| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <8609778b-7bbe-fb05-7317-d88f15daba6b@redhat.com>
Date: Thu, 6 Apr 2023 14:30:16 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: "Box, David E" <david.e.box@...el.com>,
"Brown, Len" <len.brown@...el.com>,
"jstultz@...gle.com" <jstultz@...gle.com>,
"pavel@....cz" <pavel@....cz>,
"mario.limonciello@....com" <mario.limonciello@....com>,
"svenva@...omium.org" <svenva@...omium.org>,
"rafael@...nel.org" <rafael@...nel.org>
Cc: "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"Shyam-sundar.S-k@....com" <Shyam-sundar.S-k@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"platform-driver-x86@...r.kernel.org"
<platform-driver-x86@...r.kernel.org>,
"rrangel@...omium.org" <rrangel@...omium.org>,
"Jain, Rajat" <rajatja@...gle.com>
Subject: Re: [PATCH v6 1/4] PM: Add sysfs files to represent time spent in
hardware sleep state
Hi,
On 4/5/23 02:42, Box, David E wrote:
> Hi Mario,
>
> On Mon, 2023-04-03 at 16:18 -0500, Mario Limonciello wrote:
>> Userspace can't easily discover how much of a sleep cycle was spent in a
>> hardware sleep state without using kernel tracing and vendor specific sysfs
>> or debugfs files.
>>
>> To make this information more discoverable, introduce two new sysfs files:
>> 1) The time spent in a hw sleep state for last cycle.
>> 2) The time spent in a hw sleep state since the kernel booted
>> Both of these files will be present only if the system supports s2idle.
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>> v5->v6:
>> * Add total attribute as well
>> * Change text for documentation
>> * Adjust flow of is_visible callback.
>> * If overflow was detected in total attribute return -EOVERFLOW
>> * Rename symbol
>> * Add stub for symbol for builds without CONFIG_PM_SLEEP
>> v4->v5:
>> * Provide time in microseconds instead of percent. Userspace can convert
>> this if desirable.
>> ---
>> Documentation/ABI/testing/sysfs-power | 27 ++++++++++++++++
>> include/linux/suspend.h | 5 +++
>> kernel/power/main.c | 45 +++++++++++++++++++++++++++
>> 3 files changed, 77 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-power
>> b/Documentation/ABI/testing/sysfs-power
>> index f99d433ff311..37240575d282 100644
>> --- a/Documentation/ABI/testing/sysfs-power
>> +++ b/Documentation/ABI/testing/sysfs-power
>> @@ -413,6 +413,33 @@ Description:
>> The /sys/power/suspend_stats/last_failed_step file contains
>> the last failed step in the suspend/resume path.
>>
>> +What: /sys/power/suspend_stats/last_hw_sleep
>> +Date: June 2023
>> +Contact: Mario Limonciello <mario.limonciello@....com>
>> +Description:
>> + The /sys/power/suspend_stats/last_hw_sleep file
>> + contains the duration of time spent in a hardware sleep
>> + state in the most recent system suspend-resume cycle.
>> + This number is measured in microseconds.
>> +
>> + NOTE: Limitations in the size of the hardware counters may
>> + cause this value to be inaccurate in longer sleep cycles.
>> +
>> +What: /sys/power/suspend_stats/total_hw_sleep
>> +Date: June 2023
>> +Contact: Mario Limonciello <mario.limonciello@....com>
>> +Description:
>> + The /sys/power/suspend_stats/total_hw_sleep file
>> + contains the aggregate of time spent in a hardware sleep
>> + state since the kernel was booted. This number
>> + is measured in microseconds.
>> +
>> + NOTE: Limitations in the size of the hardware counters may
>> + cause this value to be inaccurate in longer sleep cycles.
>> +
>> + If an overflow has been detected this file will return
>> + -EOVERFLOW.
>> +
>> What: /sys/power/sync_on_suspend
>> Date: October 2019
>> Contact: Jonas Meurer <jonas@...esources.org>
>> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
>> index cfe19a028918..069ef0c0ae57 100644
>> --- a/include/linux/suspend.h
>> +++ b/include/linux/suspend.h
>> @@ -68,6 +68,8 @@ struct suspend_stats {
>> int last_failed_errno;
>> int errno[REC_FAILED_NUM];
>> int last_failed_step;
>> + u64 last_hw_sleep;
>> + u64 total_hw_sleep;
>> enum suspend_stat_step failed_steps[REC_FAILED_NUM];
>> };
>>
>> @@ -489,6 +491,7 @@ void restore_processor_state(void);
>> extern int register_pm_notifier(struct notifier_block *nb);
>> extern int unregister_pm_notifier(struct notifier_block *nb);
>> extern void ksys_sync_helper(void);
>> +extern void pm_report_hw_sleep_time(u64 t);
>>
>> #define pm_notifier(fn, pri) { \
>> static struct notifier_block fn##_nb = \
>> @@ -526,6 +529,8 @@ static inline int unregister_pm_notifier(struct
>> notifier_block *nb)
>> return 0;
>> }
>>
>> +static inline void pm_report_hw_sleep_time(u64 t) {};
>> +
>> static inline void ksys_sync_helper(void) {}
>>
>> #define pm_notifier(fn, pri) do { (void)(fn); } while (0)
>> diff --git a/kernel/power/main.c b/kernel/power/main.c
>> index 31ec4a9b9d70..ffd4dd43cbdd 100644
>> --- a/kernel/power/main.c
>> +++ b/kernel/power/main.c
>> @@ -6,6 +6,7 @@
>> * Copyright (c) 2003 Open Source Development Lab
>> */
>>
>> +#include <linux/acpi.h>
>> #include <linux/export.h>
>> #include <linux/kobject.h>
>> #include <linux/string.h>
>> @@ -83,6 +84,18 @@ int unregister_pm_notifier(struct notifier_block *nb)
>> }
>> EXPORT_SYMBOL_GPL(unregister_pm_notifier);
>>
>> +void pm_report_hw_sleep_time(u64 t)
>> +{
>> + suspend_stats.last_hw_sleep = t;
>> + if (suspend_stats.total_hw_sleep == -EOVERFLOW)
>> + return;
>> + if (suspend_stats.total_hw_sleep + t < suspend_stats.total_hw_sleep)
>> + suspend_stats.total_hw_sleep = -EOVERFLOW;
>> + else
>> + suspend_stats.total_hw_sleep += t;
>
> total_hw_sleep is u64. At microsecond granularity it will never realistically
> overflow and isn't worth the check IMO. The overflow concern comes from the u32
> hardware counter, but I don't think there's a good way to detect it.
>
> You could just report the maximum hardware counter time as max_hw_sleep so users
> know the value isn't reliable if suspended for longer than that.
Yes I think we need to let userspace know the longest hw-sleep time
the hw can reliably record and then userspace can (and should) chose
to not use/check the counters when the total suspend time is bigger
then the max hw-sleep time.
Other then that this patch-set seems like a good idea to me
and I have no objections / remarks on the pdx86 bits.
Regards,
Hans
>> +}
>> +EXPORT_SYMBOL_GPL(pm_report_hw_sleep_time);
>> +
>> int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long
>> val_down)
>> {
>> int ret;
>> @@ -377,6 +390,22 @@ static ssize_t last_failed_step_show(struct kobject
>> *kobj,
>> }
>> static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);
>>
>> +static ssize_t last_hw_sleep_show(struct kobject *kobj,
>> + struct kobj_attribute *attr, char *buf)
>> +{
>> + return sysfs_emit(buf, "%llu\n", suspend_stats.last_hw_sleep);
>> +}
>> +static struct kobj_attribute last_hw_sleep = __ATTR_RO(last_hw_sleep);
>> +
>> +static ssize_t total_hw_sleep_show(struct kobject *kobj,
>> + struct kobj_attribute *attr, char *buf)
>> +{
>> + if (suspend_stats.total_hw_sleep == -EOVERFLOW)
>> + return suspend_stats.total_hw_sleep;
>> + return sysfs_emit(buf, "%llu\n", suspend_stats.total_hw_sleep);
>> +}
>> +static struct kobj_attribute total_hw_sleep = __ATTR_RO(total_hw_sleep);
>> +
>> static struct attribute *suspend_attrs[] = {
>> &success.attr,
>> &fail.attr,
>> @@ -391,12 +420,28 @@ static struct attribute *suspend_attrs[] = {
>> &last_failed_dev.attr,
>> &last_failed_errno.attr,
>> &last_failed_step.attr,
>> + &last_hw_sleep.attr,
>> + &total_hw_sleep.attr,
>> NULL,
>> };
>>
>> +static umode_t suspend_attr_is_visible(struct kobject *kobj, struct attribute
>> *attr, int idx)
>> +{
>> + if (attr != &last_hw_sleep.attr &&
>> + attr != &total_hw_sleep.attr)
>> + return 0444;
>> +
>> +#ifdef CONFIG_ACPI
>> + if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)
>> + return 0444;
>> +#endif
>> + return 0;
>> +}
>> +
>> static const struct attribute_group suspend_attr_group = {
>> .name = "suspend_stats",
>> .attrs = suspend_attrs,
>> + .is_visible = suspend_attr_is_visible,
>> };
>>
>> #ifdef CONFIG_DEBUG_FS
Powered by blists - more mailing lists