tree c8ec3802d701425a771e9f15e30f269c3b6c2c91
parent d58f0b059948ac33abcf9ea6ea9623aab71169f1
author Ard Biesheuvel <ard.biesheuvel@linaro.org> 1495636317 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1541864568 -0800

ARM: 8677/1: boot/compressed: fix decompressor header layout for v7-M

[ Upstream commit 06a4b6d009a1b74a6ec46c5418b46cc53a79fcb8 ]

As reported by Patrice, the header layout of the decompressor is
incorrect when building for v7-M. In this case, the __nop macro
resolves to 'mov r0, r0', which is emitted as a narrow encoding,
resulting in the header data fields to end up at lower offsets than
required.

Given the variety of targets we need to support with the same code,
the startup sequence is a bit of a jumble, and uses instructions
and macros whose encoding widths cannot be specified (badr), or only
exist in a narrow encoding (bx)

So force the use of a wide encoding in __nop, and replace the start
sequence with a simple jump to the label marking the start of code,
preceded by a Thumb2 mode switch if required (using explicit wide
encodings where appropriate). The label itself can be moved to the
start of code [where it belongs] due to the larger range of branch
instructions as compared to adr instructions.

Reported-by: Patrice CHOTARD <patrice.chotard@st.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>