Commit 6e2ef5e4 authored by Martin Schwidefsky's avatar Martin Schwidefsky

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 45be0a02
......@@ -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 */
......
......@@ -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=
......
......@@ -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
......@@ -158,6 +158,7 @@ int main(void)
OFFSET(__LC_LAST_UPDATE_CLOCK, lowcore, last_update_clock);
OFFSET(__LC_INT_CLOCK, lowcore, int_clock);
OFFSET(__LC_MCCK_CLOCK, lowcore, mcck_clock);
OFFSET(__LC_BOOT_CLOCK, lowcore, boot_clock);
OFFSET(__LC_CURRENT, lowcore, current_task);
OFFSET(__LC_KERNEL_STACK, lowcore, kernel_stack);
OFFSET(__LC_ASYNC_STACK, lowcore, async_stack);
......
......@@ -866,7 +866,8 @@ static inline void
debug_finish_entry(debug_info_t * id, debug_entry_t* active, int level,
int exception)
{
active->id.stck = get_tod_clock_fast() - sched_clock_base_cc;
active->id.stck = get_tod_clock_fast() -
*(unsigned long long *) &tod_clock_base[1];
active->id.fields.cpuid = smp_processor_id();
active->caller = __builtin_return_address(0);
active->id.fields.exception = exception;
......@@ -1455,15 +1456,15 @@ int
debug_dflt_header_fn(debug_info_t * id, struct debug_view *view,
int area, debug_entry_t * entry, char *out_buf)
{
unsigned long sec, usec;
unsigned long base, sec, usec;
char *except_str;
unsigned long caller;
int rc = 0;
unsigned int level;
level = entry->id.fields.level;
sec = (entry->id.stck >> 12) + (sched_clock_base_cc >> 12);
sec = sec - (TOD_UNIX_EPOCH >> 12);
base = (*(unsigned long *) &tod_clock_base[0]) >> 4;
sec = (entry->id.stck >> 12) + base - (TOD_UNIX_EPOCH >> 12);
usec = do_div(sec, USEC_PER_SEC);
if (entry->id.fields.exception)
......
......@@ -53,8 +53,9 @@ static void __init reset_tod_clock(void)
if (set_tod_clock(TOD_UNIX_EPOCH) != 0 || store_tod_clock(&time) != 0)
disabled_wait(0);
sched_clock_base_cc = TOD_UNIX_EPOCH;
S390_lowcore.last_update_clock = sched_clock_base_cc;
memset(tod_clock_base, 0, 16);
*(__u64 *) &tod_clock_base[1] = TOD_UNIX_EPOCH;
S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;
}
#ifdef CONFIG_SHARED_KERNEL
......@@ -165,8 +166,8 @@ static noinline __init void create_kernel_nss(void)
}
/* re-initialize cputime accounting. */
sched_clock_base_cc = get_tod_clock();
S390_lowcore.last_update_clock = sched_clock_base_cc;
get_tod_clock_ext(tod_clock_base);
S390_lowcore.last_update_clock = *(__u64 *) &tod_clock_base[1];
S390_lowcore.last_update_timer = 0x7fffffffffffffffULL;
S390_lowcore.user_timer = 0;
S390_lowcore.system_timer = 0;
......@@ -387,6 +388,12 @@ static __init void detect_machine_facilities(void)
}
if (test_facility(133))
S390_lowcore.machine_flags |= MACHINE_FLAG_GS;
if (test_facility(139) && (tod_clock_base[1] & 0x80)) {
/* Enabled signed clock comparator comparisons */
S390_lowcore.machine_flags |= MACHINE_FLAG_SCC;
clock_comparator_max = -1ULL >> 1;
__ctl_set_bit(0, 53);
}
}
static inline void save_vector_registers(void)
......
......@@ -302,7 +302,8 @@ ENTRY(startup_kdump)
xc 0xe00(256),0xe00
xc 0xf00(256),0xf00
lctlg %c0,%c15,0x200(%r0) # initialize control registers
stck __LC_LAST_UPDATE_CLOCK
stcke __LC_BOOT_CLOCK
mvc __LC_LAST_UPDATE_CLOCK(8),__LC_BOOT_CLOCK+1
spt 6f-.LPG0(%r13)
mvc __LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
l %r15,.Lstack-.LPG0(%r13)
......
......@@ -21,8 +21,8 @@ ENTRY(startup_continue)
xc __LC_LPP+1(7,0),__LC_LPP+1 # clear lpp and current_pid
mvi __LC_LPP,0x80 # and set LPP_MAGIC
.insn s,0xb2800000,__LC_LPP # load program parameter
0: larl %r1,sched_clock_base_cc
mvc 0(8,%r1),__LC_LAST_UPDATE_CLOCK
0: larl %r1,tod_clock_base
mvc 0(16,%r1),__LC_BOOT_CLOCK
larl %r13,.LPG1 # get base
lctlg %c0,%c15,.Lctl-.LPG1(%r13) # load control registers
lg %r12,.Lparmaddr-.LPG1(%r13) # pointer to parameter area
......
......@@ -105,7 +105,8 @@ void do_IRQ(struct pt_regs *regs, int irq)
old_regs = set_irq_regs(regs);
irq_enter();
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
if (tod_after_eq(S390_lowcore.int_clock,
S390_lowcore.clock_comparator))
/* Serve timer interrupts first. */
clock_comparator_work();
generic_handle_irq(irq);
......
......@@ -323,7 +323,7 @@ static void __init setup_lowcore(void)
lc->io_new_psw.mask = PSW_KERNEL_BITS |
PSW_MASK_DAT | PSW_MASK_MCHECK;
lc->io_new_psw.addr = (unsigned long) io_int_handler;
lc->clock_comparator = -1ULL;
lc->clock_comparator = clock_comparator_max;
lc->kernel_stack = ((unsigned long) &init_thread_union)
+ THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
lc->async_stack = (unsigned long)
......
......@@ -51,8 +51,15 @@
#include <asm/cio.h>
#include "entry.h"
u64 sched_clock_base_cc = -1; /* Force to data section. */
EXPORT_SYMBOL_GPL(sched_clock_base_cc);
unsigned char tod_clock_base[16] __aligned(8) = {
/* Force to data section. */
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};
EXPORT_SYMBOL_GPL(tod_clock_base);
u64 clock_comparator_max = -1ULL;
EXPORT_SYMBOL_GPL(clock_comparator_max);
static DEFINE_PER_CPU(struct clock_event_device, comparators);
......@@ -75,7 +82,7 @@ void __init time_early_init(void)
struct ptff_qui qui;
/* Initialize TOD steering parameters */
tod_steering_end = sched_clock_base_cc;
tod_steering_end = *(unsigned long long *) &tod_clock_base[1];
vdso_data->ts_end = tod_steering_end;
if (!test_facility(28))
......@@ -111,22 +118,27 @@ unsigned long long monotonic_clock(void)
}
EXPORT_SYMBOL(monotonic_clock);
static void tod_to_timeval(__u64 todval, struct timespec64 *xt)
static void ext_to_timespec64(unsigned char *clk, struct timespec64 *xt)
{
unsigned long long sec;
unsigned long long high, low, rem, sec, nsec;
/* Split extendnd TOD clock to micro-seconds and sub-micro-seconds */
high = (*(unsigned long long *) clk) >> 4;
low = (*(unsigned long long *)&clk[7]) << 4;
/* Calculate seconds and nano-seconds */
sec = high;
rem = do_div(sec, 1000000);
nsec = (((low >> 32) + (rem << 32)) * 1000) >> 32;
sec = todval >> 12;
do_div(sec, 1000000);
xt->tv_sec = sec;
todval -= (sec * 1000000) << 12;
xt->tv_nsec = ((todval * 1000) >> 12);
xt->tv_nsec = nsec;
}
void clock_comparator_work(void)
{
struct clock_event_device *cd;
S390_lowcore.clock_comparator = -1ULL;
S390_lowcore.clock_comparator = clock_comparator_max;
cd = this_cpu_ptr(&comparators);
cd->event_handler(cd);
}
......@@ -148,7 +160,7 @@ void init_cpu_timer(void)
struct clock_event_device *cd;
int cpu;
S390_lowcore.clock_comparator = -1ULL;
S390_lowcore.clock_comparator = clock_comparator_max;
set_clock_comparator(S390_lowcore.clock_comparator);
cpu = smp_processor_id();
......@@ -179,7 +191,7 @@ static void clock_comparator_interrupt(struct ext_code ext_code,
unsigned long param64)
{
inc_irq_stat(IRQEXT_CLK);
if (S390_lowcore.clock_comparator == -1ULL)
if (S390_lowcore.clock_comparator == clock_comparator_max)
set_clock_comparator(S390_lowcore.clock_comparator);
}
......@@ -197,18 +209,28 @@ static void stp_reset(void);
void read_persistent_clock64(struct timespec64 *ts)
{
__u64 clock;
unsigned char clk[STORE_CLOCK_EXT_SIZE];
__u64 delta;
clock = get_tod_clock() - initial_leap_seconds;
tod_to_timeval(clock - TOD_UNIX_EPOCH, ts);
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
get_tod_clock_ext(clk);
*(__u64 *) &clk[1] -= delta;
if (*(__u64 *) &clk[1] > delta)
clk[0]--;
ext_to_timespec64(clk, ts);
}
void read_boot_clock64(struct timespec64 *ts)
{
__u64 clock;
unsigned char clk[STORE_CLOCK_EXT_SIZE];
__u64 delta;
clock = sched_clock_base_cc - initial_leap_seconds;
tod_to_timeval(clock - TOD_UNIX_EPOCH, ts);
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
memcpy(clk, tod_clock_base, 16);
*(__u64 *) &clk[1] -= delta;
if (*(__u64 *) &clk[1] > delta)
clk[0]--;
ext_to_timespec64(clk, ts);
}
static u64 read_tod_clock(struct clocksource *cs)
......@@ -406,7 +428,10 @@ static void clock_sync_global(unsigned long long delta)
struct ptff_qto qto;
/* Fixup the monotonic sched clock. */
sched_clock_base_cc += delta;
*(unsigned long long *) &tod_clock_base[1] += delta;
if (*(unsigned long long *) &tod_clock_base[1] < delta)
/* Epoch overflow */
tod_clock_base[0]++;
/* Adjust TOD steering parameters. */
vdso_data->tb_update_count++;
now = get_tod_clock();
......@@ -437,7 +462,7 @@ static void clock_sync_global(unsigned long long delta)
static void clock_sync_local(unsigned long long delta)
{
/* Add the delta to the clock comparator. */
if (S390_lowcore.clock_comparator != -1ULL) {
if (S390_lowcore.clock_comparator != clock_comparator_max) {
S390_lowcore.clock_comparator += delta;
set_clock_comparator(S390_lowcore.clock_comparator);
}
......
......@@ -57,7 +57,7 @@ static void __udelay_enabled(unsigned long long usecs)
end = get_tod_clock_fast() + (usecs << 12);
do {
clock_saved = 0;
if (end < S390_lowcore.clock_comparator) {
if (tod_after(S390_lowcore.clock_comparator, end)) {
clock_saved = local_tick_disable();
set_clock_comparator(end);
}
......
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