x86_32: signal: introduce signal_fault()

implement signal_fault() for 32bit.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/signal_32.c

@@ -243,7 +243,7 @@ asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 	return ax;
 
 badframe:
-	force_sig(SIGSEGV, current);
+	signal_fault(regs, frame, "rt sigreturn");
 	return 0;
 }
 
@@ -669,3 +669,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 
 	clear_thread_flag(TIF_IRET);
 }
+
+void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
+{
+	struct task_struct *me = current;
+
+	if (show_unhandled_signals && printk_ratelimit()) {
+		printk(KERN_INFO
+		       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
+		       me->comm, me->pid, where, frame,
+		       regs->ip, regs->sp, regs->orig_ax);
+		print_vma_addr(" in ", regs->ip);
+		printk(KERN_CONT "\n");
+	}
+
+	force_sig(SIGSEGV, me);
+}

include/asm-x86/ptrace.h

@@ -144,10 +144,10 @@ convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
 #ifdef CONFIG_X86_32
 extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
 			 int error_code);
-#else
-void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
 #endif
 
+void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
+
 extern long syscall_trace_enter(struct pt_regs *);
 extern void syscall_trace_leave(struct pt_regs *);