From: Christoph Hellwig <hch@lst.de>
To: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
linux-riscv@lists.infradead.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-kernel@vger.kernel.org, Max Filippov <jcmvbkbc@gmail.com>,
Greg Ungerer <gerg@linux-m68k.org>,
Anup Patel <anup.patel@wdc.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/2] binfmt_flat: allow not offsetting data start
Date: Wed, 7 Apr 2021 16:13:59 +0200 [thread overview]
Message-ID: <20210407141359.GA19843@lst.de> (raw)
In-Reply-To: <20210407115638.1055824-2-damien.lemoal@wdc.com>
On Wed, Apr 07, 2021 at 08:56:37PM +0900, Damien Le Moal wrote:
> Commit 2217b9826246 ("binfmt_flat: revert "binfmt_flat: don't offset
> the data start"") restored offsetting the start of the data section by
> a number of words defined by MAX_SHARED_LIBS. As a result, since
> MAX_SHARED_LIBS is never 0, a gap between the text and data sections
> always exist. For architecture which cannot support a such gap between
> the text and data sections (e.g. riscv nommu), flat binary programs
> cannot be executed.
>
> To allow an architecture to request contiguous text and data sections,
> introduce the macro FLAT_TEXT_DATA_NO_GAP which can be defined by the
> architecture in its asm/flat.h file. With this change, the macro
> DATA_GAP_WORDS is conditionally defined in binfmt_flat.c to
> MAX_SHARED_LIBS for architectures tolerating the gap
> (FLAT_TEXT_DATA_NO_GAP undefined case) and to 0 when
> FLAT_TEXT_DATA_NO_GAP is defined. DATA_GAP_WORDS is used in
> load_flat_file() to calculate the data section length and start
> position.
>
> The definition of FLAT_TEXT_DATA_NO_GAP by an architecture also
> prevents the use of the separate text/data load case (when
> FLAT_FLAG_RAM and FLAT_FLAG_GZIP are not set with NOMMU kernels).
Please make this a CONFIG_* option selected by the architecture,
which also allows to use IS_ENABLED() to error out early for
your check.
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next prev parent reply other threads:[~2021-04-07 14:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 11:56 [PATCH 0/2] Fix binfmt_flat loader for RISC-V Damien Le Moal
2021-04-07 11:56 ` [PATCH 1/2] binfmt_flat: allow not offsetting data start Damien Le Moal
2021-04-07 14:13 ` Christoph Hellwig [this message]
2021-04-07 11:56 ` [PATCH 2/2] riscv: introduce asm/flat.h Damien Le Moal
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