diff options
Diffstat (limited to 'linker/linker.cpp')
| -rw-r--r-- | linker/linker.cpp | 252 |
1 files changed, 132 insertions, 120 deletions
diff --git a/linker/linker.cpp b/linker/linker.cpp index abfd00f09..4ad44faa0 100644 --- a/linker/linker.cpp +++ b/linker/linker.cpp @@ -328,9 +328,7 @@ static void soinfo_free(soinfo* si) { TRACE("name %s: freeing soinfo @ %p", si->get_realpath(), si); if (!solist_remove_soinfo(si)) { - // TODO (dimitry): revisit this - for now preserving the logic - // but it does not look right, abort if soinfo is not in the list instead? - return; + async_safe_fatal("soinfo=%p is not in soinfo_list (double unload?)", si); } // clear links to/from si @@ -718,13 +716,11 @@ enum walk_action_result_t : uint32_t { // walk_dependencies_tree returns false if walk was terminated // by the action and true otherwise. template<typename F> -static bool walk_dependencies_tree(soinfo* root_soinfos[], size_t root_soinfos_size, F action) { +static bool walk_dependencies_tree(soinfo* root_soinfo, F action) { SoinfoLinkedList visit_list; SoinfoLinkedList visited; - for (size_t i = 0; i < root_soinfos_size; ++i) { - visit_list.push_back(root_soinfos[i]); - } + visit_list.push_back(root_soinfo); soinfo* si; while ((si = visit_list.pop_front()) != nullptr) { @@ -760,7 +756,7 @@ static const ElfW(Sym)* dlsym_handle_lookup(android_namespace_t* ns, const ElfW(Sym)* result = nullptr; bool skip_lookup = skip_until != nullptr; - walk_dependencies_tree(&root, 1, [&](soinfo* current_soinfo) { + walk_dependencies_tree(root, [&](soinfo* current_soinfo) { if (skip_lookup) { skip_lookup = current_soinfo != skip_until; return kWalkContinue; @@ -1478,7 +1474,6 @@ static bool find_library_internal(android_namespace_t* ns, if (load_library(linked_namespace.linked_namespace(), task, zip_archive_cache, load_tasks, rtld_flags, false)) { return true; } - // lib was not found in the namespace. Try next linked namespace. } else { // lib is already loaded return true; @@ -1491,7 +1486,6 @@ static bool find_library_internal(android_namespace_t* ns, } static void soinfo_unload(soinfo* si); -static void soinfo_unload(soinfo* soinfos[], size_t count); static void shuffle(std::vector<LoadTask*>* v) { for (size_t i = 0, size = v->size(); i < size; ++i) { @@ -1516,9 +1510,9 @@ bool find_libraries(android_namespace_t* ns, const android_dlextinfo* extinfo, bool add_as_children, bool search_linked_namespaces, - std::unordered_map<const soinfo*, ElfReader>& readers_map, std::vector<android_namespace_t*>* namespaces) { // Step 0: prepare. + std::unordered_map<const soinfo*, ElfReader> readers_map; LoadTaskList load_tasks; for (size_t i = 0; i < library_names_count; ++i) { @@ -1548,11 +1542,6 @@ bool find_libraries(android_namespace_t* ns, } }); - auto failure_guard = android::base::make_scope_guard([&]() { - // Housekeeping - soinfo_unload(soinfos, soinfos_count); - }); - ZipArchiveCache zip_archive_cache; // Step 1: expand the list of load_tasks to include @@ -1565,7 +1554,6 @@ bool find_libraries(android_namespace_t* ns, task->set_extinfo(is_dt_needed ? nullptr : extinfo); task->set_dt_needed(is_dt_needed); - // try to find the load. // Note: start from the namespace that is stored in the LoadTask. This namespace // is different from the current namespace when the LoadTask is for a transitive // dependency and the lib that created the LoadTask is not found in the @@ -1583,10 +1571,6 @@ bool find_libraries(android_namespace_t* ns, if (is_dt_needed) { needed_by->add_child(si); - - if (si->is_linked()) { - si->increment_ref_count(); - } } // When ld_preloads is not null, the first @@ -1662,77 +1646,116 @@ bool find_libraries(android_namespace_t* ns, } } - // Step 5: link libraries that are not destined to this namespace. - // Do this by recursively calling find_libraries on the namespace where the lib - // was found during Step 1. + // Step 5: Collect roots of local_groups. + // Whenever needed_by->si link crosses a namespace boundary it forms its own local_group. + // Here we collect new roots to link them separately later on. Note that we need to avoid + // collecting duplicates. Also the order is important. They need to be linked in the same + // BFS order we link individual libraries. + std::vector<soinfo*> local_group_roots; + if (start_with != nullptr && add_as_children) { + local_group_roots.push_back(start_with); + } else { + CHECK(soinfos_count == 1); + local_group_roots.push_back(soinfos[0]); + } + for (auto&& task : load_tasks) { soinfo* si = task->get_soinfo(); - if (si->get_primary_namespace() != ns) { - const char* name = task->get_name(); - if (find_libraries(si->get_primary_namespace(), task->get_needed_by(), &name, 1, - nullptr /* soinfos */, nullptr /* ld_preloads */, 0 /* ld_preload_count */, - rtld_flags, nullptr /* extinfo */, false /* add_as_children */, - false /* search_linked_namespaces */, readers_map, namespaces)) { - // If this lib is directly needed by one of the libs in this namespace, - // then increment the count - soinfo* needed_by = task->get_needed_by(); - if (needed_by != nullptr && needed_by->get_primary_namespace() == ns && si->is_linked()) { - si->increment_ref_count(); - } - } else { - return false; + soinfo* needed_by = task->get_needed_by(); + bool is_dt_needed = needed_by != nullptr && (needed_by != start_with || add_as_children); + android_namespace_t* needed_by_ns = + is_dt_needed ? needed_by->get_primary_namespace() : ns; + + if (!si->is_linked() && si->get_primary_namespace() != needed_by_ns) { + auto it = std::find(local_group_roots.begin(), local_group_roots.end(), si); + LD_LOG(kLogDlopen, + "Crossing namespace boundary (si=%s@%p, si_ns=%s@%p, needed_by=%s@%p, ns=%s@%p, needed_by_ns=%s@%p) adding to local_group_roots: %s", + si->get_realpath(), + si, + si->get_primary_namespace()->get_name(), + si->get_primary_namespace(), + needed_by == nullptr ? "(nullptr)" : needed_by->get_realpath(), + needed_by, + ns->get_name(), + ns, + needed_by_ns->get_name(), + needed_by_ns, + it == local_group_roots.end() ? "yes" : "no"); + + if (it == local_group_roots.end()) { + local_group_roots.push_back(si); } } } - // Step 6: link libraries in this namespace - soinfo_list_t local_group; - walk_dependencies_tree( - (start_with != nullptr && add_as_children) ? &start_with : soinfos, - (start_with != nullptr && add_as_children) ? 1 : soinfos_count, + // Step 6: Link all local groups + for (auto root : local_group_roots) { + soinfo_list_t local_group; + android_namespace_t* local_group_ns = root->get_primary_namespace(); + + walk_dependencies_tree(root, [&] (soinfo* si) { - if (ns->is_accessible(si)) { - local_group.push_back(si); - return kWalkContinue; - } else { - return kWalkSkip; - } - }); + if (local_group_ns->is_accessible(si)) { + local_group.push_back(si); + return kWalkContinue; + } else { + return kWalkSkip; + } + }); - soinfo_list_t global_group = ns->get_global_group(); - bool linked = local_group.visit([&](soinfo* si) { - if (!si->is_linked()) { - if (!si->link_image(global_group, local_group, extinfo) || - !get_cfi_shadow()->AfterLoad(si, solist_get_head())) { - return false; + soinfo_list_t global_group = local_group_ns->get_global_group(); + bool linked = local_group.visit([&](soinfo* si) { + // Even though local group may contain accessible soinfos from other namesapces + // we should avoid linking them (because if they are not linked -> they + // are in the local_group_roots and will be linked later). + if (!si->is_linked() && si->get_primary_namespace() == local_group_ns) { + if (!si->link_image(global_group, local_group, extinfo) || + !get_cfi_shadow()->AfterLoad(si, solist_get_head())) { + return false; + } } + + return true; + }); + + if (!linked) { + return false; } + } - return true; - }); + // Step 7: Mark all load_tasks as linked and increment refcounts + // for references between load_groups (at this point it does not matter if + // referenced load_groups were loaded by previous dlopen or as part of this + // one on step 6) + if (start_with != nullptr && add_as_children) { + start_with->set_linked(); + } - if (linked) { - local_group.for_each([](soinfo* si) { - if (!si->is_linked()) { - si->set_linked(); - } - }); + for (auto&& task : load_tasks) { + soinfo* si = task->get_soinfo(); + si->set_linked(); + } - failure_guard.Disable(); + for (auto&& task : load_tasks) { + soinfo* si = task->get_soinfo(); + soinfo* needed_by = task->get_needed_by(); + if (needed_by != nullptr && + needed_by != start_with && + needed_by->get_local_group_root() != si->get_local_group_root()) { + si->increment_ref_count(); + } } - return linked; + + return true; } static soinfo* find_library(android_namespace_t* ns, const char* name, int rtld_flags, const android_dlextinfo* extinfo, soinfo* needed_by) { - soinfo* si; + soinfo* si = nullptr; - // readers_map is shared across recursive calls to find_libraries. - // However, the map is not shared across different threads. - std::unordered_map<const soinfo*, ElfReader> readers_map; if (name == nullptr) { si = solist_get_somain(); } else if (!find_libraries(ns, @@ -1745,8 +1768,10 @@ static soinfo* find_library(android_namespace_t* ns, rtld_flags, extinfo, false /* add_as_children */, - true /* search_linked_namespaces */, - readers_map)) { + true /* search_linked_namespaces */)) { + if (si != nullptr) { + soinfo_unload(si); + } return nullptr; } @@ -1755,18 +1780,26 @@ static soinfo* find_library(android_namespace_t* ns, return si; } -static void soinfo_unload(soinfo* si) { - soinfo* root = si->is_linked() ? si->get_local_group_root() : si; +static void soinfo_unload(soinfo* unload_si) { + // Note that the library can be loaded but not linked; + // in which case there is no root but we still need + // to walk the tree and unload soinfos involved. + // + // This happens on unsuccessful dlopen, when one of + // the DT_NEEDED libraries could not be linked/found. + bool is_linked = unload_si->is_linked(); + soinfo* root = is_linked ? unload_si->get_local_group_root() : unload_si; LD_LOG(kLogDlopen, "... dlclose(realpath=\"%s\"@%p) ... load group root is \"%s\"@%p", - si->get_realpath(), - si, + unload_si->get_realpath(), + unload_si, root->get_realpath(), root); ScopedTrace trace((std::string("unload ") + root->get_realpath()).c_str()); + size_t ref_count = is_linked ? root->decrement_ref_count() : 0; if (!root->can_unload()) { LD_LOG(kLogDlopen, "... dlclose(root=\"%s\"@%p) ... not unloading - the load group is flagged with NODELETE", @@ -1775,48 +1808,17 @@ static void soinfo_unload(soinfo* si) { return; } - soinfo_unload(&root, 1); -} - -static void soinfo_unload(soinfo* soinfos[], size_t count) { - // Note that the library can be loaded but not linked; - // in which case there is no root but we still need - // to walk the tree and unload soinfos involved. - // - // This happens on unsuccessful dlopen, when one of - // the DT_NEEDED libraries could not be linked/found. - if (count == 0) { + if (ref_count > 0) { + LD_LOG(kLogDlopen, + "... dlclose(root=\"%s\"@%p) ... not unloading - decrementing ref_count to %zd", + root->get_realpath(), + root, + ref_count); return; } soinfo_list_t unload_list; - for (size_t i = 0; i < count; ++i) { - soinfo* si = soinfos[i]; - - if (si->can_unload()) { - size_t ref_count = si->is_linked() ? si->decrement_ref_count() : 0; - if (ref_count == 0) { - unload_list.push_back(si); - } else { - LD_LOG(kLogDlopen, - "... dlclose(root=\"%s\"@%p) ... not unloading - decrementing ref_count to %zd", - si->get_realpath(), - si, - ref_count); - } - } else { - LD_LOG(kLogDlopen, - "... dlclose(root=\"%s\"@%p) ... not unloading - the load group is flagged with NODELETE", - si->get_realpath(), - si); - return; - } - } - - // This is used to identify soinfos outside of the load-group - // note that we cannot have > 1 in the array and have any of them - // linked. This is why we can safely use the first one. - soinfo* root = soinfos[0]; + unload_list.push_back(root); soinfo_list_t local_unload_list; soinfo_list_t external_unload_list; @@ -1900,12 +1902,17 @@ static void soinfo_unload(soinfo* soinfos[], size_t count) { soinfo_free(si); } - while ((si = external_unload_list.pop_front()) != nullptr) { - LD_LOG(kLogDlopen, - "... dlclose: unloading external reference \"%s\"@%p ...", - si->get_realpath(), - si); - soinfo_unload(si); + if (is_linked) { + while ((si = external_unload_list.pop_front()) != nullptr) { + LD_LOG(kLogDlopen, + "... dlclose: unloading external reference \"%s\"@%p ...", + si->get_realpath(), + si); + soinfo_unload(si); + } + } else { + LD_LOG(kLogDlopen, + "... dlclose: unload_si was not linked - not unloading external references ..."); } } @@ -3368,6 +3375,10 @@ bool soinfo::prelink_image() { bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group, const android_dlextinfo* extinfo) { + if (is_image_linked()) { + // already linked. + return true; + } local_group_root_ = local_group.front(); if (local_group_root_ == nullptr) { @@ -3510,6 +3521,7 @@ bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& } notify_gdb_of_load(this); + set_image_linked(); return true; } |