linux-kernel - [PATCH 08/13] Rust: Export generated symbols

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Message-Id: <20210414184604.23473-9-ojeda@kernel.org>
Date:   Wed, 14 Apr 2021 20:45:59 +0200
From:   ojeda@...nel.org
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     rust-for-linux@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Miguel Ojeda <ojeda@...nel.org>,
        Alex Gaynor <alex.gaynor@...il.com>,
        Geoffrey Thomas <geofft@...reload.com>,
        Finn Behrens <me@...enk.de>,
        Adam Bratschi-Kaye <ark.email@...il.com>,
        Wedson Almeida Filho <wedsonaf@...gle.com>
Subject: [PATCH 08/13] Rust: Export generated symbols

From: Miguel Ojeda <ojeda@...nel.org>

Now that all the shared Rust infrastructure is in, we export all
the symbols reusing the `EXPORT_SYMBOL_GPL` macro from C. The lists
of symbols are generated on the fly when compiling the crates.

There are three main sets of symbols to distinguish:

  - The ones from the `core` and `alloc` crates (from the Rust
    standard library). The code is licensed as Apache/MIT.

  - The ones from our abstractions in the `kernel` crate.

  - The helpers (already exported since they are not generated).

We export everything as GPL. This ensures we do not mistakenly
expose GPL kernel symbols/features as non-GPL, even indirectly.

Co-developed-by: Alex Gaynor <alex.gaynor@...il.com>
Signed-off-by: Alex Gaynor <alex.gaynor@...il.com>
Co-developed-by: Geoffrey Thomas <geofft@...reload.com>
Signed-off-by: Geoffrey Thomas <geofft@...reload.com>
Co-developed-by: Finn Behrens <me@...enk.de>
Signed-off-by: Finn Behrens <me@...enk.de>
Co-developed-by: Adam Bratschi-Kaye <ark.email@...il.com>
Signed-off-by: Adam Bratschi-Kaye <ark.email@...il.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@...gle.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@...gle.com>
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
 rust/Makefile  |  2 ++
 rust/exports.c | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)
 create mode 100644 rust/exports.c

diff --git a/rust/Makefile b/rust/Makefile
index dbbbdbad6941..2d1d9d7af77c 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -9,6 +9,8 @@ extra-$(CONFIG_RUST) += bindings_generated.rs
 obj-$(CONFIG_RUST) += alloc.o kernel.o
 extra-$(CONFIG_RUST) += exports_alloc_generated.h exports_kernel_generated.h
 
+obj-$(CONFIG_RUST) += exports.o
+
 RUSTDOC = rustdoc
 
 quiet_cmd_rustdoc = RUSTDOC $<
diff --git a/rust/exports.c b/rust/exports.c
new file mode 100644
index 000000000000..d7dff1b3b919
--- /dev/null
+++ b/rust/exports.c
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// A hack to export Rust symbols for loadable modules without having to redo
+// the entire `include/linux/export.h` logic in Rust.
+//
+// This requires the Rust's new/future `v0` mangling scheme because the default
+// one ("legacy") uses invalid characters for C identifiers (thus we cannot use
+// the `EXPORT_SYMBOL_*` macros).
+
+#include <linux/module.h>
+
+#define EXPORT_SYMBOL_RUST_GPL(sym) extern int sym; EXPORT_SYMBOL_GPL(sym);
+
+#include "exports_core_generated.h"
+#include "exports_alloc_generated.h"
+#include "exports_kernel_generated.h"
-- 
2.17.1