From d16f315faaffbff7a495f26859ce6c200d7667fa Mon Sep 17 00:00:00 2001 From: Hemant Kumar Date: Mon, 20 Apr 2015 15:59:22 +0530 Subject: [PATCH] systemtap/tapsets.cxx: Fix dwarfless probes on multiple static functions With multiple static functions with same names in an ELF and in absence of dwarf, if we probe on one of the functions, then systemtap places probe only on one static function ignoring the rest. This is because the mapping between the symbol names and their func_info is a simple map which doesn't allow insertion of another symbol with the same name. This patch fixes this issue by changing this map to a multimap which allows duplicate entries for the same symbol name. lookup_symbol code will return a set of func_info * instead of a single descriptor for a function name. We also need to fix other areas in the code where lookup_symbol() and lookup_symbol_address() are being called so as to look for a set of func_info's and a list of Dwarf_Addr's respectively, instead of a single descriptor. Signed-off-by: Hemant Kumar --- tapsets.cxx | 92 +++++++++++++++++++++++++++++++++-------------------- 1 file changed, 58 insertions(+), 34 deletions(-) diff --git a/tapsets.cxx b/tapsets.cxx index 771f081fc..639ac1217 100644 --- a/tapsets.cxx +++ b/tapsets.cxx @@ -395,7 +395,7 @@ struct symbol_table { module_info *mod_info; // associated module - map map_by_name; + multimap map_by_name; multimap map_by_addr; map globals; map locals; @@ -410,8 +410,8 @@ symbol_table void prepare_section_rejection(Dwfl_Module *mod); bool reject_section(GElf_Word section); void purge_syscall_stubs(); - func_info *lookup_symbol(const string& name); - Dwarf_Addr lookup_symbol_address(const string& name); + set *lookup_symbol(const string& name); + list *lookup_symbol_address(const string& name); func_info *get_func_containing_address(Dwarf_Addr addr); func_info *get_first_func(); @@ -1113,9 +1113,15 @@ dwarf_query::query_module_symtab() } else { - fi = sym_table->lookup_symbol(function_str_val); - if (fi && !fi->descriptor && null_die(&fi->die)) - query_symtab_func_info(*fi, this); + set *fis = sym_table->lookup_symbol(function_str_val); + if (!fis || fis->empty()) + return; + for (set::iterator it=fis->begin(); it!=fis->end(); ++it) + { + fi = *it; + if (fi && !fi->descriptor && null_die(&fi->die)) + query_symtab_func_info(*fi, this); + } } } } @@ -7484,8 +7490,8 @@ suggest_dwarf_functions(systemtap_session& sess, // add all function symbols in cache if (module->symtab_status != info_present || module->sym_table == NULL) continue; - map& modfuncs = module->sym_table->map_by_name; - for (map::const_iterator itfuncs = modfuncs.begin(); + multimap& modfuncs = module->sym_table->map_by_name; + for (multimap::const_iterator itfuncs = modfuncs.begin(); itfuncs != modfuncs.end(); ++itfuncs) funcs.insert(itfuncs->first); } @@ -8072,9 +8078,8 @@ symbol_table::add_symbol(const char *name, bool weak, bool descriptor, fi->name = name; fi->weak = weak; fi->descriptor = descriptor; - map_by_name[fi->name] = fi; - // TODO: Use a multimap in case there are multiple static - // functions with the same name? + + map_by_name.insert(make_pair(fi->name, fi)); map_by_addr.insert(make_pair(addr, fi)); } @@ -8194,22 +8199,32 @@ symbol_table::get_first_func() return (iter)->second; } -func_info * +set * symbol_table::lookup_symbol(const string& name) { - map::iterator i = map_by_name.find(name); - if (i == map_by_name.end()) - return NULL; - return i->second; + set *fis = new set; + pair ::iterator, multimap::iterator> ret; + ret = map_by_name.equal_range(name); + + for (multimap::iterator it = ret.first; it != ret.second; ++it) + fis->insert(it->second); + + return fis; } -Dwarf_Addr +list * symbol_table::lookup_symbol_address(const string& name) { - func_info *fi = lookup_symbol(name); - if (fi) - return fi->addr; - return 0; + list *addrs = new list; + set *fis = lookup_symbol(name); + + if (!fis || fis->empty()) + return NULL; + + for (set::iterator it=fis->begin(); it!=fis->end(); ++it) + addrs->push_back((*it)->addr); + + return addrs; } // This is the kernel symbol table. The kernel macro cond_syscall creates @@ -8223,9 +8238,14 @@ symbol_table::lookup_symbol_address(const string& name) void symbol_table::purge_syscall_stubs() { - Dwarf_Addr stub_addr = lookup_symbol_address("sys_ni_syscall"); - if (stub_addr == 0) + list *addrs = lookup_symbol_address("sys_ni_syscall"); + if (!addrs || addrs->empty()) return; + /* Highly unlikely that multiple symbols named "sys_ni_syscall" may exist */ + if (addrs->size() > 1) + cerr << _("Multiple 'sys_ni_syscall' symbols found."); + Dwarf_Addr stub_addr = addrs->front(); + range_t purge_range = map_by_addr.equal_range(stub_addr); for (iterator_t iter = purge_range.first; iter != purge_range.second; @@ -8299,21 +8319,25 @@ module_info::update_symtab(cu_function_cache_t *funcs) // missing, so we may also need to try matching by address. See also the // notes about _Z in dwflpp::iterate_over_functions(). - func_info *fi = sym_table->lookup_symbol(func->first); - if (!fi) + set *fis = sym_table->lookup_symbol(func->first); + if (!fis || fis->empty()) continue; - // iterate over all functions at the same address - symbol_table::range_t er = sym_table->map_by_addr.equal_range(fi->addr); - for (symbol_table::iterator_t it = er.first; it != er.second; ++it) + for (set::iterator fi = fis->begin(); fi!=fis->end(); ++fi) { - // update this function with the dwarf die - it->second->die = func->second; + // iterate over all functions at the same address + symbol_table::range_t er = sym_table->map_by_addr.equal_range((*fi)->addr); + + for (symbol_table::iterator_t it = er.first; it != er.second; ++it) + { + // update this function with the dwarf die + it->second->die = func->second; - // if this function is a new alias, then - // save it to merge into the function cache - if (it->second != fi) - new_funcs.insert(make_pair(it->second->name, it->second->die)); + // if this function is a new alias, then + // save it to merge into the function cache + if (it->second != *fi) + new_funcs.insert(make_pair(it->second->name, it->second->die)); + } } } -- 2.43.5