Merge branch 'fmorgner/develop-SA-FS26/kernel-bht' into 'develop-BA-FS26'

Add experimental support for kernel tests

See merge request teachos/kernel!20

1 files changed, 78 insertions, 0 deletions

diff --git a/kernel/src/test_support/page_mapper.cpp b/kernel/src/test_support/page_mapper.cpp
new file mode 100644
index 0000000..abdcae5
--- /dev/null
+++ b/kernel/src/test_support/page_mapper.cpp
@@ -0,0 +1,78 @@
+#include "kernel/test_support/page_mapper.hpp"
+
+#include "kapi/memory.hpp"
+
+#include <kstd/units>
+
+#include <cstddef>
+#include <format>
+#include <stdexcept>
+#include <sys/mman.h>
+
+namespace kernel::tests
+{
+
+  page_mapper::page_mapper(kstd::units::bytes memory_size)
+      : memory{memory_size}
+  {}
+
+  auto page_mapper::map(kapi::memory::page page, kapi::memory::frame frame, flags) -> std::byte *
+  {
+    auto result = page_mappings.insert({page.number(), frame});
+    if (!result.second)
+    {
+      auto error = std::format("Page {} was already mapped!", page.number());
+      throw std::invalid_argument{error};
+    }
+
+    auto page_address = page.start_address();
+    auto sandbox_start = memory.heap_base();
+    auto sandbox_end = sandbox_start + memory.heap_size();
+
+    if (page_address >= sandbox_start && page_address < sandbox_end)
+    {
+      auto virtual_target = static_cast<std::byte *>(page_address);
+      auto physical_offset = frame.number() * kapi::memory::frame::size;
+      auto mapped_ptr = mmap(virtual_target, kapi::memory::page::size.value, PROT_READ | PROT_WRITE,
+                             MAP_SHARED | MAP_FIXED, memory.memory_descriptor(), physical_offset.value);
+      if (mapped_ptr == MAP_FAILED)
+      {
+        throw std::runtime_error("Failed to map page");
+      }
+
+      return static_cast<std::byte *>(mapped_ptr);
+    }
+    else if (page_address >= kapi::memory::mmio_base)
+    {
+      throw std::runtime_error("MMIO mapping not yet supported in testing!");
+    }
+    else if (page_address >= kapi::memory::higher_half_direct_map_base)
+    {
+      auto offset = frame.number() * kapi::memory::frame::size;
+      return memory.ram_base() + offset;
+    }
+
+    return nullptr;
+  }
+
+  auto page_mapper::unmap(kapi::memory::page page) -> void
+  {
+    if (!try_unmap(page))
+    {
+      auto error = std::format("Page {} was never mapped!", page.number());
+      throw std::invalid_argument{error};
+    }
+  }
+
+  auto page_mapper::try_unmap(kapi::memory::page page) noexcept -> bool
+  {
+    if (page_mappings.contains(page.number()))
+    {
+      page_mappings.erase(page.number());
+      return true;
+    }
+
+    return false;
+  }
+
+}  // namespace kernel::tests
\ No newline at end of file