linux-kernel - Re: [PATCH 08/15] tracing: Introduce names for ring buffers

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20231212191546.603c0703@gandalf.local.home>
Date:   Tue, 12 Dec 2023 19:15:46 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Alexander Graf <graf@...zon.com>
Cc:     <linux-kernel@...r.kernel.org>,
        <linux-trace-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kexec@...ts.infradead.org>, <linux-doc@...r.kernel.org>,
        <x86@...nel.org>, Eric Biederman <ebiederm@...ssion.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        Mark Rutland <mark.rutland@....com>,
        "Tom Lendacky" <thomas.lendacky@....com>,
        Ashish Kalra <ashish.kalra@....com>,
        James Gowans <jgowans@...zon.com>,
        Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>,
        <arnd@...db.de>, <pbonzini@...hat.com>,
        <madvenka@...ux.microsoft.com>,
        Anthony Yznaga <anthony.yznaga@...cle.com>,
        Usama Arif <usama.arif@...edance.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH 08/15] tracing: Introduce names for ring buffers

On Wed, 13 Dec 2023 00:04:45 +0000
Alexander Graf <graf@...zon.com> wrote:

> With KHO (Kexec HandOver), we want to preserve trace buffers across
> kexec. To carry over their state between kernels, the kernel needs a
> common handle for them that exists on both sides. As handle we introduce
> names for ring buffers. In a follow-up patch, the kernel can then use
> these names to recover buffer contents for specific ring buffers.
> 

Is there a way to use the trace_array name instead?

The trace_array is the structure that represents each tracing instance. And
it already has a name field. And if you can get the associated ring buffer
from that too.

struct trace_array *tr;

	tr->array_buffer.buffer

	tr->name

When you do: mkdir /sys/kernel/tracing/instance/foo

You create a new trace_array instance where tr->name = "foo" and allocates
the buffer for it as well.

-- Steve