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authorArnd Bergmann <arnd@arndb.de>2017-11-10 16:25:04 +0100
committerThomas Gleixner <tglx@linutronix.de>2017-11-12 15:05:52 +0100
commitdf27067e6040b51188184876253d93da002433aa (patch)
tree86cc33ed2a85cd5a971f19962e4f5e842da96da8
parentb3fe565bf47de3f79bb5dff9bee1112b46ba5434 (diff)
pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday()
__getnstimeofday() is a rather odd interface, with a number of quirks: - The caller may come from NMI context, but the implementation is not NMI safe, one way to get there from NMI is NMI handler: something bad panic() kmsg_dump() pstore_dump() pstore_record_init() __getnstimeofday() - The calling conventions are different from any other timekeeping functions, to deal with returning an error code during suspended timekeeping. Address the above issues by using a completely different method to get the time: ktime_get_real_fast_ns() is NMI safe and has a reasonable behavior when timekeeping is suspended: it returns the time at which it got suspended. As Thomas Gleixner explained, this is safe, as ktime_get_real_fast_ns() does not call into the clocksource driver that might be suspended. The result can easily be transformed into a timespec structure. Since ktime_get_real_fast_ns() was not exported to modules, add the export. The pstore behavior for the suspended case changes slightly, as it now stores the timestamp at which timekeeping was suspended instead of storing a zero timestamp. This change is not addressing y2038-safety, that's subject to a more complex follow up patch. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Kees Cook <keescook@chromium.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Anton Vorontsov <anton@enomsg.org> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Colin Cross <ccross@android.com> Link: https://lkml.kernel.org/r/20171110152530.1926955-1-arnd@arndb.de
-rw-r--r--fs/pstore/platform.c5
-rw-r--r--kernel/time/timekeeping.c1
2 files changed, 2 insertions, 4 deletions
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index ec7199e859d2..086e491faf04 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -482,10 +482,7 @@ void pstore_record_init(struct pstore_record *record,
record->psi = psinfo;
/* Report zeroed timestamp if called before timekeeping has resumed. */
- if (__getnstimeofday(&record->time)) {
- record->time.tv_sec = 0;
- record->time.tv_nsec = 0;
- }
+ record->time = ns_to_timespec(ktime_get_real_fast_ns());
}
/*
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 353f7bd1eeb0..198afa78bf69 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -528,6 +528,7 @@ u64 ktime_get_real_fast_ns(void)
{
return __ktime_get_real_fast_ns(&tk_fast_mono);
}
+EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
/**
* halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.

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