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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2016-10-27 12:41:39 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-07-26 08:25:14 +0200
commit6e2ef5e4f6cc57344762932d70d38ba4ec65fa8b (patch)
tree51e148a3b1e6991260af2ac51e6b1a6d5eb0f83a /arch/s390/kernel/debug.c
parent45be0a02f8110a13502fac6167a893c7c0eff432 (diff)
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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 <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/debug.c')
-rw-r--r--arch/s390/kernel/debug.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
index 86b3e74f569e..1d9e83c401fc 100644
--- a/arch/s390/kernel/debug.c
+++ b/arch/s390/kernel/debug.c
@@ -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)