Merge branch 'fmorgner/x86-64-double-fault-handling' into 'develop'

x86_64: handle double faults

See merge request teachos/kernel!59

1 files changed, 13 insertions, 13 deletions

diff --git a/docs/briefs/tb0003-facet-based-capability-dispatch.rst b/docs/briefs/tb0003-facet-based-capability-dispatch.rst
index 2cace2f3..70d183d0 100644
--- a/docs/briefs/tb0003-facet-based-capability-dispatch.rst
+++ b/docs/briefs/tb0003-facet-based-capability-dispatch.rst
@@ -76,12 +76,12 @@ Querying a Single Object
 
    struct device : kstd::enable_shared_from_this<device>
    {
-     [[nodiscard]] auto facet(kapi::capabilities::facet_id id) noexcept -> void *;
+     [[nodiscard]] auto facet(kapi::capabilities::facet_id id) noexcept -> kstd::observer_ptr<void>;
 
      template<typename FacetType>
      [[nodiscard]] auto facet() -> FacetType *
      {
-       return static_cast<FacetType *>(facet(FacetType::id));
+       return kstd::observer_ptr{static_cast<FacetType *>(facet(FacetType::id).get())};
      }
 
      template<typename FacetType>
@@ -91,7 +91,7 @@ Querying a Single Object
      }
 
    protected:
-     auto virtual query_facet(kapi::capabilities::facet_id facet) -> void *;
+     auto virtual query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>;
    };
 
 The base implementation of ``query_facet()`` simply returns ``nullptr``.
@@ -106,15 +106,15 @@ A concrete device overrides it, checks the requested id against every facet it s
      [[nodiscard]] auto isa_name() const -> std::string_view override;
 
    protected:
-     auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+     auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
    };
 
    // arch/x86_64/arch/devices/pit.cpp
-   auto pit::query_facet(kapi::capabilities::facet_id facet) -> void *
+   auto pit::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
    {
      if (facet == arch::bus::isa_signature::id)
      {
-       return static_cast<arch::bus::isa_signature *>(this);
+       return kstd::make_observer<arch::bus::isa_signature>(this);
      }
      return kapi::devices::device::query_facet(facet);   // <-- the delegation
    }
@@ -174,10 +174,10 @@ A device is not only queried for identification facets. ``bus`` itself answers t
 .. code-block:: cpp
 
    // kernel/kapi/devices/bus.cpp
-   auto bus::query_facet(kapi::capabilities::facet_id facet) -> void *
+   auto bus::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
    {
-     if (facet == bus::id) { return this; }
-     else if (facet == bus_protocol::id) { return m_protocol; }
+     if (facet == bus::id) { return kstd::observer_ptr{this}; }
+     else if (facet == bus_protocol::id) { return kstd::observer_ptr{m_protocol}; }
      return device::query_facet(facet);
    }
 
@@ -209,7 +209,7 @@ Everything above answers "does *this specific* device or driver support facet X"
      auto withdraw(device const & device, kapi::capabilities::facet_id id) -> void;
 
      [[nodiscard]] auto all(kapi::capabilities::facet_id id) const -> kstd::vector<entry>;
-     [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> void *;
+     [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> kstd::observer_ptr<void>;
 
      auto subscribe(kstd::weak_ptr<facet_registry_observer> observer) -> void;
      // ...
@@ -281,11 +281,11 @@ The two device-model facets already shown (``isa_signature``/``isa_claim``, ``bl
      }
 
    protected:
-     auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+     auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
      {
        if (facet == kapi::sensors::temperature_sensor::id)
        {
-         return static_cast<kapi::sensors::temperature_sensor *>(this);
+         return kstd::make_observer<kapi::sensors::temperature_sensor>(this);
        }
        return kapi::devices::device::query_facet(facet);   // never forget this line
      }
@@ -344,7 +344,7 @@ Capability query without a language-provided RTTI mechanism is a solved problem,
 COM's ``IUnknown::QueryInterface``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-This is the closest real-world relative of facet dispatch, and almost certainly its distant conceptual ancestor. Every COM object implements ``HRESULT QueryInterface(REFIID riid, void ** ppvObject)``: given a 128-bit interface identifier (a GUID) rather than a string, it returns a pointer to that interface or an error [2]_. The shape is identical — an opaque object, a caller-supplied tag, an untyped-then-cast pointer back, no shared base class needed to know about every possible interface in advance. The differences are informative rather than superficial: COM's tags are GUIDs, generated to be globally, statistically unique, specifically to avoid the collision risk a string tag carries (see *Drawbacks*, below); ``QueryInterface`` is reference-counted (``AddRef``/``Release``) as part of the same call, because COM objects can be shared across process and apartment boundaries in ways a kernel device tree is not; and COM has a formal rule that interface identity, once shipped, can never change shape — a modified interface gets a new GUID rather than breaking existing implementers. TeachOS has no equivalent discipline yet (also noted below).
+This is the closest real-world relative of facet dispatch, and almost certainly its distant conceptual ancestor. Every COM object implements ``HRESULT QueryInterface(REFIID riid, void * ppvObject)``: given a 128-bit interface identifier (a GUID) rather than a string, it returns a pointer to that interface or an error [2]_. The shape is identical — an opaque object, a caller-supplied tag, an untyped-then-cast pointer back, no shared base class needed to know about every possible interface in advance. The differences are informative rather than superficial: COM's tags are GUIDs, generated to be globally, statistically unique, specifically to avoid the collision risk a string tag carries (see *Drawbacks*, below); ``QueryInterface`` is reference-counted (``AddRef``/``Release``) as part of the same call, because COM objects can be shared across process and apartment boundaries in ways a kernel device tree is not; and COM has a formal rule that interface identity, once shipped, can never change shape — a modified interface gets a new GUID rather than breaking existing implementers. TeachOS has no equivalent discipline yet (also noted below).
 
 UEFI Protocols
 ~~~~~~~~~~~~~~~~