linux-kernel - [tip: core/rseq] uaccess: Provide put/get_user

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Message-ID: <176173344776.2601451.9104112102429510717.tip-bot2@tip-bot2>
Date: Wed, 29 Oct 2025 10:24:07 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: core/rseq] uaccess: Provide put/get_user_inline()

The following commit has been merged into the core/rseq branch of tip:

Commit-ID:     81575ebb64a2aec238d309b1a0f55b792d212e00
Gitweb:        https://git.kernel.org/tip/81575ebb64a2aec238d309b1a0f55b792d212e00
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Mon, 27 Oct 2025 09:43:56 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 29 Oct 2025 11:07:09 +01:00

uaccess: Provide put/get_user_inline()

Provide convenience wrappers around scoped user access similar to
put/get_user(), which reduce the usage sites to:

       if (!get_user_inline(val, ptr))
       		return -EFAULT;

Should only be used if there is a demonstrable performance benefit.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Link: https://patch.msgid.link/20251027083745.609031602@linutronix.de
---
 include/linux/uaccess.h | 50 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 5f142c0..be395f5 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -825,6 +825,56 @@ for (bool done = false; !done; done = true)						\
 #define scoped_user_rw_access(uptr, elbl)				\
 	scoped_user_rw_access_size(uptr, sizeof(*(uptr)), elbl)
 
+/**
+ * get_user_inline - Read user data inlined
+ * @val:	The variable to store the value read from user memory
+ * @usrc:	Pointer to the user space memory to read from
+ *
+ * Return: 0 if successful, -EFAULT when faulted
+ *
+ * Inlined variant of get_user(). Only use when there is a demonstrable
+ * performance reason.
+ */
+#define get_user_inline(val, usrc)				\
+({								\
+	__label__ efault;					\
+	typeof(usrc) _tmpsrc = usrc;				\
+	int _ret = 0;						\
+								\
+	scoped_user_read_access(_tmpsrc, efault)		\
+		unsafe_get_user(val, _tmpsrc, efault);		\
+	if (0) {						\
+	efault:							\
+		_ret = -EFAULT;					\
+	}							\
+	_ret;							\
+})
+
+/**
+ * put_user_inline - Write to user memory inlined
+ * @val:	The value to write
+ * @udst:	Pointer to the user space memory to write to
+ *
+ * Return: 0 if successful, -EFAULT when faulted
+ *
+ * Inlined variant of put_user(). Only use when there is a demonstrable
+ * performance reason.
+ */
+#define put_user_inline(val, udst)				\
+({								\
+	__label__ efault;					\
+	typeof(udst) _tmpdst = udst;				\
+	int _ret = 0;						\
+								\
+	scoped_user_write_access(_tmpdst, efault)		\
+		unsafe_put_user(val, _tmpdst, efault);		\
+	if (0) {						\
+	efault:							\
+		_ret = -EFAULT;					\
+	}							\
+	_ret;							\
+})
+
 #ifdef CONFIG_HARDENED_USERCOPY
 void __noreturn usercopy_abort(const char *name, const char *detail,
 			       bool to_user, unsigned long offset,