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References: <20180622135823.32421-1-peter.maydell@linaro.org>
From: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <953186cb-c73b-c2ba-f083-58864e0bec41@linaro.org>
Date: Sat, 30 Jun 2018 10:32:15 -0700
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Subject: Re: [Qemu-devel] [RFC PATCH] xtensa: Avoid calling
 get_page_addr_code() from helper function
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To: Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org
Cc: Max Filippov <jcmvbkbc@gmail.com>, Richard Henderson <rth@twiddle.net>, patches@linaro.org

On 06/22/2018 06:58 AM, Peter Maydell wrote:
> The xtensa frontend calls get_page_addr_code() from its
> itlb_hit_test helper function. This function is really part
> of the TCG core's internals, and calling it from a target
> helper makes it awkward to make changes to that core code.
> It also means that we don't pass the correct retaddr to
> tlb_fill(), so we won't correctly handle the case where
> an exception is generated.
> 
> The helper is used for the instructions IHI, IHU and IPFL.

I think the implementation of these instructions is completely wrong.

(1a) IHI is not invalidating the cacheline within env->config->itlb,
(1b) IHI is not invalidating the qemu TLB that might contain a copy
     of same.

(2a) IPFL is not locking the entry in env->config->itlb,
(2b) IHU is not unlocking the same entry.
(2c) "Xtensa ISA implementations that do not implement cache locking
     must raise an illegal instruction exception when [IPFL or IHU]
     is executed."


r~