Test the correctness of the 32bit narrow reads by reading both halves
of the 64 bit field and doing a binary or on them to see if we get the
original value.
This isn't really tested - the program is not being run, because
BPF_PROG_TYPE_PERF_EVENT is not supported by bpf_test_run_prog.
Signed-off-by: Krzesimir Nowak <krzesi...@kinvolk.io>
---
tools/testing/selftests/bpf/verifier/var_off.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/tools/testing/selftests/bpf/verifier/var_off.c
b/tools/testing/selftests/bpf/verifier/var_off.c
index 8504ac937809..2668819dcc85 100644
--- a/tools/testing/selftests/bpf/verifier/var_off.c
+++ b/tools/testing/selftests/bpf/verifier/var_off.c
@@ -246,3 +246,18 @@
.result = ACCEPT,
.prog_type = BPF_PROG_TYPE_LWT_IN,
},
+{
+ "32bit loads of a 64bit field (both least and most significant words)",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1, offsetof(struct
bpf_perf_event_data, sample_period)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1, offsetof(struct
bpf_perf_event_data, sample_period) + 4),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct
bpf_perf_event_data, sample_period)),
+ BPF_ALU64_IMM(BPF_LSH, BPF_REG_4, 32),
+ BPF_ALU64_REG(BPF_OR, BPF_REG_4, BPF_REG_5),
+ BPF_ALU64_REG(BPF_XOR, BPF_REG_4, BPF_REG_6),
+ BPF_MOV64_REG(BPF_REG_0, BPF_REG_4),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
--
2.20.1
