Clean up __stack_chk_fail_local slightly.
Motivated by the fact that bazel doesn't like #include "../", but this
feels like it could use a deeper clean.
In fact, even after this change, I think we should remove this entirely,
since as far as I can tell Clang never implemented this GCC workaround
for 32-bit x86's awful PIC code.
Test: treehugger
Change-Id: I72715ee46f873f42d5707712aebe246ef78fcde1
diff --git a/libc/arch-x86/bionic/__stack_chk_fail_local.h b/libc/arch-common/bionic/__stack_chk_fail_local.h
similarity index 62%
rename from libc/arch-x86/bionic/__stack_chk_fail_local.h
rename to libc/arch-common/bionic/__stack_chk_fail_local.h
index 0b0fd7f..99e2f92 100644
--- a/libc/arch-x86/bionic/__stack_chk_fail_local.h
+++ b/libc/arch-common/bionic/__stack_chk_fail_local.h
@@ -28,30 +28,21 @@
#include <sys/cdefs.h>
-/*
- __stack_chk_fail routine is runtime part of stack protector compiler
- feature. It's implemented in libc and represents die routine when stack
- corruption is detected.
+#if defined(__i386__)
- Calls are generated by compiler and injected into user functions when
- -fstack-protector* options are used.
+// __stack_chk_fail() is called when a check emitted by -fstack-protector
+// fails.
+//
+// But because 32-bit x86 PIC code is so awful, for x86 the compiler uses
+// local calls to __stack_chk_fail_local() instead. Unfortunately that means
+// that __stack_chk_fail_local() has to be in every executable or library.
+//
+// TODO: it seems like only GCC does this, not clang, so this is obsolete?
- __stack_chk_fail_local is wrapper for __stack_chk_fail. Compiler generates
- wrapper calls instead for PIC code only and only on IA32 for optimization
- purpose (see gcc/config/i386/i386.c). Wrapper body is always included into
- executable or library. This is the idea of optimization.
-
- Glibc is doing this via libc_nonshared.a which is linked automatically
- everytime with libc.so. In bionic we have to bring it within crtfiles
- because libc.so is real library and not a link script like libc.so at glibc.
-
- For x86_64 or non-PIC code compiler always generates __stack_chk_fail calls.
-*/
-
-#ifdef __i386__
extern void __stack_chk_fail();
__LIBC_HIDDEN__ void __stack_chk_fail_local() {
__stack_chk_fail();
}
+
#endif
diff --git a/libc/arch-common/bionic/crtbegin.c b/libc/arch-common/bionic/crtbegin.c
index f2b6638..3e5bb90 100644
--- a/libc/arch-common/bionic/crtbegin.c
+++ b/libc/arch-common/bionic/crtbegin.c
@@ -87,8 +87,6 @@
#endif
#include "__dso_handle.h"
+#include "__stack_chk_fail_local.h"
#include "atexit.h"
#include "pthread_atfork.h"
-#ifdef __i386__
-# include "../../arch-x86/bionic/__stack_chk_fail_local.h"
-#endif
diff --git a/libc/arch-common/bionic/crtbegin_so.c b/libc/arch-common/bionic/crtbegin_so.c
index cf369cc..7b4057b 100644
--- a/libc/arch-common/bionic/crtbegin_so.c
+++ b/libc/arch-common/bionic/crtbegin_so.c
@@ -72,7 +72,5 @@
# include "__dso_handle_so.h"
# include "atexit.h"
#endif
+#include "__stack_chk_fail_local.h"
#include "pthread_atfork.h"
-#ifdef __i386__
-# include "../../arch-x86/bionic/__stack_chk_fail_local.h"
-#endif