[PATCH] ARM: PJ4: make coprocessor access sequences buildable in Thumb2 mode

Arnd Bergmann arnd at arndb.de
Thu Dec 17 07:34:46 PST 2015

On Thursday 17 December 2015 16:25:12 Ard Biesheuvel wrote:
> 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. Unlike Xscale, where this code
> originated, PJ4 is strictly ARMv7 so this should always be supported.
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

Looks good to me,

Acked-by: Arnd Bergmann <arnd at arndb.de>

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