linux-kernel - Re: [PATCH v12 2/5] perf: Add a counter for number of user access events in context

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87sfv84ff8.ffs@tglx>
Date:   Sat, 04 Dec 2021 15:23:39 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Rob Herring <robh@...nel.org>
Cc:     Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v12 2/5] perf: Add a counter for number of user access
 events in context

On Fri, Dec 03 2021 at 09:58, Rob Herring wrote:
> On Tue, Nov 30, 2021 at 4:57 PM Thomas Gleixner <tglx@...utronix.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@...utronix.de>