Commit 0ec33c01 authored by Al Viro's avatar Al Viro
Browse files

x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end() 



Lift stac/clac pairs from __futex_atomic_op{1,2} into arch_futex_atomic_op_inuser(),
fold them with access_ok() in there.  The switch in arch_futex_atomic_op_inuser()
is what has required the previous (objtool) commit...

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 36b1c700

arch/x86/include/asm/futex.h

+36 −26
Original line number Diff line number Diff line
@@ -12,26 +12,33 @@ 
#include <asm/processor.h>

#include <asm/smap.h>



#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)	\

	asm volatile("\t" ASM_STAC "\n"				\

		     "1:\t" insn "\n"				\

		     "2:\t" ASM_CLAC "\n"			\

#define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)	\

do {								\

	int oldval = 0, ret;					\

	asm volatile("1:\t" insn "\n"				\

		     "2:\n"					\

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

		     "3:\tmov\t%3, %1\n"			\

		     "\tjmp\t2b\n"				\

		     "\t.previous\n"				\

		     _ASM_EXTABLE_UA(1b, 3b)			\

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

		     : "i" (-EFAULT), "0" (oparg), "1" (0))

		     : "i" (-EFAULT), "0" (oparg), "1" (0));	\

	if (ret)						\

		goto label;					\

	*oval = oldval;						\

} while(0)



#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)	\

	asm volatile("\t" ASM_STAC "\n"				\

		     "1:\tmovl	%2, %0\n"			\



#define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)	\

do {								\

	int oldval = 0, ret, tem;				\

	asm volatile("1:\tmovl	%2, %0\n"			\

		     "\tmovl\t%0, %3\n"				\

		     "\t" insn "\n"				\

		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\

		     "\tjnz\t1b\n"				\

		     "3:\t" ASM_CLAC "\n"			\

		     "3:\n"					\

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

		     "4:\tmov\t%5, %1\n"			\

		     "\tjmp\t3b\n"				\
@@ -40,41 +47,44 @@ 
		     _ASM_EXTABLE_UA(2b, 4b)			\

		     : "=&a" (oldval), "=&r" (ret),		\

		       "+m" (*uaddr), "=&r" (tem)		\

		     : "r" (oparg), "i" (-EFAULT), "1" (0))

		     : "r" (oparg), "i" (-EFAULT), "1" (0));	\

	if (ret)						\

		goto label;					\

	*oval = oldval;						\

} while(0)



static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,

static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,

		u32 __user *uaddr)

{

	int oldval = 0, ret, tem;



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

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

		return -EFAULT;



	switch (op) {

	case FUTEX_OP_SET:

		__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);

		unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);

		break;

	case FUTEX_OP_ADD:

		__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,

				   uaddr, oparg);

		unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,

				   uaddr, oparg, Efault);

		break;

	case FUTEX_OP_OR:

		__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);

		unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);

		break;

	case FUTEX_OP_ANDN:

		__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);

		unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);

		break;

	case FUTEX_OP_XOR:

		__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);

		unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);

		break;

	default:

		ret = -ENOSYS;

		user_access_end();

		return -ENOSYS;

	}



	if (!ret)

		*oval = oldval;



	return ret;

	user_access_end();

	return 0;

Efault:

	user_access_end();

	return -EFAULT;

}



static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,