On Tue, Aug 20, 2024 at 3:24 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> +
> +struct local_labels {
> + bool print_phase;
> + __u32 prog_len;
> + __u32 cnt;
> + __u32 pcs[MAX_LOCAL_LABELS];
> + char names[MAX_LOCAL_LABELS][4];
> +};
> +
> +static const char *lookup_symbol(void *data, uint64_t ref_value, uint64_t *ref_type,
> + uint64_t ref_pc, const char **ref_name)
> +{
> + struct local_labels *labels = data;
> + uint64_t type = *ref_type;
> + int i;
> +
> + *ref_type = LLVMDisassembler_ReferenceType_InOut_None;
> + *ref_name = NULL;
> + if (type != LLVMDisassembler_ReferenceType_In_Branch)
> + return NULL;
> + /* Depending on labels->print_phase either discover local labels or
> + * return a name assigned with local jump target:
> + * - if print_phase is true and ref_value is in labels->pcs,
> + * return corresponding labels->name.
> + * - if print_phase is false, save program-local jump targets
> + * in labels->pcs;
> + */
> + if (labels->print_phase) {
> + for (i = 0; i < labels->cnt; ++i)
> + if (labels->pcs[i] == ref_value)
> + return labels->names[i];
> + } else {
> + if (labels->cnt < MAX_LOCAL_LABELS && ref_value < labels->prog_len)
> + labels->pcs[labels->cnt++] = ref_value;
> + }
> + return NULL;
> +}
bpftool should probably adopt similar logic
just to be consistent?
> +
> +static int disasm_insn(LLVMDisasmContextRef ctx, uint8_t *image, __u32 len, __u32 pc,
> + char *buf, __u32 buf_sz)
> +{
> + int i, cnt;
> +
> + cnt = LLVMDisasmInstruction(ctx, image + pc, len - pc, pc,
> + buf, buf_sz);
> + if (cnt > 0)
> + return cnt;
> + PRINT_FAIL("Can't disasm instruction at offset %d:", pc);
> + for (i = 0; i < 16 && pc + i < len; ++i)
> + printf(" %02x", image[pc + i]);
> + printf("\n");
> + return -EINVAL;
> +}
> +
> +static int cmp_u32(const void *_a, const void *_b)
> +{
> + __u32 a = *(__u32 *)_a;
> + __u32 b = *(__u32 *)_b;
> +
> + if (a < b)
> + return -1;
> + if (a > b)
> + return 1;
> + return 0;
> +}
> +
> +static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len)
> +{
> + char *label, *colon, *triple = NULL;
> + LLVMDisasmContextRef ctx = NULL;
> + struct local_labels labels = {};
> + __u32 *label_pc, pc;
> + int i, cnt, err = 0;
> + char buf[64];
> +
> + triple = LLVMGetDefaultTargetTriple();
> + ctx = LLVMCreateDisasm(triple, &labels, 0, NULL, lookup_symbol);
> + if (!ASSERT_OK_PTR(ctx, "LLVMCreateDisasm")) {
> + err = -EINVAL;
> + goto out;
> + }
> +
> + cnt = LLVMSetDisasmOptions(ctx, LLVMDisassembler_Option_PrintImmHex);
> + if (!ASSERT_EQ(cnt, 1, "LLVMSetDisasmOptions")) {
> + err = -EINVAL;
> + goto out;
> + }
> +
> + /* discover labels */
> + labels.prog_len = len;
> + pc = 0;
> + while (pc < len) {
> + cnt = disasm_insn(ctx, image, len, pc, buf, 1);
> + if (cnt < 0) {
> + err = cnt;
> + goto out;
> + }
> + pc += cnt;
> + }
> + 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);
100 here and names[..][4] are a bit of magic.
Pls add some #define and comments to clarify in the follow up.
Overall it looks to be a great improvement to selftests.
Applied.
Pls add necessary packages to bpf CI.
