From: Guo Ren <ren_guo@c-sky.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, daniel.lezcano@linaro.org,
jason@lakedaemon.net, arnd@arndb.de,
c-sky_gcc_upstream@c-sky.com, gnu-csky@mentor.com,
thomas.petazzoni@bootlin.com, wbx@uclibc-ng.org,
green.hu@gmail.com
Subject: Re: [PATCH V2 11/19] csky: Atomic operations
Date: Fri, 6 Jul 2018 21:46:16 +0800 [thread overview]
Message-ID: <20180706134616.GA25190@guoren> (raw)
In-Reply-To: <20180706120532.GX2476@hirez.programming.kicks-ass.net>
On Fri, Jul 06, 2018 at 02:05:32PM +0200, Peter Zijlstra wrote:
> On Fri, Jul 06, 2018 at 07:48:12PM +0800, Guo Ren wrote:
> > On Thu, Jul 05, 2018 at 08:00:08PM +0200, Peter Zijlstra wrote:
> > > On Mon, Jul 02, 2018 at 01:30:14AM +0800, Guo Ren wrote:
> > > > +#ifdef CONFIG_CPU_HAS_LDSTEX
> > > > +ENTRY(csky_cmpxchg)
> > > > + USPTOKSP
> > > > + mfcr a3, epc
> > > > + INCTRAP a3
> > > > +
> > > > + subi sp, 8
> > > > + stw a3, (sp, 0)
> > > > + mfcr a3, epsr
> > > > + stw a3, (sp, 4)
> > > > +
> > > > + psrset ee
> > > > +1:
> > > > + ldex a3, (a2)
> > > > + cmpne a0, a3
> > > > + bt16 2f
> > > > + mov a3, a1
> > > > + stex a3, (a2)
> > > > + bez a3, 1b
> > > > +2:
> > > > + sync.is
> > > > + mvc a0
> > > > + ldw a3, (sp, 0)
> > > > + mtcr a3, epc
> > > > + ldw a3, (sp, 4)
> > > > + mtcr a3, epsr
> > > > + addi sp, 8
> > > > + KSPTOUSP
> > > > + rte
> > > > +END(csky_cmpxchg)
> > > > +#else
> > >
> > > Please explain... if the CPU has LDEX/STEX, then _why_ do you need this?
> > Our libc use csky_cmpxchg and we want it compatible. Of course, we'll
> > also implement the ldex/stex atomic operations in libs in future.
>
> I would strongly suggest not providing this syscall on SMP systems from
> the get go. There is no point in starting with legacy problems without
> an actual legacy.
Ok.
next prev parent reply other threads:[~2018-07-06 13:46 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-01 17:30 [PATCH V2 00/19] C-SKY(csky) Linux Kernel Port Guo Ren
2018-07-01 17:30 ` [PATCH V2 01/19] csky: Build infrastructure Guo Ren
2018-07-01 21:01 ` Randy Dunlap
2018-07-02 1:13 ` Guo Ren
2018-07-03 3:33 ` Rob Herring
2018-07-03 9:14 ` Guo Ren
2018-07-03 16:03 ` Arnd Bergmann
2018-07-04 11:40 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 02/19] csky: defconfig Guo Ren
2018-07-03 3:16 ` Rob Herring
2018-07-03 8:31 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 03/19] csky: Kernel booting Guo Ren
2018-07-01 17:30 ` [PATCH V2 04/19] csky: Exception handling Guo Ren
2018-07-01 17:30 ` [PATCH V2 05/19] csky: System Call Guo Ren
2018-07-03 19:53 ` Arnd Bergmann
2018-07-04 11:49 ` Guo Ren
2018-07-04 21:04 ` Arnd Bergmann
2018-07-05 5:38 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 06/19] csky: Cache and TLB routines Guo Ren
2018-07-05 17:40 ` Peter Zijlstra
2018-07-07 11:51 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 07/19] csky: MMU and page table management Guo Ren
2018-07-02 13:29 ` Christoph Hellwig
2018-07-03 2:53 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 08/19] csky: Process management and Signal Guo Ren
2018-07-01 17:30 ` [PATCH V2 09/19] csky: VDSO and rt_sigreturn Guo Ren
2018-07-01 17:30 ` [PATCH V2 10/19] csky: IRQ handling Guo Ren
2018-07-01 17:30 ` [PATCH V2 11/19] csky: Atomic operations Guo Ren
2018-07-05 17:50 ` Peter Zijlstra
2018-07-06 11:01 ` Guo Ren
2018-07-06 11:56 ` Peter Zijlstra
2018-07-06 12:17 ` Peter Zijlstra
2018-07-07 8:08 ` Guo Ren
2018-07-07 20:10 ` Andrea Parri
2018-07-08 1:05 ` Guo Ren
2018-07-07 7:42 ` Guo Ren
2018-07-07 19:54 ` Andrea Parri
2018-07-08 0:39 ` Guo Ren
2018-07-05 17:59 ` Peter Zijlstra
2018-07-06 11:44 ` Guo Ren
2018-07-06 12:03 ` Peter Zijlstra
2018-07-06 13:01 ` Peter Zijlstra
2018-07-06 14:06 ` Guo Ren
2018-07-05 18:00 ` Peter Zijlstra
2018-07-06 11:48 ` Guo Ren
2018-07-06 12:05 ` Peter Zijlstra
2018-07-06 13:46 ` Guo Ren [this message]
2018-07-01 17:30 ` [PATCH V2 12/19] csky: ELF and module probe Guo Ren
2018-07-01 17:30 ` [PATCH V2 13/19] csky: Library functions Guo Ren
2018-07-03 20:04 ` Arnd Bergmann
2018-07-04 10:51 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 14/19] csky: User access Guo Ren
2018-07-01 17:30 ` [PATCH V2 15/19] csky: Debug and Ptrace GDB Guo Ren
2018-07-01 17:30 ` [PATCH V2 16/19] csky: SMP support Guo Ren
2018-07-05 18:05 ` Peter Zijlstra
2018-07-06 6:07 ` Guo Ren
2018-07-06 9:39 ` Peter Zijlstra
2018-07-06 13:22 ` Guo Ren
2018-07-06 5:24 ` Mark Rutland
2018-07-06 11:32 ` Guo Ren
2018-07-06 11:43 ` Mark Rutland
2018-07-06 12:26 ` Guo Ren
2018-07-06 16:21 ` Mark Rutland
2018-07-07 6:16 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 17/19] csky: Misc headers Guo Ren
2018-07-01 17:30 ` [PATCH V2 18/19] clocksource: add C-SKY clocksource drivers Guo Ren
2018-07-01 17:34 ` Guo Ren
2018-07-03 9:39 ` Thomas Gleixner
2018-07-04 10:49 ` Guo Ren
2018-07-04 14:35 ` Thomas Gleixner
2018-07-05 5:03 ` Guo Ren
2018-07-04 17:05 ` Daniel Lezcano
2018-07-05 3:30 ` Guo Ren
2018-07-05 9:23 ` Daniel Lezcano
2018-07-06 5:57 ` Guo Ren
2018-07-01 17:30 ` [PATCH V2 19/19] irqchip: add C-SKY irqchip drivers Guo Ren
2018-07-03 3:27 ` Rob Herring
2018-07-03 7:38 ` Guo Ren
2018-07-03 9:28 ` Thomas Gleixner
2018-07-04 5:08 ` Guo Ren
2018-07-04 6:43 ` Thomas Gleixner
2018-07-04 11:58 ` Guo Ren
2018-07-11 9:51 ` [PATCH V2 00/19] C-SKY(csky) Linux Kernel Port David Howells
2018-07-12 12:51 ` Guo Ren
2018-07-12 16:04 ` Sandra Loosemore
2018-07-13 1:30 ` Guo Ren
2018-07-13 10:23 ` David Howells
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