From: sashiko-bot@kernel.org
To: "Matt Turner" <mattst88@gmail.com>
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v2 5/5] alpha: fill in pc for software event samples
Date: Sat, 17 Oct 2026 01:59:02 +0000 [thread overview]
Message-ID: <sashiko-outbox-175169@kernel.org> (raw)
In-Reply-To: <20261016-alpha-perf-regs-v3-v2-5-17654742226a@gmail.com>
> Context switch and tracepoint events have no trap frame, so perf builds
> one with perf_fetch_caller_regs(). Alpha does not define
> perf_arch_fetch_caller_regs(), which leaves that pt_regs zeroed, and
> these samples report pc as 0.
>
> Record the caller's address as pc. The zero ps already marks the frame
> as kernel mode, and pt_regs has nowhere to keep sp, so pc is all that
> can be filled in.
>
> Reported-by: Magnus Lindholm <linmag7@gmail.com>
> Closes: https://lore.kernel.org/all/CA%2B%3DFv5S8-Zk8-LUpZnWiBfTGSQXthepmRc_-a9O%2BpEPmVW0mRA@mail.gmail.com/
> Assisted-by: Claude:claude-opus-5-5
> Signed-off-by: Matt Turner <mattst88@gmail.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261016-alpha-perf-regs-v3-v2-0-17654742226a@gmail.com?part=5
prev parent reply other threads:[~2026-10-17 1:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 1:55 [PATCH v2 0/5] alpha: perf register sampling and user stack dumps Matt Turner
2026-10-17 1:55 ` [PATCH v2 1/5] alpha: fix stale user_stack_pointer() Matt Turner
2026-10-17 2:00 ` sashiko-bot
2026-10-17 1:55 ` [PATCH v2 2/5] alpha: stop storing the user stack pointer in pt_regs Matt Turner
2026-10-17 2:00 ` sashiko-bot
2026-10-17 1:55 ` [PATCH v2 3/5] alpha: use user_stack_pointer() in KSTK_ESP() and dump_elf_thread() Matt Turner
2026-10-17 1:59 ` sashiko-bot
2026-10-17 1:55 ` [PATCH v2 4/5] alpha: add HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP support Matt Turner
2026-10-17 2:08 ` sashiko-bot
2026-10-17 1:55 ` [PATCH v2 5/5] alpha: fill in pc for software event samples Matt Turner
2026-10-17 1:59 ` sashiko-bot [this message]
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