Merge pull request iovisor#1529 from iovisor/yhs_dev

usdt: ignore location with incorrect probe virtual address

src/cc/bcc_elf.c

@@ -85,7 +85,7 @@ static const char *parse_stapsdt_note(struct bcc_elf_usdt *probe,
 
 static int do_note_segment(Elf_Scn *section, int elf_class,
  bcc_elf_probecb callback, const char *binpath,
- void *payload) {
+ uint64_t first_inst_offset, void *payload) {
  Elf_Data *data = NULL;
 
  while ((data = elf_getdata(section, data)) != 0) {
@@ -110,8 +110,14 @@ static int do_note_segment(Elf_Scn *section, int elf_class,
  desc = (const char *)data->d_buf + desc_off;
  desc_end = desc + hdr.n_descsz;
 
- if (parse_stapsdt_note(&probe, desc, elf_class) == desc_end)
- callback(binpath, &probe, payload);
+ if (parse_stapsdt_note(&probe, desc, elf_class) == desc_end) {
+ if (probe.pc < first_inst_offset)
+ fprintf(stderr,
+ "WARNING: invalid address 0x%lx for probe (%s,%s) in binary %s\n",
+ probe.pc, probe.provider, probe.name, binpath);
+ else
+ callback(binpath, &probe, payload);
+ }
  }
  }
  return 0;
@@ -122,10 +128,26 @@ static int listprobes(Elf *e, bcc_elf_probecb callback, const char *binpath,
  Elf_Scn *section = NULL;
  size_t stridx;
  int elf_class = gelf_getclass(e);
+ uint64_t first_inst_offset = 0;
 
  if (elf_getshdrstrndx(e, &stridx) != 0)
  return -1;
 
+ // Get the offset to the first instruction
+ while ((section = elf_nextscn(e, section)) != 0) {
+ GElf_Shdr header;
+
+ if (!gelf_getshdr(section, &header))
+ continue;
+
+ // The elf file section layout is based on increasing virtual address,
+ // getting the first section with SHF_EXECINSTR is enough.
+ if (header.sh_flags & SHF_EXECINSTR) {
+ first_inst_offset = header.sh_addr;
+ break;
+ }
+ }
+
  while ((section = elf_nextscn(e, section)) != 0) {
  GElf_Shdr header;
  char *name;
@@ -138,7 +160,8 @@ static int listprobes(Elf *e, bcc_elf_probecb callback, const char *binpath,
 
  name = elf_strptr(e, stridx, header.sh_name);
  if (name && !strcmp(name, ".note.stapsdt")) {
- if (do_note_segment(section, elf_class, callback, binpath, payload) < 0)
+ if (do_note_segment(section, elf_class, callback, binpath,
+ first_inst_offset, payload) < 0)
  return -1;
  }
  }