From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/2] tracing/wprobe: Fix to avoid inifinite watchpoint exception on arm64
Date: Mon, 17 Nov 2025 11:46:24 +0900 [thread overview]
Message-ID: <20251117114624.5fc972e65edac5bb91caa4b2@kernel.org> (raw)
In-Reply-To: <aRdWAshGkWjgXW3L@willie-the-truck>
On Fri, 14 Nov 2025 16:17:06 +0000
Will Deacon <will@kernel.org> wrote:
> On Tue, Nov 04, 2025 at 10:37:35PM +0900, Masami Hiramatsu wrote:
> > Gently ping.
> >
> > There is a bugfix (or strange behavior) on arm64 hw breakpoint but
> > to fix it cleanly, it should change the perf itself (but I'm not
> > sure why arm64 changes the behavior only for the default overflow
> > handlers.) Anyone knows it?
>
> It's because GDB expects to handle the stepping itself when using the
> ptrace interface (with a custom overflow handler to deliver SIGTRAP).
Hmm, would you mean GDB for user program?
If so, it expects hw breakpoint is used by:
- user-space ptrace (for GDB)
- kernel-space perf (must be default overflow handler)
And not expects to be used by
- kernel-space custom overflow handler
This series is to handle the third use case.
Thank you,
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
next prev parent reply other threads:[~2025-11-17 2:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-30 3:26 [PATCH 0/2] tracing/wprobe: Fix to avoid inifinite watchpoint exception on arm64 Masami Hiramatsu (Google)
2025-10-30 3:27 ` [PATCH 1/2] perf: Introduce default_overflow_compatible flag Masami Hiramatsu (Google)
2025-10-30 3:27 ` [PATCH 2/2] tracing: wprobe: Make wprobe_handler default overflow_handler compatible Masami Hiramatsu (Google)
2025-11-04 13:37 ` [PATCH 0/2] tracing/wprobe: Fix to avoid inifinite watchpoint exception on arm64 Masami Hiramatsu
2025-11-14 16:17 ` Will Deacon
2025-11-17 2:46 ` Masami Hiramatsu [this message]
2025-11-10 4:58 ` Masami Hiramatsu
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