linker: allow using reserved space for multiple libraries.

Introduce a new flag ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE which
instructs the linker to use the reserved address space to load all of
the newly-loaded libraries required by a dlopen() call instead of only
the main library. They will be loaded consecutively into that region if
they fit. The RELRO sections of all the loaded libraries will also be
considered for reading/writing shared RELRO data.

This will allow the WebView implementation to potentially consist of
more than one .so file while still benefiting from the RELRO sharing
optimisation, which would otherwise only apply to the "root" .so file.

Test: bionic-unit-tests (existing and newly added)
Bug: 110790153
Change-Id: I61da775c29fd5017d9a1e2b6b3757c3d20a355b3

1 files changed, 5 insertions, 4 deletions

diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 7486cd79b..763b15c4b 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -165,7 +165,7 @@ static void add_vdso() {
   si->load_bias = get_elf_exec_load_bias(ehdr_vdso);
 
   si->prelink_image();
-  si->link_image(g_empty_list, soinfo_list_t::make_list(si), nullptr);
+  si->link_image(g_empty_list, soinfo_list_t::make_list(si), nullptr, nullptr);
   // prevents accidental unloads...
   si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_NODELETE);
   si->set_linked();
@@ -281,7 +281,8 @@ static ExecutableInfo load_executable(const char* orig_path) {
   if (!elf_reader.Read(result.path.c_str(), fd.get(), file_offset, result.file_stat.st_size)) {
     __linker_error("error: %s\n", linker_get_error_buffer());
   }
-  if (!elf_reader.Load(nullptr)) {
+  address_space_params address_space;
+  if (!elf_reader.Load(&address_space)) {
     __linker_error("error: %s\n", linker_get_error_buffer());
   }
 
@@ -448,7 +449,7 @@ static ElfW(Addr) linker_main(KernelArgumentBlock& args, const char* exe_to_load
                       &namespaces)) {
     __linker_cannot_link(g_argv[0]);
   } else if (needed_libraries_count == 0) {
-    if (!si->link_image(g_empty_list, soinfo_list_t::make_list(si), nullptr)) {
+    if (!si->link_image(g_empty_list, soinfo_list_t::make_list(si), nullptr, nullptr)) {
       __linker_cannot_link(g_argv[0]);
     }
     si->increment_ref_count();
@@ -615,7 +616,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
   // itself without having to look into local_group and (2) allocators
   // are not yet initialized, and therefore we cannot use linked_list.push_*
   // functions at this point.
-  if (!tmp_linker_so.link_image(g_empty_list, g_empty_list, nullptr)) __linker_cannot_link(args.argv[0]);
+  if (!tmp_linker_so.link_image(g_empty_list, g_empty_list, nullptr, nullptr)) __linker_cannot_link(args.argv[0]);
 
   return __linker_init_post_relocation(args, tmp_linker_so);
 }