linux-kernel - Re: Missing operand for tlbie instruction on Power7

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Message-ID: <1443816930.13186.214.camel@otta>
Date:	Fri, 02 Oct 2015 15:15:30 -0500
From:	Peter Bergner <bergner@...t.ibm.com>
To:	Denis Kirjanov <kda@...ux-powerpc.org>
Cc:	Laura Abbott <labbott@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Missing operand for tlbie instruction on Power7

On Fri, 2015-10-02 at 22:03 +0300, Denis Kirjanov wrote:
> arch/powerpc/kernel/swsusp_asm64.S: Assembler messages:
>> arch/powerpc/kernel/swsusp_asm64.S:188: Error: missing operand
>> scripts/Makefile.build:294: recipe for target
>> 'arch/powerpc/kernel/swsusp_asm64.o' failed
>> make[1]: *** [arch/powerpc/kernel/swsusp_asm64.o] Error 1
>> Makefile:941: recipe for target 'arch/powerpc/kernel' failed
>> make: *** [arch/powerpc/kernel] Error 2
[snip]
>> I don't know enough ppc assembly to properly fix this but I can test.
> 
> Could you please test the patch attached?
[snip]
> -0:     tlbie   r4;                             \
> +0:     tlbie   r4, 0;                          \

This isn't correct.  With POWER7 and later (which this compile
is, since it's on LE), the tlbie instruction takes two register
operands:

    tlbie RB, RS

The tlbie instruction on pre POWER7 cpus had one required register
operand (RB) and an optional second L operand, where if you omitted
it, it was the same as using "0":

    tlbie RB, L

This is a POWER7 and later build, so your change which adds the "0"
above is really adding r0 for RS.  The new tlbie instruction doesn't
treat r0 specially, so you'll be using whatever random bits which
happen to be in r0 which I don't think that is what you want.


Peter



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