ARM: 7743/1: compressed/head.S: work around new binutils
 warning

commit da94a829305f1c217cfdf6771cb1faca0917e3b9 upstream.

In August 2012, Matthew Gretton-Dann checked a change into binutils
labelled "Error on obsolete & warn on deprecated registers", apparently as
part of ARMv8 support. Apparently, this was supposed to emit the message
"Warning: This coprocessor register access is deprecated in ARMv8" when
using certain mcr/mrc instructions and building for ARMv8. Unfortunately,
the message that is actually emitted appears to be '(null)', which is
less helpful in comparison.

Even more unfortunately, this is biting us on every single kernel
build with a new gas, because arch/arm/boot/compressed/head.S and some
other files in that directory are built with -march=all since kernel
commit 80cec14a8 "[ARM] Add -march=all to assembly file build in
arch/arm/boot/compressed" back in v2.6.28.

This patch reverts Russell's nice solution and instead marks the head.S
file to be built for armv7-a, which fortunately lets us build all
instructions in that file without warnings even on the broken binutils.

Without this patch, building anything results in:

arch/arm/boot/compressed/head.S: Assembler messages:
arch/arm/boot/compressed/head.S:565: Warning: (null)
arch/arm/boot/compressed/head.S:676: Warning: (null)
arch/arm/boot/compressed/head.S:698: Warning: (null)
arch/arm/boot/compressed/head.S:722: Warning: (null)
arch/arm/boot/compressed/head.S:726: Warning: (null)
arch/arm/boot/compressed/head.S:957: Warning: (null)
arch/arm/boot/compressed/head.S:996: Warning: (null)
arch/arm/boot/compressed/head.S:997: Warning: (null)
arch/arm/boot/compressed/head.S:1027: Warning: (null)
arch/arm/boot/compressed/head.S:1035: Warning: (null)
arch/arm/boot/compressed/head.S:1046: Warning: (null)
arch/arm/boot/compressed/head.S:1060: Warning: (null)
arch/arm/boot/compressed/head.S:1092: Warning: (null)
arch/arm/boot/compressed/head.S:1094: Warning: (null)
arch/arm/boot/compressed/head.S:1095: Warning: (null)
arch/arm/boot/compressed/head.S:1102: Warning: (null)
arch/arm/boot/compressed/head.S:1134: Warning: (null)

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Gretton-Dann <matthew.gretton-dann@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[bwh: Backported to 3.2:
 - Adjust context
 - Remove definition of asflags-y as it is now empty]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	arch/arm/boot/compressed/Makefile (reverted from commit 5ae5801b4b27cd06a6691390d89f086623801afa)
ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
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ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls.  Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).

We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.

Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code.  This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.

Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-K철nig <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Backported from Linux 3.17 to Linux 3.4.

Following commands were used :

find arch/arm -name '*.S' -exec sed -i -e 's/mov    pc, /ret    /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq    pc, /reteq    /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne    pc, /retne    /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs    pc, /reths    /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls    pc, /retls    /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo    pc, /retlo    /g' {} \;

find arch/arm -name '*.S' -exec sed -i -e 's/mov     pc, /ret     /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq     pc, /reteq     /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne     pc, /retne     /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs     pc, /reths     /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls     pc, /retls     /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo     pc, /retlo     /g' {} \;

find arch/arm -name '*.S' -exec sed -i -e 's/mov\tpc, /ret\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq\tpc, /reteq\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne\tpc, /retne\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs\tpc, /reths\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls\tpc, /retls\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo\tpc, /retlo\t/g' {} \;

find arch/arm -name '*.S' -exec sed -i -e 's/mov\tpc,/ret\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq\tpc,/reteq\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movw_pc/ret.w/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne\tpc,/retne\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs\tpc,/reths\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls\tpc,/retls\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo\tpc,/retlo\t/g' {} \;

find arch/arm -name '*.S' -exec sed -i -e 's/mov\t\tpc, /ret\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq\t\tpc, /reteq\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne\t\tpc, /retne\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs\t\tpc, /reths\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls\t\tpc, /retls\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo\t\tpc, /retlo\t\t/g' {} \;

find arch/arm -name '*.S' -exec sed -i -e 's/mov\t\tpc,/ret\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq\t\tpc,/reteq\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne\t\tpc,/retne\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs\t\tpc,/reths\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls\t\tpc,/retls\t\t/g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo\t\tpc,/retlo\t\t/g' {} \;

find arch/arm -name '*.S' -exec sed -i -e 's/mov pc,/ret /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/moveq pc,/reteq /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movne pc,/retne /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movhs pc,/reths /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movls pc,/retls /g' {} \;
find arch/arm -name '*.S' -exec sed -i -e 's/movlo pc,/retlo /g' {} \;

git checkout -- arch/arm/mm/proc-v7-2level.S arch/arm/boot/compressed/head.S
sed -i -e 's/mov    pc, /bx    /g' arch/arm/mm/proc-v7-2level.S
sed -i -e 's/mov     pc, /bx     /g' arch/arm/mm/proc-v7-2level.S
sed -i -e 's/mov\tpc, /bx\t/g' arch/arm/mm/proc-v7-2level.S
sed -i -e 's/mov\tpc,/bx\t/g' arch/arm/mm/proc-v7-2level.S
sed -i -e 's/mov\t\tpc, /bx\t\t/g' arch/arm/mm/proc-v7-2level.S
sed -i -e 's/mov\t\tpc,/bx\t\t/g' arch/arm/mm/proc-v7-2level.S
sed -i -e 's/mov pc,/bx /g' arch/arm/mm/proc-v7-2level.S

EOF

 - Patch arch/arm/include/asm/assembler.h
 - Patch arch/arm/kernel/entry-header.S
 - Add '#include <asm/assembler.h>' to missing files.
 - Manually patch 'arch/arm/mm/proc-v7.S' to add bx (reverted from commit 5cd5ad1ec09f5740e7261b3550a6d565c1acc6a9)