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/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
18 namespace simgrid::mc {
20 Region::Region(PageStore& store, RegionType region_type, void* start_addr, size_t size)
21 : region_type_(region_type), start_addr_(start_addr), size_(size)
23 xbt_assert((((uintptr_t)start_addr) & (xbt_pagesize - 1)) == 0, "Start address not at the beginning of a page");
26 ChunkedData(store, mc_model_checker->get_remote_process(), RemotePtr<void>(start_addr), mmu::chunk_count(size));
29 /** @brief Restore a region from a snapshot
31 * @param region Target region
33 void Region::restore() const
35 xbt_assert(((start().address()) & (xbt_pagesize - 1)) == 0, "Not at the beginning of a page");
36 xbt_assert(simgrid::mc::mmu::chunk_count(size()) == get_chunks().page_count());
38 for (size_t i = 0; i != get_chunks().page_count(); ++i) {
39 auto* target_page = (void*)simgrid::mc::mmu::join(i, (std::uintptr_t)(void*)start().address());
40 const void* source_page = get_chunks().page(i);
41 mc_model_checker->get_remote_process().write_bytes(source_page, xbt_pagesize, remote(target_page));
45 static XBT_ALWAYS_INLINE void* mc_translate_address_region(uintptr_t addr, const simgrid::mc::Region* region)
47 auto [pageno, offset] = simgrid::mc::mmu::split(addr - region->start().address());
48 void* snapshot_page = region->get_chunks().page(pageno);
49 return (char*)snapshot_page + offset;
52 void* Region::read(void* target, const void* addr, std::size_t size) const
54 xbt_assert(contain(simgrid::mc::remote(addr)), "Trying to read out of the region boundary.");
56 // Last byte of the region:
57 const void* end_addr = (const char*)addr + size - 1;
58 if (simgrid::mc::mmu::same_chunk((std::uintptr_t)addr, (std::uintptr_t)end_addr)) {
59 // The memory is contained in a single page:
60 return mc_translate_address_region((uintptr_t)addr, this);
62 // Otherwise, the memory spans several pages. Let's copy it all into the provided buffer
63 xbt_assert(target != nullptr, "Missing destination buffer for fragmented memory access");
65 // TODO, we assume the chunks are aligned to natural chunk boundaries.
66 // We should remove this assumption.
68 // Page of the last byte of the memory area:
69 size_t page_end = simgrid::mc::mmu::split((std::uintptr_t)end_addr).first;
71 void* dest = target; // iterator in the buffer to where we should copy next
74 while (simgrid::mc::mmu::split((std::uintptr_t)addr).first != page_end) {
75 const void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
76 auto* next_page = (void*)simgrid::mc::mmu::join(simgrid::mc::mmu::split((std::uintptr_t)addr).first + 1, 0);
77 size_t readable = (char*)next_page - (const char*)addr;
78 memcpy(dest, snapshot_addr, readable);
79 addr = (const char*)addr + readable;
80 dest = (char*)dest + readable;
85 const void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
86 memcpy(dest, snapshot_addr, size);
91 } // namespace simgrid::mc
93 /** Compare memory between snapshots (with known regions)
95 * @param addr1 Address in the first snapshot
96 * @param region1 Region of the address in the first snapshot
97 * @param addr2 Address in the second snapshot
98 * @param region2 Region of the address in the second snapshot
99 * @return same semantic as memcmp
101 int MC_snapshot_region_memcmp(const void* addr1, const simgrid::mc::Region* region1, const void* addr2,
102 const simgrid::mc::Region* region2, size_t size)
104 // Using alloca() for large allocations may trigger stack overflow:
105 // use malloc if the buffer is too big.
106 bool stack_alloc = size < 64;
107 void* buffer1a = stack_alloc ? alloca(size) : ::operator new(size);
108 void* buffer2a = stack_alloc ? alloca(size) : ::operator new(size);
109 const void* buffer1 = region1->read(buffer1a, addr1, size);
110 const void* buffer2 = region2->read(buffer2a, addr2, size);
112 if (buffer1 == buffer2)
115 res = memcmp(buffer1, buffer2, size);
116 if (not stack_alloc) {
117 ::operator delete(buffer1a);
118 ::operator delete(buffer2a);