scripts: `make rust-analyzer` for out-of-tree modules

Adds support for out-of-tree rust modules to use the `rust-analyzer`
make target to generate the rust-project.json file.

The change involves adding an optional parameter `external_src` to the
`generate_rust_analyzer.py` which expects the path to the out-of-tree
module's source directory. When this parameter is passed, I have chosen
not to add the non-core modules (samples and drivers) into the result
since these are not expected to be used in third party modules. Related
changes are also made to the Makefile and rust/Makefile allowing the
`rust-analyzer` target to be used for out-of-tree modules as well.

Link: https://github.com/Rust-for-Linux/linux/pull/914
Link: https://github.com/Rust-for-Linux/rust-out-of-tree-module/pull/2
Signed-off-by: Vinay Varma <varmavinaym@gmail.com>
Link: https://lore.kernel.org/r/20230411091714.130525-1-varmavinaym@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 18 insertions, 9 deletions

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index 946e250c1b2a..848fa1ad92ba 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -6,10 +6,11 @@
 import argparse
 import json
 import logging
+import os
 import pathlib
 import sys
 
-def generate_crates(srctree, objtree, sysroot_src):
+def generate_crates(srctree, objtree, sysroot_src, external_src):
     # Generate the configuration list.
     cfg = []
     with open(objtree / "include" / "generated" / "rustc_cfg") as fd:
@@ -65,7 +66,7 @@ def generate_crates(srctree, objtree, sysroot_src):
         [],
         is_proc_macro=True,
     )
-    crates[-1]["proc_macro_dylib_path"] = "rust/libmacros.so"
+    crates[-1]["proc_macro_dylib_path"] = f"{objtree}/rust/libmacros.so"
 
     append_crate(
         "build_error",
@@ -95,19 +96,26 @@ def generate_crates(srctree, objtree, sysroot_src):
         "exclude_dirs": [],
     }
 
+    def is_root_crate(build_file, target):
+        try:
+            return f"{target}.o" in open(build_file).read()
+        except FileNotFoundError:
+            return False
+
     # Then, the rest outside of `rust/`.
     #
     # We explicitly mention the top-level folders we want to cover.
-    for folder in ("samples", "drivers"):
-        for path in (srctree / folder).rglob("*.rs"):
+    extra_dirs = map(lambda dir: srctree / dir, ("samples", "drivers"))
+    if external_src is not None:
+        extra_dirs = [external_src]
+    for folder in extra_dirs:
+        for path in folder.rglob("*.rs"):
             logging.info("Checking %s", path)
             name = path.name.replace(".rs", "")
 
             # Skip those that are not crate roots.
-            try:
-                if f"{name}.o" not in open(path.parent / "Makefile").read():
-                    continue
-            except FileNotFoundError:
+            if not is_root_crate(path.parent / "Makefile", name) and \
+               not is_root_crate(path.parent / "Kbuild", name):
                 continue
 
             logging.info("Adding %s", name)
@@ -126,6 +134,7 @@ def main():
     parser.add_argument("srctree", type=pathlib.Path)
     parser.add_argument("objtree", type=pathlib.Path)
     parser.add_argument("sysroot_src", type=pathlib.Path)
+    parser.add_argument("exttree", type=pathlib.Path, nargs="?")
     args = parser.parse_args()
 
     logging.basicConfig(
@@ -134,7 +143,7 @@ def main():
     )
 
     rust_project = {
-        "crates": generate_crates(args.srctree, args.objtree, args.sysroot_src),
+        "crates": generate_crates(args.srctree, args.objtree, args.sysroot_src, args.exttree),
         "sysroot_src": str(args.sysroot_src),
     }