Tero Kristo wrote:
Add selftest for bpf_rdtsc() which reads the TSC (Time Stamp Counter) on x86_64 architectures. The test reads the TSC from both userspace and the BPF program, and verifies the TSC values are in incremental order as expected. The test is automatically skipped on architectures that do not support the feature.
Signed-off-by: Tero Kristo tero.kristo@linux.intel.com
.../selftests/bpf/prog_tests/test_rdtsc.c | 67 +++++++++++++++++++ .../testing/selftests/bpf/progs/test_rdtsc.c | 21 ++++++ 2 files changed, 88 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/test_rdtsc.c create mode 100644 tools/testing/selftests/bpf/progs/test_rdtsc.c
diff --git a/tools/testing/selftests/bpf/prog_tests/test_rdtsc.c b/tools/testing/selftests/bpf/prog_tests/test_rdtsc.c new file mode 100644 index 000000000000..2b26deb5b35a --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_rdtsc.c @@ -0,0 +1,67 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright(c) 2023 Intel Corporation */
+#include "test_progs.h" +#include "test_rdtsc.skel.h"
+#ifdef __x86_64__
+static inline u64 _rdtsc(void) +{
- u32 low, high;
- __asm__ __volatile__("rdtscp" : "=a" (low), "=d" (high));
I think its ok but note this could fail if user doesn't have access to rdtscp and iirc that can be restricted?
- return ((u64)high << 32) | low;
+}