Adding the aligned(1024) attribute to the definition of __rseq_abi did not increase its size to 1024, for this attribute to impact the size of __rseq_abi it would need to be added to the declaration of 'struct rseq_abi'. We only want to increase the size of the TLS allocation to ensure registration will succeed with future extended ABI. Use a union with a dummy member to ensure we allocate 1024 bytes.
Signed-off-by: Michael Jeanson mjeanson@efficios.com Reviewed-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com --- tools/testing/selftests/rseq/rseq.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c index f6156790c3b4..aa9ae866bc1a 100644 --- a/tools/testing/selftests/rseq/rseq.c +++ b/tools/testing/selftests/rseq/rseq.c @@ -71,9 +71,20 @@ static int rseq_ownership; /* Original struct rseq allocation size is 32 bytes. */ #define ORIG_RSEQ_ALLOC_SIZE 32
+/* + * Use a union to ensure we allocate a TLS area of 1024 bytes to accomodate an + * rseq registration that is larger than the current rseq ABI. + */ +union rseq { + struct rseq_abi abi; + char dummy[RSEQ_THREAD_AREA_ALLOC_SIZE]; +}; + static -__thread struct rseq_abi __rseq_abi __attribute__((tls_model("initial-exec"), aligned(RSEQ_THREAD_AREA_ALLOC_SIZE))) = { - .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED, +__thread union rseq __rseq __attribute__((tls_model("initial-exec"))) = { + .abi = { + .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED, + }, };
static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len, @@ -149,7 +160,7 @@ int rseq_register_current_thread(void) /* Treat libc's ownership as a successful registration. */ return 0; } - rc = sys_rseq(&__rseq_abi, get_rseq_min_alloc_size(), 0, RSEQ_SIG); + rc = sys_rseq(&__rseq.abi, get_rseq_min_alloc_size(), 0, RSEQ_SIG); if (rc) { /* * After at least one thread has registered successfully @@ -183,7 +194,7 @@ int rseq_unregister_current_thread(void) /* Treat libc's ownership as a successful unregistration. */ return 0; } - rc = sys_rseq(&__rseq_abi, get_rseq_min_alloc_size(), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG); + rc = sys_rseq(&__rseq.abi, get_rseq_min_alloc_size(), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG); if (rc) return -1; return 0; @@ -249,7 +260,7 @@ void rseq_init(void) rseq_ownership = 1;
/* Calculate the offset of the rseq area from the thread pointer. */ - rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer(); + rseq_offset = (void *)&__rseq.abi - rseq_thread_pointer();
/* rseq flags are deprecated, always set to 0. */ rseq_flags = 0;