commit 7752bcb234a9960d2e9e89766d143b7ac0c5f332
author Ryan Prichard <rprichard@google.com> Thu Nov 22 02:41:04 2018 -0800
committer Ryan Prichard <rprichard@google.com> Wed Nov 28 14:26:14 2018 -0800
tree e7bcae45f66a0682f07d242f18b33681fc9e4cfa
parent abf736a7803f4acc8b70a2dab0d43b931aa9c5c0

Move the abort message to libc_shared_globals

__libc_shared_globals() is available in dynamic modules as soon as
relocation has finished (i.e. after ifuncs run). Before ifuncs have run,
the android_set_abort_message() function already doesn't work because it
calls public APIs via the PLT. (If this matters, we can use a static
bool variable to enable android_set_abort_message after libc
initialization).

__libc_shared_globals() is hidden, so it's available in the linker
immediately (i.e. before relocation). TLS memory (e.g. errno) currently
isn't accessible until after relocation, but a later patch fixes that.

Bug: none
Test: bionic unit tests
Change-Id: Ied4433758ed2da9ee404c6158e319cf502d05a53

linker/linker_main.cpp

diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 963e82c..442ecd9 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -116,7 +116,6 @@
 }
 
 int g_ld_debug_verbosity;
-abort_msg_t* g_abort_message = nullptr; // For debuggerd.
 
 static std::vector<std::string> g_ld_preload_names;
 
@@ -300,7 +299,7 @@
 #ifdef __ANDROID__
   debuggerd_callbacks_t callbacks = {
     .get_abort_message = []() {
-      return g_abort_message;
+      return __libc_shared_globals()->abort_msg;
     },
     .post_dump = &notify_gdb_of_libraries,
   };
@@ -664,7 +663,6 @@
   g_default_namespace.add_soinfo(solinker);
   init_link_map_head(*solinker, kLinkerPath);
 
-  args.abort_message_ptr = &g_abort_message;
   ElfW(Addr) start_address = linker_main(args, exe_to_load);
 
   INFO("[ Jumping to _start (%p)... ]", reinterpret_cast<void*>(start_address));