From: Andi Kleen <ak@linux.intel.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-fsdevel@vger.kernel.org,
Nick Desaulniers <ndesaulniers@google.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
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
Subject: Re: [PATCH] fs/select: avoid clang stack usage warning
Date: Thu, 7 Mar 2019 08:19:55 -0800 [thread overview]
Message-ID: <20190307161955.GD7535@tassilo.jf.intel.com> (raw)
In-Reply-To: <20190307090146.1874906-1-arnd@arndb.de>
On Thu, Mar 07, 2019 at 10:01:36AM +0100, Arnd Bergmann wrote:
> The select() implementation is carefully tuned to put a sensible amount
> of data on the stack for holding a copy of the user space fd_set,
> but not too large to risk overflowing the kernel stack.
>
> When building a 32-bit kernel with clang, we need a little more space
> than with gcc, which often triggers a warning:
>
> fs/select.c:619:5: error: stack frame size of 1048 bytes in function 'core_sys_select' [-Werror,-Wframe-larger-than=]
> int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
>
> I experimentally found that for 32-bit ARM, reducing the maximum
> stack usage by 64 bytes keeps us reliably under the warning limit
> again.
Could just use 768 bytes unconditionally. I doubt a few bytes more or less
will make too much difference.
Other than that
Reviewed-by: Andi Kleen <ak@linux.intel.com>
-Andi
next prev parent reply other threads:[~2019-03-07 16:19 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 [this message]
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 ` [PATCH] fs/select: avoid clang stack usage warning Kees Cook
2022-10-09 10:49 ` 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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