From: Jiri Olsa <jolsa@redhat.com>
To: Leo Yan <leo.yan@linaro.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Kate Stewart <kstewart@linuxfoundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Allison Randal <allison@lohutok.net>,
John Garry <john.garry@huawei.com>,
Enrico Weigelt <info@metux.net>,
linux-kernel@vger.kernel.org, Mike Leach <mike.leach@linaro.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Hendrik Brueckner <brueckner@linux.vnet.ibm.com>,
Thomas Richter <tmricht@linux.vnet.ibm.com>
Subject: Re: [PATCH v3] perf symbols: Consolidate symbol fixup issue
Date: Wed, 18 Mar 2020 12:06:59 +0100 [thread overview]
Message-ID: <20200318110659.GA845874@krava> (raw)
In-Reply-To: <20200306015759.10084-1-leo.yan@linaro.org>
On Fri, Mar 06, 2020 at 09:57:58AM +0800, Leo Yan wrote:
> After copying Arm64's perf archive with object files and perf.data file
> to x86 laptop, the x86's perf kernel symbol resolution fails. It
> outputs 'unknown' for all symbols parsing.
>
> This issue is root caused by the function elf__needs_adjust_symbols(),
> x86 perf tool uses one weak version, Arm64 (and powerpc) has rewritten
> their own version. elf__needs_adjust_symbols() decides if need to parse
> symbols with the relative offset address; but x86 building uses the weak
> function which misses to check for the elf type 'ET_DYN', so that it
> cannot parse symbols in Arm DSOs due to the wrong result from
> elf__needs_adjust_symbols().
>
> The DSO parsing should not depend on any specific architecture perf
> building; e.g. x86 perf tool can parse Arm and Arm64 DSOs, vice versa.
> And confirmed by Naveen N. Rao that powerpc64 kernels are not being
> built as ET_DYN anymore and change to ET_EXEC.
>
> This patch removes the arch specific functions for Arm64 and powerpc and
> changes elf__needs_adjust_symbols() as a common function.
>
> In the common elf__needs_adjust_symbols(), it checks an extra condition
> 'ET_DYN' for elf header type. With this fixing, the Arm64 DSO can be
> parsed properly with x86's perf tool.
>
> Before:
>
> # perf script
> main 3258 1 branches: 0 [unknown] ([unknown]) => ffff800010c4665c [unknown] ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c46670 [unknown] ([kernel.kallsyms]) => ffff800010c4eaec [unknown] ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4eaec [unknown] ([kernel.kallsyms]) => ffff800010c4eb00 [unknown] ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4eb08 [unknown] ([kernel.kallsyms]) => ffff800010c4e780 [unknown] ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4e7a0 [unknown] ([kernel.kallsyms]) => ffff800010c4eeac [unknown] ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4eebc [unknown] ([kernel.kallsyms]) => ffff800010c4ed80 [unknown] ([kernel.kallsyms])
>
> After:
>
> # perf script
> main 3258 1 branches: 0 [unknown] ([unknown]) => ffff800010c4665c coresight_timeout+0x54 ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c46670 coresight_timeout+0x68 ([kernel.kallsyms]) => ffff800010c4eaec etm4_enable_hw+0x3cc ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4eaec etm4_enable_hw+0x3cc ([kernel.kallsyms]) => ffff800010c4eb00 etm4_enable_hw+0x3e0 ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4eb08 etm4_enable_hw+0x3e8 ([kernel.kallsyms]) => ffff800010c4e780 etm4_enable_hw+0x60 ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4e7a0 etm4_enable_hw+0x80 ([kernel.kallsyms]) => ffff800010c4eeac etm4_enable+0x2d4 ([kernel.kallsyms])
> main 3258 1 branches: ffff800010c4eebc etm4_enable+0x2e4 ([kernel.kallsyms]) => ffff800010c4ed80 etm4_enable+0x1a8 ([kernel.kallsyms])
>
> v3: Changed to check for ET_DYN across all architectures.
>
> v2: Fixed Arm64 and powerpc native building.
>
> Reported-by: Mike Leach <mike.leach@linaro.org>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks,
jirka
next prev parent reply other threads:[~2020-03-18 11:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 1:57 [PATCH v3] perf symbols: Consolidate symbol fixup issue Leo Yan
2020-03-18 2:18 ` Leo Yan
2020-03-18 11:06 ` Jiri Olsa [this message]
2020-03-18 14:46 ` Arnaldo Carvalho de Melo
2020-04-04 8:42 ` [tip: perf/urgent] " tip-bot2 for Leo Yan
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