Commit f5544ba7 authored by Al Viro's avatar Al Viro
Browse files

x86: get rid of user_atomic_cmpxchg_inatomic() 



Only one user left; the thing had been made polymorphic back in 2013
for the sake of MPX.  No point keeping it now that MPX is gone.
Convert futex_atomic_cmpxchg_inatomic() to user_access_{begin,end}()
while we are at it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent a251b2d5

arch/x86/include/asm/futex.h

+19 −1
Original line number Diff line number Diff line
@@ -90,7 +90,25 @@ Efault: 
static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,

						u32 oldval, u32 newval)

{

	return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);

	int ret = 0;



	if (!user_access_begin(uaddr, sizeof(u32)))

		return -EFAULT;

	asm volatile("\n"

		"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"

		"2:\n"

		"\t.section .fixup, \"ax\"\n"

		"3:\tmov     %3, %0\n"

		"\tjmp     2b\n"

		"\t.previous\n"

		_ASM_EXTABLE_UA(1b, 3b)

		: "+r" (ret), "=a" (oldval), "+m" (*uaddr)

		: "i" (-EFAULT), "r" (newval), "1" (oldval)

		: "memory"

	);

	user_access_end();

	*uval = oldval;

	return ret;

}



#endif

arch/x86/include/asm/uaccess.h

+0 −93
Original line number Diff line number Diff line
@@ -584,99 +584,6 @@ extern __must_check long strnlen_user(const char __user *str, long n); 
unsigned long __must_check clear_user(void __user *mem, unsigned long len);

unsigned long __must_check __clear_user(void __user *mem, unsigned long len);



extern void __cmpxchg_wrong_size(void)

	__compiletime_error("Bad argument size for cmpxchg");



#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)	\

({									\

	int __ret = 0;							\

	__typeof__(*(ptr)) __old = (old);				\

	__typeof__(*(ptr)) __new = (new);				\

	__uaccess_begin_nospec();					\

	switch (size) {							\

	case 1:								\

	{								\

		asm volatile("\n"					\

			"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"		\

			"2:\n"						\

			"\t.section .fixup, \"ax\"\n"			\

			"3:\tmov     %3, %0\n"				\

			"\tjmp     2b\n"				\

			"\t.previous\n"					\

			_ASM_EXTABLE_UA(1b, 3b)				\

			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\

			: "i" (-EFAULT), "q" (__new), "1" (__old)	\

			: "memory"					\

		);							\

		break;							\

	}								\

	case 2:								\

	{								\

		asm volatile("\n"					\

			"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"		\

			"2:\n"						\

			"\t.section .fixup, \"ax\"\n"			\

			"3:\tmov     %3, %0\n"				\

			"\tjmp     2b\n"				\

			"\t.previous\n"					\

			_ASM_EXTABLE_UA(1b, 3b)				\

			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\

			: "i" (-EFAULT), "r" (__new), "1" (__old)	\

			: "memory"					\

		);							\

		break;							\

	}								\

	case 4:								\

	{								\

		asm volatile("\n"					\

			"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"		\

			"2:\n"						\

			"\t.section .fixup, \"ax\"\n"			\

			"3:\tmov     %3, %0\n"				\

			"\tjmp     2b\n"				\

			"\t.previous\n"					\

			_ASM_EXTABLE_UA(1b, 3b)				\

			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\

			: "i" (-EFAULT), "r" (__new), "1" (__old)	\

			: "memory"					\

		);							\

		break;							\

	}								\

	case 8:								\

	{								\

		if (!IS_ENABLED(CONFIG_X86_64))				\

			__cmpxchg_wrong_size();				\

									\

		asm volatile("\n"					\

			"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"		\

			"2:\n"						\

			"\t.section .fixup, \"ax\"\n"			\

			"3:\tmov     %3, %0\n"				\

			"\tjmp     2b\n"				\

			"\t.previous\n"					\

			_ASM_EXTABLE_UA(1b, 3b)				\

			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\

			: "i" (-EFAULT), "r" (__new), "1" (__old)	\

			: "memory"					\

		);							\

		break;							\

	}								\

	default:							\

		__cmpxchg_wrong_size();					\

	}								\

	__uaccess_end();						\

	*(uval) = __old;						\

	__ret;								\

})



#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)		\

({									\

	access_ok((ptr), sizeof(*(ptr))) ?		\

		__user_atomic_cmpxchg_inatomic((uval), (ptr),		\

				(old), (new), sizeof(*(ptr))) :		\

		-EFAULT;						\

})



/*

 * movsl can be slow when source and dest are not both 8-byte aligned

 */

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