1 /* MC interface: definitions that non-MC modules must see, but not the user */
3 /* Copyright (c) 2014-2015. The SimGrid Team.
4 * All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
9 #include <unistd.h> // pread, pwrite
11 #include "PageStore.hpp"
13 #include "mc_private.h"
14 #include "mc_snapshot.h"
16 #include <xbt/mmalloc.h>
18 #define SOFT_DIRTY_BIT_NUMBER 55
19 #define SOFT_DIRTY (((uint64_t)1) << SOFT_DIRTY_BIT_NUMBER)
21 using simgrid::mc::remote;
26 /** @brief Take a per-page snapshot of a region
28 * @param data The start of the region (must be at the beginning of a page)
29 * @param pag_count Number of pages of the region
30 * @return Snapshot page numbers of this new snapshot
32 PerPageCopy::PerPageCopy(PageStore& store, AddressSpace& as,
33 remote_ptr<void> addr, std::size_t page_count,
34 const size_t* ref_page_numbers, const std::uint64_t* pagemap)
37 this->pagenos_.resize(page_count);
38 std::vector<char> buffer(xbt_pagesize);
40 for (size_t i = 0; i != page_count; ++i) {
42 // We don't have to compare soft-clean pages:
43 if (ref_page_numbers && pagemap && !(pagemap[i] & SOFT_DIRTY)) {
44 pagenos_[i] = ref_page_numbers[i];
45 store_->ref_page(ref_page_numbers[i]);
49 remote_ptr<void> page = remote(addr.address() + (i << xbt_pagebits));
50 xbt_assert(mc_page_offset((void*)page.address())==0,
51 "Not at the beginning of a page");
53 /* Adding another copy (and a syscall) will probably slow things a lot.
54 TODO, optimize this somehow (at least by grouping the syscalls)
56 - reduce the number of syscalls;
57 - let the application snapshot itself;
58 - move the segments in shared memory (this will break `fork` however).
62 buffer.data(), xbt_pagesize, page,
63 simgrid::mc::ProcessIndexDisabled);
65 pagenos_[i] = store_->store_page(buffer.data());
75 /** @brief Restore a snapshot of a region
77 * If possible, the restoration will be incremental
78 * (the modified pages will not be touched).
81 * @param page_count Number of pages of the region
84 void mc_restore_page_snapshot_region(simgrid::mc::Process* process,
85 void* start_addr, simgrid::mc::PerPageCopy const& pages_copy)
87 for (size_t i = 0; i != pages_copy.page_count(); ++i) {
88 // Otherwise, copy the page:
89 void* target_page = mc_page_from_number(start_addr, i);
90 const void* source_page = pages_copy.page(i);
91 process->write_bytes(source_page, xbt_pagesize, remote(target_page));
95 // ***** High level API
97 void mc_region_restore_sparse(simgrid::mc::Process* process, mc_mem_region_t reg)
99 xbt_assert(((reg->permanent_address().address()) & (xbt_pagesize-1)) == 0,
100 "Not at the beginning of a page");
101 xbt_assert(mc_page_count(reg->size()) == reg->page_data().page_count());
102 mc_restore_page_snapshot_region(process,
103 (void*) reg->permanent_address().address(), reg->page_data());