linux-kernel - Re: [PATCH v2 1/3] perf/sdt/x86: Add renaming logic for (missing) 8 bit registers

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Date:   Tue, 28 Mar 2017 12:24:44 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     acme@...hat.com, alexis.berlemont@...il.com,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        naveen.n.rao@...ux.vnet.ibm.com, mpe@...erman.id.au,
        hemant@...ux.vnet.ibm.com,
        Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Subject: Re: [PATCH v2 1/3] perf/sdt/x86: Add renaming logic for (missing) 8
 bit registers

Hi Masami, Thanks for the review.

On Monday 27 March 2017 07:47 PM, Masami Hiramatsu wrote:
> On Mon, 27 Mar 2017 13:28:27 +0530
> Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com> wrote:
>
>> I found couple of events using al, bl, cl and dl registers for
>> argument. These are not directly accepted by uprobe_events and
>> thus needs to be mapped to ax, bx, cx and dx respectively.
>>
>> Few ex,
>>
>>   /usr/bin/qemu-system-s390x
>>     css_adapter_interrupt: 1@%bl
>>     css_chpid_add: 1@%cl 1@...l 1@%dl
>>     dma_bdrv_io: 8@...x 8@...p -8@...4 1@%al
>>
>>   /usr/bin/postgres
>>     buffer__read__done: ... -1@...sh -1@%al
>>     buffer__read__start: ... -1@%al
> Of course, it should be suppoted. BTW, wouldn't we take care about ah, bh ... too?

I thought about them while preparing this patch, but I couldn't find any
events using those registers. So I ignored them.

But I think no one stops compiler to use those registers for sdt argument.
And if so, they should get included.

Will send v3 for this.

Thanks,
Ravi