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Subject: Re: [PATCH v1 03/16] powerpc/32: move LOAD_MSR_KERNEL() into
 head_32.h and use it
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
References: <cover.1549630193.git.christophe.leroy@c-s.fr>
 <1946d8ed86a92a9a6827ec260d0d9c99e0d88184.1549630193.git.christophe.leroy@c-s.fr>
 <749f719a0881531cad2071a7011dc5e894812d3d.camel@kernel.crashing.org>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <b074648b-8896-5591-16fe-3ecaf5c7553a@c-s.fr>
Date:   Mon, 11 Feb 2019 07:26:51 +0100
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Le 11/02/2019 à 01:21, Benjamin Herrenschmidt a écrit :
> On Fri, 2019-02-08 at 12:52 +0000, Christophe Leroy wrote:
>>   /*
>> + * MSR_KERNEL is > 0x8000 on 4xx/Book-E since it include MSR_CE.
>> + */
>> +.macro __LOAD_MSR_KERNEL r, x
>> +.if \x >= 0x8000
>> +       lis \r, (\x)@h
>> +       ori \r, \r, (\x)@l
>> +.else
>> +       li \r, (\x)
>> +.endif
>> +.endm
>> +#define LOAD_MSR_KERNEL(r, x) __LOAD_MSR_KERNEL r, x
>> +
> 
> You changed the limit from >= 0x10000 to >= 0x8000 without a
> corresponding explanation as to why...

Yes, the existing LOAD_MSR_KERNEL() was buggy because 'li' takes a 
signed u16, ie between -0x8000 and 0x7999.

By chance it was working because until now nobody was trying to set 
MSR_KERNEL | MSR_EE.

Christophe