From: sashiko-bot@kernel.org
To: "Matt Turner" <mattst88@gmail.com>
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v3 1/5] alpha: fix stale user_stack_pointer()
Date: Sun, 18 Oct 2026 14:28:13 +0000 [thread overview]
Message-ID: <sashiko-outbox-176198@kernel.org> (raw)
In-Reply-To: <20261018-alpha-perf-regs-v3-v3-1-52be85332c57@gmail.com>
> PALcode keeps the user stack pointer in the PCB, not the trap frame, so
> pt_regs->usp is only valid where entry code stores it: entSys,
> do_entArith() and do_entIF(). Interrupts, page faults and unaligned
> traps leave it stale, and ptrace and /proc/<pid>/syscall read it
> through user_stack_pointer().
>
> A user-mode pt_regs is at the top of its task's stack, so find the
> thread_info from it and use rdusp() for current or pcb.usp otherwise,
> as KSTK_ESP() and the regset code already do.
>
> Fixes: 8a2857bc2b30 ("alpha: enable regset-based ptrace and core dumps")
> Assisted-by: Claude:claude-opus-5-5
> Reviewed-by: Magnus Lindholm <linmag7@gmail.com>
> Tested-by: Magnus Lindholm <linmag7@gmail.com>
> Acked-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Matt Turner <mattst88@gmail.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261018-alpha-perf-regs-v3-v3-0-52be85332c57@gmail.com?part=1
next prev parent reply other threads:[~2026-10-18 14:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-18 14:22 [PATCH v3 0/5] alpha: perf register sampling and user stack dumps Matt Turner
2026-10-18 14:22 ` [PATCH v3 1/5] alpha: fix stale user_stack_pointer() Matt Turner
2026-10-18 14:28 ` sashiko-bot [this message]
2026-10-18 14:22 ` [PATCH v3 2/5] alpha: stop storing the user stack pointer in pt_regs Matt Turner
2026-10-18 14:25 ` sashiko-bot
2026-10-18 14:22 ` [PATCH v3 3/5] alpha: use user_stack_pointer() in KSTK_ESP() and dump_elf_thread() Matt Turner
2026-10-18 14:26 ` sashiko-bot
2026-10-18 14:22 ` [PATCH v3 4/5] alpha: add HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP support Matt Turner
2026-10-18 14:36 ` sashiko-bot
2026-10-18 14:22 ` [PATCH v3 5/5] alpha: fill in pc for software event samples Matt Turner
2026-10-18 14:31 ` sashiko-bot
2026-10-18 17:50 ` Magnus Lindholm
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