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Subject[PATCH 2/2] x86/mm: Fix sparse warnings in untagged_ptr()
Date
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().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: kernel test robot <lkp@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 1d2c79246681..bd92e1ee1c1a 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)); \
})

/**
--
2.38.0
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