linux-kernel - Re: [PATCH v2 1/2] KVM: selftests: Make rseq compatible with glibc-2.35

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Date:   Wed, 10 Aug 2022 14:29:02 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Gavin Shan <gshan@...hat.com>
Cc:     kvmarm <kvmarm@...ts.cs.columbia.edu>,
        KVM list <kvm@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-kselftest <linux-kselftest@...r.kernel.org>,
        Florian Weimer <fweimer@...hat.com>,
        shan gavin <shan.gavin@...il.com>, maz <maz@...nel.org>,
        andrew jones <andrew.jones@...ux.dev>,
        yihyu <yihyu@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        oliver upton <oliver.upton@...ux.dev>
Subject: Re: [PATCH v2 1/2] KVM: selftests: Make rseq compatible with
 glibc-2.35

On 8/10/22 14:22, Mathieu Desnoyers wrote:
>>
>> 	/*
>> 	 * Create and run a dummy VM that immediately exits to userspace via
>> @@ -256,7 +244,7 @@ int main(int argc, char *argv[])
>> 			 */
>> 			smp_rmb();
>> 			cpu = sched_getcpu();
>> -			rseq_cpu = READ_ONCE(__rseq.cpu_id);
>> +			rseq_cpu = READ_ONCE(__rseq->cpu_id);
> #include <rseq.h>
> 
> and use
> 
> rseq_current_cpu_raw().

Thanks, I squashed it and queued it for -rc1 (tested on both
glibc 2.34 and 2.35).

diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c
index 84e8425edc2c..987a76674f4f 100644
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -29,7 +29,6 @@
  #define NR_TASK_MIGRATIONS 100000
  
  static pthread_t migration_thread;
-static struct rseq_abi *__rseq;
  static cpu_set_t possible_mask;
  static int min_cpu, max_cpu;
  static bool done;
@@ -218,7 +217,6 @@ int main(int argc, char *argv[])
  	r = rseq_register_current_thread();
  	TEST_ASSERT(!r, "rseq_register_current_thread failed, errno = %d (%s)",
  		    errno, strerror(errno));
-	__rseq = rseq_get_abi();
  
  	/*
  	 * Create and run a dummy VM that immediately exits to userspace via
@@ -256,7 +254,7 @@ int main(int argc, char *argv[])
  			 */
  			smp_rmb();
  			cpu = sched_getcpu();
-			rseq_cpu = READ_ONCE(__rseq->cpu_id);
+			rseq_cpu = rseq_current_cpu_raw();
  			smp_rmb();
  		} while (snapshot != atomic_read(&seq_cnt));
  

Paolo