+/* MC interface: definitions that non-MC modules must see, but not the user */
+
+/* Copyright (c) 2014-2015. The SimGrid Team. All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
#include <unistd.h> // pread, pwrite
#include "mc_page_store.h"
#include <xbt/mmalloc.h>
-#define SOFT_DIRTY_BIT_NUMBER 55
-#define SOFT_DIRTY (((uint64_t)1) << SOFT_DIRTY_BIT_NUMBER)
-
extern "C" {
// ***** Region management:
*
* @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(mc_process_t process,
- void* data, size_t page_count, uint64_t* pagemap, size_t* reference_pages)
+ void* data, size_t page_count)
{
size_t* pagenos = (size_t*) malloc(page_count * sizeof(size_t));
void* temp = NULL;
if (!is_self)
- temp = malloc(xbt_pagebits);
+ temp = malloc(xbt_pagesize);
for (size_t i=0; i!=page_count; ++i) {
- 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 way
// (by reading its content):
void* page = (char*) data + (i << xbt_pagebits);
- move the segments in shared memory (this will break `fork` however).
*/
page_data = temp;
- MC_process_read(process, temp, page, xbt_pagesize);
+ MC_process_read(process, MC_ADDRESS_SPACE_READ_FLAGS_NONE,
+ temp, page, xbt_pagesize, MC_PROCESS_INDEX_DISABLED);
}
- pagenos[i] = mc_model_checker->pages->store_page(page_data);
- }
+ pagenos[i] = mc_model_checker->page_store().store_page(page_data);
+
}
free(temp);
void mc_free_page_snapshot_region(size_t* pagenos, size_t page_count)
{
for (size_t i=0; i!=page_count; ++i) {
- mc_model_checker->pages->unref_page(pagenos[i]);
+ mc_model_checker->page_store().unref_page(pagenos[i]);
}
}
* @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(mc_process_t process,
- void* start_addr, size_t page_count, size_t* pagenos, uint64_t* pagemap, size_t* reference_pagenos)
+ void* start_addr, size_t page_count, size_t* pagenos)
{
for (size_t i=0; i!=page_count; ++i) {
-
- bool softclean = pagemap && !(pagemap[i] & SOFT_DIRTY);
- 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(start_addr, i);
- const void* source_page = mc_model_checker->pages->get_page(pagenos[i]);
+ const void* source_page = mc_model_checker->page_store().get_page(pagenos[i]);
MC_process_write(process, source_page, target_page, xbt_pagesize);
}
}
-// ***** Soft dirty tracking
-
-/** @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 = 0;
-
- char* data = (char*) buf;
- while(count) {
- ssize_t n = pread(fd, buf, count, offset);
- // EOF
- if (n==0)
- return res;
-
- // Error (or EINTR):
- if (n==-1) {
- if (errno == EINTR)
- continue;
- else
- return -1;
- }
-
- // It might be a partial read:
- count -= n;
- data += n;
- offset += n;
- res += n;
- }
-
- return res;
-}
-
-static inline __attribute__ ((always_inline))
-void mc_ensure_fd(int* fd, const char* path, int flags) {
- if (*fd != -1)
- return;
- *fd = open(path, flags);
- if (*fd == -1) {
- xbt_die("Could not open file %s", path);
- }
-}
-
-/** @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);
- if( ::write(mc_model_checker->fd_clear_refs, "4\n", 2) != 2) {
- xbt_die("Could not reset softdirty bits");
- }
-}
-
-/** @brief Read memory page 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
- */
-static void mc_read_pagemap(uint64_t* pagemap, size_t page_start, size_t page_count)
-{
- mc_ensure_fd(&mc_model_checker->fd_pagemap, "/proc/self/pagemap", O_RDONLY|O_CLOEXEC);
- 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("Could not read pagemap");
- }
-}
-
// ***** High level API
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)
+ void *start_addr, void* permanent_addr, size_t size)
{
- mc_process_t process = &mc_model_checker->process;
+ mc_process_t process = &mc_model_checker->process();
mc_mem_region_t region = xbt_new(s_mc_mem_region_t, 1);
region->region_type = region_type;
"Not at the beginning of a page");
size_t page_count = mc_page_count(size);
- uint64_t* pagemap = NULL;
- if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot &&
- MC_process_is_self(process)) {
- 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:
region->chunked.page_numbers = mc_take_page_snapshot_region(process,
- permanent_addr, page_count, pagemap, reg_page_numbers);
+ permanent_addr, page_count);
- if(pagemap) {
- mfree(mc_heap, pagemap);
- }
return region;
}
-void mc_region_restore_sparse(mc_process_t process, mc_mem_region_t reg, mc_mem_region_t ref_reg)
+void mc_region_restore_sparse(mc_process_t process, mc_mem_region_t reg)
{
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 (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot
- && MC_process_is_self(process)) {
- 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: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(process,
- reg->permanent_addr, page_count, reg->chunked.page_numbers,
- pagemap, reg_page_numbers);
-
- if(pagemap) {
- free(pagemap);
- }
+ reg->permanent_addr, page_count, reg->chunked.page_numbers);
}
}
