1 /* Copyright (c) 2007-2022. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/mc/sosp/Region.hpp"
7 #include "src/mc/ModelChecker.hpp"
8 #include "src/mc/mc_config.hpp"
9 #include "src/mc/mc_forward.hpp"
10 #include "src/mc/remote/RemoteProcess.hpp"
15 #define MAP_POPULATE MAP_PREFAULT_READ
21 Region::Region(RegionType region_type, void* start_addr, size_t size)
22 : region_type_(region_type), start_addr_(start_addr), size_(size)
24 xbt_assert((((uintptr_t)start_addr) & (xbt_pagesize - 1)) == 0, "Start address not at the beginning of a page");
26 chunks_ = ChunkedData(mc_model_checker->page_store(), mc_model_checker->get_remote_process(),
27 RemotePtr<void>(start_addr), mmu::chunk_count(size));
30 /** @brief Restore a region from a snapshot
32 * @param region Target region
34 void Region::restore() const
36 xbt_assert(((start().address()) & (xbt_pagesize - 1)) == 0, "Not at the beginning of a page");
37 xbt_assert(simgrid::mc::mmu::chunk_count(size()) == get_chunks().page_count());
39 for (size_t i = 0; i != get_chunks().page_count(); ++i) {
40 auto* target_page = (void*)simgrid::mc::mmu::join(i, (std::uintptr_t)(void*)start().address());
41 const void* source_page = get_chunks().page(i);
42 mc_model_checker->get_remote_process().write_bytes(source_page, xbt_pagesize, remote(target_page));
46 static XBT_ALWAYS_INLINE void* mc_translate_address_region(uintptr_t addr, const simgrid::mc::Region* region)
48 auto [pageno, offset] = simgrid::mc::mmu::split(addr - region->start().address());
49 void* snapshot_page = region->get_chunks().page(pageno);
50 return (char*)snapshot_page + offset;
53 void* Region::read(void* target, const void* addr, std::size_t size) const
55 xbt_assert(contain(simgrid::mc::remote(addr)), "Trying to read out of the region boundary.");
57 // Last byte of the region:
58 const void* end = (const char*)addr + size - 1;
59 if (simgrid::mc::mmu::same_chunk((std::uintptr_t)addr, (std::uintptr_t)end)) {
60 // The memory is contained in a single page:
61 return mc_translate_address_region((uintptr_t)addr, this);
63 // Otherwise, the memory spans several pages. Let's copy it all into the provided buffer
64 xbt_assert(target != nullptr, "Missing destination buffer for fragmented memory access");
66 // TODO, we assume the chunks are aligned to natural chunk boundaries.
67 // We should remove this assumption.
69 // Page of the last byte of the memory area:
70 size_t page_end = simgrid::mc::mmu::split((std::uintptr_t)end).first;
72 void* dest = target; // iterator in the buffer to where we should copy next
75 while (simgrid::mc::mmu::split((std::uintptr_t)addr).first != page_end) {
76 const void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
77 auto* next_page = (void*)simgrid::mc::mmu::join(simgrid::mc::mmu::split((std::uintptr_t)addr).first + 1, 0);
78 size_t readable = (char*)next_page - (const char*)addr;
79 memcpy(dest, snapshot_addr, readable);
80 addr = (const char*)addr + readable;
81 dest = (char*)dest + readable;
86 const void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
87 memcpy(dest, snapshot_addr, size);
93 } // namespace simgrid
95 /** Compare memory between snapshots (with known regions)
97 * @param addr1 Address in the first snapshot
98 * @param region1 Region of the address in the first snapshot
99 * @param addr2 Address in the second snapshot
100 * @param region2 Region of the address in the second snapshot
101 * @return same semantic as memcmp
103 int MC_snapshot_region_memcmp(const void* addr1, const simgrid::mc::Region* region1, const void* addr2,
104 const simgrid::mc::Region* region2, size_t size)
106 // Using alloca() for large allocations may trigger stack overflow:
107 // use malloc if the buffer is too big.
108 bool stack_alloc = size < 64;
109 void* buffer1a = stack_alloc ? alloca(size) : ::operator new(size);
110 void* buffer2a = stack_alloc ? alloca(size) : ::operator new(size);
111 const void* buffer1 = region1->read(buffer1a, addr1, size);
112 const void* buffer2 = region2->read(buffer2a, addr2, size);
114 if (buffer1 == buffer2)
117 res = memcmp(buffer1, buffer2, size);
118 if (not stack_alloc) {
119 ::operator delete(buffer1a);
120 ::operator delete(buffer2a);