x86/entry/traps: Show unhandled signal for i386 in do_trap()

Commit abd4f7505baf ("x86: i386-show-unhandled-signals-v3") did turn on
the showing-unhandled-signal behaviour for i386 for some exception handlers,
but for no reason do_trap() is left out (my naive guess is because turning it on
for do_trap() would be too noisy since do_trap() is shared by several exceptions).

And since the same commit make "show_unhandled_signals" a debug tunable(in
/proc/sys/debug/exception-trace), and x86 by default turning it on.

So it would be strange for i386 users who turing it on manually and expect
seeing the unhandled signal output in log, but nothing.

This patch turns it on for i386 in do_trap() as well.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@suse.de
Cc: dave.hansen@linux.intel.com
Cc: heukelum@fastmail.fm
Cc: jbeulich@novell.com
Cc: jdike@addtoit.com
Cc: joe@perches.com
Cc: luto@kernel.org
Link: http://lkml.kernel.org/r/1457612398-4568-1-git-send-email-nasa4836@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/traps.c

@@ -248,7 +248,6 @@ do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_nr = trapnr;
 
-#ifdef CONFIG_X86_64
 	if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 	    printk_ratelimit()) {
 		pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
@@ -257,7 +256,6 @@ do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 		print_vma_addr(" in ", regs->ip);
 		pr_cont("\n");
 	}
-#endif
 
 	force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
 }