From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PULL 04/11] target/arm/cpu64: max cpu: Introduce sve<N> properties
Date: Wed, 13 Nov 2019 21:17:49 +0100 [thread overview]
Message-ID: <ac0c7520-2f6b-fb49-c725-37b46272c835@linaro.org> (raw)
In-Reply-To: <CAFEAcA-xYWLzsfDAWWmEk4DhXcO5zqKVZMrRp9=4t9MBAasaMA@mail.gmail.com>
On 11/12/19 11:23 AM, Peter Maydell wrote:
>> +static uint32_t sve_zcr_get_valid_len(ARMCPU *cpu, uint32_t start_len)
>> +{
>> + uint32_t start_vq = (start_len & 0xf) + 1;
>> +
>> + return arm_cpu_vq_map_next_smaller(cpu, start_vq + 1) - 1;
>
> "Subtract operation overflows on operands
> arm_cpu_vq_map_next_smaller(cpu, start_vq + 1U) and 1U"
>
> Certainly it looks as if arm_cpu_vq_map_next_smaller() can
> return 0, and claiming the valid length to be UINT_MAX
> seems a bit odd in that case.
The lsb is always set in the map, the minimum number we send to next_smaller is
2 -> so the minimum number returned from next_smaller is 1.
We should never return UINT_MAX.
> return bitnum == vq - 1 ? 0 : bitnum + 1;
But yes, this computation doesn't seem right.
The beginning assert should probably be (vq >= 2 ...)
and here we should assert bitnum != vq - 1.
r~
next prev parent reply other threads:[~2019-11-13 20:19 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-01 8:51 [PULL 00/11] target-arm queue Peter Maydell
2019-11-01 8:51 ` [PULL 01/11] target/arm/monitor: Introduce qmp_query_cpu_model_expansion Peter Maydell
2019-11-01 8:51 ` [PULL 02/11] tests: arm: Introduce cpu feature tests Peter Maydell
2019-11-01 8:51 ` [PULL 03/11] target/arm: Allow SVE to be disabled via a CPU property Peter Maydell
2019-11-01 8:51 ` [PULL 04/11] target/arm/cpu64: max cpu: Introduce sve<N> properties Peter Maydell
2019-11-12 10:23 ` Peter Maydell
2019-11-13 20:17 ` Richard Henderson [this message]
2019-11-13 21:30 ` Peter Maydell
2019-11-15 8:29 ` Richard Henderson
2019-11-01 8:51 ` [PULL 05/11] target/arm/kvm64: Add kvm_arch_get/put_sve Peter Maydell
2019-11-01 8:51 ` [PULL 06/11] target/arm/kvm64: max cpu: Enable SVE when available Peter Maydell
2019-11-01 8:51 ` [PULL 07/11] target/arm/kvm: scratch vcpu: Preserve input kvm_vcpu_init features Peter Maydell
2019-11-01 8:51 ` [PULL 08/11] target/arm/cpu64: max cpu: Support sve properties with KVM Peter Maydell
2019-11-01 8:51 ` [PULL 09/11] target/arm/kvm: host cpu: Add support for sve<N> properties Peter Maydell
2022-02-03 16:46 ` Peter Maydell
2022-02-03 17:36 ` Andrew Jones
2022-02-03 17:40 ` Peter Maydell
2022-02-04 11:26 ` Andrew Jones
2019-11-01 8:51 ` [PULL 10/11] hw/arm/boot: Rebuild hflags when modifying CPUState at boot Peter Maydell
2019-11-01 8:51 ` [PULL 11/11] target/arm: Allow reading flags from FPSCR for M-profile Peter Maydell
2019-11-01 9:30 ` [PULL 00/11] target-arm queue Peter Maydell
2019-11-01 9:54 ` Andrew Jones
2019-11-01 10:34 ` Peter Maydell
2019-11-01 12:53 ` Peter Maydell
2019-11-01 14:25 ` Andrew Jones
2019-11-02 17:57 ` Peter Maydell
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