From: Kees Cook <keescook@chromium.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
linux-fsdevel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <ak@linux.intel.com>, Christoph Hellwig <hch@lst.de>,
Eric Dumazet <edumazet@google.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
Paul Kirth <paulkirth@google.com>
Subject: Re: [PATCH] fs/select: avoid clang stack usage warning
Date: Fri, 7 Oct 2022 16:17:35 -0700 [thread overview]
Message-ID: <202210071614.4297AB65D8@keescook> (raw)
In-Reply-To: <e554eb3c-d065-4aad-b6d2-a12469eaf49c@app.fastmail.com>
On Fri, Oct 07, 2022 at 11:42:51PM +0200, Arnd Bergmann wrote:
> On Fri, Oct 7, 2022, at 9:04 PM, Nick Desaulniers wrote:
> > On Fri, Oct 7, 2022 at 1:28 AM Arnd Bergmann <arnd@arndb.de> wrote:
> >> - The behavior of -ftrivial-auto-var-init= is a bit odd here: with =zero or
> >> =pattern, the stack usage is just below the limit (1020), without the
> >> option it is up to 1044. It looks like your .config picks =zero, which
> >> was dropped in the latest clang version, so it falls back to not
> >
> > Huh? What do you mean by "was dropped?"
> >
> > The config I sent has:
> > CONFIG_CC_HAS_AUTO_VAR_INIT_PATTERN=y
> > CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO_BARE=y
> > CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO=y
> > # CONFIG_INIT_STACK_NONE is not set
> > CONFIG_INIT_STACK_ALL_ZERO=y
>
> When I use this config on my kernel tree (currently on top of
> next-20220929 for unrelated work) and build with clang-16,
> CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO is disabled, so it falls
> back from CONFIG_INIT_STACK_NONE instead of the unavailable
> CONFIG_INIT_STACK_ALL_ZERO.
I think you have a very recent Clang but are building a tree that
doesn't have commit 607e57c6c62c ("hardening: Remove Clang's enable flag
for -ftrivial-auto-var-init=zero").
--
Kees Cook
next prev parent reply other threads:[~2022-10-07 23:17 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-07 9:01 [PATCH] fs/select: avoid clang stack usage warning Arnd Bergmann
2019-03-07 16:19 ` Andi Kleen
2022-10-06 22:21 ` Nick Desaulniers
2022-10-07 8:28 ` Arnd Bergmann
2022-10-07 19:04 ` Nick Desaulniers
2022-10-07 20:11 ` [PATCH] fs/select: mark do_select noinline_for_stack for 32b Nick Desaulniers
2022-10-10 7:44 ` Christoph Hellwig
2022-10-10 16:42 ` Nick Desaulniers
2022-10-10 19:55 ` Arnd Bergmann
2022-10-13 18:52 ` kernel test robot
2022-10-07 21:42 ` [PATCH] fs/select: avoid clang stack usage warning Arnd Bergmann
2022-10-07 22:54 ` Nick Desaulniers
2022-10-10 18:40 ` Nick Desaulniers
2022-10-11 12:46 ` Arnd Bergmann
2022-10-11 20:55 ` [PATCH v2] fs/select: mark do_select noinline_for_stack Nick Desaulniers
2022-10-14 22:39 ` Nathan Chancellor
2022-10-07 23:17 ` Kees Cook [this message]
2022-10-09 10:49 ` [PATCH] fs/select: avoid clang stack usage warning David Laight
2022-10-08 1:46 ` Andi Kleen
2022-10-11 20:50 ` Nick Desaulniers
2022-10-13 20:52 ` Andi Kleen
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