linux-kernel - Re: [PATCH v4 11/39] unwind_user: Add user space unwinding API

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

Message-ID: <a02d7751-2e55-47fa-8e97-c9fd803640a1@linux.ibm.com>
Date: Fri, 24 Jan 2025 17:41:29 +0100
From: Jens Remus <jremus@...ux.ibm.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel@...r.kernel.org, Indu Bhagat <indu.bhagat@...cle.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        linux-toolchains@...r.kernel.org, Jordan Rome <jordalgo@...a.com>,
        Sam James <sam@...too.org>, linux-trace-kernel@...r.kernel.org,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Florian Weimer <fweimer@...hat.com>, Andy Lutomirski <luto@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>, Weinan Liu <wnliu@...gle.com>,
        Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH v4 11/39] unwind_user: Add user space unwinding API

On 22.01.2025 03:31, Josh Poimboeuf wrote:

> diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c

> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> +* Generic interfaces for unwinding user space
> +*/
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/sched/task_stack.h>
> +#include <linux/unwind_user.h>
> +
> +int unwind_user_next(struct unwind_user_state *state)
> +{
> +	struct unwind_user_frame _frame;
> +	struct unwind_user_frame *frame = &_frame;
> +	unsigned long cfa = 0, fp, ra = 0;

Why are cfa and ra initialized to zero? Where is that important in
subsequent patches?

"[PATCH v4 12/39] unwind_user: Add frame pointer support" does either
unconditionally set both cfa and ra or bail out.

> +
> +	/* no implementation yet */
> +	-EINVAL;
> +}

Thanks and regards,
Jens
-- 
Jens Remus
Linux on Z Development (D3303)
+49-7031-16-1128 Office
jremus@...ibm.com

IBM

IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Böblingen; Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement: https://www.ibm.com/privacy/