From: Thomas Gleixner <tglx@linutronix.de>
To: Rob Herring <robh@kernel.org>
Cc: Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Jonathan Corbet <corbet@lwn.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v12 2/5] perf: Add a counter for number of user access events in context
Date: Sat, 04 Dec 2021 15:23:39 +0100 [thread overview]
Message-ID: <87sfv84ff8.ffs@tglx> (raw)
In-Reply-To: <CAL_JsqJ9kkch_SB6LT_fwxk9QS36zbwsj5wu+dtY7yWe6SEMug@mail.gmail.com>
On Fri, Dec 03 2021 at 09:58, Rob Herring wrote:
> On Tue, Nov 30, 2021 at 4:57 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> I've rewritten it like this:
>
> On arm64, user space counter access will be controlled differently
> compared to x86. On x86, access in the strictest mode is enabled for all
> tasks in an MM when any event is mmap'ed. For arm64, access is
> explicitly requested for an event and only enabled when the event's
> context is active. This avoids hooks into the arch context switch code
> and gives better control of when access is enabled.
>
> In order to configure user space access when the PMU is enabled, it is
> necessary to know if any event (currently active or not) in the current
> context has user space accessed enabled. Add a counter similar to other
> counters in the context to avoid walking the event list every time.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
next prev parent reply other threads:[~2021-12-04 14:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-27 20:16 [PATCH v12 0/5] Another version of arm64 userspace counter access support Rob Herring
2021-10-27 20:16 ` [PATCH v12 1/5] x86: perf: Move RDPMC event flag to a common definition Rob Herring
2021-11-30 22:51 ` Thomas Gleixner
2021-10-27 20:16 ` [PATCH v12 2/5] perf: Add a counter for number of user access events in context Rob Herring
2021-11-30 22:57 ` Thomas Gleixner
2021-12-03 15:58 ` Rob Herring
2021-12-04 14:23 ` Thomas Gleixner [this message]
2021-10-27 20:16 ` [PATCH v12 3/5] arm64: perf: Add userspace counter access disable switch Rob Herring
2021-10-27 20:16 ` [PATCH v12 4/5] arm64: perf: Enable PMU counter userspace access for perf event Rob Herring
2021-10-27 20:16 ` [PATCH v12 5/5] Documentation: arm64: Document PMU counters access from userspace Rob Herring
2021-11-15 16:57 ` [PATCH v12 0/5] Another version of arm64 userspace counter access support Rob Herring
2021-11-30 21:56 ` Rob Herring
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