From: Sean Christopherson <seanjc@google.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Florian Weimer <fweimer@redhat.com>,
shan gavin <shan.gavin@gmail.com>, KVM list <kvm@vger.kernel.org>,
maz <maz@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>,
andrew jones <andrew.jones@linux.dev>,
yihyu@redhat.com,
linux-kselftest <linux-kselftest@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>, shuah <shuah@kernel.org>,
kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 1/2] KVM: selftests: Make rseq compatible with glibc-2.35
Date: Tue, 9 Aug 2022 21:38:29 +0000 [thread overview]
Message-ID: <YvLT1fd8ddybF5Uw@google.com> (raw)
In-Reply-To: <1014177394.115022.1660052656961.JavaMail.zimbra@efficios.com>
On Tue, Aug 09, 2022, Mathieu Desnoyers wrote:
> ----- On Aug 9, 2022, at 8:21 AM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
>
> > ----- Gavin Shan <gshan@redhat.com> wrote:
> >> Hi Florian,
> >>
> >> On 8/9/22 5:16 PM, Florian Weimer wrote:
> >> >>> __builtin_thread_pointer doesn't work on all architectures/GCC
> >> >>> versions.
> >> >>> Is this a problem for selftests?
> >> >>>
> >> >>
> >> >> It's a problem as the test case is running on all architectures. I think I
> >> >> need introduce our own __builtin_thread_pointer() for where it's not
> >> >> supported: (1) PowerPC (2) x86 without GCC 11
> >> >>
> >> >> Please let me know if I still have missed cases where
> >> >> __buitin_thread_pointer() isn't supported?
> >> >
> >> > As far as I know, these are the two outliers that also have rseq
> >> > support. The list is a bit longer if we also consider non-rseq
> >> > architectures (csky, hppa, ia64, m68k, microblaze, sparc, don't know
> >> > about the Linux architectures without glibc support).
> >> >
> >>
> >> For kvm/selftests, there are 3 architectures involved actually. So we
> >> just need consider 4 cases: aarch64, x86, s390 and other. For other
> >> case, we just use __builtin_thread_pointer() to maintain code's
> >> integrity, but it's not called at all.
> >>
> >> I think kvm/selftest is always relying on glibc if I'm correct.
> >
> > All those are handled in the rseq selftests and in librseq. Why duplicate all
> > that logic again?
>
> More to the point, considering that we have all the relevant rseq registration
> code in tools/testing/selftests/rseq/rseq.c already, and the relevant thread
> pointer getter code in tools/testing/selftests/rseq/rseq-*thread-pointer.h,
> is there an easy way to get test applications in tools/testing/selftests/kvm
> and in tools/testing/selftests/rseq to share that common code ?
>
> Keeping duplicated compatibility code is bad for long-term maintainability.
Any reason not to simply add tools/lib/rseq.c and then expose a helper to get the
registered rseq struct?
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next prev parent reply other threads:[~2022-08-09 21:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-09 6:06 [PATCH 0/2] kvm/selftests: Two rseq_test fixes Gavin Shan
2022-08-09 6:06 ` [PATCH 1/2] KVM: selftests: Make rseq compatible with glibc-2.35 Gavin Shan
2022-08-09 6:33 ` Florian Weimer
2022-08-09 8:45 ` Gavin Shan
2022-08-09 7:16 ` Florian Weimer
2022-08-09 9:27 ` Gavin Shan
2022-08-09 12:21 ` Mathieu Desnoyers
2022-08-09 13:44 ` Mathieu Desnoyers
2022-08-09 21:38 ` Sean Christopherson [this message]
2022-08-10 0:37 ` Gavin Shan
2022-08-10 12:29 ` Mathieu Desnoyers
2022-08-10 12:35 ` Paolo Bonzini
2022-08-10 12:13 ` Mathieu Desnoyers
2022-08-10 23:52 ` Gavin Shan
2022-08-10 9:14 ` Paolo Bonzini
2022-08-10 9:59 ` Gavin Shan
2022-08-10 12:17 ` Mathieu Desnoyers
2022-08-10 12:19 ` Paolo Bonzini
2022-08-10 23:34 ` Gavin Shan
2022-08-09 6:06 ` [PATCH 2/2] KVM: selftests: Use getcpu() instead of sched_getcpu() in rseq_test Gavin Shan
2022-08-09 6:35 ` Florian Weimer
2022-08-09 7:17 ` Florian Weimer
2022-08-09 8:46 ` Gavin Shan
2022-08-09 20:53 ` Sean Christopherson
2022-08-10 0:45 ` Gavin Shan
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