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

From: Peter Maydell
Subject: Re: [Qemu-devel] [PATCH] linux-user: Fix stale tbs after mmap
Date: Fri, 11 May 2012 16:46:37 +0100

On 7 May 2012 12:38, Alexander Graf <address@hidden> wrote:
> On 07.05.2012, at 13:32, Alexander Graf wrote:
>> 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 out of date or does that not apply to user-mode?
>>> 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)
>> Yeah, the issue does exist:
> And the below patch on top of my revised patch fixes it.

I think these two patches look correct (and as you pointed out
on irc I was wrong about mprotect, which effectively already
handles flushing the tb if needed). If you can roll them together
into a single patch with a commit message and signed-off-by
you can add my Reviewed-by: tag to it.

-- PMM

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