linux-kernel - Re: perf report does not resolve symbols on s390x

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Date:   Wed, 12 Jul 2017 10:21:22 +0200
From:   Thomas-Mich Richter <tmricht@...ux.vnet.ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     "linux-perf-use." <linux-perf-users@...r.kernel.org>,
        Hendrik Brueckner <brueckner@...ux.vnet.ibm.com>,
        Zvonko Kosic <zvonko.kosic@...ibm.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: perf report does not resolve symbols on s390x

On 07/11/2017 09:48 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Jul 11, 2017 at 04:38:28PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Jul 11, 2017 at 04:03:04PM -0300, Arnaldo Carvalho de Melo escreveu:
>>> Em Fri, Jul 07, 2017 at 02:17:25PM +0200, Thomas-Mich Richter escreveu:
.....

> 
>> Argh, this is also broken:
> 
>> static inline bool machine__kernel_ip(struct machine *machine, u64 ip)
>> {
>>         u64 kernel_start = machine__kernel_start(machine);
>>
>>         return ip >= kernel_start;
>> }
>>
>> We can't judge if a address is in the kernel like that :-\
> 
> So, this is used by:
> 
> [acme@...et linux]$ find tools/ -name "*.[ch]" | xargs grep -w machine__kernel_ip
> tools/perf/builtin-script.c:	kernel = machine__kernel_ip(machine, start);
> tools/perf/builtin-script.c:	if (kernel != machine__kernel_ip(machine, end)) {
> 
> That is just for "brstackinsn", would that make sense for Sparc, S/390?

No we don't have that on s/390
> 
> tools/perf/util/intel-bts.c:	if (machine__kernel_ip(machine, ip))
> tools/perf/util/intel-bts.c:		if (!machine__kernel_ip(btsq->bts->machine, branch->from) &&
> tools/perf/util/intel-bts.c:		    machine__kernel_ip(btsq->bts->machine, branch->to) &&
> 
> Intel specific stuff, so should be ok.
> 
> tools/perf/util/event.c:		    machine__kernel_ip(machine, al->addr)) {
> 
> For this last one, that affects all arches, I think we can just remove
> this check and look at the kernel when not finding it anywhere else?
> 
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index dc5c3bb69d73..8e435baaae6a 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -1432,8 +1432,7 @@ void thread__find_addr_map(struct thread *thread, u8 cpumode,
>  		 * in the whole kernel symbol list.
>  		 */
>  		if (cpumode == PERF_RECORD_MISC_USER && machine &&
> -		    mg != &machine->kmaps &&
> -		    machine__kernel_ip(machine, al->addr)) {
> +		    mg != &machine->kmaps) {
>  			mg = &machine->kmaps;
>  			load_map = true;
>  			goto try_again;
> 
>>>> This raises 2 questions:
>>>> 1. s390 has a 64 bit address space for user and kernel. The processor status word (PSW)
>>>>    determines which address space to use. That requires the PSW in the sample. Not sure
>>>>    this is the case?
>>>> 2. How does this work on sparc and other architectures with the same addressing scheme?
>>>>
>>>> Thanks.
>>>> --
>>>> Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
> 
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-- 
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
--
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