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_common.cpp b/libc/bionic/libc_init_common.cpp
index 2396c36..1ff6603 100644
--- a/libc/bionic/libc_init_common.cpp
+++ b/libc/bionic/libc_init_common.cpp
@@ -60,25 +60,6 @@
// Not public, but well-known in the BSDs.
const char* __progname;
-#if defined(__i386__)
-__attribute__((__naked__)) static void __libc_int0x80() {
- __asm__ volatile("int $0x80; ret");
-}
-
-__LIBC_HIDDEN__ void* __libc_sysinfo = reinterpret_cast<void*>(__libc_int0x80);
-
-__LIBC_HIDDEN__ void __libc_init_sysinfo(KernelArgumentBlock& args) {
- // Running under valgrind, AT_SYSINFO won't be set.
- void* at_sysinfo = reinterpret_cast<void*>(args.getauxval(AT_SYSINFO));
- if (at_sysinfo != nullptr) __libc_sysinfo = at_sysinfo;
-}
-
-// TODO: lose this function and just access __libc_sysinfo directly.
-__LIBC_HIDDEN__ extern "C" void* __kernel_syscall() {
- return __libc_sysinfo;
-}
-#endif
-
void __libc_init_globals(KernelArgumentBlock& args) {
#if defined(__i386__)
__libc_init_sysinfo(args);
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
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 4d62efe..038f6a7 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -45,6 +45,13 @@
#include "private/bionic_tls.h"
#include "private/KernelArgumentBlock.h"
+// Leave the variable uninitialized for the sake of the dynamic loader, which
+// links in this file. The loader will initialize this variable before
+// relocating itself.
+#if defined(__i386__)
+__LIBC_HIDDEN__ void* __libc_sysinfo;
+#endif
+
extern "C" int __cxa_atexit(void (*)(void *), void *, void *);
static void call_array(void(**list)()) {