[RFC PATCH 2/5] selftests/rseq: Remove volatile from __rseq_abi

From: Mathieu Desnoyers
Date: Mon Jan 17 2022 - 15:40:02 EST


This is done in preparation for the selftest uplift to become compatible
with glibc-2.35.

All accesses to the __rseq_abi fields are volatile, but remove the
volatile from the TLS variable declaration, otherwise we are stuck with
volatile for the upcoming rseq_get_abi() helper.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
---
tools/testing/selftests/rseq/rseq.c | 4 ++--
tools/testing/selftests/rseq/rseq.h | 6 +++---
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 7159eb777fd3..a0d8eed24035 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -31,7 +31,7 @@

#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))

-__thread volatile struct rseq __rseq_abi = {
+__thread struct rseq __rseq_abi = {
.cpu_id = RSEQ_CPU_ID_UNINITIALIZED,
};

@@ -93,7 +93,7 @@ int rseq_register_current_thread(void)
goto end;
}
if (errno != EBUSY)
- __rseq_abi.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED;
+ RSEQ_WRITE_ONCE(__rseq_abi.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
ret = -1;
__rseq_refcount--;
end:
diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h
index 3f63eb362b92..f971a9217145 100644
--- a/tools/testing/selftests/rseq/rseq.h
+++ b/tools/testing/selftests/rseq/rseq.h
@@ -43,7 +43,7 @@
#define RSEQ_INJECT_FAILED
#endif

-extern __thread volatile struct rseq __rseq_abi;
+extern __thread struct rseq __rseq_abi;
extern int __rseq_handled;

#define rseq_likely(x) __builtin_expect(!!(x), 1)
@@ -140,9 +140,9 @@ static inline uint32_t rseq_current_cpu(void)
static inline void rseq_clear_rseq_cs(void)
{
#ifdef __LP64__
- __rseq_abi.rseq_cs.ptr = 0;
+ RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr, 0);
#else
- __rseq_abi.rseq_cs.ptr.ptr32 = 0;
+ RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr.ptr32, 0);
#endif
}

--
2.17.1