kdb is the only user of the __current_kernel_time() interface, which is
not y2038 safe and should be removed at some point.
The kdb code also goes to great lengths to print the time in a
human-readable format from 'struct timespec', again using a non-y2038-safe
re-implementation of the generic time_to_tm() code.
Using __current_kernel_time() here is necessary since the regular
accessors that require a sequence lock might hang when called during the
xtime update. However, this is safe in the particular case since kdb is
only interested in the tv_sec field that is updated atomically.
In order to make this y2038-safe, I'm converting the code to the generic
time64_to_tm helper, but that introduces the problem that we have no
interface like __current_kernel_time() that provides a 64-bit timestamp
in a lockless, safe and architecture-independent way. I have multiple
ideas for how to solve that:
- __ktime_get_real_seconds() is lockless, but can return
incorrect results on 32-bit architectures in the special case that
we are in the process of changing the time across the epoch, either
during the timer tick that overflows the seconds in 2038, or while
calling settimeofday.
- ktime_get_real_fast_ns() would work in this context, but does
require a call into the clocksource driver to return a high-resolution
timestamp. This may have undesired side-effects in the debugger,
since we want to limit the interactions with the rest of the kernel.
- Adding a ktime_get_real_fast_seconds() based on tk_fast_mono
plus tkr->base_real without the tk_clock_read() delta. Not sure about
the value of adding yet another interface here.
- Changing the existing ktime_get_real_seconds() to use
tk_fast_mono on 32-bit architectures rather than xtime_sec. I think
this could work, but am not entirely sure if this is an improvement.
I picked the first of those for simplicity here. It's technically
not correct but probably good enough as the time is only used for the
debugging output and the race will likely never be hit in practice.
Another downside is having to move the declaration into a public header
file.
Let me know if anyone has a different preference.
Cc: Andy Shevchenko <andriy.shevchenko(a)linux.intel.com>
Link: https://patchwork.kernel.org/patch/9775309/
Signed-off-by: Arnd Bergmann <arnd(a)arndb.de>
---
include/linux/timekeeping.h | 1 +
kernel/debug/kdb/kdb_main.c | 45 +++++---------------------------------
kernel/time/timekeeping_internal.h | 2 --
3 files changed, 6 insertions(+), 42 deletions(-)
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index eb98cbdbb323..9b59473556fe 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -41,6 +41,7 @@ struct timespec64 get_monotonic_coarse64(void);
extern void getrawmonotonic64(struct timespec64 *ts);
extern void ktime_get_ts64(struct timespec64 *ts);
extern time64_t ktime_get_seconds(void);
+extern time64_t __ktime_get_real_seconds(void);
extern time64_t ktime_get_real_seconds(void);
extern int __getnstimeofday64(struct timespec64 *tv);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index c8146d53ca67..69e70f4021fe 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -2479,41 +2479,6 @@ static int kdb_kill(int argc, const char **argv)
return 0;
}
-struct kdb_tm {
- int tm_sec; /* seconds */
- int tm_min; /* minutes */
- int tm_hour; /* hours */
- int tm_mday; /* day of the month */
- int tm_mon; /* month */
- int tm_year; /* year */
-};
-
-static void kdb_gmtime(struct timespec *tv, struct kdb_tm *tm)
-{
- /* This will work from 1970-2099, 2100 is not a leap year */
- static int mon_day[] = { 31, 29, 31, 30, 31, 30, 31,
- 31, 30, 31, 30, 31 };
- memset(tm, 0, sizeof(*tm));
- tm->tm_sec = tv->tv_sec % (24 * 60 * 60);
- tm->tm_mday = tv->tv_sec / (24 * 60 * 60) +
- (2 * 365 + 1); /* shift base from 1970 to 1968 */
- tm->tm_min = tm->tm_sec / 60 % 60;
- tm->tm_hour = tm->tm_sec / 60 / 60;
- tm->tm_sec = tm->tm_sec % 60;
- tm->tm_year = 68 + 4*(tm->tm_mday / (4*365+1));
- tm->tm_mday %= (4*365+1);
- mon_day[1] = 29;
- while (tm->tm_mday >= mon_day[tm->tm_mon]) {
- tm->tm_mday -= mon_day[tm->tm_mon];
- if (++tm->tm_mon == 12) {
- tm->tm_mon = 0;
- ++tm->tm_year;
- mon_day[1] = 28;
- }
- }
- ++tm->tm_mday;
-}
-
/*
* Most of this code has been lifted from kernel/timer.c::sys_sysinfo().
* I cannot call that code directly from kdb, it has an unconditional
@@ -2539,8 +2504,8 @@ static void kdb_sysinfo(struct sysinfo *val)
*/
static int kdb_summary(int argc, const char **argv)
{
- struct timespec now;
- struct kdb_tm tm;
+ time64_t now;
+ struct tm tm;
struct sysinfo val;
if (argc)
@@ -2554,9 +2519,9 @@ static int kdb_summary(int argc, const char **argv)
kdb_printf("domainname %s\n", init_uts_ns.name.domainname);
kdb_printf("ccversion %s\n", __stringify(CCVERSION));
- now = __current_kernel_time();
- kdb_gmtime(&now, &tm);
- kdb_printf("date %04d-%02d-%02d %02d:%02d:%02d "
+ now = __ktime_get_real_seconds();
+ time64_to_tm(now, 0, &tm);
+ kdb_printf("date %04ld-%02d-%02d %02d:%02d:%02d "
"tz_minuteswest %d\n",
1900+tm.tm_year, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec,
diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h
index 9a18f121f399..58e79485de1b 100644
--- a/kernel/time/timekeeping_internal.h
+++ b/kernel/time/timekeeping_internal.h
@@ -30,6 +30,4 @@ static inline u64 clocksource_delta(u64 now, u64 last, u64 mask)
}
#endif
-extern time64_t __ktime_get_real_seconds(void);
-
#endif /* _TIMEKEEPING_INTERNAL_H */
--
2.9.0
The series is aimed at making input events y2038 safe.
It extends the lifetime of the realtime timestamps in the
events to year 2106.
The series is also a necessary update as glibc is set to provide
64 bit time_t support for 32 bit binaries. glibc plan is detailed
at https://sourceware.org/glibc/wiki/Y2038ProofnessDesign .
The series is a result of discussions with Arnd Bergmann and
Dmitry Torokhov at last Plumbers.
The plan is to deprecate realtime timestamps anyway as they
are not appropriate for these timestamps as noted in the patch
a80b83b7b8 by John Stultz.
The design also updates the format of the input events read/ written
to the device nodes. This breaks 32 bit interface to the input
events at compile time as preferred by the maintainer.
The userspace library changes to libevdev, libuinput and mtdev
will be posted to the respective mailing groups for review.
Changes from v2:
* Updated the design to break 32 bit interfaces at compile time.
Changes from v1:
* Updated changes according to review comments.
* Posted userspace library changes that go along with the series.
Deepa Dinamani (4):
uinput: Add ioctl for using monotonic/ boot times
input: evdev: Replace timeval with timespec64
input: Deprecate real timestamps beyond year 2106
input: serio: Replace timeval by timespec64
drivers/input/evdev.c | 43 +++++++++++++++++++-----------
drivers/input/input-compat.c | 11 ++++----
drivers/input/input-compat.h | 3 ++-
drivers/input/misc/uinput.c | 57 +++++++++++++++++++++++++++++++++++++++-
drivers/input/serio/hil_mlc.c | 37 +++++++++++++-------------
drivers/input/serio/hp_sdc.c | 17 ++++++------
drivers/input/serio/hp_sdc_mlc.c | 10 +++----
include/linux/hil_mlc.h | 6 ++---
include/linux/hp_sdc.h | 6 ++---
include/uapi/linux/input.h | 12 ++++++++-
include/uapi/linux/uinput.h | 3 +++
11 files changed, 143 insertions(+), 62 deletions(-)
base-commit: b0a84f19a5161418d4360cd57603e94ed489915e
--
2.14.1
getnstimeofday() and timespec are deprecated since they can
overflow on 32-bit architectures. This simply changes to the
explicitly typed timespec64 version that doesn't have that
problem.
It would be nice to also convert to monotonic timestamps
and call ktime_get_ts64() rather than ktime_get_real_ts64(),
but that would be a user-visible change.
Signed-off-by: Arnd Bergmann <arnd(a)arndb.de>
---
drivers/s390/block/dasd.c | 10 +++++-----
drivers/s390/block/dasd_int.h | 2 +-
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 0f1ff0813493..f48b3d5082cf 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -758,7 +758,7 @@ static void dasd_profile_end_add_data(struct dasd_profile_info *data,
/* in case of an overflow, reset the whole profile */
if (data->dasd_io_reqs == UINT_MAX) {
memset(data, 0, sizeof(*data));
- getnstimeofday(&data->starttod);
+ ktime_get_real_ts64(&data->starttod);
}
data->dasd_io_reqs++;
data->dasd_io_sects += sectors;
@@ -893,7 +893,7 @@ void dasd_profile_reset(struct dasd_profile *profile)
return;
}
memset(data, 0, sizeof(*data));
- getnstimeofday(&data->starttod);
+ ktime_get_real_ts64(&data->starttod);
spin_unlock_bh(&profile->lock);
}
@@ -910,7 +910,7 @@ int dasd_profile_on(struct dasd_profile *profile)
kfree(data);
return 0;
}
- getnstimeofday(&data->starttod);
+ ktime_get_real_ts64(&data->starttod);
profile->data = data;
spin_unlock_bh(&profile->lock);
return 0;
@@ -994,8 +994,8 @@ static void dasd_stats_array(struct seq_file *m, unsigned int *array)
static void dasd_stats_seq_print(struct seq_file *m,
struct dasd_profile_info *data)
{
- seq_printf(m, "start_time %ld.%09ld\n",
- data->starttod.tv_sec, data->starttod.tv_nsec);
+ seq_printf(m, "start_time %lld.%09ld\n",
+ (s64)data->starttod.tv_sec, data->starttod.tv_nsec);
seq_printf(m, "total_requests %u\n", data->dasd_io_reqs);
seq_printf(m, "total_sectors %u\n", data->dasd_io_sects);
seq_printf(m, "total_pav %u\n", data->dasd_io_alias);
diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index b095a23bcc0c..96709b1a7bf8 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -441,7 +441,7 @@ struct dasd_profile_info {
unsigned int dasd_io_nr_req[32]; /* hist. of # of requests in chanq */
/* new data */
- struct timespec starttod; /* time of start or last reset */
+ struct timespec64 starttod; /* time of start or last reset */
unsigned int dasd_io_alias; /* requests using an alias */
unsigned int dasd_io_tpm; /* requests using transport mode */
unsigned int dasd_read_reqs; /* total number of read requests */
--
2.9.0
