sh: Add die chain notifiers.

Add the atomic die chains in, kprobes needs these.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/process.c

@@ -7,7 +7,7 @@
  *
  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
  *		     Copyright (C) 2006 Lineo Solutions Inc. support SH4A UBC
- *		     Copyright (C) 2002 - 2006  Paul Mundt
+ *		     Copyright (C) 2002 - 2007  Paul Mundt
  */
 #include <linux/module.h>
 #include <linux/mm.h>
@@ -15,6 +15,7 @@
 #include <linux/pm.h>
 #include <linux/kallsyms.h>
 #include <linux/kexec.h>
+#include <asm/kdebug.h>
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
 #include <asm/ubc.h>
@@ -300,7 +301,7 @@ static void ubc_set_tracing(int asid, unsigned long pc)
 
 	if (current_cpu_data.type == CPU_SH7729 ||
 	    current_cpu_data.type == CPU_SH7710 ||
-	    current_cpu_data.type == CPU_SH7712 ) {
+	    current_cpu_data.type == CPU_SH7712) {
 		ctrl_outw(BBR_INST | BBR_READ | BBR_CPU, UBC_BBRA);
 		ctrl_outl(BRCR_PCBA | BRCR_PCTE, UBC_BRCR);
 	} else {
@@ -496,6 +497,10 @@ asmlinkage void debug_trap_handler(unsigned long r4, unsigned long r5,
 	/* Rewind */
 	regs->pc -= 2;
 
+	if (notify_die(DIE_TRAP, regs, regs->tra & 0xff,
+		       SIGTRAP) == NOTIFY_STOP)
+		return;
+
 	force_sig(SIGTRAP, current);
 }
 
@@ -511,6 +516,10 @@ asmlinkage void bug_trap_handler(unsigned long r4, unsigned long r5,
 	/* Rewind */
 	regs->pc -= 2;
 
+	if (notify_die(DIE_TRAP, regs, TRAPA_BUG_OPCODE & 0xff,
+		       SIGTRAP) == NOTIFY_STOP)
+		return;
+
 #ifdef CONFIG_BUG
 	if (__kernel_text_address(instruction_pointer(regs))) {
 		u16 insn = *(u16 *)instruction_pointer(regs);

arch/sh/kernel/traps.c

@@ -5,7 +5,7 @@
  *  SuperH version: Copyright (C) 1999 Niibe Yutaka
  *                  Copyright (C) 2000 Philipp Rumpf
  *                  Copyright (C) 2000 David Howells
- *                  Copyright (C) 2002 - 2006 Paul Mundt
+ *                  Copyright (C) 2002 - 2007 Paul Mundt
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
@@ -23,6 +23,7 @@
 #include <linux/limits.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
+#include <asm/kdebug.h>
 
 #ifdef CONFIG_SH_KGDB
 #include <asm/kgdb.h>
@@ -75,7 +76,21 @@ static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
 	}
 }
 
-DEFINE_SPINLOCK(die_lock);
+ATOMIC_NOTIFIER_HEAD(shdie_chain);
+
+int register_die_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&shdie_chain, nb);
+}
+EXPORT_SYMBOL(register_die_notifier);
+
+int unregister_die_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&shdie_chain, nb);
+}
+EXPORT_SYMBOL(unregister_die_notifier);
+
+static DEFINE_SPINLOCK(die_lock);
 
 void die(const char * str, struct pt_regs * regs, long err)
 {

arch/sh/mm/fault.c

@@ -2,7 +2,7 @@
  * Page fault handler for SH with an MMU.
  *
  *  Copyright (C) 1999  Niibe Yutaka
- *  Copyright (C) 2003  Paul Mundt
+ *  Copyright (C) 2003 - 2007  Paul Mundt
  *
  *  Based on linux/arch/i386/mm/fault.c:
  *   Copyright (C) 1995  Linus Torvalds
@@ -15,12 +15,42 @@
 #include <linux/mm.h>
 #include <linux/hardirq.h>
 #include <linux/kprobes.h>
+#include <asm/kdebug.h>
 #include <asm/system.h>
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>
 #include <asm/kgdb.h>
 
-extern void die(const char *,struct pt_regs *,long);
+#ifdef CONFIG_KPROBES
+ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
+
+/* Hook to register for page fault notifications */
+int register_page_fault_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
+}
+
+int unregister_page_fault_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
+}
+
+static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
+				    int trap, int sig)
+{
+	struct die_args args = {
+		.regs = regs,
+		.trapnr = trap,
+	};
+	return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
+}
+#else
+static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
+				    int trap, int sig)
+{
+	return NOTIFY_DONE;
+}
+#endif
 
 /*
  * This routine handles page faults.  It determines the address,
@@ -39,6 +69,11 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 	siginfo_t info;
 
 	trace_hardirqs_on();
+
+	if (notify_page_fault(DIE_PAGE_FAULT, regs,
+			      writeaccess, SIGSEGV) == NOTIFY_STOP)
+		return;
+
 	local_irq_enable();
 
 #ifdef CONFIG_SH_KGDB

include/asm-sh/kdebug.h

+#ifndef __ASM_SH_KDEBUG_H
+#define __ASM_SH_KDEBUG_H
+
+#include <linux/notifier.h>
+
+struct pt_regs;
+
+struct die_args {
+	struct pt_regs *regs;
+	int trapnr;
+};
+
+int register_die_notifier(struct notifier_block *nb);
+int unregister_die_notifier(struct notifier_block *nb);
+int register_page_fault_notifier(struct notifier_block *nb);
+int unregister_page_fault_notifier(struct notifier_block *nb);
+extern struct atomic_notifier_head shdie_chain;
+
+/* Grossly misnamed. */
+enum die_val {
+	DIE_TRAP,
+	DIE_PAGE_FAULT,
+};
+
+static inline int notify_die(enum die_val val, struct pt_regs *regs,
+			     int trap, int sig)
+{
+	struct die_args args = {
+		.regs = regs,
+		.trapnr = trap,
+	};
+
+	return atomic_notifier_call_chain(&shdie_chain, val, &args);
+}
+#endif /* __ASM_SH_KDEBUG_H */

include/asm-sh/system.h

@@ -9,6 +9,7 @@
 #include <linux/irqflags.h>
 #include <linux/compiler.h>
 #include <asm/types.h>
+#include <asm/ptrace.h>
 
 /*
  *	switch_to() should switch tasks to task nr n, first
@@ -255,6 +256,8 @@ static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old,
 				    (unsigned long)_n_, sizeof(*(ptr))); \
   })
 
+extern void die(const char *str, struct pt_regs *regs, long err) __attribute__ ((noreturn));
+
 extern void *set_exception_table_vec(unsigned int vec, void *handler);
 
 static inline void *set_exception_table_evt(unsigned int evt, void *handler)