From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: [PATCH -v2 25/33] locking,xtensa: Implement atomic_fetch_{add,sub,and,or,xor}() Date: Tue, 31 May 2016 12:19:50 +0200 Message-ID: <20160531102643.017585955@infradead.org> References: <20160531101925.702692792@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from bombadil.infradead.org ([198.137.202.9]:43393 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751940AbcEaK3y (ORCPT ); Tue, 31 May 2016 06:29:54 -0400 Content-Disposition: inline; filename=peterz-atomic-fetch-xtensa.patch Sender: linux-arch-owner@vger.kernel.org List-ID: To: torvalds@linux-foundation.org, mingo@kernel.org, tglx@linutronix.de, will.deacon@arm.com, paulmck@linux.vnet.ibm.com, boqun.feng@gmail.com, waiman.long@hpe.com, fweisbec@gmail.com Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rth@twiddle.net, vgupta@synopsys.com, linux@arm.linux.org.uk, egtvedt@samfundet.no, realmz6@gmail.com, ysato@users.sourceforge.jp, rkuo@codeaurora.org, tony.luck@intel.com, geert@linux-m68k.org, james.hogan@imgtec.com, ralf@linux-mips.org, dhowells@redhat.com, jejb@parisc-linux.org, mpe@ellerman.id.au, schwidefsky@de.ibm.com, dalias@libc.org, davem@davemloft.net, cmetcalf@mellanox.com, jcmvbkbc@gmail.com, arnd@arndb.de, peterz@infradead.org, dbueso@suse.de, fengguang.wu@intel.com Implement FETCH-OP atomic primitives, these are very similar to the existing OP-RETURN primitives we already have, except they return the value of the atomic variable _before_ modification. This is especially useful for irreversible operations -- such as bitops (because it becomes impossible to reconstruct the state prior to modification). Signed-off-by: Peter Zijlstra (Intel) --- arch/xtensa/include/asm/atomic.h | 54 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 50 insertions(+), 4 deletions(-) --- a/arch/xtensa/include/asm/atomic.h +++ b/arch/xtensa/include/asm/atomic.h @@ -98,6 +98,26 @@ static inline int atomic_##op##_return(i return result; \ } +#define ATOMIC_FETCH_OP(op) \ +static inline int atomic_fetch_##op(int i, atomic_t * v) \ +{ \ + unsigned long tmp; \ + int result; \ + \ + __asm__ __volatile__( \ + "1: l32i %1, %3, 0\n" \ + " wsr %1, scompare1\n" \ + " " #op " %0, %1, %2\n" \ + " s32c1i %0, %3, 0\n" \ + " bne %0, %1, 1b\n" \ + : "=&a" (result), "=&a" (tmp) \ + : "a" (i), "a" (v) \ + : "memory" \ + ); \ + \ + return result; \ +} + #else /* XCHAL_HAVE_S32C1I */ #define ATOMIC_OP(op) \ @@ -138,18 +158,44 @@ static inline int atomic_##op##_return(i return vval; \ } +#define ATOMIC_FETCH_OP(op) \ +static inline int atomic_fetch_##op(int i, atomic_t * v) \ +{ \ + unsigned int tmp, vval; \ + \ + __asm__ __volatile__( \ + " rsil a15,"__stringify(TOPLEVEL)"\n" \ + " l32i %0, %3, 0\n" \ + " " #op " %1, %0, %2\n" \ + " s32i %1, %3, 0\n" \ + " wsr a15, ps\n" \ + " rsync\n" \ + : "=&a" (vval), "=&a" (tmp) \ + : "a" (i), "a" (v) \ + : "a15", "memory" \ + ); \ + \ + return vval; \ +} + #endif /* XCHAL_HAVE_S32C1I */ -#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) +#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_OPS(add) ATOMIC_OPS(sub) -ATOMIC_OP(and) -ATOMIC_OP(or) -ATOMIC_OP(xor) +#undef ATOMIC_OPS +#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) + +#define atomic_fetch_or atomic_fetch_or + +ATOMIC_OPS(and) +ATOMIC_OPS(or) +ATOMIC_OPS(xor) #undef ATOMIC_OPS +#undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN #undef ATOMIC_OP