linux-kernel - Re: [PATCH v3 26/34] s390/ftrace: Unpoison ftrace_regs in kprobe_ftrace

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Message-ID: <20240102145648.6306-D-hca@linux.ibm.com>
Date: Tue, 2 Jan 2024 15:56:48 +0100
From: Heiko Carstens <hca@...ux.ibm.com>
To: Ilya Leoshkevich <iii@...ux.ibm.com>
Cc: Alexander Gordeev <agordeev@...ux.ibm.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>, David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, Marco Elver <elver@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Pekka Enberg <penberg@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vasily Gorbik <gor@...ux.ibm.com>, Vlastimil Babka <vbabka@...e.cz>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-s390@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Sven Schnelle <svens@...ux.ibm.com>
Subject: Re: [PATCH v3 26/34] s390/ftrace: Unpoison ftrace_regs in
 kprobe_ftrace_handler()

On Thu, Dec 14, 2023 at 12:24:46AM +0100, Ilya Leoshkevich wrote:
> s390 uses assembly code to initialize ftrace_regs and call
> kprobe_ftrace_handler(). Therefore, from the KMSAN's point of view,
> ftrace_regs is poisoned on kprobe_ftrace_handler() entry. This causes
> KMSAN warnings when running the ftrace testsuite.
> 
> Fix by trusting the assembly code and always unpoisoning ftrace_regs in
> kprobe_ftrace_handler().
> 
> Reviewed-by: Alexander Potapenko <glider@...gle.com>
> Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>
> ---
>  arch/s390/kernel/ftrace.c | 2 ++
>  1 file changed, 2 insertions(+)

Acked-by: Heiko Carstens <hca@...ux.ibm.com>