mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-12-27 14:41:22 -05:00
Code Issues Packages Projects Releases Wiki Activity

selftests/bpf: #define LOCAL_LABEL_LEN for jit_disasm_helpers.c

Browse Source 
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>
This commit is contained in:
Eduard Zingerman
2024-08-23 01:06:44 -07:00
committed by Alexei Starovoitov
parent c52a1e6eb7
commit 21a56fc503
1 changed files with 14 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
tools/testing/selftests/bpf/jit_disasm_helpers.c
View File

@@ -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;