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Message-Id: <1480410117-6605-1-git-send-email-yu.c.chen@intel.com>
Date: Tue, 29 Nov 2016 17:01:57 +0800
From: Chen Yu <yu.c.chen@...el.com>
To: linux-kernel@...r.kernel.org
Cc: linux-pm@...r.kernel.org, Chen Yu <yu.c.chen@...el.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
John Stultz <john.stultz@...aro.org>,
Xunlei Pang <xlpang@...hat.com>,
Ingo Molnar <mingo@...hat.com>, Len Brown <lenb@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>, Pavel Machek <pavel@....cz>,
Thomas Gleixner <tglx@...utronix.de>,
Prarit Bhargava <prarit@...hat.com>,
Richard Cochran <richardcochran@...il.com>
Subject: [PATCH][v8] timekeeping: Ignore the bogus sleep time if pm_trace is enabled
Previously we encountered memory overflow issues due to
bogus sleep time brought by an inconsistent RTC, which is
triggered when pm_trace is enabled, and we have fixed it
in recent kernels. However it's improper in the first place
to call __timekeeping_inject_sleeptime() in case pm_trace
is enabled simply because the "hash" time value will wreckage
the timekeeping subsystem.
This patch was originally written by Thomas, which would bypass
the bogus RTC interval when pm_trace is enabled.
Meanwhile, if the system succeeds to resume back with pm_trace set,
users are warned to adjust the bogus RTC either by 'ntpdate' or
'rdate', by resetting pm_trace_rtc_abused to false, otherwise above
tools might not work as expected.
Originally-from: Thomas Gleixner <tglx@...utronix.de>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: John Stultz <john.stultz@...aro.org>
Cc: Xunlei Pang <xlpang@...hat.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Len Brown <lenb@...nel.org>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Pavel Machek <pavel@....cz>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Richard Cochran <richardcochran@...il.com>
Acked-by: Pavel Machek <pavel@....cz>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Chen Yu <yu.c.chen@...el.com>
---
-> v8:
Rewrite the comments and function declaration according to Ingo's suggestion.
---
arch/x86/kernel/rtc.c | 9 +++++++++
drivers/base/power/trace.c | 25 +++++++++++++++++++++++++
drivers/rtc/rtc-cmos.c | 7 +++++++
include/linux/mc146818rtc.h | 1 +
include/linux/pm-trace.h | 9 ++++++++-
5 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 79c6311c..7d35a21 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 bogus.
+ */
+ 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..5bc7d80 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -10,6 +10,7 @@
#include <linux/pm-trace.h>
#include <linux/export.h>
#include <linux/rtc.h>
+#include <linux/suspend.h>
#include <linux/mc146818rtc.h>
@@ -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;
}
@@ -238,10 +243,30 @@ int show_trace_dev_match(char *buf, size_t size)
device_pm_unlock();
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 7030d7c..24a0bf6 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 as storage, tell the caller that it 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 <asm/mc146818rtc.h> /* register access macros */
#include <linux/bcd.h>
#include <linux/delay.h>
+#include <linux/pm-trace.h>
#ifdef __KERNEL__
#include <linux/spinlock.h> /* 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 <linux/types.h>
#ifdef CONFIG_PM_TRACE
#include <asm/pm-trace.h>
-#include <linux/types.h>
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)
--
2.7.4
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