tree 728eb22528c2db224e9aec379df4fabec18dfd6a
parent 36f46d6d5cdef2308027261d633e96807d64d098
author Ard Biesheuvel <ard.biesheuvel@linaro.org> 1450769099 +0100
committer Russell King <rmk+kernel@arm.linux.org.uk> 1451905930 +0000

ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode

The PJ4 inline asm sequence to write to cp15 cannot be built in Thumb-2
mode, due to the way it performs arithmetic on the program counter, so it
is built in ARM mode instead. However, building C files in ARM mode under
CONFIG_THUMB2_KERNEL is problematic, since the instrumentation performed
by subsystems like ftrace does not expect having to deal with interworking
branches.

Since the sequence in question is simply a poor man's ISB instruction,
let's use a straight 'isb' instead when building in Thumb2 mode. Thumb2
implies V7, so 'isb' should always be supported in that case.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>