Re: [Qemu-devel] [PATCH] linux-user: Fix stale tbs after mmap

[Alexander Graf]

On 07.05.2012, at 12:37, Peter Maydell wrote:

> On 7 May 2012 10:30, Alexander Graf <address@hidden> wrote:
>> @@ -587,6 +587,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int 
>> prot,
>>     page_dump(stdout);
>>     printf("\n");
>>  #endif
>> +    tb_invalidate_phys_page_range(start, start + len, 0);
>>     mmap_unlock();
>>     return start;
> 
> The comment at the top of tb_invalidate_phys_page_range() says
> "start and end must refer to the same physical page" -- is it
> out of date or does that not apply to user-mode?

:(

No, you're right. It only flushes the first page.

> Do you need to also invalidate the range on munmap() and
> mprotect-to-not-executable in order to correctly fault on
> the case of:
>  map something
>  execute it
>  unmap it
>  try to execute it again
> 
> ? (haven't tested that case but it seems like it might be an issue)

I'm not sure. But it's an unrelated issue either way, right? :)
Could you please try to quickly write a test case for this one while I fix the 
patch?


Alex