Re: [PATCH RFC v3 17/36] kmsan: x86: disable UNWINDER_ORC under KMSAN

From: Marco Elver <elver@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Qian Cai <cai@lca.pw>, Christoph Hellwig <hch@lst.de>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	 Harry Wentland <harry.wentland@amd.com>,
	Vegard Nossum <vegard.nossum@oracle.com>,
	 Dmitry Vyukov <dvyukov@google.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	 Al Viro <viro@zeniv.linux.org.uk>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	 Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andy Lutomirski <luto@kernel.org>,
	 Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	 Christoph Hellwig <hch@infradead.org>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	 "David S. Miller" <davem@davemloft.net>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	 Eric Biggers <ebiggers@google.com>,
	Eric Dumazet <edumazet@google.com>,
	 Eric Van Hensbergen <ericvh@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	 Ilya Leoshkevich <iii@linux.ibm.com>,
	Ingo Molnar <mingo@elte.hu>, Jason Wang <jasowang@redhat.com>,
	 Jens Axboe <axboe@kernel.dk>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	 Mark Rutland <mark.rutland@arm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	 Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Matthew Wilcox <willy@infradead.org>,
	 "Michael S. Tsirkin" <mst@redhat.com>,
	Michal Simek <monstr@monstr.eu>, Petr Mladek <pmladek@suse.com>,
	 Randy Dunlap <rdunlap@infradead.org>,
	Robin Murphy <robin.murphy@arm.com>,
	 Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	 Takashi Iwai <tiwai@suse.com>, "Theodore Ts'o" <tytso@mit.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	 Vasily Gorbik <gor@linux.ibm.com>,
	Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [PATCH RFC v3 17/36] kmsan: x86: disable UNWINDER_ORC under KMSAN
Date: Mon, 2 Dec 2019 14:30:13 +0100
Message-ID: <CANpmjNOO3EkDVsDMUcOVV3fr38rbE5WauQaTSY0G592YeqZSwQ@mail.gmail.com> (raw)
In-Reply-To: <20191122112621.204798-18-glider@google.com>

On Fri, 22 Nov 2019 at 12:27, <glider@google.com> wrote:
>
> KMSAN doesn't currently support UNWINDER_ORC, causing the kernel to
> freeze at boot time.
> See http://github.com/google/kmsan/issues/48.

The Github issues doesn't mention much else -- it might be useful for
future people to elaborate why it doesn't work? If it is unclear why
it doesn't work, then it's fine to mention this in commit message as
well I suppose.

> Signed-off-by: Alexander Potapenko <glider@google.com>
> Cc: Qian Cai <cai@lca.pw>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: Harry Wentland <harry.wentland@amd.com>
> Cc: Vegard Nossum <vegard.nossum@oracle.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: linux-mm@kvack.org
>
> ---
> This patch is part of "kmsan: Kconfig changes to disable options
> incompatible with KMSAN", which was split into smaller pieces.
>
> Change-Id: I9cb6ebbaeb9a38e9e1d015c68ab77d40420a7ad0
> ---
>  arch/x86/Kconfig.debug | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
> index bf9cd83de777..db3cd6147829 100644
> --- a/arch/x86/Kconfig.debug
> +++ b/arch/x86/Kconfig.debug
> @@ -292,6 +292,9 @@ choice
>  config UNWINDER_ORC
>         bool "ORC unwinder"
>         depends on X86_64
> +       # KMSAN doesn't support UNWINDER_ORC yet,
> +       # see https://github.com/google/kmsan/issues/48.
> +       depends on !KMSAN
>         select STACK_VALIDATION
>         ---help---
>           This option enables the ORC (Oops Rewind Capability) unwinder for
> --
> 2.24.0.432.g9d3f5f5b63-goog
>