[PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+

On Tuesday 01 July 2014 09:28 PM, Russell King wrote:

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.

Signed-off-by: Russell King <redacted>

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 arch/arm/mach-davinci/sleep.S            |  2 +-

I build, boot and suspend-to-RAM tested on DA850 which should exercise
the path you modified. DaVinci devices are ARMv5 (ARM926) so the new bx
instruction does not really get used.

Acked-by: Sekhar Nori <redacted>

Thanks,
Sekhar