#include "mc_page_store.h"
#include "mc_mmu.h"
+#include "mc_private.h"
+#include "mc_snapshot.h"
+
+#include <xbt/mmalloc.h>
#define SOFT_DIRTY_BIT_NUMBER 55
#define SOFT_DIRTY (((uint64_t)1) << SOFT_DIRTY_BIT_NUMBER)
// ***** Region management:
+/** @brief Take a per-page snapshot of a region
+ *
+ * @param data The start of the region (must be at the beginning of a page)
+ * @param pag_count Number of pages of the region
+ * @param pagemap Linux kernel pagemap values fot this region (or NULL)
+ * @param reference_pages Snapshot page numbers of the previous soft_dirty_reset (or NULL)
+ * @return Snapshot page numbers of this new snapshot
+ */
size_t* mc_take_page_snapshot_region(void* data, size_t page_count, uint64_t* pagemap, size_t* reference_pages)
{
size_t* pagenos = (size_t*) malloc(page_count * sizeof(size_t));
for (size_t i=0; i!=page_count; ++i) {
- if (pagemap && (pagemap[i] & SOFT_DIRTY)) {
+ bool softclean = pagemap && !(pagemap[i] & SOFT_DIRTY);
+ if (softclean && reference_pages) {
// The page is softclean, it is the same page as the reference page:
pagenos[i] = reference_pages[i];
mc_model_checker->pages->ref_page(reference_pages[i]);
} else {
- // Otherwise, we need to store the page the hard hard
+ // Otherwise, we need to store the page the hard way
// (by reading its content):
void* page = (char*) data + (i << xbt_pagebits);
pagenos[i] = mc_model_checker->pages->store_page(page);
}
}
-void mc_restore_page_snapshot_region(mc_mem_region_t region, size_t page_count, uint64_t* pagemap, mc_mem_region_t reference_region)
+/** @brief Restore a snapshot of a region
+ *
+ * If possible, the restoration will be incremental
+ * (the modified pages will not be touched).
+ *
+ * @param start_addr
+ * @param page_count Number of pages of the region
+ * @param pagenos
+ * @param pagemap Linux kernel pagemap values fot this region (or NULL)
+ * @param reference_pages Snapshot page numbers of the previous soft_dirty_reset (or NULL)
+ */
+void mc_restore_page_snapshot_region(void* start_addr, size_t page_count, size_t* pagenos, uint64_t* pagemap, size_t* reference_pagenos)
{
for (size_t i=0; i!=page_count; ++i) {
bool softclean = pagemap && !(pagemap[i] & SOFT_DIRTY);
- if (softclean && reference_region && reference_region->page_numbers[i] == region->page_numbers[i]) {
+ if (softclean && reference_pagenos && pagenos[i] == reference_pagenos[i]) {
// The page is softclean and is the same as the reference one:
// the page is already in the target state.
continue;
}
// Otherwise, copy the page:
- void* target_page = mc_page_from_number(region->start_addr, i);
- const void* source_page = mc_model_checker->pages->get_page(region->page_numbers[i]);
+ void* target_page = mc_page_from_number(start_addr, i);
+ const void* source_page = mc_model_checker->pages->get_page(pagenos[i]);
memcpy(target_page, source_page, xbt_pagesize);
}
}
/** @brief Like pread() but without partial reads */
static size_t pread_whole(int fd, void* buf, size_t count, off_t offset) {
- size_t res;
+ size_t res = 0;
char* data = (char*) buf;
while(count) {
if (n==0)
return res;
- // Error (or EAGAIN):
+ // Error (or EINTR):
if (n==-1) {
- if (errno == EAGAIN)
+ if (errno == EINTR)
continue;
else
return -1;
}
+ // It might be a partial read:
count -= n;
data += n;
offset += n;
return res;
}
-static inline void mc_ensure_fd(int* fd, const char* path, int flags) {
+static inline __attribute__ ((always_inline))
+void mc_ensure_fd(int* fd, const char* path, int flags) {
if (*fd != -1)
return;
*fd = open(path, flags);
}
}
-/** @brief Reset the softdirty bits
+/** @brief Reset the soft-dirty bits
*
* This is done after checkpointing and after checkpoint restoration
* (if per page checkpoiting is used) in order to know which pages were
* modified.
+ *
+ * See https://www.kernel.org/doc/Documentation/vm/soft-dirty.txt
* */
void mc_softdirty_reset() {
mc_ensure_fd(&mc_model_checker->fd_clear_refs, "/proc/self/clear_refs", O_WRONLY|O_CLOEXEC);
}
}
-/** @brief Read /proc/self/pagemap informations in order to find properties on the pages
+/** @brief Read memory page informations
*
- * For each virtual memory page, this file provides informations.
+ * For each virtual memory page of the process,
+ * /proc/self/pagemap provides a 64 bit field of information.
* We are interested in the soft-dirty bit: with this we can track which
* pages were modified between snapshots/restorations and avoid
* copying data which was not modified.
*
+ * See https://www.kernel.org/doc/Documentation/vm/pagemap.txt
+ *
* @param pagemap Output buffer for pagemap informations
* @param start_addr Address of the first page
* @param page_count Number of pages
size_t bytesize = sizeof(uint64_t) * page_count;
off_t offset = sizeof(uint64_t) * page_start;
if (pread_whole(mc_model_checker->fd_pagemap, pagemap, bytesize, offset) != bytesize) {
- xbt_die("Coult not read pagemap");
+ xbt_die("Could not read pagemap");
}
}
// ***** High level API
-mc_mem_region_t mc_region_new_sparse(int type, void *start_addr, size_t size, mc_mem_region_t ref_reg)
+mc_mem_region_t mc_region_new_sparse(mc_region_type_t region_type,
+ void *start_addr, void* permanent_addr, size_t size,
+ mc_mem_region_t ref_reg)
{
- mc_mem_region_t new_reg = xbt_new(s_mc_mem_region_t, 1);
-
- new_reg->start_addr = start_addr;
- new_reg->data = NULL;
- new_reg->size = size;
- new_reg->page_numbers = NULL;
+ mc_mem_region_t region = xbt_new(s_mc_mem_region_t, 1);
+ region->region_type = region_type;
+ region->storage_type = MC_REGION_STORAGE_TYPE_CHUNKED;
+ region->start_addr = start_addr;
+ region->permanent_addr = permanent_addr;
+ region->size = size;
xbt_assert((((uintptr_t)start_addr) & (xbt_pagesize-1)) == 0,
"Not at the beginning of a page");
+ xbt_assert((((uintptr_t)permanent_addr) & (xbt_pagesize-1)) == 0,
+ "Not at the beginning of a page");
size_t page_count = mc_page_count(size);
uint64_t* pagemap = NULL;
- if (mc_model_checker->parent_snapshot) {
- pagemap = (uint64_t*) alloca(sizeof(uint64_t) * page_count);
- mc_read_pagemap(pagemap, mc_page_number(start_addr), page_count);
+ if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot) {
+ pagemap = (uint64_t*) mmalloc_no_memset(mc_heap, sizeof(uint64_t) * page_count);
+ mc_read_pagemap(pagemap, mc_page_number(NULL, permanent_addr), page_count);
}
+ size_t* reg_page_numbers = NULL;
+ if (ref_reg!=NULL && ref_reg->storage_type == MC_REGION_STORAGE_TYPE_CHUNKED)
+ reg_page_numbers = ref_reg->chunked.page_numbers;
+
// Take incremental snapshot:
- new_reg->page_numbers = mc_take_page_snapshot_region(start_addr, page_count, pagemap, ref_reg->page_numbers);
+ region->chunked.page_numbers = mc_take_page_snapshot_region(
+ permanent_addr, page_count, pagemap, reg_page_numbers);
- return new_reg;
+ if(pagemap) {
+ mfree(mc_heap, pagemap);
+ }
+ return region;
}
void mc_region_restore_sparse(mc_mem_region_t reg, mc_mem_region_t ref_reg)
{
- xbt_assert((((uintptr_t)reg->start_addr) & (xbt_pagesize-1)) == 0,
+ xbt_assert((((uintptr_t)reg->permanent_addr) & (xbt_pagesize-1)) == 0,
"Not at the beginning of a page");
size_t page_count = mc_page_count(reg->size);
uint64_t* pagemap = NULL;
// Read soft-dirty bits if necessary in order to know which pages have changed:
- if (mc_model_checker->parent_snapshot) {
- pagemap = (uint64_t*) alloca(sizeof(uint64_t) * page_count);
- mc_read_pagemap(pagemap, mc_page_number(reg->start_addr), page_count);
+ if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot) {
+ pagemap = (uint64_t*) mmalloc_no_memset(mc_heap, sizeof(uint64_t) * page_count);
+ mc_read_pagemap(pagemap, mc_page_number(NULL, reg->permanent_addr), page_count);
}
- // Incremental per-page snapshot restoration:
- mc_restore_page_snapshot_region(reg, page_count, pagemap, ref_reg);
+ // Incremental per-page snapshot restoration:s
+ size_t* reg_page_numbers = NULL;
+ if (ref_reg && ref_reg->storage_type == MC_REGION_STORAGE_TYPE_CHUNKED)
+ reg_page_numbers = ref_reg->chunked.page_numbers;
+
+ mc_restore_page_snapshot_region(reg->permanent_addr, page_count, reg->chunked.page_numbers,
+ pagemap, reg_page_numbers);
+
+ if(pagemap) {
+ free(pagemap);
+ }
}
}
