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From: | Richard Henderson |
Subject: | Re: [PATCH v3] target/riscv: reduce overhead of MSTATUS_SUM change |
Date: | Thu, 23 Mar 2023 09:41:28 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 |
On 3/23/23 06:24, Wu, Fei wrote:
There is MSTATUS_MPRV and MSTATUS_MPP kind of thing, priv+sum is not able to represent all of the status, probably we can just add an extra 'priv' at the back of TB_FLAGS?MPRV+MPP looks not necessary be in TB_FLAGS, it's just used to calculate the mmu_idx. Is it necessary to encode SUM into TB_FLAGS?
We need priv separate from midx for priv_level() and similar uses. We do not want MPRV=1, MPP=U to prevent M-mode from executing M instructions.With PRIV and MIDX in TB_FLAGS, we do not need to separately encode MPRV+MPP+SUM, because all of those are composited into MIDX.
r~
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