loader: Support latest Fuchsia build

This change merges the Fuchsia-forked Vulkan-Loader branch into
the upstream.

Since last update (#478), there has been significant changes to
the way for Vulkan Loader to get manifests and the way for Vulkan
ICDs to get I/O access to GPU devices. Also, Fuchsia has completely
dropped C bindings for the FIDL API which `dlopen_fuchsia.c` uses.

This change makes the following changes:

* Add `loader_extensions_fuchsia.{cc,h}`. This allows the Vulkan
  Loader to provide a way to allow I/O to GPU devices to the ICDs
  it opens.

  The extended ICD API is defined in https://fuchsia.dev/fuchsia-src/
  contribute/governance/rfcs/0205_vulkan_loader and it's implemented
  on ICDs like Fuchsia's Intel Mesa ICD:
  https://fuchsia.googlesource.com/third_party/mesa/+/main/src/intel/
  vulkan/anv_magma.c

* Access data and manifest files from manifest file system FD:

  The Fuchsia Vulkan loader service provides manifests using a
  service-provided virtual file system. It creates these filesystems
  based on the contents of multiple ICD packages and services it
  receives through devfs. As a result, they must be constructed
  using a filesystem serving library and don't reflect anything
  on-disk (see https://fuchsia.dev/fuchsia-src/contribute/governance/
  rfcs/0205_vulkan_loader#filesystem_serving for details).

  The service-provided file system can be only opened as an FD using
  Fuchsia's FDIO (https://fuchsia.googlesource.com/fuchsia/+/main/sdk/
  lib/fdio) library. Thus, in order to read manifest files located
  in a directory opened as an FD, we need to add a `parent_dir_fd`
  param to the functions that read files, including `loader_get_json`
  and `add_data_files`.

* Migrated to the C++ FIDL bindings.

  The old C bindings are not supported anymore and have been deleted
  from the Fuchsia tree. This change migrates `dlopen_fuchsia` to use
  the C++ wire bindings (https://fuchsia.dev/fuchsia-src/reference/
  fidl/bindings/cpp-bindings) which is part of the Fuchsia SDK.

Test: libvulkan builds on Fuchsia with the changes above.
Bug: https://fxbug.dev/378964821

Change-Id: I2af9f677d706d07193aecd2dcc4640ec602b138f

Author: gnoliyil

BUILD.gn

@@ -49,7 +49,7 @@ config("vulkan_internal_config") {
   }
   if (is_fuchsia) {
     defines += [
-      "SYSCONFDIR=\"/config\"",
+      "SYSCONFDIR=\"/vulkan-loader-configuration\"",
       "EXTRASYSCONFDIR=\"/pkg/data\"",
     ]
   }
@@ -73,9 +73,7 @@ config("vulkan_loader_config") {
     "loader/generated",
     "loader",
   ]
-  defines = [
-    "LOADER_USE_UNSAFE_FILE_SEARCH=1",
-  ]
+  defines = [ "LOADER_USE_UNSAFE_FILE_SEARCH=1" ]
 
   if (is_win) {
     cflags = [ "/wd4201" ]
@@ -87,6 +85,9 @@ config("vulkan_loader_config") {
       "LOADER_ENABLE_LINUX_SORT",
     ]
   }
+  if (is_fuchsia || is_linux || is_chromeos) {
+    defines += [ "HAVE_ALLOCA_H" ]
+  }
 }
 
 if (!is_android) {
@@ -98,18 +99,15 @@ if (!is_android) {
     library_type = "static_library"
   }
   support_unknown_function_handling = false
-  if (defined(ar_path) && ar_path != "" && !is_win && (current_cpu == "arm64" || current_cpu == "x86_64")) {
+  if (defined(ar_path) && ar_path != "" && !is_win &&
+      (current_cpu == "arm64" || current_cpu == "x86_64")) {
     support_unknown_function_handling = true
     static_library("asm_offset") {
       sources = [ "loader/asm_offset.c" ]
-      deps = [
-        "$vulkan_headers_dir:vulkan_headers",
-      ]
+      deps = [ "$vulkan_headers_dir:vulkan_headers" ]
 
       if (is_fuchsia) {
-        deps += [
-          ":dlopen_fuchsia",
-        ]
+        deps += [ ":dlopen_fuchsia" ]
       }
 
       # Output raw assembly instead of compiled object file. The assembly will be included as a member of the output ar file.
@@ -147,9 +145,7 @@ if (!is_android) {
   if (is_win) {
     action("gen_loader_rc") {
       script = "scripts/generate_loader_rc.py"
-      inputs = [
-        "loader/loader.rc",
-      ]
+      inputs = [ "loader/loader.rc" ]
       args = [
         rebase_path("loader/loader.rc", root_build_dir),
         rebase_path("$target_gen_dir/loader.rc", root_build_dir),
@@ -170,33 +166,35 @@ if (!is_android) {
       "loader/cJSON.h",
       "loader/debug_utils.c",
       "loader/debug_utils.h",
+
       # Should only be linked when assembler is used
       # "loader/dev_ext_trampoline.c",
       "loader/extension_manual.c",
       "loader/extension_manual.h",
       "loader/generated/vk_layer_dispatch_table.h",
       "loader/generated/vk_loader_extensions.h",
       "loader/generated/vk_object_types.h",
-      "loader/gpa_helper.h",
       "loader/gpa_helper.c",
+      "loader/gpa_helper.h",
+      "loader/loader.c",
+      "loader/loader.h",
       "loader/loader_common.h",
       "loader/loader_environment.c",
       "loader/loader_environment.h",
-      "loader/loader.c",
-      "loader/loader.h",
       "loader/loader_json.c",
       "loader/loader_json.h",
       "loader/log.c",
       "loader/log.h",
+
       # Should only be linked when assembler is used
       # "loader/phys_dev_ext.c",
       "loader/settings.c",
       "loader/settings.h",
       "loader/stack_allocation.h",
       "loader/terminator.c",
       "loader/trampoline.c",
-      "loader/unknown_function_handling.h",
       "loader/unknown_function_handling.c",
+      "loader/unknown_function_handling.h",
       "loader/vk_loader_layer.h",
       "loader/vk_loader_platform.h",
       "loader/wsi.c",
@@ -221,11 +219,11 @@ if (!is_android) {
     deps = []
     if (is_win) {
       sources += [
+        "$target_gen_dir/loader.rc",
         "loader/dirent_on_windows.c",
         "loader/dirent_on_windows.h",
         "loader/loader_windows.c",
         "loader/loader_windows.h",
-        "$target_gen_dir/loader.rc",
         "loader/vulkan-1.def",
       ]
       if (!is_clang) {
@@ -270,18 +268,41 @@ if (!is_android) {
 
     if (is_fuchsia) {
       category = "partner"
+      sdk_name = "vulkan"
+
+      symbols_api = "vulkan.ifs"
 
       # The Vulkan loader's interface is defined by standard Khronos vulkan headers
       # which can be obtained separately from the loader implementation itself.
       no_headers = true
 
+      sources += [
+        "loader/dlopen_fuchsia.cc",
+        "loader/dlopen_fuchsia.h",
+        "loader/loader_extensions_fuchsia.cc",
+        "loader/loader_extensions_fuchsia.h",
+        "loader/loader_fuchsia.h",
+        "loader/loader_fuchsia_service.cc",
+        "loader/loader_fuchsia_service.h",
+      ]
+
       deps += [
         ":dlopen_fuchsia",
+        "//sdk/fidl/fuchsia.io:fuchsia.io_cpp",
+        "//sdk/fidl/fuchsia.vulkan.loader:fuchsia.vulkan.loader_cpp",
+        "//sdk/lib/component/incoming/cpp",
         "//sdk/lib/fdio",
       ]
+      include_dirs = [ "$target_gen_dir" ]
+
+      runtime_deps = [
+        "//sdk/lib/fdio:fdio_sdk",
+        "//zircon/system/ulib/trace-engine:trace-engine_sdk",
+      ]
 
-      runtime_deps = [ "//sdk/lib/fdio:fdio_sdk" ]
+      libcxx_linkage = "static"
     }
+
     if (support_unknown_function_handling) {
       if (current_cpu == "arm64") {
         sources += [ "loader/unknown_ext_chain_gas_aarch.S" ]
@@ -291,29 +312,17 @@ if (!is_android) {
         assert(false, "Unexpected CPU $current_cpu")
       }
 
-      defines += ["UNKNOWN_FUNCTIONS_SUPPORTED=1"]
+      defines += [ "UNKNOWN_FUNCTIONS_SUPPORTED=1" ]
       deps += [ ":gen_defines" ]
       include_dirs = [ "$target_gen_dir" ]
     }
   }
 }
 
 if (is_fuchsia) {
-  source_set("dlopen_fuchsia") {
-    sources = [
-      "loader/dlopen_fuchsia.c",
-      "loader/dlopen_fuchsia.h",
-    ]
-
-    deps = [
-      "//sdk/fidl/fuchsia.vulkan.loader:fuchsia.vulkan.loader_c_client",
-      "//sdk/lib/fdio",
-    ]
-  }
-
   sdk_documentation("vulkan_license") {
     name = "vulkan_license"
-    category = "public"
+    category = "partner"
 
     files = [
       {

BUILD.md

@@ -604,7 +604,7 @@ Fuchsia uses the project's GN build system to integrate with the Fuchsia platfor
 ### SDK Symbols
 
 The Vulkan Loader is a component of the Fuchsia SDK, so it must explicitly declare its exported symbols in
-the file vulkan.symbols.api; see [SDK](https://fuchsia.dev/fuchsia-src/development/sdk).
+the file vulkan.ifs; see [SDK](https://fuchsia.dev/fuchsia-src/development/sdk).
 
 ## Building on QNX
 

loader/README_fuchsia.md

@@ -0,0 +1,34 @@
+# Fuchsia extensions to the loader
+
+## Shared library opening
+
+The loader doesn't have direct access to the filesystem containing an ICD. Instead, it must connect
+to the [Vulkan loader service][loader-service] at `/svc/fuchsia.vulkan.loader.Loader`. That service
+can provide an executable VMO for an ICD, which can be loaded using `dlopen_vmo`.
+
+## Open in namespace callback
+
+According to the [Fuchsia system ABI][abi], Vulkan ICDs cannot directly use the filesystem to read
+files or connect to services. Instead loader will call the `vk_icdInitializeOpenInNamespaceCallback`
+function in the ICD immediately after the ICD is dlopened. The callback may be used by the ICD to
+connect to services, or the driver device node or to read from files.
+
+## Exporting device nodes
+
+If an ICD tries to open a path under `/loader-gpu-devices` using
+`vk_icdInitializeOpenInNamespaceCallback`, the loader will redirect that request to a directory
+returned by [fuchsia.vulkan.loader/Loader.ConnectToDeviceFs][connect-device-fs]. This allows the
+loader service to ensure all devnodes the ICD needs are accessible to it, without the application or
+application runtime needing to special-case device nodes in the application's component manifest.
+
+## Getting ICD manifests
+
+[ICD manifests][manifests] are retrieved using [ConnectToManifestFs][connect-manifest-fs] on the
+loader service instead of being read directly from the filesystem. This allows ICD manifests to be
+packaged alongside the ICD shared library. Layer manifests are read from the filesystem like normal.
+
+[loader-service]: https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/src/graphics/bin/vulkan_loader/README.md
+[abi]: https://fuchsia.dev/fuchsia-src/concepts/system/abi/system?hl=en
+[connect-device-fs]: https://fuchsia.dev/reference/fidl/fuchsia.vulkan.loader?hl=en#fuchsia.vulkan.loader/Loader.ConnectToDeviceFs
+[connect-manifest-fs]: https://fuchsia.dev/reference/fidl/fuchsia.vulkan.loader?hl=en#fuchsia.vulkan.loader/Loader.ConnectToManifestFs
+[manifests]: LoaderAndLayerInterface.md