x32: Add rt_sigframe_x32

Add rt_sigframe_x32 to <asm/sigframe.h>.  Unfortunately we can't just
define all the data structures unconditionally, due to the #ifdef
CONFIG_COMPAT in <linux/compat.h> and its trickle-down effects, hence
the #ifdef mess.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/sigframe.h

@@ -59,12 +59,25 @@ struct rt_sigframe_ia32 {
 #endif /* defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) */
 
 #ifdef CONFIG_X86_64
+
 struct rt_sigframe {
 	char __user *pretcode;
 	struct ucontext uc;
 	struct siginfo info;
 	/* fp state follows here */
 };
+
+#ifdef CONFIG_X86_X32_ABI
+
+struct rt_sigframe_x32 {
+	u64 pretcode;
+	struct ucontext_x32 uc;
+	compat_siginfo_t info;
+	/* fp state follows here */
+};
+
+#endif /* CONFIG_X86_X32_ABI */
+
 #endif /* CONFIG_X86_64 */
 
 #endif /* _ASM_X86_SIGFRAME_H */