Merge pull request iovisor#1022 from goldshtn/syms-multiple-regions

Symbol resolution with multiple executable regions per module

src/cc/bcc_syms.cc

@@ -101,7 +101,11 @@ void ProcSyms::refresh() {
 int ProcSyms::_add_module(const char *modname, uint64_t start, uint64_t end,
  void *payload) {
  ProcSyms *ps = static_cast<ProcSyms *>(payload);
- ps->modules_.emplace_back(modname, start, end);
+ auto it = std::find_if(ps->modules_.begin(), ps->modules_.end(),
+ [=](const ProcSyms::Module &m) { return m.name_ == modname; });
+ if (it == ps->modules_.end())
+ it = ps->modules_.insert(ps->modules_.end(), modname);
+ it->ranges_.push_back(ProcSyms::Module::Range(start, end));
  return 0;
 }
 
@@ -116,7 +120,7 @@ bool ProcSyms::resolve_addr(uint64_t addr, struct bcc_symbol *sym) {
 
  const char *original_module = nullptr;
  for (Module &mod : modules_) {
- if (addr >= mod.start_ && addr < mod.end_) {
+ if (mod.contains(addr)) {
  bool res = mod.find_addr(addr, sym);
  if (sym->name) {
  sym->demangle_name = abi::__cxa_demangle(sym->name, nullptr, nullptr, nullptr);
@@ -155,8 +159,8 @@ bool ProcSyms::resolve_name(const char *module, const char *name,
  return false;
 }
 
-ProcSyms::Module::Module(const char *name, uint64_t start, uint64_t end)
- : name_(name), start_(start), end_(end) {
+ProcSyms::Module::Module(const char *name)
+ : name_(name) {
  is_so_ = bcc_elf_is_shared_obj(name) == 1;
 }
 
@@ -184,20 +188,28 @@ void ProcSyms::Module::load_sym_table() {
  std::sort(syms_.begin(), syms_.end());
 }
 
+bool ProcSyms::Module::contains(uint64_t addr) const {
+ for (const auto &range : ranges_) {
+ if (addr >= range.start && addr < range.end)
+ return true;
+ }
+ return false;
+}
+
 bool ProcSyms::Module::find_name(const char *symname, uint64_t *addr) {
  load_sym_table();
 
  for (Symbol &s : syms_) {
  if (*(s.name) == symname) {
- *addr = is_so() ? start_ + s.start : s.start;
+ *addr = is_so() ? start() + s.start : s.start;
  return true;
  }
  }
  return false;
 }
 
 bool ProcSyms::Module::find_addr(uint64_t addr, struct bcc_symbol *sym) {
- uint64_t offset = is_so() ? (addr - start_) : addr;
+ uint64_t offset = is_so() ? (addr - start()) : addr;
 
  load_sym_table();
 
@@ -230,6 +242,9 @@ bool ProcSyms::Module::find_addr(uint64_t addr, struct bcc_symbol *sym) {
  sym->offset = (offset - it->start);
  return true;
  }
+ // But don't step beyond begin()!
+ if (it == syms_.begin())
+ break;
  }
 
  return false;

src/cc/syms.h

@@ -79,15 +79,22 @@ class ProcSyms : SymbolCache {
  };
 
  struct Module {
- Module(const char *name, uint64_t start, uint64_t end);
+ struct Range {
+ uint64_t start;
+ uint64_t end;
+ Range(uint64_t s, uint64_t e) : start(s), end(e) {}
+ };
+
+ Module(const char *name);
  std::string name_;
- uint64_t start_;
- uint64_t end_;
+ std::vector<Range> ranges_;
  bool is_so_;
  std::unordered_set<std::string> symnames_;
  std::vector<Symbol> syms_;
 
  void load_sym_table();
+ bool contains(uint64_t addr) const;
+ uint64_t start() const { return ranges_.begin()->start; }
  bool find_addr(uint64_t addr, struct bcc_symbol *sym);
  bool find_name(const char *symname, uint64_t *addr);
  bool is_so() const { return is_so_; }

src/cc/usdt.cc

@@ -63,7 +63,7 @@ bool Probe::resolve_global_address(uint64_t *global, const uint64_t addr) {
 }
 
 bool Probe::add_to_semaphore(int16_t val) {
- assert(pid_ && attached_semaphore_);
+ assert(pid_);
 
  if (!attached_semaphore_) {
  uint64_t addr;