tools/nolibc: i386: add stackprotector support

Enable the new stackprotector support for i386.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/include/nolibc/arch-i386.h

@@ -181,6 +181,8 @@ struct sys_stat_struct {
 char **environ __attribute__((weak));
 const unsigned long *_auxv __attribute__((weak));
 
+#define __ARCH_SUPPORTS_STACK_PROTECTOR
+
 /* startup code */
 /*
  * i386 System V ABI mandates:
@@ -188,9 +190,12 @@ const unsigned long *_auxv __attribute__((weak));
  * 2) The deepest stack frame should be set to zero
  *
  */
-void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
+void __attribute__((weak,noreturn,optimize("omit-frame-pointer"),no_stack_protector)) _start(void)
 {
 	__asm__ volatile (
+#ifdef NOLIBC_STACKPROTECTOR
+		"call __stack_chk_init\n"   // initialize stack protector
+#endif
 		"pop %eax\n"                // argc   (first arg, %eax)
 		"mov %esp, %ebx\n"          // argv[] (second arg, %ebx)
 		"lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx)

tools/testing/selftests/nolibc/Makefile

@@ -79,6 +79,7 @@ endif
 CFLAGS_STACKPROTECTOR = -DNOLIBC_STACKPROTECTOR \
 			$(call cc-option,-mstack-protector-guard=global) \
 			$(call cc-option,-fstack-protector-all)
+CFLAGS_STKP_i386 = $(CFLAGS_STACKPROTECTOR)
 CFLAGS_s390 = -m64
 CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables \
 		$(call cc-option,-fno-stack-protector) \