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SubjectRe: [PATCHES] Fix 'perf top' breakage on architectures not providing get_cpuid() Re: perf top for arm64?
Em Wed, Dec 11, 2019 at 02:46:43PM +0000, Mark Rutland escreveu:
> On Wed, Dec 11, 2019 at 10:33:19AM -0300, Arnaldo Carvalho de Melo wrote:
> > So can you take a look at the two patches below and provide me Acked-by
> > and/or Reviewed-by and/or Tested-by?
>
> I just gave this a spin. With vanilla v5.5-rc1 perf top behaves as John
> reported, and with these applied atop perf works as expected:
>
> Tested-by: Mark Rutland <mark.rutland@arm.com>
>
> >From scaning the code, the only other user of get_cpuid() that ends up
> giving up is perf kvm, but AFAICT that never supported arm64, so that
> looks sound to me:
>
> Reviewed-by: Mark Rutland <mark.rutland@arm.com>

Thanks guys, added all the tags, appreciated, I also added this:

Fixes: 608127f73779 ("perf top: Initialize perf_env->cpuid, needed by the per arch annotation init routine")

Thanks Jiri for pointing to it.

- Arnaldo

> Thanks,
> Mark.
>
> > From 53c6cde6a71a1a9283763bd2e938b229b50c2cd5 Mon Sep 17 00:00:00 2001
> > From: Arnaldo Carvalho de Melo <acme@redhat.com>
> > Date: Wed, 11 Dec 2019 10:09:24 -0300
> > Subject: [PATCH 1/2] perf arch: Make the default get_cpuid() return compatible
> > error
> >
> > Some of the functions calling get_cpuid() propagate back the error it
> > returns, and all are using errno (positive) values, make the weak
> > default get_cpuid() function return ENOSYS to be consistent and to allow
> > checking if this is an arch not providing this function or if a provided
> > one is having trouble getting the cpuid, to decide if the warning should
> > be provided to the user or just a debug message should be emitted.
> >
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Cc: Jiri Olsa <jolsa@kernel.org>
> > Cc: John Garry <john.garry@huawei.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Namhyung Kim <namhyung@kernel.org>
> > Cc: Will Deacon <will@kernel.org>
> > Link: https://lkml.kernel.org/n/tip-lxwjr0cd2eggzx04a780ffrv@git.kernel.org
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > ---
> > tools/perf/util/header.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> > index becc2d109423..4d39a75551a0 100644
> > --- a/tools/perf/util/header.c
> > +++ b/tools/perf/util/header.c
> > @@ -850,7 +850,7 @@ int __weak strcmp_cpuid_str(const char *mapcpuid, const char *cpuid)
> > */
> > int __weak get_cpuid(char *buffer __maybe_unused, size_t sz __maybe_unused)
> > {
> > - return -1;
> > + return ENOSYS; /* Not implemented */
> > }
> >
> > static int write_cpuid(struct feat_fd *ff,
> > --
> > 2.21.0
> >
> > From c6c6a3e2eb6982e37294abcac389effd298cf730 Mon Sep 17 00:00:00 2001
> > From: Arnaldo Carvalho de Melo <acme@redhat.com>
> > Date: Wed, 11 Dec 2019 10:21:59 -0300
> > Subject: [PATCH 2/2] perf top: Do not bail out when perf_env__read_cpuid()
> > returns ENOSYS
> >
> > 'perf top' stopped working on hw architectures that do not provide a
> > get_cpuid() implementation and thus fallback to the weak get_cpuid()
> > default function.
> >
> > This is done because at annotation time we may need it in the arch
> > specific annotation init routine, but that is only being used by arches
> > that do provide a get_cpuid() implementation:
> >
> > $ find tools/ -name "*.[ch]" | xargs grep 'evlist->env'
> > tools/perf/builtin-top.c: top.evlist->env = &perf_env;
> > tools/perf/util/evsel.c: return evsel->evlist->env;
> > tools/perf/util/s390-cpumsf.c: sf->machine_type = s390_cpumsf_get_type(session->evlist->env->cpuid);
> > tools/perf/util/header.c: session->evlist->env = &header->env;
> > tools/perf/util/sample-raw.c: const char *arch_pf = perf_env__arch(evlist->env);
> > $
> >
> > $ find tools/perf/arch -name "*.[ch]" | xargs grep -w get_cpuid
> > tools/perf/arch/x86/util/auxtrace.c: ret = get_cpuid(buffer, sizeof(buffer));
> > tools/perf/arch/x86/util/header.c:get_cpuid(char *buffer, size_t sz)
> > tools/perf/arch/powerpc/util/header.c:get_cpuid(char *buffer, size_t sz)
> > tools/perf/arch/s390/util/header.c: * Implementation of get_cpuid().
> > tools/perf/arch/s390/util/header.c:int get_cpuid(char *buffer, size_t sz)
> > tools/perf/arch/s390/util/header.c: if (buf && get_cpuid(buf, 128))
> > $
> >
> > For 'report' or 'script', i.e. tools working on perf.data files, that is
> > setup while reading the header, its just top that needs to explicitely
> > read it at tool start.
> >
> > Reported-by: John Garry <john.garry@huawei.com>
> > Analysed-by: Jiri Olsa <jolsa@kernel.org>
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Namhyung Kim <namhyung@kernel.org>
> > Cc: Will Deacon <will@kernel.org>
> > Link: https://lkml.kernel.org/n/tip-lxwjr0cd2eggzx04a780ffrv@git.kernel.org
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > ---
> > tools/perf/builtin-top.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> > index dc80044bc46f..795e353de095 100644
> > --- a/tools/perf/builtin-top.c
> > +++ b/tools/perf/builtin-top.c
> > @@ -1568,9 +1568,13 @@ int cmd_top(int argc, const char **argv)
> > */
> > status = perf_env__read_cpuid(&perf_env);
> > if (status) {
> > - pr_err("Couldn't read the cpuid for this machine: %s\n",
> > - str_error_r(errno, errbuf, sizeof(errbuf)));
> > - goto out_delete_evlist;
> > + /*
> > + * Some arches do not provide a get_cpuid(), so just use pr_debug, otherwise
> > + * warn the user explicitely.
> > + */
> > + eprintf(status == ENOSYS ? 1 : 0, verbose,
> > + "Couldn't read the cpuid for this machine: %s\n",
> > + str_error_r(errno, errbuf, sizeof(errbuf)));
> > }
> > top.evlist->env = &perf_env;
> >
> > --
> > 2.21.0
> >

--

- Arnaldo

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