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)

11 files changed, 32 insertions, 46 deletions

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 66e411badf70..f56d6a0f0624 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -487,7 +487,7 @@ static void ads7846_timer(unsigned long handle)
         spin_unlock_irq(&ts->lock);
 }
 
-static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
+static irqreturn_t ads7846_irq(int irq, void *handle)
 {
         struct ads7846 *ts = handle;
         unsigned long flags;
diff --git a/drivers/input/touchscreen/corgi_ts.c b/drivers/input/touchscreen/corgi_ts.c
index 9b66271d3ba8..ca79b2246195 100644
--- a/drivers/input/touchscreen/corgi_ts.c
+++ b/drivers/input/touchscreen/corgi_ts.c
@@ -173,7 +173,7 @@ static int read_xydata(struct corgi_ts *corgi_ts)
         return 1;
 }
 
-static void new_data(struct corgi_ts *corgi_ts, struct pt_regs *regs)
+static void new_data(struct corgi_ts *corgi_ts)
 {
         if (corgi_ts->power_mode != PWR_MODE_ACTIVE)
                 return;
@@ -181,7 +181,6 @@ static void new_data(struct corgi_ts *corgi_ts, struct pt_regs *regs)
         if (!corgi_ts->tc.pressure && corgi_ts->pendown == 0)
                 return;
 
-        input_regs(corgi_ts->input, regs);
         input_report_abs(corgi_ts->input, ABS_X, corgi_ts->tc.x);
         input_report_abs(corgi_ts->input, ABS_Y, corgi_ts->tc.y);
         input_report_abs(corgi_ts->input, ABS_PRESSURE, corgi_ts->tc.pressure);
@@ -189,14 +188,14 @@ static void new_data(struct corgi_ts *corgi_ts, struct pt_regs *regs)
         input_sync(corgi_ts->input);
 }
 
-static void ts_interrupt_main(struct corgi_ts *corgi_ts, int isTimer, struct pt_regs *regs)
+static void ts_interrupt_main(struct corgi_ts *corgi_ts, int isTimer)
 {
         if ((GPLR(IRQ_TO_GPIO(corgi_ts->irq_gpio)) & GPIO_bit(IRQ_TO_GPIO(corgi_ts->irq_gpio))) == 0) {
                 /* Disable Interrupt */
                 set_irq_type(corgi_ts->irq_gpio, IRQT_NOEDGE);
                 if (read_xydata(corgi_ts)) {
                         corgi_ts->pendown = 1;
-                        new_data(corgi_ts, regs);
+                        new_data(corgi_ts);
                 }
                 mod_timer(&corgi_ts->timer, jiffies + HZ / 100);
         } else {
@@ -208,7 +207,7 @@ static void ts_interrupt_main(struct corgi_ts *corgi_ts, int isTimer, struct pt_
 
                 if (corgi_ts->pendown) {
                         corgi_ts->tc.pressure = 0;
-                        new_data(corgi_ts, regs);
+                        new_data(corgi_ts);
                 }
 
                 /* Enable Falling Edge */
@@ -223,10 +222,10 @@ static void corgi_ts_timer(unsigned long data)
         ts_interrupt_main(corgits_data, 1, NULL);
 }
 
-static irqreturn_t ts_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t ts_interrupt(int irq, void *dev_id)
 {
         struct corgi_ts *corgits_data = dev_id;
-        ts_interrupt_main(corgits_data, 0, regs);
+        ts_interrupt_main(corgits_data, 0);
         return IRQ_HANDLED;
 }
 
diff --git a/drivers/input/touchscreen/elo.c b/drivers/input/touchscreen/elo.c
index ab565335ee44..913e1b73bb0e 100644
--- a/drivers/input/touchscreen/elo.c
+++ b/drivers/input/touchscreen/elo.c
@@ -67,7 +67,7 @@ struct elo {
         char phys[32];
 };
 
-static void elo_process_data_10(struct elo *elo, unsigned char data, struct pt_regs *regs)
+static void elo_process_data_10(struct elo *elo, unsigned char data)
 {
         struct input_dev *dev = elo->dev;
 
@@ -95,7 +95,6 @@ static void elo_process_data_10(struct elo *elo, unsigned char data, struct pt_r
                                 break;
                         }
                         if (likely(elo->data[1] == ELO10_TOUCH_PACKET)) {
-                                input_regs(dev, regs);
                                 input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
                                 input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
                                 if (elo->data[2] & ELO10_PRESSURE)
@@ -116,7 +115,7 @@ static void elo_process_data_10(struct elo *elo, unsigned char data, struct pt_r
         elo->csum += data;
 }
 
-static void elo_process_data_6(struct elo *elo, unsigned char data, struct pt_regs *regs)
+static void elo_process_data_6(struct elo *elo, unsigned char data)
 {
         struct input_dev *dev = elo->dev;
 
@@ -134,7 +133,6 @@ static void elo_process_data_6(struct elo *elo, unsigned char data, struct pt_re
                                 break;
                         }
 
-                        input_regs(dev, regs);
                         input_report_abs(dev, ABS_X, ((elo->data[0] & 0x3f) << 6) | (elo->data[1] & 0x3f));
                         input_report_abs(dev, ABS_Y, ((elo->data[2] & 0x3f) << 6) | (elo->data[3] & 0x3f));
 
@@ -164,7 +162,7 @@ static void elo_process_data_6(struct elo *elo, unsigned char data, struct pt_re
         }
 }
 
-static void elo_process_data_3(struct elo *elo, unsigned char data, struct pt_regs *regs)
+static void elo_process_data_3(struct elo *elo, unsigned char data)
 {
         struct input_dev *dev = elo->dev;
 
@@ -177,7 +175,6 @@ static void elo_process_data_3(struct elo *elo, unsigned char data, struct pt_re
                                 elo->idx = 0;
                         break;
                 case 2:
-                        input_regs(dev, regs);
                         input_report_key(dev, BTN_TOUCH, !(elo->data[1] & 0x80));
                         input_report_abs(dev, ABS_X, elo->data[1]);
                         input_report_abs(dev, ABS_Y, elo->data[2]);
@@ -188,22 +185,22 @@ static void elo_process_data_3(struct elo *elo, unsigned char data, struct pt_re
 }
 
 static irqreturn_t elo_interrupt(struct serio *serio,
-                unsigned char data, unsigned int flags, struct pt_regs *regs)
+                unsigned char data, unsigned int flags)
 {
         struct elo *elo = serio_get_drvdata(serio);
 
         switch(elo->id) {
                 case 0:
-                        elo_process_data_10(elo, data, regs);
+                        elo_process_data_10(elo, data);
                         break;
 
                 case 1:
                 case 2:
-                        elo_process_data_6(elo, data, regs);
+                        elo_process_data_6(elo, data);
                         break;
 
                 case 3:
-                        elo_process_data_3(elo, data, regs);
+                        elo_process_data_3(elo, data);
                         break;
         }
 
diff --git a/drivers/input/touchscreen/gunze.c b/drivers/input/touchscreen/gunze.c
index b769b21973b7..817c2198933d 100644
--- a/drivers/input/touchscreen/gunze.c
+++ b/drivers/input/touchscreen/gunze.c
@@ -60,7 +60,7 @@ struct gunze {
         char phys[32];
 };
 
-static void gunze_process_packet(struct gunze* gunze, struct pt_regs *regs)
+static void gunze_process_packet(struct gunze* gunze)
 {
         struct input_dev *dev = gunze->dev;
 
@@ -70,7 +70,6 @@ static void gunze_process_packet(struct gunze* gunze, struct pt_regs *regs)
                 return;
         }
 
-        input_regs(dev, regs);
         input_report_abs(dev, ABS_X, simple_strtoul(gunze->data + 1, NULL, 10));
         input_report_abs(dev, ABS_Y, 1024 - simple_strtoul(gunze->data + 6, NULL, 10));
         input_report_key(dev, BTN_TOUCH, gunze->data[0] == 'T');
@@ -78,12 +77,12 @@ static void gunze_process_packet(struct gunze* gunze, struct pt_regs *regs)
 }
 
 static irqreturn_t gunze_interrupt(struct serio *serio,
-                unsigned char data, unsigned int flags, struct pt_regs *regs)
+                unsigned char data, unsigned int flags)
 {
         struct gunze* gunze = serio_get_drvdata(serio);
 
         if (data == '\r') {
-                gunze_process_packet(gunze, regs);
+                gunze_process_packet(gunze);
                 gunze->idx = 0;
         } else {
                 if (gunze->idx < GUNZE_MAX_LENGTH)
diff --git a/drivers/input/touchscreen/h3600_ts_input.c b/drivers/input/touchscreen/h3600_ts_input.c
index e2b910018773..d9e61ee05ea9 100644
--- a/drivers/input/touchscreen/h3600_ts_input.c
+++ b/drivers/input/touchscreen/h3600_ts_input.c
@@ -106,19 +106,18 @@ struct h3600_dev {
         char phys[32];
 };
 
-static irqreturn_t action_button_handler(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t action_button_handler(int irq, void *dev_id)
 {
         int down = (GPLR & GPIO_BITSY_ACTION_BUTTON) ? 0 : 1;
         struct input_dev *dev = (struct input_dev *) dev_id;
 
-        input_regs(dev, regs);
         input_report_key(dev, KEY_ENTER, down);
         input_sync(dev);
 
         return IRQ_HANDLED;
 }
 
-static irqreturn_t npower_button_handler(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t npower_button_handler(int irq, void *dev_id)
 {
         int down = (GPLR & GPIO_BITSY_NPOWER_BUTTON) ? 0 : 1;
         struct input_dev *dev = (struct input_dev *) dev_id;
@@ -127,7 +126,6 @@ static irqreturn_t npower_button_handler(int irq, void *dev_id, struct pt_regs *
          * This interrupt is only called when we release the key. So we have
          * to fake a key press.
          */
-        input_regs(dev, regs);
         input_report_key(dev, KEY_SUSPEND, 1);
         input_report_key(dev, KEY_SUSPEND, down);
         input_sync(dev);
@@ -165,14 +163,12 @@ unsigned int h3600_flite_power(struct input_dev *dev, enum flite_pwr pwr)
  * packets. Some packets coming from serial are not touchscreen related. In
  * this case we send them off to be processed elsewhere.
  */
-static void h3600ts_process_packet(struct h3600_dev *ts, struct pt_regs *regs)
+static void h3600ts_process_packet(struct h3600_dev *ts)
 {
         struct input_dev *dev = ts->dev;
         static int touched = 0;
         int key, down = 0;
 
-        input_regs(dev, regs);
-
         switch (ts->event) {
                 /*
                    Buttons - returned as a single byte
@@ -301,7 +297,7 @@ static int state;
 #define STATE_EOF       3       /* state where we decode checksum or EOF */
 
 static irqreturn_t h3600ts_interrupt(struct serio *serio, unsigned char data,
-                                     unsigned int flags, struct pt_regs *regs)
+                                     unsigned int flags)
 {
         struct h3600_dev *ts = serio_get_drvdata(serio);
 
@@ -333,7 +329,7 @@ static irqreturn_t h3600ts_interrupt(struct serio *serio, unsigned char data,
                 case STATE_EOF:
                         state = STATE_SOF;
                         if (data == CHAR_EOF || data == ts->chksum)
-                                h3600ts_process_packet(ts, regs);
+                                h3600ts_process_packet(ts);
                         break;
                 default:
                         printk("Error3\n");
diff --git a/drivers/input/touchscreen/hp680_ts_input.c b/drivers/input/touchscreen/hp680_ts_input.c
index ee6c2f40cdf6..e31c6c55b2e2 100644
--- a/drivers/input/touchscreen/hp680_ts_input.c
+++ b/drivers/input/touchscreen/hp680_ts_input.c
@@ -66,7 +66,7 @@ static void do_softint(void *data)
         enable_irq(HP680_TS_IRQ);
 }
 
-static irqreturn_t hp680_ts_interrupt(int irq, void *dev, struct pt_regs *regs)
+static irqreturn_t hp680_ts_interrupt(int irq, void *dev)
 {
         disable_irq_nosync(irq);
         schedule_delayed_work(&work, HZ / 20);
diff --git a/drivers/input/touchscreen/mk712.c b/drivers/input/touchscreen/mk712.c
index 3226830eea08..4cbcaa6a71e5 100644
--- a/drivers/input/touchscreen/mk712.c
+++ b/drivers/input/touchscreen/mk712.c
@@ -80,7 +80,7 @@ MODULE_PARM_DESC(irq, "IRQ of MK712 touchscreen controller");
 static struct input_dev *mk712_dev;
 static DEFINE_SPINLOCK(mk712_lock);
 
-static irqreturn_t mk712_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t mk712_interrupt(int irq, void *dev_id)
 {
         unsigned char status;
         static int debounce = 1;
@@ -88,7 +88,6 @@ static irqreturn_t mk712_interrupt(int irq, void *dev_id, struct pt_regs *regs)
         static unsigned short last_y;
 
         spin_lock(&mk712_lock);
-        input_regs(mk712_dev, regs);
 
         status = inb(mk712_io + MK712_STATUS);
 
diff --git a/drivers/input/touchscreen/mtouch.c b/drivers/input/touchscreen/mtouch.c
index 8647a905df80..3b4c61664b63 100644
--- a/drivers/input/touchscreen/mtouch.c
+++ b/drivers/input/touchscreen/mtouch.c
@@ -63,12 +63,11 @@ struct mtouch {
         char phys[32];
 };
 
-static void mtouch_process_format_tablet(struct mtouch *mtouch, struct pt_regs *regs)
+static void mtouch_process_format_tablet(struct mtouch *mtouch)
 {
         struct input_dev *dev = mtouch->dev;
 
         if (MTOUCH_FORMAT_TABLET_LENGTH == ++mtouch->idx) {
-                input_regs(dev, regs);
                 input_report_abs(dev, ABS_X, MTOUCH_GET_XC(mtouch->data));
                 input_report_abs(dev, ABS_Y, MTOUCH_MAX_YC - MTOUCH_GET_YC(mtouch->data));
                 input_report_key(dev, BTN_TOUCH, MTOUCH_GET_TOUCHED(mtouch->data));
@@ -78,7 +77,7 @@ static void mtouch_process_format_tablet(struct mtouch *mtouch, struct pt_regs *
         }
 }
 
-static void mtouch_process_response(struct mtouch *mtouch, struct pt_regs *regs)
+static void mtouch_process_response(struct mtouch *mtouch)
 {
         if (MTOUCH_RESPONSE_END_BYTE == mtouch->data[mtouch->idx++]) {
                 /* FIXME - process response */
@@ -90,16 +89,16 @@ static void mtouch_process_response(struct mtouch *mtouch, struct pt_regs *regs)
 }
 
 static irqreturn_t mtouch_interrupt(struct serio *serio,
-                unsigned char data, unsigned int flags, struct pt_regs *regs)
+                unsigned char data, unsigned int flags)
 {
         struct mtouch* mtouch = serio_get_drvdata(serio);
 
         mtouch->data[mtouch->idx] = data;
 
         if (MTOUCH_FORMAT_TABLET_STATUS_BIT & mtouch->data[0])
-                mtouch_process_format_tablet(mtouch, regs);
+                mtouch_process_format_tablet(mtouch);
         else if (MTOUCH_RESPONSE_BEGIN_BYTE == mtouch->data[0])
-                mtouch_process_response(mtouch, regs);
+                mtouch_process_response(mtouch);
         else
                 printk(KERN_DEBUG "mtouch.c: unknown/unsynchronized data from device, byte %x\n",mtouch->data[0]);
 
diff --git a/drivers/input/touchscreen/penmount.c b/drivers/input/touchscreen/penmount.c
index f7370109d43e..6c7d0c2c76cc 100644
--- a/drivers/input/touchscreen/penmount.c
+++ b/drivers/input/touchscreen/penmount.c
@@ -46,7 +46,7 @@ struct pm {
 };
 
 static irqreturn_t pm_interrupt(struct serio *serio,
-                unsigned char data, unsigned int flags, struct pt_regs *regs)
+                unsigned char data, unsigned int flags)
 {
         struct pm *pm = serio_get_drvdata(serio);
         struct input_dev *dev = pm->dev;
@@ -55,7 +55,6 @@ static irqreturn_t pm_interrupt(struct serio *serio,
 
         if (pm->data[0] & 0x80) {
                 if (PM_MAX_LENGTH == ++pm->idx) {
-                        input_regs(dev, regs);
                         input_report_abs(dev, ABS_X, pm->data[2] * 128 + pm->data[1]);
                         input_report_abs(dev, ABS_Y, pm->data[4] * 128 + pm->data[3]);
                         input_report_key(dev, BTN_TOUCH, !!(pm->data[0] & 0x40));
diff --git a/drivers/input/touchscreen/touchright.c b/drivers/input/touchscreen/touchright.c
index 1c89fa538651..c74f74e57af0 100644
--- a/drivers/input/touchscreen/touchright.c
+++ b/drivers/input/touchscreen/touchright.c
@@ -56,7 +56,7 @@ struct tr {
 };
 
 static irqreturn_t tr_interrupt(struct serio *serio,
-                unsigned char data, unsigned int flags, struct pt_regs *regs)
+                unsigned char data, unsigned int flags)
 {
         struct tr *tr = serio_get_drvdata(serio);
         struct input_dev *dev = tr->dev;
@@ -65,7 +65,6 @@ static irqreturn_t tr_interrupt(struct serio *serio,
 
         if ((tr->data[0] & TR_FORMAT_STATUS_MASK) == TR_FORMAT_STATUS_BYTE) {
                 if (++tr->idx == TR_LENGTH) {
-                        input_regs(dev, regs);
                         input_report_abs(dev, ABS_X,
                                 (tr->data[1] << 5) | (tr->data[2] >> 1));
                         input_report_abs(dev, ABS_Y,
diff --git a/drivers/input/touchscreen/touchwin.c b/drivers/input/touchscreen/touchwin.c
index a7b4c755958e..9911820fa2fe 100644
--- a/drivers/input/touchscreen/touchwin.c
+++ b/drivers/input/touchscreen/touchwin.c
@@ -60,7 +60,7 @@ struct tw {
 };
 
 static irqreturn_t tw_interrupt(struct serio *serio,
-                unsigned char data, unsigned int flags, struct pt_regs *regs)
+                unsigned char data, unsigned int flags)
 {
         struct tw *tw = serio_get_drvdata(serio);
         struct input_dev *dev = tw->dev;
@@ -70,7 +70,6 @@ static irqreturn_t tw_interrupt(struct serio *serio,
                 tw->data[tw->idx++] = data;
                 /* verify length and that the two Y's are the same */
                 if (tw->idx == TW_LENGTH && tw->data[1] == tw->data[2]) {
-                        input_regs(dev, regs);
                         input_report_abs(dev, ABS_X, tw->data[0]);
                         input_report_abs(dev, ABS_Y, tw->data[1]);
                         input_report_key(dev, BTN_TOUCH, 1);