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Message-ID: <876568572.367.1660134156963.JavaMail.zimbra@efficios.com>
Date: Wed, 10 Aug 2022 08:22:36 -0400 (EDT)
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: 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>,
Paolo Bonzini <pbonzini@...hat.com>, 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 Aug 10, 2022, at 6:41 AM, Gavin Shan gshan@...hat.com wrote:
> The rseq information is registered by TLS, starting from glibc-2.35.
> In this case, the test always fails due to syscall(__NR_rseq). For
> example, on RHEL9.1 where upstream glibc-2.35 features are enabled
> on downstream glibc-2.34, the test fails like below.
>
> # ./rseq_test
> ==== Test Assertion Failure ====
> rseq_test.c:60: !r
> pid=112043 tid=112043 errno=22 - Invalid argument
> 1 0x0000000000401973: main at rseq_test.c:226
> 2 0x0000ffff84b6c79b: ?? ??:0
> 3 0x0000ffff84b6c86b: ?? ??:0
> 4 0x0000000000401b6f: _start at ??:?
> rseq failed, errno = 22 (Invalid argument)
> # rpm -aq | grep glibc-2
> glibc-2.34-39.el9.aarch64
>
> Fix the issue by using "../rseq/rseq.c" to fetch the rseq information,
> registred by TLS if it exists. Otherwise, we're going to register our
> own rseq information as before.
>
> Reported-by: Yihuang Yu <yihyu@...hat.com>
> Suggested-by: Florian Weimer <fweimer@...hat.com>
> Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Gavin Shan <gshan@...hat.com>
> ---
> tools/testing/selftests/kvm/Makefile | 5 +++--
> tools/testing/selftests/kvm/rseq_test.c | 28 +++++++------------------
> 2 files changed, 11 insertions(+), 22 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/Makefile
> b/tools/testing/selftests/kvm/Makefile
> index c7f47429d6cd..89c9a8c52c5f 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -197,7 +197,8 @@ endif
> CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -O2 -g -std=gnu99 \
> -fno-stack-protector -fno-PIE -I$(LINUX_TOOL_INCLUDE) \
> -I$(LINUX_TOOL_ARCH_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude \
> - -I$(<D) -Iinclude/$(UNAME_M) -I.. $(EXTRA_CFLAGS) $(KHDR_INCLUDES)
> + -I$(<D) -Iinclude/$(UNAME_M) -I ../rseq -I.. $(EXTRA_CFLAGS) \
> + $(KHDR_INCLUDES)
>
> no-pie-option := $(call try-run, echo 'int main() { return 0; }' | \
> $(CC) -Werror -no-pie -x c - -o "$$TMP", -no-pie)
> @@ -206,7 +207,7 @@ no-pie-option := $(call try-run, echo 'int main() { return
> 0; }' | \
> pgste-option = $(call try-run, echo 'int main() { return 0; }' | \
> $(CC) -Werror -Wl$(comma)--s390-pgste -x c - -o "$$TMP",-Wl$(comma)--s390-pgste)
>
> -
> +LDLIBS += -ldl
> LDFLAGS += -pthread $(no-pie-option) $(pgste-option)
>
> # After inclusion, $(OUTPUT) is defined and
> diff --git a/tools/testing/selftests/kvm/rseq_test.c
> b/tools/testing/selftests/kvm/rseq_test.c
> index a54d4d05a058..2cd5fe49ac8b 100644
> --- a/tools/testing/selftests/kvm/rseq_test.c
> +++ b/tools/testing/selftests/kvm/rseq_test.c
> @@ -20,15 +20,7 @@
> #include "processor.h"
> #include "test_util.h"
>
> -static __thread volatile struct rseq __rseq = {
> - .cpu_id = RSEQ_CPU_ID_UNINITIALIZED,
> -};
> -
> -/*
> - * Use an arbitrary, bogus signature for configuring rseq, this test does not
> - * actually enter an rseq critical section.
> - */
> -#define RSEQ_SIG 0xdeadbeef
> +#include "../rseq/rseq.c"
>
> /*
> * Any bug related to task migration is likely to be timing-dependent; perform
> @@ -37,6 +29,7 @@ static __thread volatile struct rseq __rseq = {
> #define NR_TASK_MIGRATIONS 100000
>
> static pthread_t migration_thread;
> +static struct rseq_abi *__rseq;
What is this ?
> static cpu_set_t possible_mask;
> static int min_cpu, max_cpu;
> static bool done;
> @@ -49,14 +42,6 @@ static void guest_code(void)
> GUEST_SYNC(0);
> }
>
> -static void sys_rseq(int flags)
> -{
> - int r;
> -
> - r = syscall(__NR_rseq, &__rseq, sizeof(__rseq), flags, RSEQ_SIG);
> - TEST_ASSERT(!r, "rseq failed, errno = %d (%s)", errno, strerror(errno));
> -}
> -
> static int next_cpu(int cpu)
> {
> /*
> @@ -218,7 +203,10 @@ int main(int argc, char *argv[])
>
> calc_min_max_cpu();
>
> - sys_rseq(0);
> + 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 +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,
Mathieu
> smp_rmb();
> } while (snapshot != atomic_read(&seq_cnt));
>
> @@ -278,7 +266,7 @@ int main(int argc, char *argv[])
>
> kvm_vm_free(vm);
>
> - sys_rseq(RSEQ_FLAG_UNREGISTER);
> + rseq_unregister_current_thread();
>
> return 0;
> }
> --
> 2.23.0
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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