sh: support 1 and 2 byte xchg

This completes the xchg implementation for sh architecture.  Note: The
llsc variant is tricky since this only supports 4 byte atomics, the
existing implementation of 1 byte xchg is wrong: we need to do a 4 byte
cmpxchg and retry if any bytes changed meanwhile.

Write this in C for clarity.

Suggested-by: Rich Felker <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>

0 files changed, 0 insertions, 0 deletions