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Date: Fri, 13 Jun 2014 07:43:08 -0400
From: Josh Boyer <jwboyer@...oraproject.org>
To: Kees Cook <keescook@...omium.org>
Cc: "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"H. Peter Anvin" <hpa@...or.com>,
Randy Dunlap <rdunlap@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, x86 <x86@...nel.org>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
linux-doc@...r.kernel.org, Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] hibernate: create "nohibernate" boot parameter
On Thu, Jun 12, 2014 at 5:00 PM, Kees Cook <keescook@...omium.org> wrote:
> To support using kernel features that are not compatible with hibernation,
> this creates the "nohibernate" kernel boot parameter to disable both
> hibernation and resume. This allows hibernation support to be a boot-time
> choice instead of only a compile-time choice.
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
This looks really useful. We have a similar mechanism in Fedora to
disable hibernation for Secure Boot purposes, but this is much more
generic. Other than the rather minor comment below, I think it looks
good.
> ---
> Documentation/kernel-parameters.txt | 3 +++
> include/linux/suspend.h | 2 ++
> kernel/power/hibernate.c | 31 ++++++++++++++++++++++++++++++-
> kernel/power/main.c | 6 ++----
> kernel/power/user.c | 3 +++
> 5 files changed, 40 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 6eaa9cdb7094..f8f0466b8b1d 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2184,6 +2184,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> in certain environments such as networked servers or
> real-time systems.
>
> + nohibernate [HIBERNATION] Disable hibernation and resume.
> +
> nohz= [KNL] Boottime enable/disable dynamic ticks
> Valid arguments: on, off
> Default: on
> @@ -2980,6 +2982,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> noresume Don't check if there's a hibernation image
> present during boot.
> nocompress Don't compress/decompress hibernation images.
> + no Disable hibernation and resume.
>
> retain_initrd [RAM] Keep initrd memory after extraction
>
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index f76994b9396c..519064e0c943 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -327,6 +327,7 @@ extern unsigned long get_safe_page(gfp_t gfp_mask);
> extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
> extern int hibernate(void);
> extern bool system_entering_hibernation(void);
> +extern bool hibernation_available(void);
> asmlinkage int swsusp_save(void);
> extern struct pbe *restore_pblist;
> #else /* CONFIG_HIBERNATION */
> @@ -339,6 +340,7 @@ static inline void swsusp_unset_page_free(struct page *p) {}
> static inline void hibernation_set_ops(const struct platform_hibernation_ops *ops) {}
> static inline int hibernate(void) { return -ENOSYS; }
> static inline bool system_entering_hibernation(void) { return false; }
> +static inline bool hibernation_available(void) { return false; }
> #endif /* CONFIG_HIBERNATION */
>
> /* Hibernation and suspend events */
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index df88d55dc436..fd3e785dbc37 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -34,6 +34,7 @@
>
> static int nocompress;
> static int noresume;
> +static int nohibernate;
> static int resume_wait;
> static unsigned int resume_delay;
> static char resume_file[256] = CONFIG_PM_STD_PARTITION;
> @@ -61,6 +62,11 @@ bool freezer_test_done;
>
> static const struct platform_hibernation_ops *hibernation_ops;
>
> +bool hibernation_available(void)
> +{
> + return (nohibernate == 0);
> +}
> +
> /**
> * hibernation_set_ops - Set the global hibernate operations.
> * @ops: Hibernation operations to use in subsequent hibernation transitions.
> @@ -639,6 +645,11 @@ int hibernate(void)
> {
> int error;
>
> + if (!hibernation_available()) {
> + pr_debug("PM: Hibernation not available.\n");
> + return -EINVAL;
> + }
> +
> lock_system_sleep();
> /* The snapshot device should not be opened while we're running */
> if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
> @@ -731,7 +742,7 @@ static int software_resume(void)
> /*
> * If the user said "noresume".. bail out early.
> */
> - if (noresume)
> + if (noresume || !hibernation_available())
> return 0;
>
> /*
> @@ -897,6 +908,9 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
> int i;
> char *start = buf;
>
> + if (!hibernation_available())
> + return sprintf(buf, "[disabled]\n");
> +
> for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
> if (!hibernation_modes[i])
> continue;
> @@ -931,6 +945,9 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
> char *p;
> int mode = HIBERNATION_INVALID;
>
> + if (!hibernation_available())
> + return -EINVAL;
> +
Similar to Pavel's comment, EINVAL works but isn't exactly clear. We
use -EPERM in our current patch which might be more accurate. I could
see arguments either way.
> p = memchr(buf, '\n', n);
> len = p ? p - buf : n;
>
> @@ -1098,6 +1115,10 @@ static int __init hibernate_setup(char *str)
> noresume = 1;
> else if (!strncmp(str, "nocompress", 10))
> nocompress = 1;
> + else if (!strncmp(str, "no", 2)) {
> + noresume = 1;
> + nohibernate = 1;
> + }
> return 1;
> }
>
> @@ -1122,9 +1143,17 @@ static int __init resumedelay_setup(char *str)
> return 1;
> }
>
> +static int __init nohibernate_setup(char *str)
> +{
> + noresume = 1;
> + nohibernate = 1;
> + return 1;
> +}
> +
> __setup("noresume", noresume_setup);
> __setup("resume_offset=", resume_offset_setup);
> __setup("resume=", resume_setup);
> __setup("hibernate=", hibernate_setup);
> __setup("resumewait", resumewait_setup);
> __setup("resumedelay=", resumedelay_setup);
> +__setup("nohibernate", nohibernate_setup);
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 573410d6647e..8e90f330f139 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -300,13 +300,11 @@ static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
> s += sprintf(s,"%s ", pm_states[i].label);
>
> #endif
> -#ifdef CONFIG_HIBERNATION
> - s += sprintf(s, "%s\n", "disk");
> -#else
> + if (hibernation_available())
> + s += sprintf(s, "disk ");
> if (s != buf)
> /* convert the last space to a newline */
> *(s-1) = '\n';
> -#endif
> return (s - buf);
> }
>
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index 98d357584cd6..000b94419182 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -49,6 +49,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
> struct snapshot_data *data;
> int error;
>
> + if (!hibernation_available())
> + return -EINVAL;
> +
Same comment as above.
josh
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