X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/d2435e5aed6141ff0d9e97bc341ff0225c29adca..8bf8303f84623a9346997d71d828a2e843c685d3:/src/mc/sosp/Region.cpp

diff --git a/src/mc/sosp/Region.cpp b/src/mc/sosp/Region.cpp
index b7dbbca9e4..4eb5d6ffb0 100644
--- a/src/mc/sosp/Region.cpp
+++ b/src/mc/sosp/Region.cpp
@@ -46,5 +46,83 @@ void Region::restore()
   }
 }
 
+static XBT_ALWAYS_INLINE void* mc_translate_address_region(uintptr_t addr, simgrid::mc::Region* region)
+{
+  auto split                = simgrid::mc::mmu::split(addr - region->start().address());
+  auto pageno               = split.first;
+  auto offset               = split.second;
+  const void* snapshot_page = region->get_chunks().page(pageno);
+  return (char*)snapshot_page + offset;
+}
+
+const void* Region::read(void* target, const void* addr, std::size_t size)
+{
+  xbt_assert(contain(simgrid::mc::remote(addr)), "Trying to read out of the region boundary.");
+
+  // Last byte of the region:
+  void* end = (char*)addr + size - 1;
+  if (simgrid::mc::mmu::same_chunk((std::uintptr_t)addr, (std::uintptr_t)end)) {
+    // The memory is contained in a single page:
+    return mc_translate_address_region((uintptr_t)addr, this);
+  }
+  // Otherwise, the memory spans several pages. Let's copy it all into the provided buffer
+  xbt_assert(target != nullptr, "Missing destination buffer for fragmented memory access");
+
+  // TODO, we assume the chunks are aligned to natural chunk boundaries.
+  // We should remove this assumption.
+
+  // Page of the last byte of the memory area:
+  size_t page_end = simgrid::mc::mmu::split((std::uintptr_t)end).first;
+
+  void* dest = target; // iterator in the buffer to where we should copy next
+
+  // Read each page:
+  while (simgrid::mc::mmu::split((std::uintptr_t)addr).first != page_end) {
+    void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
+    void* next_page     = (void*)simgrid::mc::mmu::join(simgrid::mc::mmu::split((std::uintptr_t)addr).first + 1, 0);
+    size_t readable     = (char*)next_page - (char*)addr;
+    memcpy(dest, snapshot_addr, readable);
+    addr = (char*)addr + readable;
+    dest = (char*)dest + readable;
+    size -= readable;
+  }
+
+  // Read the end:
+  void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
+  memcpy(dest, snapshot_addr, size);
+
+  return target;
+}
+
 } // namespace mc
 } // namespace simgrid
+
+/** Compare memory between snapshots (with known regions)
+ *
+ * @param addr1 Address in the first snapshot
+ * @param region1 Region of the address in the first snapshot
+ * @param addr2 Address in the second snapshot
+ * @param region2 Region of the address in the second snapshot
+ * @return same semantic as memcmp
+ */
+int MC_snapshot_region_memcmp(const void* addr1, simgrid::mc::Region* region1, const void* addr2,
+                              simgrid::mc::Region* region2, size_t size)
+{
+  // Using alloca() for large allocations may trigger stack overflow:
+  // use malloc if the buffer is too big.
+  bool stack_alloc    = size < 64;
+  void* buffer1a      = stack_alloc ? alloca(size) : ::operator new(size);
+  void* buffer2a      = stack_alloc ? alloca(size) : ::operator new(size);
+  const void* buffer1 = region1->read(buffer1a, addr1, size);
+  const void* buffer2 = region2->read(buffer2a, addr2, size);
+  int res;
+  if (buffer1 == buffer2)
+    res = 0;
+  else
+    res = memcmp(buffer1, buffer2, size);
+  if (not stack_alloc) {
+    ::operator delete(buffer1a);
+    ::operator delete(buffer2a);
+  }
+  return res;
+}