MN10300: Create generic kernel debugger hooks

Create generic kernel debugger hooks in the MN10300 arch and make gdbstub use
them.  This is a preparation for KGDB support.

Signed-off-by: David Howells <dhowells@redhat.com>

arch/mn10300/Kconfig

@@ -401,8 +401,8 @@ comment "[!] NOTE: A lower number/level indicates a higher priority (0 is highes
 comment "____Non-maskable interrupt levels____"
 comment "The following must be set to a higher priority than local_irq_disable() and on-chip serial"
 
-config GDBSTUB_IRQ_LEVEL
-	int "GDBSTUB interrupt priority"
+config DEBUGGER_IRQ_LEVEL
+	int "DEBUGGER interrupt priority"
 	depends on KERNEL_DEBUGGER
 	range 0 1 if LINUX_CLI_LEVEL = 2
 	range 0 2 if LINUX_CLI_LEVEL = 3
@@ -437,7 +437,7 @@ config LINUX_CLI_LEVEL
 	  EPSW.IM from 7.  Any interrupt is permitted for which the level is
 	  lower than EPSW.IM.
 
-	  Certain interrupts, such as GDBSTUB and virtual MN10300 on-chip
+	  Certain interrupts, such as DEBUGGER and virtual MN10300 on-chip
 	  serial DMA interrupts are allowed to interrupt normal disabled
 	  sections.
 

arch/mn10300/include/asm/debugger.h

@@ -14,6 +14,9 @@
 
 #if defined(CONFIG_KERNEL_DEBUGGER)
 
+extern int debugger_intercept(enum exception_code, int, int, struct pt_regs *);
+extern int at_debugger_breakpoint(struct pt_regs *);
+
 #ifndef CONFIG_MN10300_DEBUGGER_CACHE_NO_FLUSH
 extern void debugger_local_cache_flushinv(void);
 extern void debugger_local_cache_flushinv_one(u8 *);
@@ -24,5 +27,17 @@ static inline void debugger_local_cache_flushinv_one(u8 *addr) {}
 
 #else /* CONFIG_KERNEL_DEBUGGER */
 
+static inline int debugger_intercept(enum exception_code excep,
+				     int signo, int si_code,
+				     struct pt_regs *regs)
+{
+	return 0;
+}
+
+static inline int at_debugger_breakpoint(struct pt_regs *regs)
+{
+	return 0;
+}
+
 #endif /* CONFIG_KERNEL_DEBUGGER */
 #endif /* _ASM_DEBUGGER_H */

arch/mn10300/include/asm/fpu.h

@@ -55,7 +55,6 @@ static inline void clear_using_fpu(struct task_struct *tsk)
 
 extern asmlinkage void fpu_kill_state(struct task_struct *);
 extern asmlinkage void fpu_exception(struct pt_regs *, enum exception_code);
-extern asmlinkage void fpu_invalid_op(struct pt_regs *, enum exception_code);
 extern asmlinkage void fpu_init_state(void);
 extern asmlinkage void fpu_save(struct fpu_state_struct *);
 extern int fpu_setup_sigcontext(struct fpucontext *buf);
@@ -113,7 +112,6 @@ static inline void flush_fpu(void)
 
 extern asmlinkage
 void unexpected_fpu_exception(struct pt_regs *, enum exception_code);
-#define fpu_invalid_op unexpected_fpu_exception
 #define fpu_exception unexpected_fpu_exception
 
 struct task_struct;

arch/mn10300/include/asm/irqflags.h

@@ -20,7 +20,7 @@
 /*
  * interrupt control
  * - "disabled": run in IM1/2
- *   - level 0 - GDB stub
+ *   - level 0 - kernel debugger
  *   - level 1 - virtual serial DMA (if present)
  *   - level 5 - normal interrupt priority
  *   - level 6 - timer interrupt

arch/mn10300/include/asm/smp.h

@@ -34,7 +34,7 @@
 #define LOCAL_TIMER_IPI		193
 #define FLUSH_CACHE_IPI		194
 #define CALL_FUNCTION_NMI_IPI	195
-#define GDB_NMI_IPI		196
+#define DEBUGGER_NMI_IPI	196
 
 #define SMP_BOOT_IRQ		195
 
@@ -43,6 +43,7 @@
 #define LOCAL_TIMER_GxICR_LV	GxICR_LEVEL_4
 #define FLUSH_CACHE_GxICR_LV	GxICR_LEVEL_0
 #define SMP_BOOT_GxICR_LV	GxICR_LEVEL_0
+#define DEBUGGER_GxICR_LV	CONFIG_DEBUGGER_IRQ_LEVEL
 
 #define TIME_OUT_COUNT_BOOT_IPI	100
 #define DELAY_TIME_BOOT_IPI	75000

arch/mn10300/kernel/entry.S

@@ -266,7 +266,11 @@ ENTRY(raw_bus_error)
 
 ###############################################################################
 #
-# Miscellaneous exception entry points
+# NMI exception entry points
+#
+# This is used by ordinary interrupt channels that have the GxICR_NMI bit set
+# in addition to the main NMI and Watchdog channels.  SMP NMI IPIs use this
+# facility.
 #
 ###############################################################################
 ENTRY(nmi_handler)
@@ -281,7 +285,7 @@ ENTRY(nmi_handler)
 	and	NMIAGR_GN,d0
 	lsr	0x2,d0
 	cmp	CALL_FUNCTION_NMI_IPI,d0
-	bne	5f			# if not call function, jump
+	bne	nmi_not_smp_callfunc	# if not call function, jump
 
 	# function call nmi ipi
 	add	4,sp			# no need to store TBR
@@ -295,30 +299,38 @@ ENTRY(nmi_handler)
 	call	smp_nmi_call_function_interrupt[],0
 	RESTORE_ALL
 
-5:
-#ifdef CONFIG_GDBSTUB
-	cmp	GDB_NMI_IPI,d0
-	bne	3f			# if not gdb nmi ipi, jump
+nmi_not_smp_callfunc:
+#ifdef CONFIG_KERNEL_DEBUGGER
+	cmp	DEBUGGER_NMI_IPI,d0
+	bne	nmi_not_debugger	# if not kernel debugger NMI IPI, jump
 
-	# gdb nmi ipi
+	# kernel debugger NMI IPI
 	add	4,sp			# no need to store TBR
 	mov	GxICR_DETECT,d0		# clear NMI
-	movbu	d0,(GxICR(GDB_NMI_IPI))
-	movhu	(GxICR(GDB_NMI_IPI)),d0
+	movbu	d0,(GxICR(DEBUGGER_NMI_IPI))
+	movhu	(GxICR(DEBUGGER_NMI_IPI)),d0
 	and	~EPSW_NMID,epsw		# enable NMI
 
 	mov     (sp),d0
 	SAVE_ALL
-	call    gdbstub_nmi_wait[],0
+	mov	fp,d0			# arg 0: stacked register file
+	mov	a2,d1			# arg 1: exception number
+	call    debugger_nmi_interrupt[],0
 	RESTORE_ALL
-3:
-#endif /* CONFIG_GDBSTUB */
+
+nmi_not_debugger:
+#endif /* CONFIG_KERNEL_DEBUGGER */
 	mov     (sp),d0                 # restore TBR to d0
 	add     4,sp
 #endif /* CONFIG_SMP */
 
 	bra	__common_exception_nonmi
 
+###############################################################################
+#
+# General exception entry point
+#
+###############################################################################
 ENTRY(__common_exception)
 	add	-4,sp
 	mov	d0,(sp)

arch/mn10300/kernel/fpu.c

@@ -69,24 +69,6 @@ asmlinkage void fpu_exception(struct pt_regs *regs, enum exception_code code)
 	force_sig_info(SIGFPE, &info, tsk);
 }
 
-/*
- * handle an FPU invalid_op exception
- * - Derived from DO_EINFO() macro in arch/mn10300/kernel/traps.c
- */
-asmlinkage void fpu_invalid_op(struct pt_regs *regs, enum exception_code code)
-{
-	siginfo_t info;
-
-	if (!user_mode(regs))
-		die_if_no_fixup("FPU invalid opcode", regs, code);
-
-	info.si_signo = SIGILL;
-	info.si_errno = 0;
-	info.si_code = ILL_COPROC;
-	info.si_addr = (void *) regs->pc;
-	force_sig_info(info.si_signo, &info, current);
-}
-
 /*
  * save the FPU state to a signal context
  */

arch/mn10300/kernel/gdb-io-ttysm.c

@@ -59,10 +59,10 @@ void __init gdbstub_io_init(void)
 
 	/* we want to get serial receive interrupts */
 	set_intr_level(gdbstub_port->rx_irq,
-		NUM2GxICR_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL));
+		NUM2GxICR_LEVEL(CONFIG_DEBUGGER_IRQ_LEVEL));
 	set_intr_level(gdbstub_port->tx_irq,
-		NUM2GxICR_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL));
-	set_intr_stub(NUM2EXCEP_IRQ_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL),
+		NUM2GxICR_LEVEL(CONFIG_DEBUGGER_IRQ_LEVEL));
+	set_intr_stub(NUM2EXCEP_IRQ_LEVEL(CONFIG_DEBUGGER_IRQ_LEVEL),
 		gdbstub_io_rx_handler);
 
 	*gdbstub_port->rx_icr |= GxICR_ENABLE;
@@ -88,7 +88,7 @@ void __init gdbstub_io_init(void)
 
 	/* permit level 0 IRQs only */
 	arch_local_change_intr_mask_level(
-		NUM2EPSW_IM(CONFIG_GDBSTUB_IRQ_LEVEL + 1));
+		NUM2EPSW_IM(CONFIG_DEBUGGER_IRQ_LEVEL + 1));
 }
 
 /*

arch/mn10300/kernel/gdb-stub.c

@@ -1173,7 +1173,7 @@ int gdbstub_clear_breakpoint(u8 *addr, int len)
 
 /*
  * This function does all command processing for interfacing to gdb
- * - returns 1 if the exception should be skipped, 0 otherwise.
+ * - returns 0 if the exception should be skipped, -ERROR otherwise.
  */
 static int gdbstub(struct pt_regs *regs, enum exception_code excep)
 {
@@ -1188,7 +1188,7 @@ static int gdbstub(struct pt_regs *regs, enum exception_code excep)
 	int loop;
 
 	if (excep == EXCEP_FPU_DISABLED)
-		return 0;
+		return -ENOTSUPP;
 
 	gdbstub_flush_caches = 0;
 
@@ -1197,7 +1197,7 @@ static int gdbstub(struct pt_regs *regs, enum exception_code excep)
 	asm volatile("mov mdr,%0" : "=d"(mdr));
 	local_save_flags(epsw);
 	arch_local_change_intr_mask_level(
-		NUM2EPSW_IM(CONFIG_GDBSTUB_IRQ_LEVEL + 1));
+		NUM2EPSW_IM(CONFIG_DEBUGGER_IRQ_LEVEL + 1));
 
 	gdbstub_store_fpu();
 
@@ -1675,14 +1675,23 @@ static int gdbstub(struct pt_regs *regs, enum exception_code excep)
 	touch_softlockup_watchdog();
 
 	local_irq_restore(epsw);
-	return 1;
+	return 0;
+}
+
+/*
+ * Determine if we hit a debugger special breakpoint that needs skipping over
+ * automatically.
+ */
+int at_debugger_breakpoint(struct pt_regs *regs)
+{
+	return 0;
 }
 
 /*
  * handle event interception
  */
-asmlinkage int gdbstub_intercept(struct pt_regs *regs,
-				 enum exception_code excep)
+asmlinkage int debugger_intercept(enum exception_code excep,
+				  int signo, int si_code, struct pt_regs *regs)
 {
 	static u8 notfirst = 1;
 	int ret;
@@ -1696,7 +1705,7 @@ asmlinkage int gdbstub_intercept(struct pt_regs *regs,
 		asm("mov mdr,%0" : "=d"(mdr));
 
 		gdbstub_entry(
-			"--> gdbstub_intercept(%p,%04x) [MDR=%lx PC=%lx]\n",
+			"--> debugger_intercept(%p,%04x) [MDR=%lx PC=%lx]\n",
 			regs, excep, mdr, regs->pc);
 
 		gdbstub_entry(
@@ -1730,7 +1739,7 @@ asmlinkage int gdbstub_intercept(struct pt_regs *regs,
 
 	ret = gdbstub(regs, excep);
 
-	gdbstub_entry("<-- gdbstub_intercept()\n");
+	gdbstub_entry("<-- debugger_intercept()\n");
 	gdbstub_busy = 0;
 	return ret;
 }

arch/mn10300/kernel/internal.h

@@ -29,6 +29,13 @@ extern void ret_from_fork(struct task_struct *) __attribute__((noreturn));
 extern void mn10300_low_ipi_handler(void);
 #endif
 
+/*
+ * smp.c
+ */
+#ifdef CONFIG_SMP
+extern void smp_jump_to_debugger(void);
+#endif
+
 /*
  * time.c
  */

arch/mn10300/kernel/irq.c

@@ -153,7 +153,7 @@ mn10300_cpupic_setaffinity(struct irq_data *d, const struct cpumask *mask,
 	case LOCAL_TIMER_IPI:
 	case FLUSH_CACHE_IPI:
 	case CALL_FUNCTION_NMI_IPI:
-	case GDB_NMI_IPI:
+	case DEBUGGER_NMI_IPI:
 #ifdef CONFIG_MN10300_TTYSM0
 	case SC0RXIRQ:
 	case SC0TXIRQ:

arch/mn10300/kernel/smp.c

@@ -439,6 +439,22 @@ int smp_nmi_call_function(smp_call_func_t func, void *info, int wait)
 	return ret;
 }
 
+/**
+ * smp_jump_to_debugger - Make other CPUs enter the debugger by sending an IPI
+ *
+ * Send a non-maskable request to all other CPUs in the system, instructing
+ * them to jump into the debugger.  The caller is responsible for checking that
+ * the other CPUs responded to the instruction.
+ *
+ * The caller should make sure that this CPU's debugger IPI is disabled.
+ */
+void smp_jump_to_debugger(void)
+{
+	if (num_online_cpus() > 1)
+		/* Send a message to all other CPUs */
+		send_IPI_allbutself(DEBUGGER_NMI_IPI);
+}
+
 /**
  * stop_this_cpu - Callback to stop a CPU.
  * @unused: Callback context (ignored).
@@ -603,7 +619,7 @@ static void __init smp_cpu_init(void)
 /**
  * smp_prepare_cpu_init - Initialise CPU in startup_secondary
  *
- * Set interrupt level 0-6 setting and init ICR of gdbstub.
+ * Set interrupt level 0-6 setting and init ICR of the kernel debugger.
  */
 void smp_prepare_cpu_init(void)
 {
@@ -622,15 +638,15 @@ void smp_prepare_cpu_init(void)
 	for (loop = 0; loop < GxICR_NUM_IRQS; loop++)
 		GxICR(loop) = GxICR_LEVEL_6 | GxICR_DETECT;
 
-#ifdef CONFIG_GDBSTUB
-	/* initialise GDB-stub */
+#ifdef CONFIG_KERNEL_DEBUGGER
+	/* initialise the kernel debugger interrupt */
 	do {
 		unsigned long flags;
 		u16 tmp16;
 
 		flags = arch_local_cli_save();
-		GxICR(GDB_NMI_IPI) = GxICR_NMI | GxICR_ENABLE | GxICR_DETECT;
-		tmp16 = GxICR(GDB_NMI_IPI);
+		GxICR(DEBUGGER_NMI_IPI) = GxICR_NMI | GxICR_ENABLE | GxICR_DETECT;
+		tmp16 = GxICR(DEBUGGER_NMI_IPI);
 		arch_local_irq_restore(flags);
 	} while (0);
 #endif