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Re: [Qemu-devel] [PATCH] linux-user/sparc/signal.c: Remove unnecessary c
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-devel] [PATCH] linux-user/sparc/signal.c: Remove unnecessary comment |
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Date: |
Tue, 9 Oct 2018 13:42:17 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 10/9/18 12:45 PM, Laurent Vivier wrote:
> Le 09/10/2018 à 20:40, Peter Maydell a écrit :
>> Remove a comment suggesting that we need to call tb_flush()
>> after writing the SPARC signal frame trampoline insns.
>> This isn't necessary in QEMU, because (even if the guest
>> architecture requires explicit icache maintenance) we
>> ensure that memory writes result in invalidation of
>> translated code from that memory.
>
> By curiosity, where/how is it done?
Guest pages that have had code translated from them are mprotect'd read-only.
The host SIGSEGV handler notices writes to such pages, invalidates the
translated code, and marks the page read-write again. At which point the guest
program continues.
r~