From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>,
qemu-arm@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [PATCH 2/7] target/arm: Handle FPU being disabled in FPCXT_NS accesses
Date: Fri, 18 Jun 2021 08:10:56 -0700 [thread overview]
Message-ID: <b265ef2d-e963-e742-ce2a-d8df717c91d4@linaro.org> (raw)
In-Reply-To: <20210618141019.10671-3-peter.maydell@linaro.org>
On 6/18/21 7:10 AM, Peter Maydell wrote:
> If the guest makes an FPCXT_NS access when the FPU is disabled,
> one of two things happens:
> * if there is no active FP context, then the insn behaves the
> same way as if the FPU was enabled: writes ignored, reads
> same value as FPDSCR_NS
> * if there is an active FP context, then we take a NOCP
> exception
>
> Add code to the sysreg read/write functions which emits
> code to take the NOCP exception in the latter case.
>
> At the moment this will never be used, because the NOCP checks in
> m-nocp.decode happen first, and so the trans functions are never
> called when the FPU is disabled. The code will be needed when we
> move the sysreg access insns to before the NOCP patterns in the
> following commit.
>
> Cc:qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
r~
next prev parent reply other threads:[~2021-06-18 15:12 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 14:10 [PATCH 0/7] target/arm: Fix FPCXT_NS accesses when FPU disabled Peter Maydell
2021-06-18 14:10 ` [PATCH 1/7] target/arm/translate-vfp.c: Whitespace fixes Peter Maydell
2021-06-18 15:07 ` Richard Henderson
2021-06-18 14:10 ` [PATCH 2/7] target/arm: Handle FPU being disabled in FPCXT_NS accesses Peter Maydell
2021-06-18 15:10 ` Richard Henderson [this message]
2021-06-18 14:10 ` [PATCH 3/7] target/arm: Don't NOCP fault for " Peter Maydell
2021-06-18 15:29 ` Richard Henderson
2021-06-18 14:10 ` [PATCH 4/7] target/arm: Handle writeback in VLDR/VSTR sysreg with no memory access Peter Maydell
2021-06-18 16:15 ` Richard Henderson
2021-06-18 16:54 ` Peter Maydell
2021-06-18 14:10 ` [PATCH 5/7] target/arm: Factor FP context update code out into helper function Peter Maydell
2021-06-18 16:20 ` Richard Henderson
2021-06-18 14:10 ` [PATCH 6/7] target/arm: Split vfp_access_check() into A and M versions Peter Maydell
2021-06-18 16:23 ` Richard Henderson
2021-06-18 14:10 ` [PATCH 7/7] target/arm: Handle FPU check for FPCXT_NS insns via vfp_access_check_m() Peter Maydell
2021-06-18 16:25 ` Richard Henderson
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