Comment 4 for bug 1735384

Thomas Huth <email address hidden> writes:

> On 01.12.2017 00:25, John Paul Adrian Glaubitz wrote:
>> The offending commit is:
>>
>> d25f2a72272b9ffe0d06710d6217d1169bc2cc7d is the first bad commit
>> commit d25f2a72272b9ffe0d06710d6217d1169bc2cc7d
>> Author: Alex Bennée <email address hidden>
>> Date: Mon Nov 13 13:55:27 2017 +0000
>>
>> accel/tcg/translate-all: expand cpu_restore_state addr check
>>
>> 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: Alex Bennée <email address hidden>
>> Reported-by: Peter Maydell <email address hidden>
>> Reviewed-by: Laurent Vivier <email address hidden>
>> Reviewed-by: Richard Henderson <email address hidden>
>> Message-id: <email address hidden>
>> Suggested-by: Paolo Bonzini <email address hidden>
>> Cc: Richard Henderson <email address hidden>
>> Tested-by: Peter Maydell <email address hidden>
>> Signed-off-by: Peter Maydell <email address hidden>
>>
>> :040000 040000 da50c4c43089d3ee7d1e9ad50d3c9036114e5f11 cd6a0dcaa1d284fe5439f6f3b61547d4b0662768 M accel
>> :040000 040000 c294a7c102d27295f8d81cc06b5d4d17357440ad 5a1268b7634f69f0806f22161ec7d6a1a26c8812 M include
>>
>> Reverting the commit resolves the issue.
>>
>
> Alex, any ideas what might be wrong here?

It's hard to imagine a scenario where taking the tb_lock() for resolving
something that will fail is going to be an improvement. However maybe
there is a subtle difference with sh4's javavm implementation.

A backtrace QEMU after the segv would be useful here.

--
Alex Bennée