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Re: [Qemu-arm] [PATCH 4/7] target/arm: Split M profile MNegPri mmu index

From: Richard Henderson
Subject: Re: [Qemu-arm] [PATCH 4/7] target/arm: Split M profile MNegPri mmu index into user and priv
Date: Sun, 3 Dec 2017 07:09:27 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0

On 12/01/2017 10:44 AM, Peter Maydell wrote:
> For M profile, we currently have an mmu index MNegPri for
> "requested execution priority negative". This fails to
> distinguish "requested execution priority negative, privileged"
> from "requested execution priority negative, usermode", but
> the two can return different results for MPU lookups. Fix this
> by splitting MNegPri into MNegPriPriv and MNegPriUser, and
> similarly for the Secure equivalent MSNegPri.
> This takes us from 6 M profile MMU modes to 8, which means
> we need to bump NB_MMU_MODES; this is OK since the point
> where we are forced to reduce TLB sizes is 9 MMU modes.
> (It would in theory be possible to stick with 6 MMU indexes:
> {mpu-disabled,user,privileged} x {secure,nonsecure} since
> in the MPU-disabled case the result of an MPU lookup is
> always the same for both user and privileged code. However
> we would then need to rework the TB flags handling to put
> user/priv into the TB flags separately from the mmuidx.
> Adding an extra couple of mmu indexes is simpler.)
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  target/arm/cpu.h       | 49 ++++++++++++++++++++++++++++---------------------
>  target/arm/internals.h |  6 ++++--
>  target/arm/helper.c    | 14 ++++++++++----
>  target/arm/translate.c |  8 ++++++--
>  4 files changed, 48 insertions(+), 29 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>


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