[PATCH] swsusp: low level interface
Introduce the low level interface that can be used for handling the
snapshot of the system memory by the in-kernel swap-writing/reading code of
swsusp and the userland interface code (to be introduced shortly).
Also change the way in which swsusp records the allocated swap pages and,
consequently, simplifies the in-kernel swap-writing/reading code (this is
necessary for the userland interface too). To this end, it introduces two
helper functions in mm/swapfile.c, so that the swsusp code does not refer
directly to the swap internals.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 8d5a598..cc34943 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -10,6 +10,7 @@
*/
+#include <linux/version.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/suspend.h>
@@ -34,7 +35,8 @@
#include "power.h"
struct pbe *pagedir_nosave;
-unsigned int nr_copy_pages;
+static unsigned int nr_copy_pages;
+static unsigned int nr_meta_pages;
#ifdef CONFIG_HIGHMEM
unsigned int count_highmem_pages(void)
@@ -235,7 +237,7 @@
* free_pagedir - free pages allocated with alloc_pagedir()
*/
-void free_pagedir(struct pbe *pblist)
+static void free_pagedir(struct pbe *pblist)
{
struct pbe *pbe;
@@ -301,7 +303,7 @@
static struct eaten_page *eaten_pages = NULL;
-void release_eaten_pages(void)
+static void release_eaten_pages(void)
{
struct eaten_page *p, *q;
@@ -376,7 +378,6 @@
if (!nr_pages)
return NULL;
- pr_debug("alloc_pagedir(): nr_pages = %d\n", nr_pages);
pblist = alloc_image_page(gfp_mask, safe_needed);
/* FIXME: rewrite this ugly loop */
for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
@@ -414,6 +415,9 @@
}
}
}
+ nr_copy_pages = 0;
+ nr_meta_pages = 0;
+ pagedir_nosave = NULL;
}
@@ -437,7 +441,7 @@
(nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
}
-int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed)
+static int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed)
{
struct pbe *p;
@@ -504,7 +508,319 @@
*/
nr_copy_pages = nr_pages;
+ nr_meta_pages = (nr_pages * sizeof(long) + PAGE_SIZE - 1) >> PAGE_SHIFT;
printk("swsusp: critical section/: done (%d pages copied)\n", nr_pages);
return 0;
}
+
+static void init_header(struct swsusp_info *info)
+{
+ memset(info, 0, sizeof(struct swsusp_info));
+ info->version_code = LINUX_VERSION_CODE;
+ info->num_physpages = num_physpages;
+ memcpy(&info->uts, &system_utsname, sizeof(system_utsname));
+ info->cpus = num_online_cpus();
+ info->image_pages = nr_copy_pages;
+ info->pages = nr_copy_pages + nr_meta_pages + 1;
+}
+
+/**
+ * pack_orig_addresses - the .orig_address fields of the PBEs from the
+ * list starting at @pbe are stored in the array @buf[] (1 page)
+ */
+
+static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pbe)
+{
+ int j;
+
+ for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
+ buf[j] = pbe->orig_address;
+ pbe = pbe->next;
+ }
+ if (!pbe)
+ for (; j < PAGE_SIZE / sizeof(long); j++)
+ buf[j] = 0;
+ return pbe;
+}
+
+/**
+ * snapshot_read_next - used for reading the system memory snapshot.
+ *
+ * On the first call to it @handle should point to a zeroed
+ * snapshot_handle structure. The structure gets updated and a pointer
+ * to it should be passed to this function every next time.
+ *
+ * The @count parameter should contain the number of bytes the caller
+ * wants to read from the snapshot. It must not be zero.
+ *
+ * On success the function returns a positive number. Then, the caller
+ * is allowed to read up to the returned number of bytes from the memory
+ * location computed by the data_of() macro. The number returned
+ * may be smaller than @count, but this only happens if the read would
+ * cross a page boundary otherwise.
+ *
+ * The function returns 0 to indicate the end of data stream condition,
+ * and a negative number is returned on error. In such cases the
+ * structure pointed to by @handle is not updated and should not be used
+ * any more.
+ */
+
+int snapshot_read_next(struct snapshot_handle *handle, size_t count)
+{
+ static unsigned long *buffer;
+
+ if (handle->page > nr_meta_pages + nr_copy_pages)
+ return 0;
+ if (!buffer) {
+ /* This makes the buffer be freed by swsusp_free() */
+ buffer = alloc_image_page(GFP_ATOMIC, 0);
+ if (!buffer)
+ return -ENOMEM;
+ }
+ if (!handle->offset) {
+ init_header((struct swsusp_info *)buffer);
+ handle->buffer = buffer;
+ handle->pbe = pagedir_nosave;
+ }
+ if (handle->prev < handle->page) {
+ if (handle->page <= nr_meta_pages) {
+ handle->pbe = pack_orig_addresses(buffer, handle->pbe);
+ if (!handle->pbe)
+ handle->pbe = pagedir_nosave;
+ } else {
+ handle->buffer = (void *)handle->pbe->address;
+ handle->pbe = handle->pbe->next;
+ }
+ handle->prev = handle->page;
+ }
+ handle->buf_offset = handle->page_offset;
+ if (handle->page_offset + count >= PAGE_SIZE) {
+ count = PAGE_SIZE - handle->page_offset;
+ handle->page_offset = 0;
+ handle->page++;
+ } else {
+ handle->page_offset += count;
+ }
+ handle->offset += count;
+ return count;
+}
+
+/**
+ * mark_unsafe_pages - mark the pages that cannot be used for storing
+ * the image during resume, because they conflict with the pages that
+ * had been used before suspend
+ */
+
+static int mark_unsafe_pages(struct pbe *pblist)
+{
+ struct zone *zone;
+ unsigned long zone_pfn;
+ struct pbe *p;
+
+ if (!pblist) /* a sanity check */
+ return -EINVAL;
+
+ /* Clear page flags */
+ for_each_zone (zone) {
+ for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
+ if (pfn_valid(zone_pfn + zone->zone_start_pfn))
+ ClearPageNosaveFree(pfn_to_page(zone_pfn +
+ zone->zone_start_pfn));
+ }
+
+ /* Mark orig addresses */
+ for_each_pbe (p, pblist) {
+ if (virt_addr_valid(p->orig_address))
+ SetPageNosaveFree(virt_to_page(p->orig_address));
+ else
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+static void copy_page_backup_list(struct pbe *dst, struct pbe *src)
+{
+ /* We assume both lists contain the same number of elements */
+ while (src) {
+ dst->orig_address = src->orig_address;
+ dst = dst->next;
+ src = src->next;
+ }
+}
+
+static int check_header(struct swsusp_info *info)
+{
+ char *reason = NULL;
+
+ if (info->version_code != LINUX_VERSION_CODE)
+ reason = "kernel version";
+ if (info->num_physpages != num_physpages)
+ reason = "memory size";
+ if (strcmp(info->uts.sysname,system_utsname.sysname))
+ reason = "system type";
+ if (strcmp(info->uts.release,system_utsname.release))
+ reason = "kernel release";
+ if (strcmp(info->uts.version,system_utsname.version))
+ reason = "version";
+ if (strcmp(info->uts.machine,system_utsname.machine))
+ reason = "machine";
+ if (reason) {
+ printk(KERN_ERR "swsusp: Resume mismatch: %s\n", reason);
+ return -EPERM;
+ }
+ return 0;
+}
+
+/**
+ * load header - check the image header and copy data from it
+ */
+
+static int load_header(struct snapshot_handle *handle,
+ struct swsusp_info *info)
+{
+ int error;
+ struct pbe *pblist;
+
+ error = check_header(info);
+ if (!error) {
+ pblist = alloc_pagedir(info->image_pages, GFP_ATOMIC, 0);
+ if (!pblist)
+ return -ENOMEM;
+ pagedir_nosave = pblist;
+ handle->pbe = pblist;
+ nr_copy_pages = info->image_pages;
+ nr_meta_pages = info->pages - info->image_pages - 1;
+ }
+ return error;
+}
+
+/**
+ * unpack_orig_addresses - copy the elements of @buf[] (1 page) to
+ * the PBEs in the list starting at @pbe
+ */
+
+static inline struct pbe *unpack_orig_addresses(unsigned long *buf,
+ struct pbe *pbe)
+{
+ int j;
+
+ for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
+ pbe->orig_address = buf[j];
+ pbe = pbe->next;
+ }
+ return pbe;
+}
+
+/**
+ * create_image - use metadata contained in the PBE list
+ * pointed to by pagedir_nosave to mark the pages that will
+ * be overwritten in the process of restoring the system
+ * memory state from the image and allocate memory for
+ * the image avoiding these pages
+ */
+
+static int create_image(struct snapshot_handle *handle)
+{
+ int error = 0;
+ struct pbe *p, *pblist;
+
+ p = pagedir_nosave;
+ error = mark_unsafe_pages(p);
+ if (!error) {
+ pblist = alloc_pagedir(nr_copy_pages, GFP_ATOMIC, 1);
+ if (pblist)
+ copy_page_backup_list(pblist, p);
+ free_pagedir(p);
+ if (!pblist)
+ error = -ENOMEM;
+ }
+ if (!error)
+ error = alloc_data_pages(pblist, GFP_ATOMIC, 1);
+ if (!error) {
+ release_eaten_pages();
+ pagedir_nosave = pblist;
+ } else {
+ pagedir_nosave = NULL;
+ handle->pbe = NULL;
+ nr_copy_pages = 0;
+ nr_meta_pages = 0;
+ }
+ return error;
+}
+
+/**
+ * snapshot_write_next - used for writing the system memory snapshot.
+ *
+ * On the first call to it @handle should point to a zeroed
+ * snapshot_handle structure. The structure gets updated and a pointer
+ * to it should be passed to this function every next time.
+ *
+ * The @count parameter should contain the number of bytes the caller
+ * wants to write to the image. It must not be zero.
+ *
+ * On success the function returns a positive number. Then, the caller
+ * is allowed to write up to the returned number of bytes to the memory
+ * location computed by the data_of() macro. The number returned
+ * may be smaller than @count, but this only happens if the write would
+ * cross a page boundary otherwise.
+ *
+ * The function returns 0 to indicate the "end of file" condition,
+ * and a negative number is returned on error. In such cases the
+ * structure pointed to by @handle is not updated and should not be used
+ * any more.
+ */
+
+int snapshot_write_next(struct snapshot_handle *handle, size_t count)
+{
+ static unsigned long *buffer;
+ int error = 0;
+
+ if (handle->prev && handle->page > nr_meta_pages + nr_copy_pages)
+ return 0;
+ if (!buffer) {
+ /* This makes the buffer be freed by swsusp_free() */
+ buffer = alloc_image_page(GFP_ATOMIC, 0);
+ if (!buffer)
+ return -ENOMEM;
+ }
+ if (!handle->offset)
+ handle->buffer = buffer;
+ if (handle->prev < handle->page) {
+ if (!handle->prev) {
+ error = load_header(handle, (struct swsusp_info *)buffer);
+ if (error)
+ return error;
+ } else if (handle->prev <= nr_meta_pages) {
+ handle->pbe = unpack_orig_addresses(buffer, handle->pbe);
+ if (!handle->pbe) {
+ error = create_image(handle);
+ if (error)
+ return error;
+ handle->pbe = pagedir_nosave;
+ handle->buffer = (void *)handle->pbe->address;
+ }
+ } else {
+ handle->pbe = handle->pbe->next;
+ handle->buffer = (void *)handle->pbe->address;
+ }
+ handle->prev = handle->page;
+ }
+ handle->buf_offset = handle->page_offset;
+ if (handle->page_offset + count >= PAGE_SIZE) {
+ count = PAGE_SIZE - handle->page_offset;
+ handle->page_offset = 0;
+ handle->page++;
+ } else {
+ handle->page_offset += count;
+ }
+ handle->offset += count;
+ return count;
+}
+
+int snapshot_image_loaded(struct snapshot_handle *handle)
+{
+ return !(!handle->pbe || handle->pbe->next || !nr_copy_pages ||
+ handle->page <= nr_meta_pages + nr_copy_pages);
+}