From 6e2ef5e4f6cc57344762932d70d38ba4ec65fa8b Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 27 Oct 2016 12:41:39 +0200 Subject: s390/time: add support for the TOD clock epoch extension The TOD epoch extension adds 8 epoch bits to the TOD clock to provide a continuous clock after 2042/09/17. The store-clock-extended (STCKE) instruction will store the epoch index in the first byte of the 16 bytes stored by the instruction. The read_boot_clock64 and the read_presistent_clock64 functions need to take the additional bits into account to give the correct result after 2042/09/17. The clock-comparator register will stay 64 bit wide. The comparison of the clock-comparator with the TOD clock is limited to bytes 1 to 8 of the extended TOD format. To deal with the overflow problem due to an epoch change the clock-comparator sign control in CR0 can be used to switch the comparison of the 64-bit TOD clock with the clock-comparator to a signed comparison. The decision between the signed vs. unsigned clock-comparator comparisons is done at boot time. Only if the TOD clock is in the second half of a 142 year epoch the signed comparison is used. This solves the epoch overflow issue as long as the machine is booted at least once in an epoch. Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/lowcore.h | 48 ++++++++++++++++++++--------------------- arch/s390/include/asm/setup.h | 2 ++ arch/s390/include/asm/timex.h | 38 ++++++++++++++++++++++++++++---- 3 files changed, 60 insertions(+), 28 deletions(-) (limited to 'arch/s390/include/asm') diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h index 8a5b082797f8..a6870ea6ea8b 100644 --- a/arch/s390/include/asm/lowcore.h +++ b/arch/s390/include/asm/lowcore.h @@ -95,46 +95,46 @@ struct lowcore { __u64 int_clock; /* 0x0310 */ __u64 mcck_clock; /* 0x0318 */ __u64 clock_comparator; /* 0x0320 */ + __u64 boot_clock[2]; /* 0x0328 */ /* Current process. */ - __u64 current_task; /* 0x0328 */ - __u8 pad_0x318[0x320-0x318]; /* 0x0330 */ - __u64 kernel_stack; /* 0x0338 */ + __u64 current_task; /* 0x0338 */ + __u64 kernel_stack; /* 0x0340 */ /* Interrupt, panic and restart stack. */ - __u64 async_stack; /* 0x0340 */ - __u64 panic_stack; /* 0x0348 */ - __u64 restart_stack; /* 0x0350 */ + __u64 async_stack; /* 0x0348 */ + __u64 panic_stack; /* 0x0350 */ + __u64 restart_stack; /* 0x0358 */ /* Restart function and parameter. */ - __u64 restart_fn; /* 0x0358 */ - __u64 restart_data; /* 0x0360 */ - __u64 restart_source; /* 0x0368 */ + __u64 restart_fn; /* 0x0360 */ + __u64 restart_data; /* 0x0368 */ + __u64 restart_source; /* 0x0370 */ /* Address space pointer. */ - __u64 kernel_asce; /* 0x0370 */ - __u64 user_asce; /* 0x0378 */ + __u64 kernel_asce; /* 0x0378 */ + __u64 user_asce; /* 0x0380 */ /* * The lpp and current_pid fields form a * 64-bit value that is set as program * parameter with the LPP instruction. */ - __u32 lpp; /* 0x0380 */ - __u32 current_pid; /* 0x0384 */ + __u32 lpp; /* 0x0388 */ + __u32 current_pid; /* 0x038c */ /* SMP info area */ - __u32 cpu_nr; /* 0x0388 */ - __u32 softirq_pending; /* 0x038c */ - __u64 percpu_offset; /* 0x0390 */ - __u64 vdso_per_cpu_data; /* 0x0398 */ - __u64 machine_flags; /* 0x03a0 */ - __u32 preempt_count; /* 0x03a8 */ - __u8 pad_0x03ac[0x03b0-0x03ac]; /* 0x03ac */ - __u64 gmap; /* 0x03b0 */ - __u32 spinlock_lockval; /* 0x03b8 */ - __u32 fpu_flags; /* 0x03bc */ - __u8 pad_0x03c0[0x0400-0x03c0]; /* 0x03c0 */ + __u32 cpu_nr; /* 0x0390 */ + __u32 softirq_pending; /* 0x0394 */ + __u64 percpu_offset; /* 0x0398 */ + __u64 vdso_per_cpu_data; /* 0x03a0 */ + __u64 machine_flags; /* 0x03a8 */ + __u32 preempt_count; /* 0x03b0 */ + __u8 pad_0x03b4[0x03b8-0x03b4]; /* 0x03b4 */ + __u64 gmap; /* 0x03b8 */ + __u32 spinlock_lockval; /* 0x03c0 */ + __u32 fpu_flags; /* 0x03c4 */ + __u8 pad_0x03c8[0x0400-0x03c8]; /* 0x03c8 */ /* Per cpu primary space access list */ __u32 paste[16]; /* 0x0400 */ diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h index 49c425903894..61da4bd6edad 100644 --- a/arch/s390/include/asm/setup.h +++ b/arch/s390/include/asm/setup.h @@ -32,6 +32,7 @@ #define MACHINE_FLAG_TLB_GUEST _BITUL(14) #define MACHINE_FLAG_NX _BITUL(15) #define MACHINE_FLAG_GS _BITUL(16) +#define MACHINE_FLAG_SCC _BITUL(17) #define LPP_MAGIC _BITUL(31) #define LPP_PFAULT_PID_MASK _AC(0xffffffff, UL) @@ -72,6 +73,7 @@ extern void detect_memory_memblock(void); #define MACHINE_HAS_TLB_GUEST (S390_lowcore.machine_flags & MACHINE_FLAG_TLB_GUEST) #define MACHINE_HAS_NX (S390_lowcore.machine_flags & MACHINE_FLAG_NX) #define MACHINE_HAS_GS (S390_lowcore.machine_flags & MACHINE_FLAG_GS) +#define MACHINE_HAS_SCC (S390_lowcore.machine_flags & MACHINE_FLAG_SCC) /* * Console mode. Override with conmode= diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index 118535123f34..0ea03c11458d 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -15,6 +15,8 @@ /* The value of the TOD clock for 1.1.1970. */ #define TOD_UNIX_EPOCH 0x7d91048bca000000ULL +extern u64 clock_comparator_max; + /* Inline functions for clock register access. */ static inline int set_tod_clock(__u64 time) { @@ -126,7 +128,7 @@ static inline unsigned long long local_tick_disable(void) unsigned long long old; old = S390_lowcore.clock_comparator; - S390_lowcore.clock_comparator = -1ULL; + S390_lowcore.clock_comparator = clock_comparator_max; set_clock_comparator(S390_lowcore.clock_comparator); return old; } @@ -178,20 +180,20 @@ int get_phys_clock(unsigned long long *clock); void init_cpu_timer(void); unsigned long long monotonic_clock(void); -extern u64 sched_clock_base_cc; +extern unsigned char tod_clock_base[16] __aligned(8); /** * get_clock_monotonic - returns current time in clock rate units * * The caller must ensure that preemption is disabled. - * The clock and sched_clock_base get changed via stop_machine. + * The clock and tod_clock_base get changed via stop_machine. * Therefore preemption must be disabled when calling this * function, otherwise the returned value is not guaranteed to * be monotonic. */ static inline unsigned long long get_tod_clock_monotonic(void) { - return get_tod_clock() - sched_clock_base_cc; + return get_tod_clock() - *(unsigned long long *) &tod_clock_base[1]; } /** @@ -218,4 +220,32 @@ static inline unsigned long long tod_to_ns(unsigned long long todval) return ((todval >> 9) * 125) + (((todval & 0x1ff) * 125) >> 9); } +/** + * tod_after - compare two 64 bit TOD values + * @a: first 64 bit TOD timestamp + * @b: second 64 bit TOD timestamp + * + * Returns: true if a is later than b + */ +static inline int tod_after(unsigned long long a, unsigned long long b) +{ + if (MACHINE_HAS_SCC) + return (long long) a > (long long) b; + return a > b; +} + +/** + * tod_after_eq - compare two 64 bit TOD values + * @a: first 64 bit TOD timestamp + * @b: second 64 bit TOD timestamp + * + * Returns: true if a is later than b + */ +static inline int tod_after_eq(unsigned long long a, unsigned long long b) +{ + if (MACHINE_HAS_SCC) + return (long long) a >= (long long) b; + return a >= b; +} + #endif -- cgit v1.2.3-59-g8ed1b