linux-kernel - [PATCH 0/1] perf symbols: ignore mapping symbols on ARM

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Message-Id: <1281352878-8735-1-git-send-email-dave.martin@linaro.org>
Date:	Mon,  9 Aug 2010 12:21:17 +0100
From:	Dave Martin <dave.martin@...aro.org>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Dave Martin <dave.martin@...aro.org>
Subject: [PATCH 0/1] perf symbols: ignore mapping symbols on ARM

Applies to linux-2.6-tip/master or acme/perf-core

ARM ELF files use symbols with special names $a, $t, $d to
identify regions of ARM code, Thumb code and data within code
sections.  This can cause confusing output from the perf tools,
especially for partially stripped binaries, or binaries
containing user-added zero-sized symbols (which may occur in
hand-written assembler which hasn't been fully annotated with
.size directives).

This patch filters out these symbols at load time.

Addressing architecture-specific cases in this way could get
quite messy-- if one architecture-specific hack is needed in
the symbol loading loop, more might be needed over time.
Adding a generic per-architecture symbol filtering hook might
help to mitigate this if more cases need to be supported.

Switching to libbfd as a generic image-handling backend for all
architectures might be a better long-term solution, since
libelf seems to be essentially a low-level parsing library only
at this stage, and doesn't deal with all the architecture
specifics.  There's a generic bfd_is_target_special_symbol()
function which is used by binutils to filter out architecture-
specific symbols which are not "normal" symbols, which could
help us for this case.

Dave Martin (1):
  perf symbols: ignore mapping symbols on ARM

 tools/perf/util/symbol.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

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