linux-kernel - Re: [PATCH] powerpc/8xx: hide itlbie and dtlbie symbols

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Message-ID: <3da93325-bb9a-1a09-68b3-43923b7fea5a@c-s.fr>
Date:   Thu, 13 Dec 2018 09:09:44 +0100
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] powerpc/8xx: hide itlbie and dtlbie symbols



Le 12/12/2018 à 14:05, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@....fr> writes:
> 
>> When disassembling InstructionTLBError we get the following messy code:
>>
>> c000138c:       7d 84 63 78     mr      r4,r12
>> c0001390:       75 25 58 00     andis.  r5,r9,22528
>> c0001394:       75 2a 40 00     andis.  r10,r9,16384
>> c0001398:       41 a2 00 08     beq     c00013a0 <itlbie>
>> c000139c:       7c 00 22 64     tlbie   r4,r0
>>
>> c00013a0 <itlbie>:
>> c00013a0:       39 40 04 01     li      r10,1025
>> c00013a4:       91 4b 00 b0     stw     r10,176(r11)
>> c00013a8:       39 40 10 32     li      r10,4146
>> c00013ac:       48 00 cc 59     bl      c000e004 <transfer_to_handler>
>>
>> For a cleaner code dump, this patch replaces itlbie and dtlbie
>> symbols by numeric symbols.
>>
>> c000138c:       7d 84 63 78     mr      r4,r12
>> c0001390:       75 25 58 00     andis.  r5,r9,22528
>> c0001394:       75 2a 40 00     andis.  r10,r9,16384
>> c0001398:       41 a2 00 08     beq     c00013a0 <InstructionTLBError+0xa0>
>> c000139c:       7c 00 22 64     tlbie   r4,r0
>> c00013a0:       39 40 04 01     li      r10,1025
>> c00013a4:       91 4b 00 b0     stw     r10,176(r11)
>> c00013a8:       39 40 10 32     li      r10,4146
>> c00013ac:       48 00 cc 59     bl      c000e004 <transfer_to_handler>
>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>> ---
>>   arch/powerpc/kernel/head_8xx.S | 14 ++++++--------
>>   1 file changed, 6 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
>> index 3b67b9533c82..8c848acfe249 100644
>> --- a/arch/powerpc/kernel/head_8xx.S
>> +++ b/arch/powerpc/kernel/head_8xx.S
>> @@ -552,11 +552,10 @@ InstructionTLBError:
>>   	mr	r4,r12
>>   	andis.	r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
>>   	andis.	r10,r9,SRR1_ISI_NOPT@h
>> -	beq+	1f
>> +	beq+	1301f
>>   	tlbie	r4
>> -itlbie:
>>   	/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
>> -1:	EXC_XFER_LITE(0x400, handle_page_fault)
>> +1301:	EXC_XFER_LITE(0x400, handle_page_fault)
> 
> You could use a local symbol, something like:

Thanks for the tip, I sent v2

Christophe

> 
> 	beq+	1f
>   	tlbie	r4
> .Litlbie:
>   	/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
> 1:	EXC_XFER_LITE(0x400, handle_page_fault)
> 
> 
> cheers
>