IRQ: Maintain regs pointer globally rather than passing to IRQ handlers

Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)

14 files changed, 33 insertions, 37 deletions

diff --git a/drivers/input/serio/ambakmi.c b/drivers/input/serio/ambakmi.c
index 3df5eedf8f3..5a7b49c3553 100644
--- a/drivers/input/serio/ambakmi.c
+++ b/drivers/input/serio/ambakmi.c
@@ -37,14 +37,14 @@ struct amba_kmi_port {
 	unsigned int		open;
 };
 
-static irqreturn_t amba_kmi_int(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t amba_kmi_int(int irq, void *dev_id)
 {
 	struct amba_kmi_port *kmi = dev_id;
 	unsigned int status = readb(KMIIR);
 	int handled = IRQ_NONE;
 
 	while (status & KMIIR_RXINTR) {
-		serio_interrupt(kmi->io, readb(KMIDATA), 0, regs);
+		serio_interrupt(kmi->io, readb(KMIDATA), 0);
 		status = readb(KMIIR);
 		handled = IRQ_HANDLED;
 	}
diff --git a/drivers/input/serio/ct82c710.c b/drivers/input/serio/ct82c710.c
index bc6e87add09..0d35018c23a 100644
--- a/drivers/input/serio/ct82c710.c
+++ b/drivers/input/serio/ct82c710.c
@@ -71,9 +71,9 @@ static struct resource ct82c710_iores;
  * is waiting in the 82C710.
  */
 
-static irqreturn_t ct82c710_interrupt(int cpl, void *dev_id, struct pt_regs * regs)
+static irqreturn_t ct82c710_interrupt(int cpl, void *dev_id)
 {
-	return serio_interrupt(ct82c710_port, inb(CT82C710_DATA), 0, regs);
+	return serio_interrupt(ct82c710_port, inb(CT82C710_DATA), 0);
 }
 
 /*
diff --git a/drivers/input/serio/gscps2.c b/drivers/input/serio/gscps2.c
index cde036a9216..081fdc3c773 100644
--- a/drivers/input/serio/gscps2.c
+++ b/drivers/input/serio/gscps2.c
@@ -82,7 +82,7 @@ MODULE_DEVICE_TABLE(parisc, gscps2_device_tbl);
 #define GSC_ID_MOUSE		1
 
 
-static irqreturn_t gscps2_interrupt(int irq, void *dev, struct pt_regs *regs);
+static irqreturn_t gscps2_interrupt(int irq, void *dev);
 
 #define BUFFER_SIZE 0x0f
 
@@ -226,7 +226,7 @@ static LIST_HEAD(ps2port_list);
  * later.
  */
 
-static irqreturn_t gscps2_interrupt(int irq, void *dev, struct pt_regs *regs)
+static irqreturn_t gscps2_interrupt(int irq, void *dev)
 {
 	struct gscps2port *ps2port;
 
@@ -267,7 +267,7 @@ static irqreturn_t gscps2_interrupt(int irq, void *dev, struct pt_regs *regs)
 	    rxflags =	((status & GSC_STAT_TERR) ? SERIO_TIMEOUT : 0 ) |
 			((status & GSC_STAT_PERR) ? SERIO_PARITY  : 0 );
 
-	    serio_interrupt(ps2port->port, data, rxflags, regs);
+	    serio_interrupt(ps2port->port, data, rxflags);
 
 	  } /* while() */
 
diff --git a/drivers/input/serio/hp_sdc.c b/drivers/input/serio/hp_sdc.c
index a10348bb25e..ba7b920347e 100644
--- a/drivers/input/serio/hp_sdc.c
+++ b/drivers/input/serio/hp_sdc.c
@@ -202,7 +202,7 @@ static void hp_sdc_take (int irq, void *dev_id, uint8_t status, uint8_t data) {
 	}
 }
 
-static irqreturn_t hp_sdc_isr(int irq, void *dev_id, struct pt_regs * regs) {
+static irqreturn_t hp_sdc_isr(int irq, void *dev_id) {
 	uint8_t status, data;
 
 	status = hp_sdc_status_in8();
@@ -253,7 +253,7 @@ static irqreturn_t hp_sdc_isr(int irq, void *dev_id, struct pt_regs * regs) {
 }
 
 
-static irqreturn_t hp_sdc_nmisr(int irq, void *dev_id, struct pt_regs * regs) {
+static irqreturn_t hp_sdc_nmisr(int irq, void *dev_id) {
 	int status;
 	
 	status = hp_sdc_status_in8();
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 1bb0c76a925..09b06e605b5 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -108,7 +108,7 @@ static unsigned char i8042_kbd_irq_registered;
 static unsigned char i8042_aux_irq_registered;
 static struct platform_device *i8042_platform_device;
 
-static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t i8042_interrupt(int irq, void *dev_id);
 
 /*
  * The i8042_wait_read() and i8042_wait_write functions wait for the i8042 to
@@ -271,7 +271,7 @@ static int i8042_aux_write(struct serio *serio, unsigned char c)
  * characters later.
  */
 
-	i8042_interrupt(0, NULL, NULL);
+	i8042_interrupt(0, NULL);
 	return retval;
 }
 
@@ -309,7 +309,7 @@ static void i8042_stop(struct serio *serio)
  * to the upper layers.
  */
 
-static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t i8042_interrupt(int irq, void *dev_id)
 {
 	struct i8042_port *port;
 	unsigned long flags;
@@ -379,7 +379,7 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 	    dfl & SERIO_TIMEOUT ? ", timeout" : "");
 
 	if (likely(port->exists))
-		serio_interrupt(port->serio, data, dfl, regs);
+		serio_interrupt(port->serio, data, dfl);
 
 	ret = 1;
  out:
@@ -519,7 +519,7 @@ static int __devinit i8042_check_mux(void)
 static struct completion i8042_aux_irq_delivered __devinitdata;
 static int i8042_irq_being_tested __devinitdata;
 
-static irqreturn_t __devinit i8042_aux_test_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t __devinit i8042_aux_test_irq(int irq, void *dev_id)
 {
 	unsigned long flags;
 	unsigned char str, data;
@@ -905,7 +905,7 @@ static int i8042_resume(struct platform_device *dev)
 	if (i8042_ports[I8042_KBD_PORT_NO].serio)
 		i8042_enable_kbd_port();
 
-	i8042_interrupt(0, NULL, NULL);
+	i8042_interrupt(0, NULL);
 
 	return 0;
 }
diff --git a/drivers/input/serio/maceps2.c b/drivers/input/serio/maceps2.c
index f08a5d0cd5f..558200e96d0 100644
--- a/drivers/input/serio/maceps2.c
+++ b/drivers/input/serio/maceps2.c
@@ -72,8 +72,7 @@ static int maceps2_write(struct serio *dev, unsigned char val)
 	return -1;
 }
 
-static irqreturn_t maceps2_interrupt(int irq, void *dev_id,
-				     struct pt_regs *regs)
+static irqreturn_t maceps2_interrupt(int irq, void *dev_id)
 {
 	struct serio *dev = dev_id;
 	struct mace_ps2port *port = ((struct maceps2_data *)dev->port_data)->port;
@@ -81,7 +80,7 @@ static irqreturn_t maceps2_interrupt(int irq, void *dev_id,
 
 	if (port->status & PS2_STATUS_RX_FULL) {
 		byte = port->rx;
-		serio_interrupt(dev, byte & 0xff, 0, regs);
+		serio_interrupt(dev, byte & 0xff, 0);
         }
 
 	return IRQ_HANDLED;
diff --git a/drivers/input/serio/parkbd.c b/drivers/input/serio/parkbd.c
index a5c1fb3a4a5..688610e86a3 100644
--- a/drivers/input/serio/parkbd.c
+++ b/drivers/input/serio/parkbd.c
@@ -102,7 +102,7 @@ static int parkbd_write(struct serio *port, unsigned char c)
 	return 0;
 }
 
-static void parkbd_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static void parkbd_interrupt(int irq, void *dev_id)
 {
 
 	if (parkbd_writing) {
@@ -134,7 +134,7 @@ static void parkbd_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 		parkbd_buffer |= (parkbd_readlines() >> 1) << parkbd_counter++;
 
 		if (parkbd_counter == parkbd_mode + 10)
-			serio_interrupt(parkbd_port, (parkbd_buffer >> (2 - parkbd_mode)) & 0xff, 0, regs);
+			serio_interrupt(parkbd_port, (parkbd_buffer >> (2 - parkbd_mode)) & 0xff, 0);
 	}
 
 	parkbd_last = jiffies;
diff --git a/drivers/input/serio/pcips2.c b/drivers/input/serio/pcips2.c
index fb727c66525..ea5e3c6ddb6 100644
--- a/drivers/input/serio/pcips2.c
+++ b/drivers/input/serio/pcips2.c
@@ -58,7 +58,7 @@ static int pcips2_write(struct serio *io, unsigned char val)
 	return 0;
 }
 
-static irqreturn_t pcips2_interrupt(int irq, void *devid, struct pt_regs *regs)
+static irqreturn_t pcips2_interrupt(int irq, void *devid)
 {
 	struct pcips2_data *ps2if = devid;
 	unsigned char status, scancode;
@@ -80,7 +80,7 @@ static irqreturn_t pcips2_interrupt(int irq, void *devid, struct pt_regs *regs)
 		if (hweight8(scancode) & 1)
 			flag ^= SERIO_PARITY;
 
-		serio_interrupt(ps2if->io, scancode, flag, regs);
+		serio_interrupt(ps2if->io, scancode, flag);
 	} while (1);
 	return IRQ_RETVAL(handled);
 }
diff --git a/drivers/input/serio/q40kbd.c b/drivers/input/serio/q40kbd.c
index d3827c5fe11..cb89aff2e16 100644
--- a/drivers/input/serio/q40kbd.c
+++ b/drivers/input/serio/q40kbd.c
@@ -53,14 +53,14 @@ DEFINE_SPINLOCK(q40kbd_lock);
 static struct serio *q40kbd_port;
 static struct platform_device *q40kbd_device;
 
-static irqreturn_t q40kbd_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t q40kbd_interrupt(int irq, void *dev_id)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&q40kbd_lock, flags);
 
 	if (Q40_IRQ_KEYB_MASK & master_inb(INTERRUPT_REG))
-		serio_interrupt(q40kbd_port, master_inb(KEYCODE_REG), 0, regs);
+		serio_interrupt(q40kbd_port, master_inb(KEYCODE_REG), 0);
 
 	master_outb(-1, KEYBOARD_UNLOCK_REG);
 
diff --git a/drivers/input/serio/rpckbd.c b/drivers/input/serio/rpckbd.c
index 513d37fc1ac..49f84315cb3 100644
--- a/drivers/input/serio/rpckbd.c
+++ b/drivers/input/serio/rpckbd.c
@@ -56,7 +56,7 @@ static int rpckbd_write(struct serio *port, unsigned char val)
 	return 0;
 }
 
-static irqreturn_t rpckbd_rx(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t rpckbd_rx(int irq, void *dev_id)
 {
 	struct serio *port = dev_id;
 	unsigned int byte;
@@ -65,13 +65,13 @@ static irqreturn_t rpckbd_rx(int irq, void *dev_id, struct pt_regs *regs)
 	while (iomd_readb(IOMD_KCTRL) & (1 << 5)) {
 		byte = iomd_readb(IOMD_KARTRX);
 
-		serio_interrupt(port, byte, 0, regs);
+		serio_interrupt(port, byte, 0);
 		handled = IRQ_HANDLED;
 	}
 	return handled;
 }
 
-static irqreturn_t rpckbd_tx(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t rpckbd_tx(int irq, void *dev_id)
 {
 	return IRQ_HANDLED;
 }
diff --git a/drivers/input/serio/sa1111ps2.c b/drivers/input/serio/sa1111ps2.c
index ebd9976fc81..559508795af 100644
--- a/drivers/input/serio/sa1111ps2.c
+++ b/drivers/input/serio/sa1111ps2.c
@@ -40,7 +40,7 @@ struct ps2if {
  * at the most one, but we loop for safety.  If there was a
  * framing error, we have to manually clear the status.
  */
-static irqreturn_t ps2_rxint(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t ps2_rxint(int irq, void *dev_id)
 {
 	struct ps2if *ps2if = dev_id;
 	unsigned int scancode, flag, status;
@@ -58,7 +58,7 @@ static irqreturn_t ps2_rxint(int irq, void *dev_id, struct pt_regs *regs)
 		if (hweight8(scancode) & 1)
 			flag ^= SERIO_PARITY;
 
-		serio_interrupt(ps2if->io, scancode, flag, regs);
+		serio_interrupt(ps2if->io, scancode, flag);
 
 		status = sa1111_readl(ps2if->base + SA1111_PS2STAT);
         }
@@ -69,7 +69,7 @@ static irqreturn_t ps2_rxint(int irq, void *dev_id, struct pt_regs *regs)
 /*
  * Completion of ps2 write
  */
-static irqreturn_t ps2_txint(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t ps2_txint(int irq, void *dev_id)
 {
 	struct ps2if *ps2if = dev_id;
 	unsigned int status;
diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index 3e76ad71c9a..960fae3c3ce 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -911,7 +911,7 @@ void serio_close(struct serio *serio)
 }
 
 irqreturn_t serio_interrupt(struct serio *serio,
-		unsigned char data, unsigned int dfl, struct pt_regs *regs)
+		unsigned char data, unsigned int dfl)
 {
 	unsigned long flags;
 	irqreturn_t ret = IRQ_NONE;
@@ -919,7 +919,7 @@ irqreturn_t serio_interrupt(struct serio *serio,
 	spin_lock_irqsave(&serio->lock, flags);
 
         if (likely(serio->drv)) {
-                ret = serio->drv->interrupt(serio, data, dfl, regs);
+                ret = serio->drv->interrupt(serio, data, dfl);
 	} else if (!dfl && serio->registered) {
 		serio_rescan(serio);
 		ret = IRQ_HANDLED;
diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
index 71a8eea816c..ba2a2035d64 100644
--- a/drivers/input/serio/serio_raw.c
+++ b/drivers/input/serio/serio_raw.c
@@ -250,7 +250,7 @@ static struct file_operations serio_raw_fops = {
  *********************************************************************/
 
 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
-					unsigned int dfl, struct pt_regs *regs)
+					unsigned int dfl)
 {
 	struct serio_raw *serio_raw = serio_get_drvdata(serio);
 	struct serio_raw_list *list;
diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c
index 54a680cc704..e1a3a79ab3f 100644
--- a/drivers/input/serio/serport.c
+++ b/drivers/input/serio/serport.c
@@ -117,9 +117,6 @@ static void serport_ldisc_close(struct tty_struct *tty)
  * serport_ldisc_receive() is called by the low level tty driver when characters
  * are ready for us. We forward the characters, one by one to the 'interrupt'
  * routine.
- *
- * FIXME: We should get pt_regs from the tty layer and forward them to
- *	  serio_interrupt here.
  */
 
 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
@@ -134,7 +131,7 @@ static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *c
 		goto out;
 
 	for (i = 0; i < count; i++)
-		serio_interrupt(serport->serio, cp[i], 0, NULL);
+		serio_interrupt(serport->serio, cp[i], 0);
 
 out:
 	spin_unlock_irqrestore(&serport->lock, flags);