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)

8 files changed, 25 insertions, 25 deletions

diff --git a/drivers/net/pcmcia/3c574_cs.c b/drivers/net/pcmcia/3c574_cs.c
index 2418cdb9d317..046009928526 100644
--- a/drivers/net/pcmcia/3c574_cs.c
+++ b/drivers/net/pcmcia/3c574_cs.c
@@ -238,7 +238,7 @@ static void tc574_reset(struct net_device *dev);
 static void media_check(unsigned long arg);
 static int el3_open(struct net_device *dev);
 static int el3_start_xmit(struct sk_buff *skb, struct net_device *dev);
-static irqreturn_t el3_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t el3_interrupt(int irq, void *dev_id);
 static void update_stats(struct net_device *dev);
 static struct net_device_stats *el3_get_stats(struct net_device *dev);
 static int el3_rx(struct net_device *dev, int worklimit);
@@ -817,7 +817,7 @@ static int el3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 }
 
 /* The EL3 interrupt handler. */
-static irqreturn_t el3_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t el3_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct el3_private *lp = netdev_priv(dev);
@@ -927,7 +927,7 @@ static void media_check(unsigned long arg)
 	if ((inw(ioaddr + EL3_STATUS) & IntLatch) && (inb(ioaddr + Timer) == 0xff)) {
 		if (!lp->fast_poll)
 			printk(KERN_INFO "%s: interrupt(s) dropped!\n", dev->name);
-		el3_interrupt(dev->irq, lp, NULL);
+		el3_interrupt(dev->irq, lp);
 		lp->fast_poll = HZ;
 	}
 	if (lp->fast_poll) {
diff --git a/drivers/net/pcmcia/3c589_cs.c b/drivers/net/pcmcia/3c589_cs.c
index a0e2b01c027c..231fa2c9ec6c 100644
--- a/drivers/net/pcmcia/3c589_cs.c
+++ b/drivers/net/pcmcia/3c589_cs.c
@@ -151,7 +151,7 @@ static void media_check(unsigned long arg);
 static int el3_config(struct net_device *dev, struct ifmap *map);
 static int el3_open(struct net_device *dev);
 static int el3_start_xmit(struct sk_buff *skb, struct net_device *dev);
-static irqreturn_t el3_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t el3_interrupt(int irq, void *dev_id);
 static void update_stats(struct net_device *dev);
 static struct net_device_stats *el3_get_stats(struct net_device *dev);
 static int el3_rx(struct net_device *dev);
@@ -645,7 +645,7 @@ static int el3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 }
 
 /* The EL3 interrupt handler. */
-static irqreturn_t el3_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t el3_interrupt(int irq, void *dev_id)
 {
     struct net_device *dev = (struct net_device *) dev_id;
     struct el3_private *lp = netdev_priv(dev);
@@ -748,7 +748,7 @@ static void media_check(unsigned long arg)
 	(inb(ioaddr + EL3_TIMER) == 0xff)) {
 	if (!lp->fast_poll)
 	    printk(KERN_WARNING "%s: interrupt(s) dropped!\n", dev->name);
-	el3_interrupt(dev->irq, lp, NULL);
+	el3_interrupt(dev->irq, lp);
 	lp->fast_poll = HZ;
     }
     if (lp->fast_poll) {
diff --git a/drivers/net/pcmcia/axnet_cs.c b/drivers/net/pcmcia/axnet_cs.c
index a8891a9000ac..e5f366910914 100644
--- a/drivers/net/pcmcia/axnet_cs.c
+++ b/drivers/net/pcmcia/axnet_cs.c
@@ -92,7 +92,7 @@ static int axnet_open(struct net_device *dev);
 static int axnet_close(struct net_device *dev);
 static int axnet_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 static const struct ethtool_ops netdev_ethtool_ops;
-static irqreturn_t ei_irq_wrapper(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t ei_irq_wrapper(int irq, void *dev_id);
 static void ei_watchdog(u_long arg);
 static void axnet_reset_8390(struct net_device *dev);
 
@@ -112,7 +112,7 @@ static void axdev_setup(struct net_device *dev);
 static void AX88190_init(struct net_device *dev, int startp);
 static int ax_open(struct net_device *dev);
 static int ax_close(struct net_device *dev);
-static irqreturn_t ax_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t ax_interrupt(int irq, void *dev_id);
 
 /*====================================================================*/
 
@@ -599,11 +599,11 @@ static void axnet_reset_8390(struct net_device *dev)
 
 /*====================================================================*/
 
-static irqreturn_t ei_irq_wrapper(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t ei_irq_wrapper(int irq, void *dev_id)
 {
     struct net_device *dev = dev_id;
     PRIV(dev)->stale = 0;
-    return ax_interrupt(irq, dev_id, regs);
+    return ax_interrupt(irq, dev_id);
 }
 
 static void ei_watchdog(u_long arg)
@@ -621,7 +621,7 @@ static void ei_watchdog(u_long arg)
     if (info->stale++ && (inb_p(nic_base + EN0_ISR) & ENISR_ALL)) {
 	if (!info->fast_poll)
 	    printk(KERN_INFO "%s: interrupt(s) dropped!\n", dev->name);
-	ei_irq_wrapper(dev->irq, dev, NULL);
+	ei_irq_wrapper(dev->irq, dev);
 	info->fast_poll = HZ;
     }
     if (info->fast_poll) {
@@ -1193,7 +1193,7 @@ static int ei_start_xmit(struct sk_buff *skb, struct net_device *dev)
  * needed.
  */
 
-static irqreturn_t ax_interrupt(int irq, void *dev_id, struct pt_regs * regs)
+static irqreturn_t ax_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
 	long e8390_base;
diff --git a/drivers/net/pcmcia/fmvj18x_cs.c b/drivers/net/pcmcia/fmvj18x_cs.c
index d682f30dea6e..65f6fdf43725 100644
--- a/drivers/net/pcmcia/fmvj18x_cs.c
+++ b/drivers/net/pcmcia/fmvj18x_cs.c
@@ -97,7 +97,7 @@ static int fjn_config(struct net_device *dev, struct ifmap *map);
 static int fjn_open(struct net_device *dev);
 static int fjn_close(struct net_device *dev);
 static int fjn_start_xmit(struct sk_buff *skb, struct net_device *dev);
-static irqreturn_t fjn_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t fjn_interrupt(int irq, void *dev_id);
 static void fjn_rx(struct net_device *dev);
 static void fjn_reset(struct net_device *dev);
 static struct net_device_stats *fjn_get_stats(struct net_device *dev);
@@ -733,7 +733,7 @@ module_exit(exit_fmvj18x_cs);
 
 /*====================================================================*/
 
-static irqreturn_t fjn_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t fjn_interrupt(int irq, void *dev_id)
 {
     struct net_device *dev = dev_id;
     local_info_t *lp = netdev_priv(dev);
diff --git a/drivers/net/pcmcia/nmclan_cs.c b/drivers/net/pcmcia/nmclan_cs.c
index 7d5687e94607..e77110e4c288 100644
--- a/drivers/net/pcmcia/nmclan_cs.c
+++ b/drivers/net/pcmcia/nmclan_cs.c
@@ -426,7 +426,7 @@ static int mace_open(struct net_device *dev);
 static int mace_close(struct net_device *dev);
 static int mace_start_xmit(struct sk_buff *skb, struct net_device *dev);
 static void mace_tx_timeout(struct net_device *dev);
-static irqreturn_t mace_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t mace_interrupt(int irq, void *dev_id);
 static struct net_device_stats *mace_get_stats(struct net_device *dev);
 static int mace_rx(struct net_device *dev, unsigned char RxCnt);
 static void restore_multicast_list(struct net_device *dev);
@@ -1002,7 +1002,7 @@ static int mace_start_xmit(struct sk_buff *skb, struct net_device *dev)
 mace_interrupt
 	The interrupt handler.
 ---------------------------------------------------------------------------- */
-static irqreturn_t mace_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t mace_interrupt(int irq, void *dev_id)
 {
   struct net_device *dev = (struct net_device *) dev_id;
   mace_private *lp = netdev_priv(dev);
diff --git a/drivers/net/pcmcia/pcnet_cs.c b/drivers/net/pcmcia/pcnet_cs.c
index a09c22840f63..0c00d182e7fd 100644
--- a/drivers/net/pcmcia/pcnet_cs.c
+++ b/drivers/net/pcmcia/pcnet_cs.c
@@ -109,7 +109,7 @@ static int pcnet_open(struct net_device *dev);
 static int pcnet_close(struct net_device *dev);
 static int ei_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 static const struct ethtool_ops netdev_ethtool_ops;
-static irqreturn_t ei_irq_wrapper(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t ei_irq_wrapper(int irq, void *dev_id);
 static void ei_watchdog(u_long arg);
 static void pcnet_reset_8390(struct net_device *dev);
 static int set_config(struct net_device *dev, struct ifmap *map);
@@ -1071,11 +1071,11 @@ static int set_config(struct net_device *dev, struct ifmap *map)
 
 /*====================================================================*/
 
-static irqreturn_t ei_irq_wrapper(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t ei_irq_wrapper(int irq, void *dev_id)
 {
     struct net_device *dev = dev_id;
     pcnet_dev_t *info;
-    irqreturn_t ret = ei_interrupt(irq, dev_id, regs);
+    irqreturn_t ret = ei_interrupt(irq, dev_id);
 
     if (ret == IRQ_HANDLED) {
 	    info = PRIV(dev);
@@ -1100,7 +1100,7 @@ static void ei_watchdog(u_long arg)
     if (info->stale++ && (inb_p(nic_base + EN0_ISR) & ENISR_ALL)) {
 	if (!info->fast_poll)
 	    printk(KERN_INFO "%s: interrupt(s) dropped!\n", dev->name);
-	ei_irq_wrapper(dev->irq, dev, NULL);
+	ei_irq_wrapper(dev->irq, dev);
 	info->fast_poll = HZ;
     }
     if (info->fast_poll) {
diff --git a/drivers/net/pcmcia/smc91c92_cs.c b/drivers/net/pcmcia/smc91c92_cs.c
index a2f3a0e2a005..20fcc3576202 100644
--- a/drivers/net/pcmcia/smc91c92_cs.c
+++ b/drivers/net/pcmcia/smc91c92_cs.c
@@ -287,7 +287,7 @@ static int smc_close(struct net_device *dev);
 static int smc_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 static void smc_tx_timeout(struct net_device *dev);
 static int smc_start_xmit(struct sk_buff *skb, struct net_device *dev);
-static irqreturn_t smc_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t smc_interrupt(int irq, void *dev_id);
 static void smc_rx(struct net_device *dev);
 static struct net_device_stats *smc_get_stats(struct net_device *dev);
 static void set_rx_mode(struct net_device *dev);
@@ -1545,7 +1545,7 @@ static void smc_eph_irq(struct net_device *dev)
 
 /*====================================================================*/
 
-static irqreturn_t smc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t smc_interrupt(int irq, void *dev_id)
 {
     struct net_device *dev = dev_id;
     struct smc_private *smc = netdev_priv(dev);
@@ -1966,7 +1966,7 @@ static void media_check(u_long arg)
     if (smc->watchdog++ && ((i>>8) & i)) {
 	if (!smc->fast_poll)
 	    printk(KERN_INFO "%s: interrupt(s) dropped!\n", dev->name);
-	smc_interrupt(dev->irq, smc, NULL);
+	smc_interrupt(dev->irq, smc);
 	smc->fast_poll = HZ;
     }
     if (smc->fast_poll) {
diff --git a/drivers/net/pcmcia/xirc2ps_cs.c b/drivers/net/pcmcia/xirc2ps_cs.c
index 62664c01eb45..f3914f58d67f 100644
--- a/drivers/net/pcmcia/xirc2ps_cs.c
+++ b/drivers/net/pcmcia/xirc2ps_cs.c
@@ -308,7 +308,7 @@ static void xirc2ps_detach(struct pcmcia_device *p_dev);
  * less on other parts of the kernel.
  */
 
-static irqreturn_t xirc2ps_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t xirc2ps_interrupt(int irq, void *dev_id);
 
 /****************
  * A linked list of "instances" of the device.  Each actual
@@ -1121,7 +1121,7 @@ static int xirc2ps_resume(struct pcmcia_device *link)
  * This is the Interrupt service route.
  */
 static irqreturn_t
-xirc2ps_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+xirc2ps_interrupt(int irq, void *dev_id)
 {
     struct net_device *dev = (struct net_device *)dev_id;
     local_info_t *lp = netdev_priv(dev);