1 files changed, 106 insertions, 0 deletions
diff --git a/kernel/src/test_support/simulated_memory.cpp b/kernel/src/test_support/simulated_memory.cpp
new file mode 100644
index 0000000..074e6b1
--- /dev/null
+++ b/kernel/src/test_support/simulated_memory.cpp
@@ -0,0 +1,106 @@
+#include <kernel/test_support/simulated_memory.hpp>
+
+#include <kapi/memory.hpp>
+
+#include <kstd/units>
+
+#include <cerrno>
+#include <cstddef>
+#include <cstring>
+#include <format>
+#include <stdexcept>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/types.h>
+
+namespace kernel::tests
+{
+
+  simulated_memory::simulated_memory(kstd::units::bytes physical_size, kstd::units::bytes virtual_size)
+      : m_descriptor{memfd_create("teachos_simulated_memory", 0)}
+      , m_physical_size{physical_size}
+      , m_virtual_size{virtual_size}
+  {
+    if (m_descriptor < 0)
+    {
+      auto error = std::format("Failed to allocate backing memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    if (ftruncate(m_descriptor, static_cast<off_t>(m_physical_size.value)) < 0)
+    {
+      auto error = std::format("Failed to reserve backing memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    auto physical_storage = mmap(nullptr, m_physical_size.value, PROT_READ | PROT_WRITE, MAP_SHARED, m_descriptor, 0);
+    if (physical_storage == MAP_FAILED)
+    {
+      auto error = std::format("Failed to map backing memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    auto virtual_pointer = mmap(nullptr, virtual_size.value, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (virtual_pointer == MAP_FAILED)
+    {
+      auto error = std::format("Failed to reserve virtual memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    m_physical_base = static_cast<std::byte *>(physical_storage);
+    m_virtual_base = static_cast<std::byte *>(virtual_pointer);
+
+    clear();
+  }
+
+  simulated_memory::~simulated_memory()
+  {
+    munmap(m_virtual_base, m_virtual_size.value);
+    munmap(m_physical_base, m_physical_size.value);
+    close(m_descriptor);
+  }
+
+  auto simulated_memory::clear() -> void
+  {
+    std::memset(m_physical_base, 0, m_physical_size.value);
+  }
+
+  auto simulated_memory::physical_base() noexcept -> std::byte *
+  {
+    return m_physical_base;
+  }
+
+  auto simulated_memory::physical_base() const noexcept -> std::byte const *
+  {
+    return m_physical_base;
+  }
+
+  auto simulated_memory::physical_size() const noexcept -> kstd::units::bytes
+  {
+    return m_physical_size;
+  }
+
+  auto simulated_memory::virtual_base() const noexcept -> kapi::memory::linear_address
+  {
+    return kapi::memory::linear_address{m_virtual_base};
+  }
+
+  auto simulated_memory::virtual_size() const noexcept -> kstd::units::bytes
+  {
+    return m_virtual_size;
+  }
+
+  auto simulated_memory::map(kstd::units::bytes size, std::byte * to, off_t offset) -> std::byte *
+  {
+    auto mapped_ptr = mmap(to, size.value, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, m_descriptor, offset);
+    if (mapped_ptr == MAP_FAILED)
+    {
+      auto error = std::format("Failed to map page: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    return static_cast<std::byte *>(mapped_ptr);
+  }
+
+}  // namespace kernel::tests
+\ No newline at end of file