Move __libc_int0x80 to an assembly file
Bug: http://b/157081822
If __libc_int0x80 is in a C/C++ file, Clang's coverage instrumentation
adds instructions to count the number of times it gets executed [1].
With coverage instrumentation, __libc_sysinfo, used on 32-bit x86, is
initialized to the wrong value, causing dl.preinit_system_calls to fail.
Moving the function to an assembly file leaves __libc_sysinfo properly
initialized.
[1] We could change clang so it doesn't instrument functions marked
__attribute__((naked)) as a followup.
Test: `m CLANG_COVERAGE=true NATIVE_COVERAGE_PATHS=bionic` and run
bionic-unit-tests
Change-Id: I73558253512392d345de8d5b66d38bb14b308fdf
diff --git a/libc/Android.bp b/libc/Android.bp
index 6a3a7c0..0451cfd 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -170,6 +170,7 @@
x86: {
srcs: [
"arch-x86/bionic/__libc_init_sysinfo.cpp",
+ "arch-x86/bionic/__libc_int0x80.S",
"arch-x86/bionic/__set_tls.cpp",
],
},
diff --git a/libc/arch-x86/bionic/__libc_init_sysinfo.cpp b/libc/arch-x86/bionic/__libc_init_sysinfo.cpp
index db931d1..de099b8 100644
--- a/libc/arch-x86/bionic/__libc_init_sysinfo.cpp
+++ b/libc/arch-x86/bionic/__libc_init_sysinfo.cpp
@@ -32,10 +32,6 @@
// This file is compiled without stack protection, because it runs before TLS
// has been set up.
-__LIBC_HIDDEN__ __attribute__((__naked__)) void __libc_int0x80() {
- __asm__ volatile("int $0x80; ret");
-}
-
__LIBC_HIDDEN__ void __libc_init_sysinfo() {
bool unused;
__libc_sysinfo = reinterpret_cast<void*>(__bionic_getauxval(AT_SYSINFO, &unused));
diff --git a/libc/arch-x86/bionic/__libc_int0x80.S b/libc/arch-x86/bionic/__libc_int0x80.S
new file mode 100644
index 0000000..66f0a1a
--- /dev/null
+++ b/libc/arch-x86/bionic/__libc_int0x80.S
@@ -0,0 +1,7 @@
+#include <private/bionic_asm.h>
+
+// void __libc_int0x80();
+ENTRY_PRIVATE(__libc_int0x80)
+ int $0x80
+ ret
+END(__libc_int0x80)
diff --git a/libc/private/bionic_globals.h b/libc/private/bionic_globals.h
index 8132261..16f89bf 100644
--- a/libc/private/bionic_globals.h
+++ b/libc/private/bionic_globals.h
@@ -123,7 +123,7 @@
#if defined(__i386__)
__LIBC_HIDDEN__ extern void* __libc_sysinfo;
-__LIBC_HIDDEN__ void __libc_int0x80();
+extern "C" __LIBC_HIDDEN__ void __libc_int0x80();
__LIBC_HIDDEN__ void __libc_init_sysinfo();
#endif