linux-kernel - Re: [PATCH Resent] perf annotate: Fix s390 target function disassembly

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Date:   Tue, 6 Mar 2018 15:52:35 +0100
From:   Thomas-Mich Richter <tmricht@...ux.vnet.ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        brueckner@...ux.vnet.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com
Subject: Re: [PATCH Resent] perf annotate: Fix s390 target function
 disassembly

On 03/06/2018 03:04 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Mar 06, 2018 at 01:39:55PM +0100, Thomas Richter escreveu:
>> Perf annotate displays function call assembler instructions
>> with a right arrow. Hitting enter on this line/instruction
>> causes the browser to disassemble this target function and
>> show it on the screen.  On s390 this results in an error
>> message 'The called function was not found.'
>>
>> The function call assembly line parsing does not handle
>> the s390 bras and brasl instructions. Function call__parse
>> expects the target as first operand:
>> 	callq	e9140 <__fxstat>
>> S390 has a register number as first operand:
>> 	brasl	%r14,41d60 <abort>
>> Therefore the target addresses on s390 are always zero
>> which is an invalid address.
>>
>> Fix this by skipping the first operand on s390.
>>
>> Signed-off-by: Thomas Richter <tmricht@...ux.vnet.ibm.com>
>> Tested-by: Christian Borntraeger <borntraeger@...ibm.com>
>> Reviewed-by: Hendrik Brueckner <brueckner@...ux.vnet.ibm.com>
>> ---
>>  tools/perf/util/annotate.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
>> index 49ff825f745c..feb6006b676d 100644
>> --- a/tools/perf/util/annotate.c
>> +++ b/tools/perf/util/annotate.c
>> @@ -192,6 +192,14 @@ static int call__parse(struct arch *arch, struct ins_operands *ops, struct map *
>>  	};
>>  
>>  	ops->target.addr = strtoull(ops->raw, &endptr, 16);
>> +	if (!strcmp(arch->name, "s390")) {
>> +		/* s390 function call 1st operand is register */
>> +		tok = strchr(ops->raw, ',');
>> +		if (tok)
>> +			ops->target.addr = strtoull(tok + 1, &endptr, 16);
>> +		else
>> +			ops->target.addr = 0;
>> +	} else
>> +		ops->target.addr = strtoull(ops->raw, &endptr, 16);
> 
> Do we have to do this here? Can't we have a s390_call__parse() and set
> that in the s/390 instructions?


Originally I wanted to add an architecture specific weak function to handle s390
This did not work because file util/annotate.c includes the architecture specific versions
around line 100:

#include "arch/arm/annotate/instructions.c"
#include "arch/arm64/annotate/instructions.c"
#include "arch/x86/annotate/instructions.c"
#include "arch/powerpc/annotate/instructions.c"
#include "arch/s390/annotate/instructions.c"

This includes the C file for s390 so we end up having function call__parse defined twice,
one with a weak definition and one without which results in a compiler error.

I will use  a s390 specific call__parse function and sent another patch.

>> -- 
>> 2.14.3
> --
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-- 
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
--
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