Commit eaa3babc authored by Yeoreum Yun's avatar Yeoreum Yun Committed by Catalin Marinas
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arm64: futex: Refactor futex atomic operation



Refactor the futex atomic operations using ll/sc instructions in
preparation for FEAT_LSUI support. In addition, use named operands for
the inline asm.

No functional change.

Signed-off-by: default avatarYeoreum Yun <yeoreum.yun@arm.com>
[catalin.marinas@arm.com: remove unnecessary stringify.h include]
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 42550d7d
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+97 −58
Original line number Diff line number Diff line
@@ -12,68 +12,133 @@

#define FUTEX_MAX_LOOPS	128 /* What's the largest number you can think of? */

#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)		\
do {									\
#define LLSC_FUTEX_ATOMIC_OP(op, insn)					\
static __always_inline int						\
__llsc_futex_atomic_##op(int oparg, u32 __user *uaddr, int *oval)	\
{									\
	unsigned int loops = FUTEX_MAX_LOOPS;				\
	int ret, oldval, newval;					\
									\
	uaccess_enable_privileged();					\
	asm volatile(							\
"	prfm	pstl1strm, %2\n"					\
"1:	ldxr	%w1, %2\n"						\
	asm volatile("// __llsc_futex_atomic_" #op "\n"			\
"	prfm	pstl1strm, %[uaddr]\n"					\
"1:	ldxr	%w[oldval], %[uaddr]\n"					\
	insn "\n"							\
"2:	stlxr	%w0, %w3, %2\n"						\
"	cbz	%w0, 3f\n"						\
"	sub	%w4, %w4, %w0\n"					\
"	cbnz	%w4, 1b\n"						\
"	mov	%w0, %w6\n"						\
"2:	stlxr	%w[ret], %w[newval], %[uaddr]\n"			\
"	cbz	%w[ret], 3f\n"						\
"	sub	%w[loops], %w[loops], %w[ret]\n"			\
"	cbnz	%w[loops], 1b\n"					\
"	mov	%w[ret], %w[err]\n"					\
"3:\n"									\
"	dmb	ish\n"							\
	_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0)				\
	_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w0)				\
	: "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp),	\
	  "+r" (loops)							\
	: "r" (oparg), "Ir" (-EAGAIN)					\
	_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w[ret])			\
	_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w[ret])			\
	: [ret] "=&r" (ret), [oldval] "=&r" (oldval),			\
	  [uaddr] "+Q" (*uaddr), [newval] "=&r" (newval),		\
	  [loops] "+r" (loops)						\
	: [oparg] "r" (oparg), [err] "Ir" (-EAGAIN)			\
	: "memory");							\
	uaccess_disable_privileged();					\
} while (0)
									\
	if (!ret)							\
		*oval = oldval;						\
									\
	return ret;							\
}

LLSC_FUTEX_ATOMIC_OP(add, "add	%w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(or,  "orr	%w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(and, "and	%w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(eor, "eor	%w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(set, "mov	%w[newval], %w[oparg]")

static __always_inline int
__llsc_futex_cmpxchg(u32 __user *uaddr, u32 oldval, u32 newval, u32 *oval)
{
	int ret = 0;
	unsigned int loops = FUTEX_MAX_LOOPS;
	u32 val, tmp;

	uaccess_enable_privileged();
	asm volatile("//__llsc_futex_cmpxchg\n"
"	prfm	pstl1strm, %[uaddr]\n"
"1:	ldxr	%w[curval], %[uaddr]\n"
"	eor	%w[tmp], %w[curval], %w[oldval]\n"
"	cbnz	%w[tmp], 4f\n"
"2:	stlxr	%w[tmp], %w[newval], %[uaddr]\n"
"	cbz	%w[tmp], 3f\n"
"	sub	%w[loops], %w[loops], %w[tmp]\n"
"	cbnz	%w[loops], 1b\n"
"	mov	%w[ret], %w[err]\n"
"3:\n"
"	dmb	ish\n"
"4:\n"
	_ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w[ret])
	_ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w[ret])
	: [ret] "+r" (ret), [curval] "=&r" (val),
	  [uaddr] "+Q" (*uaddr), [tmp] "=&r" (tmp),
	  [loops] "+r" (loops)
	: [oldval] "r" (oldval), [newval] "r" (newval),
	  [err] "Ir" (-EAGAIN)
	: "memory");
	uaccess_disable_privileged();

	if (!ret)
		*oval = val;

	return ret;
}

#define FUTEX_ATOMIC_OP(op)						\
static __always_inline int						\
__futex_atomic_##op(int oparg, u32 __user *uaddr, int *oval)		\
{									\
	return __llsc_futex_atomic_##op(oparg, uaddr, oval);		\
}

FUTEX_ATOMIC_OP(add)
FUTEX_ATOMIC_OP(or)
FUTEX_ATOMIC_OP(and)
FUTEX_ATOMIC_OP(eor)
FUTEX_ATOMIC_OP(set)

static __always_inline int
__futex_cmpxchg(u32 __user *uaddr, u32 oldval, u32 newval, u32 *oval)
{
	return __llsc_futex_cmpxchg(uaddr, oldval, newval, oval);
}

static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
{
	int oldval = 0, ret, tmp;
	u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
	int ret;
	u32 __user *uaddr;

	if (!access_ok(_uaddr, sizeof(u32)))
		return -EFAULT;

	uaddr = __uaccess_mask_ptr(_uaddr);

	switch (op) {
	case FUTEX_OP_SET:
		__futex_atomic_op("mov	%w3, %w5",
				  ret, oldval, uaddr, tmp, oparg);
		ret = __futex_atomic_set(oparg, uaddr, oval);
		break;
	case FUTEX_OP_ADD:
		__futex_atomic_op("add	%w3, %w1, %w5",
				  ret, oldval, uaddr, tmp, oparg);
		ret = __futex_atomic_add(oparg, uaddr, oval);
		break;
	case FUTEX_OP_OR:
		__futex_atomic_op("orr	%w3, %w1, %w5",
				  ret, oldval, uaddr, tmp, oparg);
		ret = __futex_atomic_or(oparg, uaddr, oval);
		break;
	case FUTEX_OP_ANDN:
		__futex_atomic_op("and	%w3, %w1, %w5",
				  ret, oldval, uaddr, tmp, ~oparg);
		ret = __futex_atomic_and(~oparg, uaddr, oval);
		break;
	case FUTEX_OP_XOR:
		__futex_atomic_op("eor	%w3, %w1, %w5",
				  ret, oldval, uaddr, tmp, oparg);
		ret = __futex_atomic_eor(oparg, uaddr, oval);
		break;
	default:
		ret = -ENOSYS;
	}

	if (!ret)
		*oval = oldval;

	return ret;
}

@@ -81,40 +146,14 @@ static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
			      u32 oldval, u32 newval)
{
	int ret = 0;
	unsigned int loops = FUTEX_MAX_LOOPS;
	u32 val, tmp;
	u32 __user *uaddr;

	if (!access_ok(_uaddr, sizeof(u32)))
		return -EFAULT;

	uaddr = __uaccess_mask_ptr(_uaddr);
	uaccess_enable_privileged();
	asm volatile("// futex_atomic_cmpxchg_inatomic\n"
"	prfm	pstl1strm, %2\n"
"1:	ldxr	%w1, %2\n"
"	sub	%w3, %w1, %w5\n"
"	cbnz	%w3, 4f\n"
"2:	stlxr	%w3, %w6, %2\n"
"	cbz	%w3, 3f\n"
"	sub	%w4, %w4, %w3\n"
"	cbnz	%w4, 1b\n"
"	mov	%w0, %w7\n"
"3:\n"
"	dmb	ish\n"
"4:\n"
	_ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w0)
	_ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w0)
	: "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
	: "r" (oldval), "r" (newval), "Ir" (-EAGAIN)
	: "memory");
	uaccess_disable_privileged();

	if (!ret)
		*uval = val;

	return ret;
	return __futex_cmpxchg(uaddr, oldval, newval, uval);
}

#endif /* __ASM_FUTEX_H */