From f577eb30afdc68233f25d4d82b04102129262365 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 23 Mar 2006 02:59:59 -0800 Subject: [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 Acked-by: Pavel Machek Signed-off-by: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/power/snapshot.c | 326 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 321 insertions(+), 5 deletions(-) (limited to 'kernel/power/snapshot.c') diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 8d5a5986d621..cc349437fb72 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -10,6 +10,7 @@ */ +#include #include #include #include @@ -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 @@ static void copy_data_pages(struct pbe *pblist) * 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 @@ struct eaten_page { 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 @@ struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask, int safe_needed 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 @@ void swsusp_free(void) } } } + nr_copy_pages = 0; + nr_meta_pages = 0; + pagedir_nosave = NULL; } @@ -437,7 +441,7 @@ static int enough_free_mem(unsigned int nr_pages) (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 @@ asmlinkage int swsusp_save(void) */ 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); +} -- cgit v1.2.1