Correct ldrexd and strexd code to always read and write the
high word of the 64-bit value from addr+4.
Also make ldrexd and strexd agree that for a 64 bit value the
address in env->exclusive_addr is that of the low word.
This fixes the issues reported in
https://bugs.launchpad.net/qemu/+bug/670883
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Nathan Froyd <froydnj@codesourcery.com>
2c9adbda72