MIPS: die() does not call die notifier chain

The MIPS implementation of die() forgets to call notify_die() and thus notifiers
registered via register_die_notifier() are not called.  This results in kgdb not
being activated on exceptions.

The only subtlety is that notify_die declares its regs argument w/o const, so
the const had to be removed from mips die() as well.

[Ralf: Fixed build error for SGI IP22 and IP28 platforms.]
Signed-off-by: Yury Polyanskiy <ypolyans@princeton.edu>
Cc: linux-mips@linux-mips.org
Patchworks: http://patchwork.linux-mips.org/patch/1142/Acked-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

---

arch/mips/include/asm/ptrace.h

@@ -142,9 +142,9 @@ extern int ptrace_set_watch_regs(struct task_struct *child,
 
 extern asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit);
 
-extern NORET_TYPE void die(const char *, const struct pt_regs *) ATTRIB_NORET;
+extern NORET_TYPE void die(const char *, struct pt_regs *) ATTRIB_NORET;
 
-static inline void die_if_kernel(const char *str, const struct pt_regs *regs)
+static inline void die_if_kernel(const char *str, struct pt_regs *regs)
 {
 	if (unlikely(!user_mode(regs)))
 		die(str, regs);

arch/mips/kernel/traps.c

@@ -352,9 +352,10 @@ void show_registers(const struct pt_regs *regs)
 
 static DEFINE_SPINLOCK(die_lock);
 
-void __noreturn die(const char * str, const struct pt_regs * regs)
+void __noreturn die(const char * str, struct pt_regs * regs)
 {
 	static int die_counter;
+	int sig = SIGSEGV;
 #ifdef CONFIG_MIPS_MT_SMTC
 	unsigned long dvpret = dvpe();
 #endif /* CONFIG_MIPS_MT_SMTC */
@@ -365,6 +366,10 @@ void __noreturn die(const char * str, const struct pt_regs * regs)
 #ifdef CONFIG_MIPS_MT_SMTC
 	mips_mt_regdump(dvpret);
 #endif /* CONFIG_MIPS_MT_SMTC */
+
+	if (notify_die(DIE_OOPS, str, regs, 0, current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
+		sig = 0;
+
 	printk("%s[#%d]:\n", str, ++die_counter);
 	show_registers(regs);
 	add_taint(TAINT_DIE);
@@ -379,7 +384,7 @@ void __noreturn die(const char * str, const struct pt_regs * regs)
 		panic("Fatal exception");
 	}
 
-	do_exit(SIGSEGV);
+	do_exit(sig);
 }
 
 extern struct exception_table_entry __start___dbe_table[];

arch/mips/sgi-ip22/ip22-berr.c

@@ -89,7 +89,7 @@ static void print_buserr(void)
 void ip22_be_interrupt(int irq)
 {
 	const int field = 2 * sizeof(unsigned long);
-	const struct pt_regs *regs = get_irq_regs();
+	struct pt_regs *regs = get_irq_regs();
 
 	save_and_clear_buserr();
 	print_buserr();

arch/mips/sgi-ip22/ip28-berr.c

@@ -453,7 +453,7 @@ mips_be_fatal:
 
 void ip22_be_interrupt(int irq)
 {
-	const struct pt_regs *regs = get_irq_regs();
+	struct pt_regs *regs = get_irq_regs();
 
 	count_be_interrupt++;