Initialize __libc_sysinfo early on.
__libc_sysinfo is hidden, so accessing it doesn't require a relocated GOT.
It is important not to have a relocatable initializer on __libc_sysinfo,
because if it did have one, and if we initialized it before relocating the
linker, then on 32-bit x86 (which uses REL rather than RELA), the
relocation step would calculate the wrong addend and overwrite
__libc_sysinfo with garbage.
Asides:
* It'd be simpler to keep the __libc_sysinfo initializer for static
executables, but the loader pulls in libc_init_static (even though it
uses almost none of the code in that file, like __libc_init).
* The loader has called __libc_init_sysinfo three times by the time it
has relocated itself. A static executable calls it twice, while libc.so
calls it only once.
Bug: none
Test: lunch aosp_x86-userdebug ; emulator
Test: adb shell /data/nativetest/bionic-unit-tests/bionic-unit-tests
Test: adb shell /data/nativetest/bionic-unit-tests-static/bionic-unit-tests-static
Change-Id: I5944f57847db7191608f4f83dde22b49e279e6cb
diff --git a/libc/bionic/libc_init_dynamic.cpp b/libc/bionic/libc_init_dynamic.cpp
index fb086c8..6b8f57f 100644
--- a/libc/bionic/libc_init_dynamic.cpp
+++ b/libc/bionic/libc_init_dynamic.cpp
@@ -62,6 +62,12 @@
extern int __cxa_atexit(void (*)(void *), void *, void *);
};
+// Use an initializer so __libc_sysinfo will have a fallback implementation
+// while .preinit_array constructors run.
+#if defined(__i386__)
+__LIBC_HIDDEN__ void* __libc_sysinfo = reinterpret_cast<void*>(__libc_int0x80);
+#endif
+
// We need a helper function for __libc_preinit because compiling with LTO may
// inline functions requiring a stack protector check, but __stack_chk_guard is
// not initialized at the start of __libc_preinit. __libc_preinit_impl will run