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Commit 4ac46db1 authored by Stefan Kristiansson's avatar Stefan Kristiansson Committed by Stafford Horne
Browse files

openrisc: add futex_atomic_* implementations 



Support for the futex_atomic_* operations by using the
load-link/store-conditional l.lwa/l.swa instructions.
Most openrisc cores provide these instructions now if not available,
emulation is provided.

Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarStefan Kristiansson <stefan.kristiansson@saunalahti.fi>
[shorne@gmail.com: remove OPENRISC_HAVE_INST_LWA_SWA config suggesed by
Alan Cox https://lkml.org/lkml/2014/7/23/666

]
Signed-off-by: default avatarStafford Horne <shorne@gmail.com>
parent bc19598f

arch/openrisc/include/asm/Kbuild

+0 −1
Original line number Diff line number Diff line
@@ -20,7 +20,6 @@ generic-y += exec.h 
generic-y += fb.h

generic-y += fcntl.h

generic-y += ftrace.h

generic-y += futex.h

generic-y += hardirq.h

generic-y += hw_irq.h

generic-y += ioctl.h

arch/openrisc/include/asm/futex.h

0 → 100644
+135 −0
Original line number Diff line number Diff line 
#ifndef __ASM_OPENRISC_FUTEX_H

#define __ASM_OPENRISC_FUTEX_H



#ifdef __KERNEL__



#include <linux/futex.h>

#include <linux/uaccess.h>

#include <asm/errno.h>



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

({								\

	__asm__ __volatile__ (					\

		"1:	l.lwa	%0, %2			\n"	\

			insn				"\n"	\

		"2:	l.swa	%2, %1			\n"	\

		"	l.bnf	1b			\n"	\

		"	 l.ori	%1, r0, 0		\n"	\

		"3:					\n"	\

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

		"4:	l.j	3b			\n"	\

		"	 l.addi	%1, r0, %3		\n"	\

		".previous				\n"	\

		".section __ex_table,\"a\"		\n"	\

		".word	1b,4b,2b,4b			\n"	\

		".previous				\n"	\

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

		: "i" (-EFAULT), "r" (oparg)			\

		: "cc", "memory"				\

		);						\

})



static inline int

futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)

{

	int op = (encoded_op >> 28) & 7;

	int cmp = (encoded_op >> 24) & 15;

	int oparg = (encoded_op << 8) >> 20;

	int cmparg = (encoded_op << 20) >> 20;

	int oldval = 0, ret;



	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))

		oparg = 1 << oparg;



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

		return -EFAULT;



	pagefault_disable();



	switch (op) {

	case FUTEX_OP_SET:

		__futex_atomic_op("l.or %1,%4,%4", ret, oldval, uaddr, oparg);

		break;

	case FUTEX_OP_ADD:

		__futex_atomic_op("l.add %1,%0,%4", ret, oldval, uaddr, oparg);

		break;

	case FUTEX_OP_OR:

		__futex_atomic_op("l.or %1,%0,%4", ret, oldval, uaddr, oparg);

		break;

	case FUTEX_OP_ANDN:

		__futex_atomic_op("l.and %1,%0,%4", ret, oldval, uaddr, ~oparg);

		break;

	case FUTEX_OP_XOR:

		__futex_atomic_op("l.xor %1,%0,%4", ret, oldval, uaddr, oparg);

		break;

	default:

		ret = -ENOSYS;

	}



	pagefault_enable();



	if (!ret) {

		switch (cmp) {

		case FUTEX_OP_CMP_EQ:

			ret = (oldval == cmparg);

			break;

		case FUTEX_OP_CMP_NE:

			ret = (oldval != cmparg);

			break;

		case FUTEX_OP_CMP_LT:

			ret = (oldval < cmparg);

			break;

		case FUTEX_OP_CMP_GE:

			ret = (oldval >= cmparg);

			break;

		case FUTEX_OP_CMP_LE:

			ret = (oldval <= cmparg);

			break;

		case FUTEX_OP_CMP_GT:

			ret = (oldval > cmparg);

			break;

		default:

			ret = -ENOSYS;

		}

	}

	return ret;

}



static inline int

futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,

			      u32 oldval, u32 newval)

{

	int ret = 0;

	u32 prev;



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

		return -EFAULT;



	__asm__ __volatile__ (				\

		"1:	l.lwa	%1, %2		\n"	\

		"	l.sfeq	%1, %3		\n"	\

		"	l.bnf	3f		\n"	\

		"	 l.nop			\n"	\

		"2:	l.swa	%2, %4		\n"	\

		"	l.bnf	1b		\n"	\

		"	 l.nop			\n"	\

		"3:				\n"	\

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

		"4:	l.j	3b		\n"	\

		"	 l.addi	%0, r0, %5	\n"	\

		".previous			\n"	\

		".section __ex_table,\"a\"	\n"	\

		".word	1b,4b,2b,4b		\n"	\

		".previous			\n"	\

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

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

		: "cc",	"memory"			\

		);



	*uval = prev;

	return ret;

}



#endif /* __KERNEL__ */



#endif /* __ASM_OPENRISC_FUTEX_H */