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Date: Fri, 8 Dec 2023 09:31:33 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Alexander Potapenko <glider@google.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>, Alexander Gordeev
 <agordeev@linux.ibm.com>, Andrew Morton <akpm@linux-foundation.org>,
 Christoph Lameter <cl@linux.com>, David Rientjes <rientjes@google.com>,
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 Marco Elver <elver@google.com>, Masami Hiramatsu <mhiramat@kernel.org>,
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 Vlastimil Babka <vbabka@suse.cz>, Christian Borntraeger
 <borntraeger@linux.ibm.com>, Dmitry Vyukov <dvyukov@google.com>, Hyeonggon
 Yoo <42.hyeyoo@gmail.com>, kasan-dev@googlegroups.com,
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 linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark
 Rutland <mark.rutland@arm.com>, Roman Gushchin <roman.gushchin@linux.dev>,
 Sven Schnelle <svens@linux.ibm.com>
Subject: Re: [PATCH v2 01/33] ftrace: Unpoison ftrace_regs in
 ftrace_ops_list_func()
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On Fri, 8 Dec 2023 15:16:10 +0100
Alexander Potapenko <glider@google.com> wrote:

> On Tue, Nov 21, 2023 at 11:02=E2=80=AFPM Ilya Leoshkevich <iii@linux.ibm.=
com> wrote:
> >
> > Architectures use assembly code to initialize ftrace_regs and call
> > ftrace_ops_list_func(). Therefore, from the KMSAN's point of view,
> > ftrace_regs is poisoned on ftrace_ops_list_func entry(). This causes
> > KMSAN warnings when running the ftrace testsuite. =20
>=20
> I couldn't reproduce these warnings on x86, hope you really need this
> change on s390 :)

On x86, ftrace_regs sits on the stack. And IIUC, s390 doesn't have the same
concept of a "stack" as other architectures. Perhaps that's the reason s390
needs this?

-- Steve