From: Namhyung Kim <namhyung@kernel.org>
To: Kim Phillips <kim.phillips@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Will Deacon <will.deacon@arm.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Jiri Olsa <jolsa@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
kernel-team@lge.com
Subject: Re: [PATCH] perf tools: set kernel end address properly
Date: Fri, 20 Apr 2018 09:11:05 +0900 [thread overview]
Message-ID: <20180420001105.GB19067@sejong> (raw)
In-Reply-To: <20180419183313.db3e3a105191a7f30b7650b2@arm.com>
On Thu, Apr 19, 2018 at 06:33:13PM -0500, Kim Phillips wrote:
> On Thu, 19 Apr 2018 11:54:24 +0900
> Namhyung Kim <namhyung@kernel.org> wrote:
>
> > On Wed, Apr 18, 2018 at 07:37:59PM -0500, Kim Phillips wrote:
> > > diff --git a/tools/perf/arch/arm64/util/sym-handling.c b/tools/perf/arch/arm64/util/sym-handling.c
> > > index 0051b1ee8450..5c4a2e208bbc 100644
> > > --- a/tools/perf/arch/arm64/util/sym-handling.c
> > > +++ b/tools/perf/arch/arm64/util/sym-handling.c
> > > @@ -20,3 +20,16 @@ bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
> > > ehdr.e_type == ET_DYN;
> > > }
> > > #endif
> > > +
> > > +const char *arch__normalize_symbol_name(const char *name)
> > > +{
> > > + /*
> > > + * arm64 kernels compensating for a CPU erratum can put up a
> > > + * module_emit_adrp_veneer in place of a module_emit_plt_entry
> > > + */
> > > + if (name && strlen(name) >= 23 &&
> > > + !strncmp(name, "module_emit_adrp_veneer", 23))
> > > + return "module_emit_plt_entry";
> > > +
> > > + return name;
> > > +}
> >
> > I don't know it's always preferable or just for the test. It it's the
> > latter it may be better to move it to the test code.
>
> AFACT, the veneer is a moniker and doesn't technically exist, and
> shouldn't be being looked-up. Both chunks of this diff are needed to
> pass perf test 1: this chunk above is because in
> arch__normalize_symbol_name(), we squash the perf test 1's "<veneer>
> not in *kallsyms*" problem, and in the below chunk, we prevent it
> coming up when the test code iterates over the *vmlinux* symbols. I.e.
> we need to prevent the veneer from coming up in both kallsyms *and*
> vmlinux.
>
> > > diff --git a/tools/perf/tests/vmlinux-kallsyms.c b/tools/perf/tests/vmlinux-kallsyms.c
> > > index 1e5adb65632a..07064e76947d 100644
> > > --- a/tools/perf/tests/vmlinux-kallsyms.c
> > > +++ b/tools/perf/tests/vmlinux-kallsyms.c
> > > @@ -163,6 +163,29 @@ int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest
> > >
> > > continue;
> > > }
> > > + } else if (pair) {
> > > + s64 skew = mem_start - UM(pair->start);
> > > + struct map *kmap = map_groups__find(&kallsyms.kmaps, type, mem_start);
> > > + struct map *vmap = map_groups__find(&vmlinux.kmaps, type, mem_start);
> > > +
> > > + /*
> > > + * arm64 kernels compensating for a CPU erratum can put up a
> > > + * module_emit_adrp_veneer in place of a module_emit_plt_entry
> > > + */
> > > + if (llabs(skew) < page_size)
> >
> > It seems that we needs to check it's the ARM64 at least. If it's a
>
> OK.
>
> > rare case we might need to add more paranoid checks.
>
> It's certainly rare: Adding the authors of the veneer to cc for
> comments:
>
> Will, Ard, how probable are veneer-style symbols such as the
> one introduced in commit a257e0257 "arm64/kernel: don't ban ADRP to
> work around Cortex-A53 erratum #843419" to happen again in the future?
>
> I would have thought WARNing on within-a-pagesize would be OK,
> Namhyung. Are you suggesting checking instead for a hardcoded veneer
> symbol string?
Anything to prevent false-negatives (possibly on other archs).
Thanks,
Namhyung
>
> Thanks,
>
> Kim
>
> > > + {
> > > + pr_debug("NO ERR FOR SKEW %ld: %#" PRIx64 ": diff start addr v: %s k: %#" PRIx64 " %s\n",
> > > + skew, mem_start, sym->name, UM(pair->start), pair->name);
> > > + continue;
> > > + }
> > > +
> > > + pr_debug("ERR : %#" PRIx64 ": diff start addr v: %s k: %#" PRIx64 " %s\n",
> > > + mem_start, sym->name, UM(pair->start), pair->name);
> > > +
> > > + if (kmap && vmap) {
> > > + pr_debug(" : map v: %s k: %s\n",
> > > + vmap->dso->short_name, kmap->dso->short_name);
> > > + }
> > > } else
> > > pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
> > > mem_start, sym->name);
next prev parent reply other threads:[~2018-04-20 0:11 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-16 4:22 [PATCH] perf tools: set kernel end address properly Namhyung Kim
2018-04-16 9:23 ` Jiri Olsa
2018-04-16 13:51 ` Arnaldo Carvalho de Melo
2018-04-16 16:07 ` Kim Phillips
2018-04-16 16:58 ` Arnaldo Carvalho de Melo
2018-04-16 17:24 ` Kim Phillips
2018-04-16 22:48 ` Kim Phillips
2018-04-17 2:27 ` Namhyung Kim
2018-04-19 0:37 ` Kim Phillips
2018-04-19 2:37 ` Namhyung Kim
2018-04-19 23:20 ` Kim Phillips
2018-04-19 23:59 ` Namhyung Kim
2018-04-20 23:23 ` Kim Phillips
2018-04-23 13:52 ` Arnaldo Carvalho de Melo
2018-04-23 14:56 ` Kim Phillips
2018-04-26 5:51 ` [tip:perf/urgent] perf machine: Set main " tip-bot for Namhyung Kim
2018-04-19 2:54 ` [PATCH] perf tools: set " Namhyung Kim
2018-04-19 23:33 ` Kim Phillips
2018-04-20 0:11 ` Namhyung Kim [this message]
2018-04-20 8:10 ` Ard Biesheuvel
2018-04-23 21:43 ` Kim Phillips
2018-04-24 6:13 ` Ard Biesheuvel
2018-04-24 12:50 ` Kim Phillips
2018-04-24 13:07 ` Ard Biesheuvel
2018-04-24 15:13 ` [PATCH] arm64/kernel: rename module_emit_adrp_veneer->module_emit_veneer_for_adrp Kim Phillips
2018-04-24 15:15 ` Ard Biesheuvel
2018-04-24 15:39 ` [PATCH v2] " Kim Phillips
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