linux-kernel - [PATCH] uaccess: decouple INLINE_COPY_FROM_USER and CONFIG

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Message-ID: <20251023171607.1171534-1-yury.norov@gmail.com>
Date: Thu, 23 Oct 2025 13:16:06 -0400
From: "Yury Norov (NVIDIA)" <yury.norov@...il.com>
To: Miguel Ojeda <ojeda@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Danilo Krummrich <dakr@...nel.org>
Cc: "Yury Norov (NVIDIA)" <yury.norov@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Gary Guo <gary@...yguo.net>,
	John Hubbard <jhubbard@...dia.com>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Trevor Gross <tmgross@...ch.edu>,
	linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org
Subject: [PATCH] uaccess: decouple INLINE_COPY_FROM_USER and CONFIG_RUST

Commit 1f9a8286bc0c ("uaccess: always export _copy_[from|to]_user with
CONFIG_RUST") exports _copy_{from,to}_user() unconditionally, if RUST
is enabled. This pollutes exported symbols namespace, and spreads RUST
ifdefery in core files.

It's better to declare a corresponding helper under the rust/helpers,
similarly to how non-underscored copy_{from,to}_user() is handled.

Signed-off-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
---
 lib/usercopy.c         |  4 ++--
 rust/helpers/uaccess.c | 12 ++++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/lib/usercopy.c b/lib/usercopy.c
index 7b17b83c8042..b00a3a957de6 100644
--- a/lib/usercopy.c
+++ b/lib/usercopy.c
@@ -12,7 +12,7 @@
 
 /* out-of-line parts */
 
-#if !defined(INLINE_COPY_FROM_USER) || defined(CONFIG_RUST)
+#if !defined(INLINE_COPY_FROM_USER)
 unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
 {
 	return _inline_copy_from_user(to, from, n);
@@ -20,7 +20,7 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n
 EXPORT_SYMBOL(_copy_from_user);
 #endif
 
-#if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)
+#if !defined(INLINE_COPY_TO_USER)
 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
 {
 	return _inline_copy_to_user(to, from, n);
diff --git a/rust/helpers/uaccess.c b/rust/helpers/uaccess.c
index f49076f813cd..4629b2d15529 100644
--- a/rust/helpers/uaccess.c
+++ b/rust/helpers/uaccess.c
@@ -13,3 +13,15 @@ unsigned long rust_helper_copy_to_user(void __user *to, const void *from,
 {
 	return copy_to_user(to, from, n);
 }
+
+#ifdef INLINE_COPY_FROM_USER
+unsigned long rust_helper__copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	return _inline_copy_from_user(to, from, n);
+}
+
+unsigned long rust_helper__copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	return _inline_copy_to_user(to, from, n);
+}
+#endif
-- 
2.43.0