Messages in this thread | | | Date | Wed, 18 Oct 2023 10:42:01 -0500 | Subject | Re: [PATCH v2 3/3] arm64: cpufeature: Change 32-bit EL0 to display enabled cores | From | Jeremy Linton <> |
| |
On 10/18/23 07:43, Marc Zyngier wrote: > On Tue, 17 Oct 2023 20:15:43 +0100, > Jeremy Linton <jeremy.linton@arm.com> wrote: >> >> Hi, >> >> On 10/17/23 13:01, Marc Zyngier wrote: >>> On Tue, 17 Oct 2023 06:23:22 +0100, >>> Jeremy Linton <jeremy.linton@arm.com> wrote: >>>> >>>> Now that we have the ability to display the list of cores >>>> with a feature when it is selectivly enabled, lets display the >>>> cores enabled for 32-bit use at EL0. >>>> >>>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >>>> --- >>>> arch/arm64/kernel/cpufeature.c | 15 +++++++++++++-- >>>> 1 file changed, 13 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c >>>> index b7b67bac0e60..512cbe446b41 100644 >>>> --- a/arch/arm64/kernel/cpufeature.c >>>> +++ b/arch/arm64/kernel/cpufeature.c >>>> @@ -1533,8 +1533,17 @@ static bool has_32bit_el0(const struct arm64_cpu_capabilities *entry, int scope) >>>> if (!has_cpuid_feature(entry, scope)) >>>> return allow_mismatched_32bit_el0; >>>> - if (scope == SCOPE_SYSTEM) >>>> - pr_info("detected: 32-bit EL0 Support\n"); >>>> + if (scope == SCOPE_SYSTEM) { >>>> + struct arm64_cpu_capabilities *has_32bit; >>>> + >>>> + has_32bit = (struct arm64_cpu_capabilities *)entry; >>>> + >>>> + has_32bit->cpus = system_32bit_el0_cpumask(); >>> >>> This seems rather dodgy. 'entry' comes from a static const array which >>> will, in all likelihood be mapped R/O pretty soon after the initial >>> CPU bringup. Try offlining/onlining a CPU and you should see a >>> firework similar to what I have below (I hacked the CnP property, but >>> that's no different from what you are doing): >> >> Yes, dodgy is a good word. The other choices, maintain a mask just for >> the print or dump the static key and always use the cpu_32bit_el0_mask >> or some combination, weren't much better in the "ick" category. If >> anyone sees a better way I'm open to suggestion, although simply >> dropping this last patch is fine too. > > An obvious choice would be to replace the 'cpus' cpumask with a > function that evaluates a cpumask stored separately.
Right, I was too busy trying to cleanup the 32-bit mask, that works too.
| |