linux-kernel - [PATCH 00/10] allow BFLT executables on systems with a MMU

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Message-Id: <1468358862-11799-1-git-send-email-nicolas.pitre@linaro.org>
Date:	Tue, 12 Jul 2016 17:27:32 -0400
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	David Howells <dhowells@...hat.com>,
	Greg Ungerer <gerg@...ux-m68k.org>
Subject: [PATCH 00/10] allow BFLT executables on systems with a MMU

This series provides the necessary changes to allow "flat" executable
binaries meant for no-MMU systems to actually run on systems with a MMU.

*Why?*

Because developing and testing natively on a large system with lots of
RAM makes it so much more convenient to use all the existing profiling
tools and debugging facilities that a kernel with lots of RAM can give.
And incidentally, those systems with lots of RAM all have a MMU.

*Why not use elf_fdpic?*

The flat executable format is simple with very small footprint
overhead, either in the executables themselves or kernel support.
This makes the flat format more suitable than elf_fdpic for very small
single-user-app embedded systems.

And while elf_fdpic binaries can run on MMU systems, flat binaries still
couldn't, which just felt wrong.

So here it is.  The no-MMU support should remain unaffected.

Tested on ARM only with a busybox build.

 arch/arm/include/asm/flat.h    |   5 +-
 arch/m68k/include/asm/flat.h   |   5 +-
 arch/sh/include/asm/flat.h     |   5 +-
 arch/xtensa/include/asm/flat.h |   5 +-
 fs/Kconfig.binfmt              |   3 +-
 fs/binfmt_elf_fdpic.c          |  38 +----
 fs/binfmt_flat.c               | 372 ++++++++++++++++++++++++-----------------
 fs/exec.c                      |  33 ++++
 include/linux/binfmts.h        |   2 +
 9 files changed, 274 insertions(+), 194 deletions(-)