From: sashiko-bot@kernel.org
To: "Matthew Wood" <thepacketgeek@gmail.com>
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v1] perf machine: Don't unwind the arm64 leaf frame caller without symbols
Date: Wed, 14 Oct 2026 15:23:14 +0000 [thread overview]
Message-ID: <sashiko-outbox-171466@kernel.org> (raw)
In-Reply-To: <20261014151326.4142140-1-thepacketgeek@gmail.com>
> On arm64, 'perf record --call-graph fp' also samples LR so that
> thread__resolve_callchain_sample() can recover the leaf function's
> caller, which is missing from the frame pointer chain. It does so via
> get_leaf_frame_caller_aarch64(), which runs a DWARF unwind. The
> unwinder looks up the symbol of every frame it visits, so the first
> lookup in a DSO loads its full symbol table and demangles every symbol
> in it.
>
> Commit 02b2705017d2 ("perf callchain: Allow symbols to be optional when
> resolving a callchain") added the symbols argument so that callers which
> only need maps can avoid loading symbols, and passed it down to every
> add_callchain_ip() call. The leaf frame unwind was missed and still runs
> for symbols=false, so 'perf inject' on arm64 has been loading symbols it
> doesn't need ever since.
>
> [ ... ]
> in the same DSO as the sampled IP or the next frame in the chain, so
> build-id marking loses nothing in practice.
>
> Fixes: 02b2705017d2 ("perf callchain: Allow symbols to be optional when resolving a callchain")
> Signed-off-by: Matthew Wood <thepacketgeek@gmail.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261014151326.4142140-1-thepacketgeek@gmail.com?part=1
prev parent reply other threads:[~2026-10-14 15:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 15:13 [PATCH v1] perf machine: Don't unwind the arm64 leaf frame caller without symbols Matthew Wood
2026-10-14 15:23 ` sashiko-bot [this message]
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