diff options
Diffstat (limited to 'kernel/power/tuxonice_copy_before_write.c')
| -rw-r--r-- | kernel/power/tuxonice_copy_before_write.c | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/kernel/power/tuxonice_copy_before_write.c b/kernel/power/tuxonice_copy_before_write.c new file mode 100644 index 000000000..eb627915e --- /dev/null +++ b/kernel/power/tuxonice_copy_before_write.c @@ -0,0 +1,240 @@ +/* + * kernel/power/tuxonice_copy_before_write.c + * + * Copyright (C) 2015 Nigel Cunningham (nigel at nigelcunningham com au) + * + * This file is released under the GPLv2. + * + * Routines (apart from the fault handling code) to deal with allocating memory + * for copying pages before they are modified, restoring the contents and getting + * the contents written to disk. + */ + +#include <linux/percpu-defs.h> +#include <linux/sched.h> +#include <linux/tuxonice.h> +#include "tuxonice_alloc.h" +#include "tuxonice_modules.h" +#include "tuxonice_sysfs.h" +#include "tuxonice.h" + +DEFINE_PER_CPU(struct toi_cbw_state, toi_cbw_states); +#define CBWS_PER_PAGE (PAGE_SIZE / sizeof(struct toi_cbw)) +#define toi_cbw_pool_size 100 + +static void _toi_free_cbw_data(struct toi_cbw_state *state) +{ + struct toi_cbw *page_ptr, *ptr, *next; + + page_ptr = ptr = state->first; + + while(ptr) { + next = ptr->next; + + if (ptr->virt) { + toi__free_page(40, virt_to_page(ptr->virt)); + } + if ((((unsigned long) ptr) & PAGE_MASK) != (unsigned long) page_ptr) { + /* Must be on a new page - free the previous one. */ + toi__free_page(40, virt_to_page(page_ptr)); + page_ptr = ptr; + } + ptr = next; + } + + if (page_ptr) { + toi__free_page(40, virt_to_page(page_ptr)); + } + + state->first = state->next = state->last = NULL; + state->size = 0; +} + +void toi_free_cbw_data(void) +{ + int i; + + for_each_online_cpu(i) { + struct toi_cbw_state *state = &per_cpu(toi_cbw_states, i); + + if (!state->first) + continue; + + state->enabled = 0; + + while (state->active) { + schedule(); + } + + _toi_free_cbw_data(state); + } +} + +static int _toi_allocate_cbw_data(struct toi_cbw_state *state) +{ + while(state->size < toi_cbw_pool_size) { + int i; + struct toi_cbw *ptr; + + ptr = (struct toi_cbw *) toi_get_zeroed_page(40, GFP_KERNEL); + + if (!ptr) { + return -ENOMEM; + } + + if (!state->first) { + state->first = state->next = state->last = ptr; + } + + for (i = 0; i < CBWS_PER_PAGE; i++) { + struct toi_cbw *cbw = &ptr[i]; + + cbw->virt = (char *) toi_get_zeroed_page(40, GFP_KERNEL); + if (!cbw->virt) { + state->size += i; + printk("Out of memory allocating CBW pages.\n"); + return -ENOMEM; + } + + if (cbw == state->first) + continue; + + state->last->next = cbw; + state->last = cbw; + } + + state->size += CBWS_PER_PAGE; + } + + state->enabled = 1; + + return 0; +} + + +int toi_allocate_cbw_data(void) +{ + int i, result; + + for_each_online_cpu(i) { + struct toi_cbw_state *state = &per_cpu(toi_cbw_states, i); + + result = _toi_allocate_cbw_data(state); + + if (result) + return result; + } + + return 0; +} + +void toi_cbw_restore(void) +{ + if (!toi_keeping_image) + return; + +} + +void toi_cbw_write(void) +{ + if (!toi_keeping_image) + return; + +} + +/** + * toi_cbw_test_read - Test copy before write on one page + * + * Allocate copy before write buffers, then make one page only copy-before-write + * and attempt to write to it. We should then be able to retrieve the original + * version from the cbw buffer and the modified version from the page itself. + */ +static int toi_cbw_test_read(const char *buffer, int count) +{ + unsigned long virt = toi_get_zeroed_page(40, GFP_KERNEL); + char *original = "Original contents"; + char *modified = "Modified material"; + struct page *page = virt_to_page(virt); + int i, len = 0, found = 0, pfn = page_to_pfn(page); + + if (!page) { + printk("toi_cbw_test_read: Unable to allocate a page for testing.\n"); + return -ENOMEM; + } + + memcpy((char *) virt, original, strlen(original)); + + if (toi_allocate_cbw_data()) { + printk("toi_cbw_test_read: Unable to allocate cbw data.\n"); + return -ENOMEM; + } + + toi_reset_dirtiness_one(pfn, 0); + + SetPageTOI_CBW(page); + + memcpy((char *) virt, modified, strlen(modified)); + + if (strncmp((char *) virt, modified, strlen(modified))) { + len += sprintf((char *) buffer + len, "Failed to write to page after protecting it.\n"); + } + + for_each_online_cpu(i) { + struct toi_cbw_state *state = &per_cpu(toi_cbw_states, i); + struct toi_cbw *ptr = state->first, *last_ptr = ptr; + + if (!found) { + while (ptr) { + if (ptr->pfn == pfn) { + found = 1; + if (strncmp(ptr->virt, original, strlen(original))) { + len += sprintf((char *) buffer + len, "Contents of original buffer are not original.\n"); + } else { + len += sprintf((char *) buffer + len, "Test passed. Buffer changed and original contents preserved.\n"); + } + break; + } + + last_ptr = ptr; + ptr = ptr->next; + } + } + + if (!last_ptr) + len += sprintf((char *) buffer + len, "All available CBW buffers on cpu %d used.\n", i); + } + + if (!found) + len += sprintf((char *) buffer + len, "Copy before write buffer not found.\n"); + + toi_free_cbw_data(); + + return len; +} + +/* + * This array contains entries that are automatically registered at + * boot. Modules and the console code register their own entries separately. + */ +static struct toi_sysfs_data sysfs_params[] = { + SYSFS_CUSTOM("test", SYSFS_RW, toi_cbw_test_read, + NULL, SYSFS_NEEDS_SM_FOR_READ, NULL), +}; + +static struct toi_module_ops toi_cbw_ops = { + .type = MISC_HIDDEN_MODULE, + .name = "copy_before_write debugging", + .directory = "cbw", + .module = THIS_MODULE, + .early = 1, + + .sysfs_data = sysfs_params, + .num_sysfs_entries = sizeof(sysfs_params) / + sizeof(struct toi_sysfs_data), +}; + +int toi_cbw_init(void) +{ + int result = toi_register_module(&toi_cbw_ops); + return result; +} |