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

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Message-ID: <CAOJe8K2GOsBk=CcWaZqq9KN=McLad97BP6ZhEdRB7i2Ag4csOg@mail.gmail.com>
Date:	Sat, 3 Oct 2015 00:37:35 +0300
From:	Denis Kirjanov <kda@...ux-powerpc.org>
To:	Peter Bergner <bergner@...t.ibm.com>
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 10/2/15, Peter Bergner <bergner@...t.ibm.com> wrote:
> 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.

Ok, than we can just zero out r5 for example and use it in tlbie as RS,
right?


>
>
> Peter
>
>
>
>

View attachment "tlbie_fix2.patch" of type "text/x-patch" (512 bytes)