linux-kernel - [PATCH v6 03/12] x86/uaccess: Add unsafe_copy_from

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Message-ID: <20250617225117.521934161@goodmis.org>
Date: Tue, 17 Jun 2025 18:50:12 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org,
 bpf@...r.kernel.org,
 x86@...nel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>,
 Jiri Olsa <jolsa@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Andrii Nakryiko <andrii@...nel.org>,
 Indu Bhagat <indu.bhagat@...cle.com>,
 "Jose E. Marchesi" <jemarch@....org>,
 Beau Belgrave <beaub@...ux.microsoft.com>,
 Jens Remus <jremus@...ux.ibm.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v6 03/12] x86/uaccess: Add unsafe_copy_from_user() implementation

From: Josh Poimboeuf <jpoimboe@...nel.org>

Add an x86 implementation of unsafe_copy_from_user() similar to the
existing unsafe_copy_to_user().

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 arch/x86/include/asm/uaccess.h | 39 +++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 3a7755c1a441..3caf02d0503e 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -599,7 +599,7 @@ _label:									\
  * We want the unsafe accessors to always be inlined and use
  * the error labels - thus the macro games.
  */
-#define unsafe_copy_loop(dst, src, len, type, label)				\
+#define unsafe_copy_to_user_loop(dst, src, len, type, label)			\
 	while (len >= sizeof(type)) {						\
 		unsafe_put_user(*(type *)(src),(type __user *)(dst),label);	\
 		dst += sizeof(type);						\
@@ -607,15 +607,34 @@ _label:									\
 		len -= sizeof(type);						\
 	}
 
-#define unsafe_copy_to_user(_dst,_src,_len,label)			\
-do {									\
-	char __user *__ucu_dst = (_dst);				\
-	const char *__ucu_src = (_src);					\
-	size_t __ucu_len = (_len);					\
-	unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label);	\
-	unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label);	\
-	unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label);	\
-	unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label);	\
+#define unsafe_copy_to_user(_dst, _src, _len, label)				\
+do {										\
+	void __user *__dst = (_dst);						\
+	const void *__src = (_src);						\
+	size_t __len = (_len);							\
+	unsafe_copy_to_user_loop(__dst, __src, __len, u64, label);		\
+	unsafe_copy_to_user_loop(__dst, __src, __len, u32, label);		\
+	unsafe_copy_to_user_loop(__dst, __src, __len, u16, label);		\
+	unsafe_copy_to_user_loop(__dst, __src, __len, u8,  label);		\
+} while (0)
+
+#define unsafe_copy_from_user_loop(dst, src, len, type, label)			\
+	while (len >= sizeof(type)) {						\
+		unsafe_get_user(*(type *)(dst), (type __user *)(src), label);	\
+		dst += sizeof(type);						\
+		src += sizeof(type);						\
+		len -= sizeof(type);						\
+	}
+
+#define unsafe_copy_from_user(_dst, _src, _len, label)				\
+do {										\
+	void *__dst = (_dst);							\
+	void __user *__src = (_src);						\
+	size_t __len = (_len);							\
+	unsafe_copy_from_user_loop(__dst, __src, __len, u64, label);		\
+	unsafe_copy_from_user_loop(__dst, __src, __len, u32, label);		\
+	unsafe_copy_from_user_loop(__dst, __src, __len, u16, label);		\
+	unsafe_copy_from_user_loop(__dst, __src, __len, u8,  label);		\
 } while (0)
 
 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
-- 
2.47.2