riscv: cleanup do_trap_break

If we always compile the get_break_insn_length inline function we can
remove the ifdefs and let dead code elimination take care of the warn
branch that is now unreadable because the report_bug stub always
returns BUG_TRAP_TYPE_BUG.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/kernel/traps.c

@@ -111,7 +111,6 @@ DO_ERROR_INFO(do_trap_ecall_s,
 DO_ERROR_INFO(do_trap_ecall_m,
 	SIGILL, ILL_ILLTRP, "environment call from M-mode");
 
-#ifdef CONFIG_GENERIC_BUG
 static inline unsigned long get_break_insn_length(unsigned long pc)
 {
 	bug_insn_t insn;
@@ -120,27 +119,14 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
 		return 0;
 	return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
 }
-#endif /* CONFIG_GENERIC_BUG */
 
 asmlinkage void do_trap_break(struct pt_regs *regs)
 {
-	if (user_mode(regs)) {
-		force_sig_fault(SIGTRAP, TRAP_BRKPT,
-				(void __user *)(regs->sepc));
-		return;
-	}
-#ifdef CONFIG_GENERIC_BUG
-	{
-		enum bug_trap_type type;
-
-		type = report_bug(regs->sepc, regs);
-		if (type == BUG_TRAP_TYPE_WARN) {
+	if (user_mode(regs))
+		force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->sepc);
+	else if (report_bug(regs->sepc, regs) == BUG_TRAP_TYPE_WARN)
 		regs->sepc += get_break_insn_length(regs->sepc);
-			return;
-		}
-	}
-#endif /* CONFIG_GENERIC_BUG */
-
+	else
 		die(regs, "Kernel BUG");
 }