linux-kernel - [patch 6/9] x86/uaccess: Add missing __force to casts in __access_ok() and valid_user

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Message-ID: <20240304005104.677606054@linutronix.de>
Date: Mon,  4 Mar 2024 11:12:25 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org,
 Linus Torvalds <torvalds@...uxfoundation.org>,
 Uros Bizjak <ubizjak@...il.com>,
 linux-sparse@...r.kernel.org,
 lkp@...el.com,
 oe-kbuild-all@...ts.linux.dev
Subject: [patch 6/9] x86/uaccess: Add missing __force to casts in
 __access_ok() and valid_user_address()

sparse complains about losing the __user address space due to the cast to
long:

uaccess_64.h:88:24: sparse: warning: cast removes address space '__user' of expression

Annotate it with __force to tell sparse that this is intentional.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/include/asm/uaccess_64.h |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -54,7 +54,7 @@ static inline unsigned long __untagged_a
  * half and a user half.  When cast to a signed type, user pointers
  * are positive and kernel pointers are negative.
  */
-#define valid_user_address(x) ((long)(x) >= 0)
+#define valid_user_address(x) ((__force long)(x) >= 0)
 
 /*
  * User pointers can have tag bits on x86-64.  This scheme tolerates
@@ -87,8 +87,9 @@ static inline bool __access_ok(const voi
 	if (__builtin_constant_p(size <= PAGE_SIZE) && size <= PAGE_SIZE) {
 		return valid_user_address(ptr);
 	} else {
-		unsigned long sum = size + (unsigned long)ptr;
-		return valid_user_address(sum) && sum >= (unsigned long)ptr;
+		unsigned long sum = size + (__force unsigned long)ptr;
+
+		return valid_user_address(sum) && sum >= (__force unsigned long)ptr;
 	}
 }
 #define __access_ok __access_ok