diff options
| author | Eduard Zingerman <eddyz87@gmail.com> | 2024-08-23 01:06:44 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-08-23 07:29:03 -0700 |
| commit | 21a56fc503faae7589167fcd2771ab6dce36ab39 (patch) | |
| tree | 0288f89c2540dda329dbd0297e215e6f5dd2af25 /tools/testing/selftests/bpf/jit_disasm_helpers.c | |
| parent | c52a1e6eb74ffe4f217e9b53ed75440a45b08c4c (diff) | |
selftests/bpf: #define LOCAL_LABEL_LEN for jit_disasm_helpers.c
Extract local label length as a #define directive and
elaborate why 'i % MAX_LOCAL_LABELS' expression is needed
for local labels array initialization.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240823080644.263943-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/testing/selftests/bpf/jit_disasm_helpers.c')
| -rw-r--r-- | tools/testing/selftests/bpf/jit_disasm_helpers.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/tools/testing/selftests/bpf/jit_disasm_helpers.c b/tools/testing/selftests/bpf/jit_disasm_helpers.c index 1b0f1fd267c0..febd6b12e372 100644 --- a/tools/testing/selftests/bpf/jit_disasm_helpers.c +++ b/tools/testing/selftests/bpf/jit_disasm_helpers.c @@ -16,6 +16,11 @@ */ #define MAX_LOCAL_LABELS 32 +/* Local labels are encoded as 'L42', this requires 4 bytes of storage: + * 3 characters + zero byte + */ +#define LOCAL_LABEL_LEN 4 + static bool llvm_initialized; struct local_labels { @@ -23,7 +28,7 @@ struct local_labels { __u32 prog_len; __u32 cnt; __u32 pcs[MAX_LOCAL_LABELS]; - char names[MAX_LOCAL_LABELS][4]; + char names[MAX_LOCAL_LABELS][LOCAL_LABEL_LEN]; }; static const char *lookup_symbol(void *data, uint64_t ref_value, uint64_t *ref_type, @@ -118,8 +123,14 @@ static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len) } qsort(labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32); for (i = 0; i < labels.cnt; ++i) - /* use (i % 100) to avoid format truncation warning */ - snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % 100); + /* gcc is unable to infer upper bound for labels.cnt and assumes + * it to be U32_MAX. U32_MAX takes 10 decimal digits. + * snprintf below prints into labels.names[*], + * which has space only for two digits and a letter. + * To avoid truncation warning use (i % MAX_LOCAL_LABELS), + * which informs gcc about printed value upper bound. + */ + snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % MAX_LOCAL_LABELS); /* now print with labels */ labels.print_phase = true; |