m" (psw)
+                        : "memory", "cc", "1");
         }
-
-        /* store the actual expire value */
-        asm volatile ("STPT %0" : "=m" (vt_list->idle));
-
-        /*
-         * If the CPU timer is negative we don't reprogramm
-         * it because we will get instantly an interrupt.
-         */
-        if (vt_list->idle & 1LL<<63)
-                return;
-
-        vt_list->offset += vt_list->to_expire - vt_list->idle;
-
-        /*
-         * We cannot halt the CPU timer, we just write a value that
-         * nearly never expires (only after 71 years) and re-write
-         * the stored expire value if we continue the timer
-         */
- fire:
-        set_vtimer(VTIMER_MAX_SLICE);
 }
 
 /*
@@ -195,30 +261,23 @@ static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
  */
 static void do_callbacks(struct list_head *cb_list)
 {
-        struct vtimer_queue *vt_list;
+        struct vtimer_queue *vq;
         struct vtimer_list *event, *tmp;
-        void (*fn)(unsigned long);
-        unsigned long data;
 
         if (list_empty(cb_list))
                 return;
 
-        vt_list = &__get_cpu_var(virt_cpu_timer);
+        vq = &__get_cpu_var(virt_cpu_timer);
 
         list_for_each_entry_safe(event, tmp, cb_list, entry) {
-                fn = event->function;
-                data = event->data;
-                fn(data);
-
-                if (!event->interval)
-                        /* delete one shot timer */
-                        list_del_init(&event->entry);
-                else {
-                        /* move interval timer back to list */
-                        spin_lock(&vt_list->lock);
-                        list_del_init(&event->entry);
-                        list_add_sorted(event, &vt_list->list);
-                        spin_unlock(&vt_list->lock);
+                list_del_init(&event->entry);
+                (event->function)(event->data);
+                if (event->interval) {
+                        /* Recharge interval timer */
+                        event->expires = event->interval + vq->elapsed;
+                        spin_lock(&vq->lock);
+                        list_add_sorted(event, &vq->list);
+                        spin_unlock(&vq->lock);
                 }
         }
 }
@@ -228,64 +287,57 @@ static void do_callbacks(struct list_head *cb_list)
  */
 static void do_cpu_timer_interrupt(__u16 error_code)
 {
-        __u64 next, delta;
-        struct vtimer_queue *vt_list;
+        struct vtimer_queue *vq;
         struct vtimer_list *event, *tmp;
-        struct list_head *ptr;
-        /* the callback queue */
-        struct list_head cb_list;
+        struct list_head cb_list;       /* the callback queue */
+        __u64 elapsed, next;
 
         INIT_LIST_HEAD(&cb_list);
-        vt_list = &__get_cpu_var(virt_cpu_timer);
+        vq = &__get_cpu_var(virt_cpu_timer);
 
         /* walk timer list, fire all expired events */
-        spin_lock(&vt_list->lock);
-
-        if (vt_list->to_expire < VTIMER_MAX_SLICE)
-                vt_list->offset += vt_list->to_expire;
-
-        list_for_each_entry_safe(event, tmp, &vt_list->list, entry) {
-                if (event->expires > vt_list->offset)
-                        /* found first unexpired event, leave */
-                        break;
-
-                /* re-charge interval timer, we have to add the offset */
-                if (event->interval)
-                        event->expires = event->interval + vt_list->offset;
-
-                /* move expired timer to the callback queue */
-                list_move_tail(&event->entry, &cb_list);
+        spin_lock(&vq->lock);
+
+        elapsed = vq->elapsed + (vq->timer - S390_lowcore.async_enter_timer);
+        BUG_ON((s64) elapsed < 0);
+        vq->elapsed = 0;
+        list_for_each_entry_safe(event, tmp, &vq->list, entry) {
+                if (event->expires < elapsed)
+                        /* move expired timer to the callback queue */
+                        list_move_tail(&event->entry, &cb_list);
+                else
+                        event->expires -= elapsed;
         }
-        spin_unlock(&vt_list->lock);
+        spin_unlock(&vq->lock);
+
+        vq->do_spt = list_empty(&cb_list);
         do_callbacks(&cb_list);
 
         /* next event is first in list */
-        spin_lock(&vt_list->lock);
-        if (!list_empty(&vt_list->list)) {
-                ptr = vt_list->list.next;
-                event = list_entry(ptr, struct vtimer_list, entry);
-                next = event->expires - vt_list->offset;
-
-                /* add the expired time from this interrupt handler
-                 * and the callback functions
-                 */
-                asm volatile ("STPT %0" : "=m" (delta));
-                delta = 0xffffffffffffffffLL - delta + 1;
-                vt_list->offset += delta;
-                next -= delta;
-        } else {
-                vt_list->offset = 0;
-                next = VTIMER_MAX_SLICE;
-        }
-        spin_unlock(&vt_list->lock);
-        set_vtimer(next);
+        next = VTIMER_MAX_SLICE;
+        spin_lock(&vq->lock);
+        if (!list_empty(&vq->list)) {
+                event = list_first_entry(&vq->list, struct vtimer_list, entry);
+                next = event->expires;
+        } else
+                vq->do_spt = 0;
+        spin_unlock(&vq->lock);
+        /*
+         * To improve precision add the time spent by the
+         * interrupt handler to the elapsed time.
+         * Note: CPU timer counts down and we got an interrupt,
+         *       the current content is negative
+         */
+        elapsed = S390_lowcore.async_enter_timer - get_vtimer();
+        set_vtimer(next - elapsed);
+        vq->timer = next - elapsed;
+        vq->elapsed = elapsed;
 }
 
 void init_virt_timer(struct vtimer_list *timer)
 {
         timer->function = NULL;
         INIT_LIST_HEAD(&timer->entry);
-        spin_lock_init(&timer->lock);
 }
 EXPORT_SYMBOL(init_virt_timer);
 
@@ -299,44 +351,40 @@ static inline int vtimer_pending(struct vtimer_list *timer)
  */
 static void internal_add_vtimer(struct vtimer_list *timer)
 {
+        struct vtimer_queue *vq;
         unsigned long flags;
-        __u64 done;
-        struct vtimer_list *event;
-        struct vtimer_queue *vt_list;
+        __u64 left, expires;
 
-        vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
-        spin_lock_irqsave(&vt_list->lock, flags);
+        vq = &per_cpu(virt_cpu_timer, timer->cpu);
+        spin_lock_irqsave(&vq->lock, flags);
 
         BUG_ON(timer->cpu != smp_processor_id());
 
-        /* if list is empty we only have to set the timer */
-        if (list_empty(&vt_list->list)) {
-                /* reset the offset, this may happen if the last timer was
-                 * just deleted by mod_virt_timer and the interrupt
-                 * didn't happen until here
-                 */
-                vt_list->offset = 0;
-                goto fire;
+        if (list_empty(&vq->list)) {
+                /* First timer on this cpu, just program it. */
+                list_add(&timer->entry, &vq->list);
+                set_vtimer(timer->expires);
+                vq->timer = timer->expires;
+                vq->elapsed = 0;
+        } else {
+                /* Check progress of old timers. */
+                expires = timer->expires;
+                left = get_vtimer();
+                if (likely((s64) expires < (s64) left)) {
+                        /* The new timer expires before the current timer. */
+                        set_vtimer(expires);
+                        vq->elapsed += vq->timer - left;
+                        vq->timer = expires;
+                } else {
+                        vq->elapsed += vq->timer - left;
+                        vq->timer = left;
+                }
+                /* Insert new timer into per cpu list. */
+                timer->expires += vq->elapsed;
+                list_add_sorted(timer, &vq->list);
         }
 
-        /* save progress */
-        asm volatile ("STPT %0" : "=m" (done));
-
-        /* calculate completed work */
-        done = vt_list->to_expire - done + vt_list->offset;
-        vt_list->offset = 0;
-
-        list_for_each_entry(event, &vt_list->list, entry)
-                event->expires -= done;
-
- fire:
-        list_add_sorted(timer, &vt_list->list);
-
-        /* get first element, which is the next vtimer slice */
-        event = list_entry(vt_list->list.next, struct vtimer_list, entry);
-
-        set_vtimer(event->expires);
-        spin_unlock_irqrestore(&vt_list->lock, flags);
+        spin_unlock_irqrestore(&vq->lock, flags);
         /* release CPU acquired in prepare_vtimer or mod_virt_timer() */
         put_cpu();
 }
@@ -381,14 +429,15 @@ 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.
+ * 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)
 {
-        struct vtimer_queue *vt_list;
+        struct vtimer_queue *vq;
         unsigned long flags;
         int cpu;
 
@@ -404,17 +453,17 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
                 return 1;
 
         cpu = get_cpu();
-        vt_list = &per_cpu(virt_cpu_timer, 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(&vt_list->lock, flags);
+        spin_lock_irqsave(&vq->lock, flags);
 
         /* if timer isn't pending add it on the current CPU */
         if (!vtimer_pending(timer)) {
-                spin_unlock_irqrestore(&vt_list->lock, flags);
+                spin_unlock_irqrestore(&vq->lock, flags);
                 /* we do not activate an interval timer with mod_virt_timer */
                 timer->interval = 0;
                 timer->expires = expires;
@@ -431,7 +480,7 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
                 timer->interval = expires;
 
         /* the timer can't expire anymore so we can release the lock */
-        spin_unlock_irqrestore(&vt_list->lock, flags);
+        spin_unlock_irqrestore(&vq->lock, flags);
         internal_add_vtimer(timer);
         return 1;
 }
@@ -445,25 +494,19 @@ EXPORT_SYMBOL(mod_virt_timer);
 int del_virt_timer(struct vtimer_list *timer)
 {
         unsigned long flags;
-        struct vtimer_queue *vt_list;
+        struct vtimer_queue *vq;
 
         /* check if timer is pending */
         if (!vtimer_pending(timer))
                 return 0;
 
-        vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
-        spin_lock_irqsave(&vt_list->lock, flags);
+        vq = &per_cpu(virt_cpu_timer, timer->cpu);
+        spin_lock_irqsave(&vq->lock, flags);
 
         /* we don't interrupt a running timer, just let it expire! */
         list_del_init(&timer->entry);
 
-        /* last timer removed */
-        if (list_empty(&vt_list->list)) {
-                vt_list->to_expire = 0;
-                vt_list->offset = 0;
-        }
-
-        spin_unlock_irqrestore(&vt_list->lock, flags);
+        spin_unlock_irqrestore(&vq->lock, flags);
         return 1;
 }
 EXPORT_SYMBOL(del_virt_timer);
@@ -473,24 +516,19 @@ EXPORT_SYMBOL(del_virt_timer);
  */
 void init_cpu_vtimer(void)
 {
-        struct vtimer_queue *vt_list;
+        struct vtimer_queue *vq;
 
         /* kick the virtual timer */
-        S390_lowcore.exit_timer = VTIMER_MAX_SLICE;
-        S390_lowcore.last_update_timer = VTIMER_MAX_SLICE;
-        asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_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);
+        spin_lock_init(&vq->lock);
 
         /* enable cpu timer interrupts */
         __ctl_set_bit(0,10);
-
-        vt_list = &__get_cpu_var(virt_cpu_timer);
-        INIT_LIST_HEAD(&vt_list->list);
-        spin_lock_init(&vt_list->lock);
-        vt_list->to_expire = 0;
-        vt_list->offset = 0;
-        vt_list->idle = 0;
-
 }
 
 void __init vtime_init(void)