tree b97d650f595268a33c0023bfbe407922e7c3f6b2
parent d1b6ba82a50cecf94be540a3a153aa89d97511a0
author Max Filippov <jcmvbkbc@gmail.com> 1407358981 +0400
committer Max Filippov <jcmvbkbc@gmail.com> 1408003172 +0400

xtensa: don't allow overflow/underflow on unaligned stack

Double exceptions that happen during register window overflow/underflow
are handled in the topmost stack frame, as if it was the only exception
that occured. However unaligned access exception handler is special
because it needs to analyze instruction that caused the exception, but
the userspace instruction that triggered window exception is completely
irrelevant. Unaligned data access is rather normal in the generic
userspace code, but stack pointer manipulation must always be done by
architecture-aware code and thus unaligned stack means a serious problem
anyway.
Use the default unaligned access handler that raises SIGBUS in case
of unaligned access in window overflow/underflow handler.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>