1 /* Copyright (c) 2007-2023. 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/mc_config.hpp"
8 #include "src/mc/mc_forward.hpp"
9 #include "src/mc/sosp/RemoteProcessMemory.hpp"
14 #define MAP_POPULATE MAP_PREFAULT_READ
17 namespace simgrid::mc {
19 Region::Region(PageStore& store, RemoteProcessMemory& memory, RegionType region_type, void* start_addr, size_t size)
20 : region_type_(region_type), start_addr_(start_addr), size_(size)
22 xbt_assert((((uintptr_t)start_addr) & (xbt_pagesize - 1)) == 0, "Start address not at the beginning of a page");
24 chunks_ = ChunkedData(store, memory, RemotePtr<void>(start_addr), mmu::chunk_count(size));
27 /** @brief Restore a region from a snapshot
29 * @param region Target region
31 void Region::restore(RemoteProcessMemory& memory) const
33 xbt_assert(((start().address()) & (xbt_pagesize - 1)) == 0, "Not at the beginning of a page");
34 xbt_assert(simgrid::mc::mmu::chunk_count(size()) == get_chunks().page_count());
36 for (size_t i = 0; i != get_chunks().page_count(); ++i) {
37 auto* target_page = (void*)simgrid::mc::mmu::join(i, (std::uintptr_t)(void*)start().address());
38 const void* source_page = get_chunks().page(i);
39 memory.write_bytes(source_page, xbt_pagesize, remote(target_page));
43 static XBT_ALWAYS_INLINE void* mc_translate_address_region(uintptr_t addr, const simgrid::mc::Region* region)
45 auto [pageno, offset] = simgrid::mc::mmu::split(addr - region->start().address());
46 void* snapshot_page = region->get_chunks().page(pageno);
47 return (char*)snapshot_page + offset;
50 void* Region::read(void* target, const void* addr, std::size_t size) const
52 xbt_assert(contain(simgrid::mc::remote(addr)), "Trying to read out of the region boundary.");
54 // Last byte of the region:
55 const void* end_addr = (const char*)addr + size - 1;
56 if (simgrid::mc::mmu::same_chunk((std::uintptr_t)addr, (std::uintptr_t)end_addr)) {
57 // The memory is contained in a single page:
58 return mc_translate_address_region((uintptr_t)addr, this);
60 // Otherwise, the memory spans several pages. Let's copy it all into the provided buffer
61 xbt_assert(target != nullptr, "Missing destination buffer for fragmented memory access");
63 // TODO, we assume the chunks are aligned to natural chunk boundaries.
64 // We should remove this assumption.
66 // Page of the last byte of the memory area:
67 size_t page_end = simgrid::mc::mmu::split((std::uintptr_t)end_addr).first;
69 void* dest = target; // iterator in the buffer to where we should copy next
72 while (simgrid::mc::mmu::split((std::uintptr_t)addr).first != page_end) {
73 const void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
74 auto* next_page = (void*)simgrid::mc::mmu::join(simgrid::mc::mmu::split((std::uintptr_t)addr).first + 1, 0);
75 size_t readable = (char*)next_page - (const char*)addr;
76 memcpy(dest, snapshot_addr, readable);
77 addr = (const char*)addr + readable;
78 dest = (char*)dest + readable;
83 const void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
84 memcpy(dest, snapshot_addr, size);
89 } // namespace simgrid::mc
91 /** Compare memory between snapshots (with known regions)
93 * @param addr1 Address in the first snapshot
94 * @param region1 Region of the address in the first snapshot
95 * @param addr2 Address in the second snapshot
96 * @param region2 Region of the address in the second snapshot
97 * @return same semantic as memcmp
99 int MC_snapshot_region_memcmp(const void* addr1, const simgrid::mc::Region* region1, const void* addr2,
100 const simgrid::mc::Region* region2, size_t size)
102 // Using alloca() for large allocations may trigger stack overflow:
103 // use malloc if the buffer is too big.
104 bool stack_alloc = size < 64;
105 void* buffer1a = stack_alloc ? alloca(size) : ::operator new(size);
106 void* buffer2a = stack_alloc ? alloca(size) : ::operator new(size);
107 const void* buffer1 = region1->read(buffer1a, addr1, size);
108 const void* buffer2 = region2->read(buffer2a, addr2, size);
110 if (buffer1 == buffer2)
113 res = memcmp(buffer1, buffer2, size);
114 if (not stack_alloc) {
115 ::operator delete(buffer1a);
116 ::operator delete(buffer2a);