[PATCH 0/3] Remove interrupt debug code

[PATCH 0/3] Remove interrupt debug code

[Finn Thain]

This patch series removes some interrupt debug code:
printk statements, associated macros, dead code, etc.


Finn Thain (3):
  m68k/mac: Improve NMI handler
  m68k/mac: Remove SHUTUP_SONIC interrupt hack
  m68k/mac: Clean up interrupt debug macros and printk statements

 arch/m68k/include/asm/macints.h | 16 --------
 arch/m68k/mac/baboon.c          | 16 --------
 arch/m68k/mac/macints.c         | 87 ++++-------------------------------------
 arch/m68k/mac/oss.c             | 20 ----------
 arch/m68k/mac/psc.c             | 11 ------
 arch/m68k/mac/via.c             |  8 ----
 6 files changed, 8 insertions(+), 150 deletions(-)

-- 
2.10.2

[PATCH 2/3] m68k/mac: Remove SHUTUP_SONIC interrupt hack

[Finn Thain]

In macints.c there is some startup code which disables the SONIC interrupt
in an attempt to avoid an unhandled slot interrupt, which would be fatal.
This only works on those machines where the SONIC device is on-board.

When the mac_sonic driver is built-in, there's little point in doing this,
because the device will be initialized a few seconds later anyway. But
when mac_sonic is a module, the window for an unhandled interrupt is
longer.

Either way, we've already run the gauntlet for 5 or 10 seconds by the time
we get around to disabling this particular device. It's only by sheer luck
that we got this far.

Really, this is too little too late. The general problem of unhandled
early interrupts also affects other devices on other models. There are
better ways to resolve this problem.

1) When using the Penguin bootloader, boot Mac OS with extensions disabled
   (by holding down the shift key at startup or by use of the Extensions
   Manager control panel). The Penguin docs already contain this advice,
   as it is always effective.

2) Have the Penguin bootloader disable the device. It already attempts
   to disable slot interrupts. But since some hardware cannot mask slot
   interrupts, Penguin should probably close the relevant device
   drivers.

3) Use Emile instead of Penguin. AFAIK the boot ROM never enables network
   device interrupts and hence they don't need to be disabled.

Remove this hack. It requires maintenance and it doesn't solve the
problem. It improves the odds for a few models, but so does setting
CONFIG_MAC_SONIC=y.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
---
 arch/m68k/mac/macints.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/arch/m68k/mac/macints.c b/arch/m68k/mac/macints.c
index f9672bb..1244d36 100644
--- a/arch/m68k/mac/macints.c
+++ b/arch/m68k/mac/macints.c
@@ -125,8 +125,6 @@
 #include <asm/hwtest.h>
 #include <asm/irq_regs.h>
 
-#define SHUTUP_SONIC
-
 extern void show_registers(struct pt_regs *);
 
 irqreturn_t mac_nmi_handler(int, void *);
@@ -151,16 +149,6 @@ void __init mac_init_IRQ(void)
 #endif
 	m68k_setup_irq_controller(&mac_irq_chip, handle_simple_irq, IRQ_USER,
 				  NUM_MAC_SOURCES - IRQ_USER);
-	/* Make sure the SONIC interrupt is cleared or things get ugly */
-#ifdef SHUTUP_SONIC
-	printk("Killing onboard sonic... ");
-	/* This address should hopefully be mapped already */
-	if (hwreg_present((void*)(0x50f0a000))) {
-		*(long *)(0x50f0a014) = 0x7fffL;
-		*(long *)(0x50f0a010) = 0L;
-	}
-	printk("Done.\n");
-#endif /* SHUTUP_SONIC */
 
 	/*
 	 * Now register the handlers for the master IRQ handlers
-- 
2.10.2

[PATCH 3/3] m68k/mac: Clean up interrupt debug macros and printk statements

[Finn Thain]

Mac interrupt code has been debugged. The Penguin deficiencies that
still cause unhandled interrupts aren't fixable here. Besides,
interrupts are fast and frequent and these printk statements
were never really useful IMO. Remove them.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 arch/m68k/include/asm/macints.h | 16 ----------------
 arch/m68k/mac/baboon.c          | 16 ----------------
 arch/m68k/mac/macints.c         |  8 --------
 arch/m68k/mac/oss.c             | 20 --------------------
 arch/m68k/mac/psc.c             | 11 -----------
 arch/m68k/mac/via.c             |  8 --------
 6 files changed, 79 deletions(-)

diff --git a/arch/m68k/include/asm/macints.h b/arch/m68k/include/asm/macints.h
index 92aa8a4..cddb2d3 100644
--- a/arch/m68k/include/asm/macints.h
+++ b/arch/m68k/include/asm/macints.h
@@ -14,22 +14,6 @@
 
 #include <asm/irq.h>
 
-/* Setting this prints debugging info for unclaimed interrupts */
-
-#define DEBUG_SPURIOUS
-
-/* Setting this prints debugging info on each autovector interrupt */
-
-/* #define DEBUG_IRQS */
-
-/* Setting this prints debugging info on each Nubus interrupt */
-
-/* #define DEBUG_NUBUS_INT */
-
-/* Setting this prints debugging info on irqs as they enabled and disabled. */
-
-/* #define DEBUG_IRQUSE */
-
 /*
  * Base IRQ number for all Mac68K interrupt sources. Each source
  * has eight indexes (base -> base+7).
diff --git a/arch/m68k/mac/baboon.c b/arch/m68k/mac/baboon.c
index f6f7d42..514acde 100644
--- a/arch/m68k/mac/baboon.c
+++ b/arch/m68k/mac/baboon.c
@@ -14,8 +14,6 @@
 #include <asm/macints.h>
 #include <asm/mac_baboon.h>
 
-/* #define DEBUG_IRQS */
-
 int baboon_present;
 static volatile struct baboon *baboon;
 
@@ -50,12 +48,6 @@ static void baboon_irq(struct irq_desc *desc)
 	int irq_bit, irq_num;
 	unsigned char events;
 
-#ifdef DEBUG_IRQS
-	printk("baboon_irq: mb_control %02X mb_ifr %02X mb_status %02X\n",
-		(uint) baboon->mb_control, (uint) baboon->mb_ifr,
-		(uint) baboon->mb_status);
-#endif
-
 	events = baboon->mb_ifr & 0x07;
 	if (!events)
 		return;
@@ -97,18 +89,10 @@ void __init baboon_register_interrupts(void)
 
 void baboon_irq_enable(int irq)
 {
-#ifdef DEBUG_IRQUSE
-	printk("baboon_irq_enable(%d)\n", irq);
-#endif
-
 	mac_irq_enable(irq_get_irq_data(IRQ_NUBUS_C));
 }
 
 void baboon_irq_disable(int irq)
 {
-#ifdef DEBUG_IRQUSE
-	printk("baboon_irq_disable(%d)\n", irq);
-#endif
-
 	mac_irq_disable(irq_get_irq_data(IRQ_NUBUS_C));
 }
diff --git a/arch/m68k/mac/macints.c b/arch/m68k/mac/macints.c
index 1244d36..b5cd06d 100644
--- a/arch/m68k/mac/macints.c
+++ b/arch/m68k/mac/macints.c
@@ -129,8 +129,6 @@ extern void show_registers(struct pt_regs *);
 
 irqreturn_t mac_nmi_handler(int, void *);
 
-/* #define DEBUG_MACINTS */
-
 static unsigned int mac_irq_startup(struct irq_data *);
 static void mac_irq_shutdown(struct irq_data *);
 
@@ -144,9 +142,6 @@ static struct irq_chip mac_irq_chip = {
 
 void __init mac_init_IRQ(void)
 {
-#ifdef DEBUG_MACINTS
-	printk("mac_init_IRQ(): Setting things up...\n");
-#endif
 	m68k_setup_irq_controller(&mac_irq_chip, handle_simple_irq, IRQ_USER,
 				  NUM_MAC_SOURCES - IRQ_USER);
 
@@ -167,9 +162,6 @@ void __init mac_init_IRQ(void)
 	if (request_irq(IRQ_AUTO_7, mac_nmi_handler, 0, "NMI",
 			mac_nmi_handler))
 		pr_err("Couldn't register NMI\n");
-#ifdef DEBUG_MACINTS
-	printk("mac_init_IRQ(): Done!\n");
-#endif
 }
 
 /*
diff --git a/arch/m68k/mac/oss.c b/arch/m68k/mac/oss.c
index 55d65927..ca84dcf 100644
--- a/arch/m68k/mac/oss.c
+++ b/arch/m68k/mac/oss.c
@@ -68,15 +68,6 @@ static void oss_irq(struct irq_desc *desc)
 	int events = oss->irq_pending &
 		(OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM);
 
-#ifdef DEBUG_IRQS
-	if ((console_loglevel == 10) && !(events & OSS_IP_SCSI)) {
-		unsigned int irq = irq_desc_get_irq(desc);
-
-		printk("oss_irq: irq %u events = 0x%04X\n", irq,
-			(int) oss->irq_pending);
-	}
-#endif
-
 	if (events & OSS_IP_IOPSCC) {
 		oss->irq_pending &= ~OSS_IP_IOPSCC;
 		generic_handle_irq(IRQ_MAC_SCC);
@@ -107,11 +98,6 @@ static void oss_nubus_irq(struct irq_desc *desc)
 	if (!events)
 		return;
 
-#ifdef DEBUG_NUBUS_INT
-	if (console_loglevel > 7) {
-		printk("oss_nubus_irq: events = 0x%04X\n", events);
-	}
-#endif
 	/* There are only six slots on the OSS, not seven */
 
 	i = 6;
@@ -163,9 +149,6 @@ void __init oss_register_interrupts(void)
  */
 
 void oss_irq_enable(int irq) {
-#ifdef DEBUG_IRQUSE
-	printk("oss_irq_enable(%d)\n", irq);
-#endif
 	switch(irq) {
 		case IRQ_MAC_SCC:
 			oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
@@ -199,9 +182,6 @@ void oss_irq_enable(int irq) {
  */
 
 void oss_irq_disable(int irq) {
-#ifdef DEBUG_IRQUSE
-	printk("oss_irq_disable(%d)\n", irq);
-#endif
 	switch(irq) {
 		case IRQ_MAC_SCC:
 			oss->irq_level[OSS_IOPSCC] = 0;
diff --git a/arch/m68k/mac/psc.c b/arch/m68k/mac/psc.c
index cb2b1a3..439a2a2 100644
--- a/arch/m68k/mac/psc.c
+++ b/arch/m68k/mac/psc.c
@@ -122,11 +122,6 @@ static void psc_irq(struct irq_desc *desc)
 	int irq_num;
 	unsigned char irq_bit, events;
 
-#ifdef DEBUG_IRQS
-	printk("psc_irq: irq %u pIFR = 0x%02X pIER = 0x%02X\n",
-		irq, (int) psc_read_byte(pIFR), (int) psc_read_byte(pIER));
-#endif
-
 	events = psc_read_byte(pIFR) & psc_read_byte(pIER) & 0xF;
 	if (!events)
 		return;
@@ -160,9 +155,6 @@ void psc_irq_enable(int irq) {
 	int irq_idx	= IRQ_IDX(irq);
 	int pIER	= pIERbase + (irq_src << 4);
 
-#ifdef DEBUG_IRQUSE
-	printk("psc_irq_enable(%d)\n", irq);
-#endif
 	psc_write_byte(pIER, (1 << irq_idx) | 0x80);
 }
 
@@ -171,8 +163,5 @@ void psc_irq_disable(int irq) {
 	int irq_idx	= IRQ_IDX(irq);
 	int pIER	= pIERbase + (irq_src << 4);
 
-#ifdef DEBUG_IRQUSE
-	printk("psc_irq_disable(%d)\n", irq);
-#endif
 	psc_write_byte(pIER, 1 << irq_idx);
 }
diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index 920ff63..16629e9 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -550,10 +550,6 @@ void via_irq_enable(int irq) {
 	int irq_src	= IRQ_SRC(irq);
 	int irq_idx	= IRQ_IDX(irq);
 
-#ifdef DEBUG_IRQUSE
-	printk(KERN_DEBUG "via_irq_enable(%d)\n", irq);
-#endif
-
 	if (irq_src == 1) {
 		via1[vIER] = IER_SET_BIT(irq_idx);
 	} else if (irq_src == 2) {
@@ -582,10 +578,6 @@ void via_irq_disable(int irq) {
 	int irq_src	= IRQ_SRC(irq);
 	int irq_idx	= IRQ_IDX(irq);
 
-#ifdef DEBUG_IRQUSE
-	printk(KERN_DEBUG "via_irq_disable(%d)\n", irq);
-#endif
-
 	if (irq_src == 1) {
 		via1[vIER] = IER_CLR_BIT(irq_idx);
 	} else if (irq_src == 2) {
-- 
2.10.2

[PATCH 1/3] m68k/mac: Improve NMI handler

[Finn Thain]

mac_nmi_handler() is useless in its present form and locks up my PowerBook
180. Let's throw out the dead code and make it do something useful: print
a register dump and a stack trace.

mac_debug_handler() is also dead code. Remove it along with its static
data.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 arch/m68k/mac/macints.c | 67 ++++++-------------------------------------------
 1 file changed, 8 insertions(+), 59 deletions(-)

diff --git a/arch/m68k/mac/macints.c b/arch/m68k/mac/macints.c
index 9f98c08..f9672bb 100644
--- a/arch/m68k/mac/macints.c
+++ b/arch/m68k/mac/macints.c
@@ -127,12 +127,9 @@
 
 #define SHUTUP_SONIC
 
-/*
- * console_loglevel determines NMI handler function
- */
+extern void show_registers(struct pt_regs *);
 
 irqreturn_t mac_nmi_handler(int, void *);
-irqreturn_t mac_debug_handler(int, void *);
 
 /* #define DEBUG_MACINTS */
 
@@ -276,65 +273,17 @@ static void mac_irq_shutdown(struct irq_data *data)
 		mac_irq_disable(data);
 }
 
-static int num_debug[8];
-
-irqreturn_t mac_debug_handler(int irq, void *dev_id)
-{
-	if (num_debug[irq] < 10) {
-		printk("DEBUG: Unexpected IRQ %d\n", irq);
-		num_debug[irq]++;
-	}
-	return IRQ_HANDLED;
-}
-
-static int in_nmi;
-static volatile int nmi_hold;
+static volatile int in_nmi;
 
 irqreturn_t mac_nmi_handler(int irq, void *dev_id)
 {
-	int i;
-	/*
-	 * generate debug output on NMI switch if 'debug' kernel option given
-	 * (only works with Penguin!)
-	 */
-
-	in_nmi++;
-	for (i=0; i<100; i++)
-		udelay(1000);
-
-	if (in_nmi == 1) {
-		nmi_hold = 1;
-		printk("... pausing, press NMI to resume ...");
-	} else {
-		printk(" ok!\n");
-		nmi_hold = 0;
-	}
+	if (in_nmi)
+		return IRQ_HANDLED;
+	in_nmi = 1;
 
-	barrier();
+	pr_info("Non-Maskable Interrupt\n");
+	show_registers(get_irq_regs());
 
-	while (nmi_hold == 1)
-		udelay(1000);
-
-	if (console_loglevel >= 8) {
-#if 0
-		struct pt_regs *fp = get_irq_regs();
-		show_state();
-		printk("PC: %08lx\nSR: %04x  SP: %p\n", fp->pc, fp->sr, fp);
-		printk("d0: %08lx    d1: %08lx    d2: %08lx    d3: %08lx\n",
-		       fp->d0, fp->d1, fp->d2, fp->d3);
-		printk("d4: %08lx    d5: %08lx    a0: %08lx    a1: %08lx\n",
-		       fp->d4, fp->d5, fp->a0, fp->a1);
-
-		if (STACK_MAGIC != *(unsigned long *)current->kernel_stack_page)
-			printk("Corrupted stack page\n");
-		printk("Process %s (pid: %d, stackpage=%08lx)\n",
-			current->comm, current->pid, current->kernel_stack_page);
-		if (intr_count == 1)
-			dump_stack((struct frame *)fp);
-#else
-		/* printk("NMI "); */
-#endif
-	}
-	in_nmi--;
+	in_nmi = 0;
 	return IRQ_HANDLED;
 }
-- 
2.10.2

Re: [PATCH 1/3] m68k/mac: Improve NMI handler

[Geert Uytterhoeven]

Hi Finn,

On Mon, Jan 2, 2017 at 10:53 AM, Finn Thain <fthain@telegraphics.com.au> wrote:
> mac_nmi_handler() is useless in its present form and locks up my PowerBook
> 180. Let's throw out the dead code and make it do something useful: print
> a register dump and a stack trace.
>
> mac_debug_handler() is also dead code. Remove it along with its static
> data.

Thanks for your patch!

> --- a/arch/m68k/mac/macints.c
> +++ b/arch/m68k/mac/macints.c
> @@ -127,12 +127,9 @@
>
>  #define SHUTUP_SONIC
>
> -/*
> - * console_loglevel determines NMI handler function
> - */
> +extern void show_registers(struct pt_regs *);

Seems like we do have a declaration in ... <linux/kprobes.h>.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 1/3] m68k/mac: Improve NMI handler

[Finn Thain]

On Mon, 2 Jan 2017, Geert Uytterhoeven wrote:

> >
> > -/*
> > - * console_loglevel determines NMI handler function
> > - */
> > +extern void show_registers(struct pt_regs *);
> 
> Seems like we do have a declaration in ... <linux/kprobes.h>.
> 

Yes, and it would have to be moved outside of the #ifdef CONFIG_KPROBES 
portion before it could be used by m68k, openrisc, cris or mn10300, which 
all lack HAVE_KPROBES.

I can't see why linux/kprobes.h is more appropriate for this declaration 
than, say linux/sched.h.

Despite the checkpatch warning, placing the extern at the call site is 
very popular.

$ egrep -r "extern.*show_registers" arch/
arch/mips/kernel/unaligned.c:extern void show_registers(struct pt_regs *regs);
arch/openrisc/kernel/process.c: extern void show_registers(struct pt_regs *regs);
arch/cris/kernel/traps.c:extern void show_registers(struct pt_regs *regs);
arch/cris/mm/fault.c:extern void show_registers(struct pt_regs *regs);
arch/cris/arch-v32/mach-a3/arbiter.c:extern void show_registers(struct pt_regs *regs);
arch/cris/arch-v32/kernel/time.c:extern void show_registers(struct pt_regs *regs);
arch/cris/arch-v32/mach-fs/arbiter.c:extern void show_registers(struct pt_regs *regs);
arch/mn10300/include/asm/gdb-stub.h:extern void show_registers_only(struct pt_regs *regs);
arch/mn10300/include/asm/processor.h:extern void show_registers(struct pt_regs *regs);
arch/frv/include/asm/gdb-stub.h:extern void show_registers_only(struct pt_regs *regs);
$ 
$ egrep -r "extern.*show_registers" include/
include/linux/kprobes.h:extern void show_registers(struct pt_regs *regs);
$ 

The situation with show_regs(struct pt_regs *) is a bit better in that the 
declaration is not found at multiple call sites (as with cris) but still 
appears in multiple header files.

$ egrep -r "extern.*show_regs" arch/
arch/x86/include/asm/kdebug.h:extern void __show_regs(struct pt_regs *regs, int all);
arch/nios2/include/asm/ptrace.h:extern void show_regs(struct pt_regs *);
arch/arm/include/asm/bug.h:extern void __show_regs(struct pt_regs *);
arch/tile/include/asm/stack.h:extern void tile_show_regs(struct pt_regs *);
arch/arm64/include/asm/system_misc.h:extern void __show_regs(struct pt_regs *);
arch/c6x/include/asm/ptrace.h:extern void show_regs(struct pt_regs *);
arch/avr32/include/asm/processor.h:extern void show_regs_log_lvl(struct pt_regs *regs, const char *log_lvl);
arch/unicore32/kernel/setup.h:extern void __show_regs(struct pt_regs *);
arch/alpha/kernel/proto.h:extern void dik_show_regs(struct pt_regs *regs, unsigned long *r9_15);
$ 
$ egrep -r "extern.*show_regs" include/
include/linux/sched.h:extern void show_regs(struct pt_regs *);
$ 

I guess we could put a show_registers() declaration in 
arch/m68k/include/asm/ptrace.h, as that's where struct pt_regs definition 
comes from (actually uapi/asm/ptrace.h). Both nios2 and c6x do this for 
show_regs().

Or we could just leave the patch as it is, because thus far m68k has no 
need for any declaration except a sole call site in macints.c.

-- 

Re: [PATCH 1/3] m68k/mac: Improve NMI handler

[Geert Uytterhoeven]

Hi Finn,

On Tue, Jan 3, 2017 at 5:31 AM, Finn Thain <fthain@telegraphics.com.au> wrote:
> On Mon, 2 Jan 2017, Geert Uytterhoeven wrote:
>> >
>> > -/*
>> > - * console_loglevel determines NMI handler function
>> > - */
>> > +extern void show_registers(struct pt_regs *);
>>
>> Seems like we do have a declaration in ... <linux/kprobes.h>.
>
> Yes, and it would have to be moved outside of the #ifdef CONFIG_KPROBES
> portion before it could be used by m68k, openrisc, cris or mn10300, which
> all lack HAVE_KPROBES.

Right, seems my manual cpp made a mistake here. It's indeed inside.

> Or we could just leave the patch as it is, because thus far m68k has no
> need for any declaration except a sole call site in macints.c.

Fine for me. Sorry for the noise.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 0/3] Remove interrupt debug code

[Geert Uytterhoeven]

On Mon, Jan 2, 2017 at 10:53 AM, Finn Thain <fthain@telegraphics.com.au> wrote:
> This patch series removes some interrupt debug code:
> printk statements, associated macros, dead code, etc.
>
>
> Finn Thain (3):
>   m68k/mac: Improve NMI handler
>   m68k/mac: Remove SHUTUP_SONIC interrupt hack
>   m68k/mac: Clean up interrupt debug macros and printk statements

Thanks, applied and queued for v4.11.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds