From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756253AbcK2RLn (ORCPT ); Tue, 29 Nov 2016 12:11:43 -0500 Received: from terminus.zytor.com ([198.137.202.10]:38622 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756161AbcK2RLO (ORCPT ); Tue, 29 Nov 2016 12:11:14 -0500 Date: Tue, 29 Nov 2016 09:10:51 -0800 From: tip-bot for Chen Yu Message-ID: Cc: linux-kernel@vger.kernel.org, lenb@kernel.org, richardcochran@gmail.com, mingo@kernel.org, xlpang@redhat.com, pavel@ucw.cz, yu.c.chen@intel.com, rjw@rjwysocki.net, hpa@zytor.com, tglx@linutronix.de, john.stultz@linaro.org, prarit@redhat.com Reply-To: prarit@redhat.com, john.stultz@linaro.org, richardcochran@gmail.com, lenb@kernel.org, linux-kernel@vger.kernel.org, xlpang@redhat.com, pavel@ucw.cz, mingo@kernel.org, rjw@rjwysocki.net, hpa@zytor.com, yu.c.chen@intel.com, tglx@linutronix.de In-Reply-To: <1480372524-15181-3-git-send-email-john.stultz@linaro.org> References: <1480372524-15181-3-git-send-email-john.stultz@linaro.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] timekeeping: Ignore the bogus sleep time if pm_trace is enabled Git-Commit-ID: ba58d1020a54933c6b087a3107661c8513556cb8 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ba58d1020a54933c6b087a3107661c8513556cb8 Gitweb: http://git.kernel.org/tip/ba58d1020a54933c6b087a3107661c8513556cb8 Author: Chen Yu AuthorDate: Mon, 28 Nov 2016 14:35:19 -0800 Committer: Thomas Gleixner CommitDate: Tue, 29 Nov 2016 18:02:58 +0100 timekeeping: Ignore the bogus sleep time if pm_trace is enabled Power management suspend/resume tracing (ab)uses the RTC to store suspend/resume information persistently. As a consequence the RTC value is clobbered when timekeeping is resumed and tries to inject the sleep time. Commit a4f8f6667f09 ("timekeeping: Cap array access in timekeeping_debug") plugged a out of bounds array access in the timekeeping debug code which was caused by the clobbered RTC value, but we still use the clobbered RTC value for sleep time injection into kernel timekeeping, which will result in random adjustments depending on the stored "hash" value. To prevent this keep track of the RTC clobbering and ignore the invalid RTC timestamp at resume. If the system resumed successfully clear the flag, which marks the RTC as unusable, warn the user about the RTC clobber and recommend to adjust the RTC with 'ntpdate' or 'rdate'. [jstultz: Fixed up pr_warn formating, and implemented suggestions from Ingo] [ tglx: Rewrote changelog ] Originally-from: Thomas Gleixner Signed-off-by: Chen Yu Signed-off-by: John Stultz Acked-by: Pavel Machek Acked-by: Thomas Gleixner Cc: Prarit Bhargava Cc: "Rafael J. Wysocki" Cc: Richard Cochran Cc: Xunlei Pang Cc: Len Brown Link: http://lkml.kernel.org/r/1480372524-15181-3-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner --- arch/x86/kernel/rtc.c | 9 +++++++++ drivers/base/power/trace.c | 27 +++++++++++++++++++++++++++ drivers/rtc/rtc-cmos.c | 7 +++++++ include/linux/mc146818rtc.h | 1 + include/linux/pm-trace.h | 9 ++++++++- 5 files changed, 52 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index 79c6311c..5b21cb7 100644 --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -64,6 +64,15 @@ void mach_get_cmos_time(struct timespec *now) unsigned int status, year, mon, day, hour, min, sec, century = 0; unsigned long flags; + /* + * If pm_trace abused the RTC as storage, set the timespec to 0, + * which tells the caller that this RTC value is unusable. + */ + if (!pm_trace_rtc_valid()) { + now->tv_sec = now->tv_nsec = 0; + return; + } + spin_lock_irqsave(&rtc_lock, flags); /* diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c index efec10b..1cda505 100644 --- a/drivers/base/power/trace.c +++ b/drivers/base/power/trace.c @@ -10,6 +10,7 @@ #include #include #include +#include #include @@ -74,6 +75,9 @@ #define DEVSEED (7919) +bool pm_trace_rtc_abused __read_mostly; +EXPORT_SYMBOL_GPL(pm_trace_rtc_abused); + static unsigned int dev_hash_value; static int set_magic_time(unsigned int user, unsigned int file, unsigned int device) @@ -104,6 +108,7 @@ static int set_magic_time(unsigned int user, unsigned int file, unsigned int dev time.tm_min = (n % 20) * 3; n /= 20; mc146818_set_time(&time); + pm_trace_rtc_abused = true; return n ? -1 : 0; } @@ -239,9 +244,31 @@ int show_trace_dev_match(char *buf, size_t size) return ret; } +static int +pm_trace_notify(struct notifier_block *nb, unsigned long mode, void *_unused) +{ + switch (mode) { + case PM_POST_HIBERNATION: + case PM_POST_SUSPEND: + if (pm_trace_rtc_abused) { + pm_trace_rtc_abused = false; + pr_warn("Possible incorrect RTC due to pm_trace, please use 'ntpdate' or 'rdate' to reset it.\n"); + } + break; + default: + break; + } + return 0; +} + +static struct notifier_block pm_trace_nb = { + .notifier_call = pm_trace_notify, +}; + static int early_resume_init(void) { hash_value_early_read = read_magic_time(); + register_pm_notifier(&pm_trace_nb); return 0; } diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index dd3d598..b27a189 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -191,6 +191,13 @@ static inline void cmos_write_bank2(unsigned char val, unsigned char addr) static int cmos_read_time(struct device *dev, struct rtc_time *t) { + /* + * If pm_trace abused the RTC for storage, set the timespec to 0, + * which tells the caller that this RTC value is unusable. + */ + if (!pm_trace_rtc_valid()) + return -EIO; + /* REVISIT: if the clock has a "century" register, use * that instead of the heuristic in mc146818_get_time(). * That'll make Y3K compatility (year > 2070) easy! diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h index a585b4b..0661af1 100644 --- a/include/linux/mc146818rtc.h +++ b/include/linux/mc146818rtc.h @@ -16,6 +16,7 @@ #include /* register access macros */ #include #include +#include #ifdef __KERNEL__ #include /* spinlock_t */ diff --git a/include/linux/pm-trace.h b/include/linux/pm-trace.h index ecbde7a..7b78793 100644 --- a/include/linux/pm-trace.h +++ b/include/linux/pm-trace.h @@ -1,11 +1,17 @@ #ifndef PM_TRACE_H #define PM_TRACE_H +#include #ifdef CONFIG_PM_TRACE #include -#include extern int pm_trace_enabled; +extern bool pm_trace_rtc_abused; + +static inline bool pm_trace_rtc_valid(void) +{ + return !pm_trace_rtc_abused; +} static inline int pm_trace_is_enabled(void) { @@ -24,6 +30,7 @@ extern int show_trace_dev_match(char *buf, size_t size); #else +static inline bool pm_trace_rtc_valid(void) { return true; } static inline int pm_trace_is_enabled(void) { return 0; } #define TRACE_DEVICE(dev) do { } while (0)