We are still seeing signals during translation time when we walk over
a page protection boundary. This expands the check to ensure the host
PC is inside the code generation buffer. The original suggestion was
to check versus tcg_ctx.code_gen_ptr but as we now segment the
translation buffer we have to settle for just a general check for
being inside.

I've also fixed up the declaration to make it clear it can deal with
invalid addresses. A later patch will fix up the call sites.
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Reported-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20171108153245.20740-2-alex.bennee@linaro.org
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Tested-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>