Re: [PATCH 2/4] ACPI hibernate: Add a mechanism to save/restore ACPI NVS memory (rev. 2)

Nigel Cunningham
2008-10-23T08:03:42Z

Hi.

On Thu, 2008-10-23 at 07:47 +0200, Rafael J. Wysocki wrote:
> On Thursday, 23 of October 2008, Nigel Cunningham wrote:
> > On Thu, 2008-10-23 at 01:08 +0200, Rafael J. Wysocki wrote:
> > > On Thursday, 23 of October 2008, Nigel Cunningham wrote:
> > > > On Wed, 2008-10-22 at 22:52 +0200, Rafael J. Wysocki wrote:
> > > > > From: Rafael J. Wysocki <rjw@sisk.pl>
> [--snip--]
> > > > > +/**
> > > > > + * hibernate_nvs_save - save NVS memory regions
> > > > > + */
> > > > > +void hibernate_nvs_save(void)
> > > > > +{
> > > > > + struct nvs_page *entry;
> > > > > +
> > > > > + printk(KERN_INFO "PM: Saving platform NVS memory\n");
> > > > > +
> > > > > + list_for_each_entry(entry, &nvs_list, node)
> > > > > + if (entry->data) {
> > > > > + entry->kaddr = ioremap(entry->phys_start, entry->size);
> > > > > + memcpy(entry->data, entry->kaddr, entry->size);
> > > >
> > > > Why not unmap here? (I know you're delaying the unmap until the free,
> > > > but it's probably clearer to map and unmap each time the memory is
> > > > accessed (ie in restore too).
> > >
> > > Ah, this one is tricky. We cannot unmap from atomic context. :-)
> >
> > Maybe a comment then, lest someone get the same idea in future and be as
> > ignorant as me? :)
>
> Well, I was considering to add one, now changed the kerneldoc comment to
> mention that.

Terrific. Thanks.

> Please find updated patch below.
>
> ---
> From: Rafael J. Wysocki <rjw@sisk.pl>
>
> ACPI hibernate: Add a mechanism to save/restore ACPI NVS memory (rev. 2)
>
> According to the ACPI Specification 3.0b, Section 15.3.2,
> "OSPM will call the _PTS control method some time before entering a
> sleeping state, to allow the platform’s AML code to update this
> memory image before entering the sleeping state. After the system
> awakes from an S4 state, OSPM will restore this memory area and call
> the _WAK control method to enable the BIOS to reclaim its memory
> image." For this reason, implement a mechanism allowing us to save
> the NVS memory during hibernation and to restore it during the
> subsequent resume.
>
> Based on a patch by Zhang Rui.
>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> Acked-by: Nigel Cunningham <nigel@tuxonice.net>
> Cc: Zhang Rui <rui.zhang@intel.com>
> ---
> drivers/acpi/sleep/main.c | 50 +++++++++++++++---
> include/linux/suspend.h | 13 ++++
> kernel/power/swsusp.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 180 insertions(+), 7 deletions(-)
>
> Index: linux-2.6/drivers/acpi/sleep/main.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/sleep/main.c
> +++ linux-2.6/drivers/acpi/sleep/main.c
> @@ -321,8 +321,23 @@ void __init acpi_no_s4_hw_signature(void
>
> static int acpi_hibernation_begin(void)
> {
> - acpi_target_sleep_state = ACPI_STATE_S4;
> - return 0;
> + int error;
> +
> + error = hibernate_nvs_alloc();
> + if (!error)
> + acpi_target_sleep_state = ACPI_STATE_S4;
> +
> + return error;
> +}
> +
> +static int acpi_hibernation_pre_snapshot(void)
> +{
> + int error = acpi_pm_prepare();
> +
> + if (!error)
> + hibernate_nvs_save();
> +
> + return error;
> }
>
> static int acpi_hibernation_enter(void)
> @@ -343,6 +358,12 @@ static int acpi_hibernation_enter(void)
> return ACPI_SUCCESS(status) ? 0 : -EFAULT;
> }
>
> +static void acpi_hibernation_finish(void)
> +{
> + hibernate_nvs_free();
> + acpi_pm_finish();
> +}
> +
> static void acpi_hibernation_leave(void)
> {
> /*
> @@ -358,6 +379,8 @@ static void acpi_hibernation_leave(void)
> "cannot resume!\n");
> panic("ACPI S4 hardware signature mismatch");
> }
> + /* Restore the NVS memory area */
> + hibernate_nvs_restore();
> }
>
> static void acpi_pm_enable_gpes(void)
> @@ -368,8 +391,8 @@ static void acpi_pm_enable_gpes(void)
> static struct platform_hibernation_ops acpi_hibernation_ops = {
> .begin = acpi_hibernation_begin,
> .end = acpi_pm_end,
> - .pre_snapshot = acpi_pm_prepare,
> - .finish = acpi_pm_finish,
> + .pre_snapshot = acpi_hibernation_pre_snapshot,
> + .finish = acpi_hibernation_finish,
> .prepare = acpi_pm_prepare,
> .enter = acpi_hibernation_enter,
> .leave = acpi_hibernation_leave,
> @@ -387,8 +410,21 @@ static int acpi_hibernation_begin_old(vo
> {
> int error = acpi_sleep_prepare(ACPI_STATE_S4);
>
> + if (!error) {
> + error = hibernate_nvs_alloc();
> + if (!error)
> + acpi_target_sleep_state = ACPI_STATE_S4;
> + }
> + return error;
> +}
> +
> +static int acpi_hibernation_pre_snapshot_old(void)
> +{
> + int error = acpi_pm_disable_gpes();
> +
> if (!error)
> - acpi_target_sleep_state = ACPI_STATE_S4;
> + hibernate_nvs_save();
> +
> return error;
> }
>
> @@ -399,8 +435,8 @@ static int acpi_hibernation_begin_old(vo
> static struct platform_hibernation_ops acpi_hibernation_ops_old = {
> .begin = acpi_hibernation_begin_old,
> .end = acpi_pm_end,
> - .pre_snapshot = acpi_pm_disable_gpes,
> - .finish = acpi_pm_finish,
> + .pre_snapshot = acpi_hibernation_pre_snapshot_old,
> + .finish = acpi_hibernation_finish,
> .prepare = acpi_pm_disable_gpes,
> .enter = acpi_hibernation_enter,
> .leave = acpi_hibernation_leave,
> Index: linux-2.6/include/linux/suspend.h
> ===================================================================
> --- linux-2.6.orig/include/linux/suspend.h
> +++ linux-2.6/include/linux/suspend.h
> @@ -233,6 +233,11 @@ extern unsigned long get_safe_page(gfp_t
> extern void hibernation_set_ops(struct platform_hibernation_ops *ops);
> extern int hibernate(void);
> extern bool system_entering_hibernation(void);
> +extern int hibernate_nvs_register(unsigned long start, unsigned long size);
> +extern int hibernate_nvs_alloc(void);
> +extern void hibernate_nvs_free(void);
> +extern void hibernate_nvs_save(void);
> +extern void hibernate_nvs_restore(void);
> #else /* CONFIG_HIBERNATION */
> static inline int swsusp_page_is_forbidden(struct page *p) { return 0; }
> static inline void swsusp_set_page_free(struct page *p) {}
> @@ -241,6 +246,14 @@ static inline void swsusp_unset_page_fre
> static inline void hibernation_set_ops(struct platform_hibernation_ops *ops) {}
> static inline int hibernate(void) { return -ENOSYS; }
> static inline bool system_entering_hibernation(void) { return false; }
> +static inline int hibernate_nvs_register(unsigned long a, unsigned long b)
> +{
> + return 0;
> +}
> +static inline int hibernate_nvs_alloc(void) { return 0; }
> +static inline void hibernate_nvs_free(void) {}
> +static inline void hibernate_nvs_save(void) {}
> +static inline void hibernate_nvs_restore(void) {}
> #endif /* CONFIG_HIBERNATION */
>
> #ifdef CONFIG_PM_SLEEP
> Index: linux-2.6/kernel/power/swsusp.c
> ===================================================================
> --- linux-2.6.orig/kernel/power/swsusp.c
> +++ linux-2.6/kernel/power/swsusp.c
> @@ -262,3 +262,127 @@ int swsusp_shrink_memory(void)
>
> return 0;
> }
> +
> +/*
> + * Platforms, like ACPI, may want us to save some memory used by them during

Both commas should be removed from the line above.

> + * hibernation and to restore the contents of this memory during the subsequent
> + * resume. The code below implements a mechanism allowing us to do that.
> + */
> +
> +struct nvs_page {
> + unsigned long phys_start;
> + unsigned int size;
> + void *kaddr;
> + void *data;
> + struct list_head node;
> +};
> +
> +static LIST_HEAD(nvs_list);
> +
> +/**
> + * hibernate_nvs_register - register platform NVS memory region to save
> + * @start - physical address of the region
> + * @size - size of the region
> + *
> + * The NVS region need not be page-aligned (both ends) and we arrange
> + * things so that the data from page-aligned addresses in this region will
> + * be copied into separate RAM pages.
> + */
> +int hibernate_nvs_register(unsigned long start, unsigned long size)
> +{
> + struct nvs_page *entry, *next;
> +
> + while (size > 0) {
> + unsigned int nr_bytes;
> +
> + entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
> + if (!entry)
> + goto Error;
> +
> + list_add_tail(&entry->node, &nvs_list);
> + entry->phys_start = start;
> + nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
> + entry->size = (size < nr_bytes) ? size : nr_bytes;
> +
> + start += entry->size;
> + size -= entry->size;
> + }
> + return 0;
> +
> + Error:
> + list_for_each_entry_safe(entry, next, &nvs_list, node) {
> + list_del(&entry->node);
> + kfree(entry);
> + }
> + return -ENOMEM;
> +}
> +
> +/**
> + * hibernate_nvs_free - free data pages allocated for saving NVS regions
> + *
> + * It is allowed to call this function many times in a row.

"This function may safely be called multiple times." .... maybe just do
without the comment?

> + */
> +void hibernate_nvs_free(void)
> +{
> + struct nvs_page *entry;
> +
> + list_for_each_entry(entry, &nvs_list, node)
> + if (entry->data) {
> + free_page((unsigned long)entry->data);
> + entry->data = NULL;
> + if (entry->kaddr) {
> + iounmap(entry->kaddr);
> + entry->kaddr = NULL;
> + }
> + }
> +}
> +
> +/**
> + * hibernate_nvs_alloc - allocate memory necessary for saving NVS regions
> + */
> +int hibernate_nvs_alloc(void)
> +{
> + struct nvs_page *entry;
> +
> + list_for_each_entry(entry, &nvs_list, node) {
> + entry->data = (void *)__get_free_page(GFP_KERNEL);
> + if (!entry->data) {
> + hibernate_nvs_free();
> + return -ENOMEM;
> + }
> + }
> + return 0;
> +}
> +
> +/**
> + * hibernate_nvs_save - save NVS memory regions
> + */
> +void hibernate_nvs_save(void)
> +{
> + struct nvs_page *entry;
> +
> + printk(KERN_INFO "PM: Saving platform NVS memory\n");
> +
> + list_for_each_entry(entry, &nvs_list, node)
> + if (entry->data) {
> + entry->kaddr = ioremap(entry->phys_start, entry->size);
> + memcpy(entry->data, entry->kaddr, entry->size);
> + }
> +}
> +
> +/**
> + * hibernate_nvs_restore - restore NVS memory regions
> + *
> + * This function is going to be called with interrupts disabled, so it
> + * cannot iounmap the virtual addresses used to access the NVS region.
> + */
> +void hibernate_nvs_restore(void)
> +{
> + struct nvs_page *entry;
> +
> + printk(KERN_INFO "PM: Restoring platform NVS memory\n");
> +
> + list_for_each_entry(entry, &nvs_list, node)
> + if (entry->data)
> + memcpy(entry->kaddr, entry->data, entry->size);
> +}

Regards,

Nigel

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