linux-kernel - [tip: x86/mm] x86/mm: Fix sparse warnings in untagged

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Date:   Mon, 12 Dec 2022 19:35:32 -0000
From:   "tip-bot2 for Kirill A. Shutemov" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     kernel test robot <lkp@...el.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/mm] x86/mm: Fix sparse warnings in untagged_ptr()

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     ce66a02538f39f071443bac9bc6ff8f3a780ab92
Gitweb:        https://git.kernel.org/tip/ce66a02538f39f071443bac9bc6ff8f3a780ab92
Author:        Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
AuthorDate:    Wed, 16 Nov 2022 03:43:53 +03:00
Committer:     Dave Hansen <dave.hansen@...ux.intel.com>
CommitterDate: Mon, 28 Nov 2022 15:12:25 -08:00

x86/mm: Fix sparse warnings in untagged_ptr()

Linear Address Masking patchset triggered a lot of sparse warnings.

The root cause is that casting pointer to '__typeof__(*(ptr)) *' will
strip all sparse tags. The type has to be defined based on the pointer
type, not based on what the pointer points to.

Fix cast in untagged_ptr() and avoid __typeof__() usage in
get/put_user().

Fixes: 5744534bdae4 ("x86/uaccess: Provide untagged_addr() and remove tags before address check")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Link: https://lore.kernel.org/all/20221116004353.15052-3-kirill.shutemov%40linux.intel.com
---
 arch/x86/include/asm/uaccess.h | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 1d2c792..bd92e1e 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -43,7 +43,7 @@ DECLARE_STATIC_KEY_FALSE(tagged_addr_key);
 #define untagged_ptr(mm, ptr)	({					\
 	u64 __ptrval = (__force u64)(ptr);				\
 	__ptrval = untagged_addr(mm, __ptrval);				\
-	(__force __typeof__(*(ptr)) *)__ptrval;				\
+	(__force __typeof__(ptr))__ptrval;				\
 })
 #else
 #define untagged_addr(mm, addr)	(addr)
@@ -158,10 +158,8 @@ extern int __get_user_bad(void);
  */
 #define get_user(x,ptr)							\
 ({									\
-	__typeof__(*(ptr)) __user *__ptr_clean;				\
-	__ptr_clean = untagged_ptr(current->mm, ptr);			\
 	might_fault();							\
-	do_get_user_call(get_user,x,__ptr_clean);			\
+	do_get_user_call(get_user,x,untagged_ptr(current->mm, ptr));	\
 })
 
 /**
@@ -263,10 +261,8 @@ extern void __put_user_nocheck_8(void);
  * Return: zero on success, or -EFAULT on error.
  */
 #define put_user(x, ptr) ({						\
-	__typeof__(*(ptr)) __user *__ptr_clean;				\
-	__ptr_clean = untagged_ptr(current->mm, ptr);			\
 	might_fault();							\
-	do_put_user_call(put_user,x,__ptr_clean);			\
+	do_put_user_call(put_user,x,untagged_ptr(current->mm, ptr));	\
 })
 
 /**