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David Howells 7d12e780e0 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)
 		2006-10-05 15:10:12 +01:00
..
aty IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
backlight Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm 2006-09-28 14:40:39 -07:00
console IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
geode [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
i810 [PATCH] i810fb: Honor the return value of pci_enable_device 2006-10-03 08:04:11 -07:00
intelfb IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
kyro [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
logo Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
matrox IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
mbx [PATCH] mbxfb: Fix framebuffer size smaller than requested 2006-10-03 08:04:12 -07:00
nvidia [PATCH] nvidia fbdev: fix powerpc xmon scribbles 2006-10-03 08:04:13 -07:00
pnx4008 [PATCH] fbdev: Add framebuffer and display update module support for pnx4008 2006-07-03 15:26:59 -07:00
riva [PATCH] fbdev: riva warning fix 2006-10-04 07:55:24 -07:00
savage [PATCH] savagefb: Use generic DDC reading 2006-10-03 08:04:10 -07:00
sis [PATCH] drivers/video/sis/sis_main.h Removal of old code 2006-10-03 08:04:12 -07:00
68328fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
Kconfig Still more typo fixes 2006-10-03 22:36:44 +02:00
Makefile [PATCH] fbdev: Add generic ddc read functionality 2006-10-03 08:04:09 -07:00
S3triofb.c Merge branch 'merge' 2006-08-01 10:37:25 +10:00
acornfb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
acornfb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
amba-clcd.c [ARM] amba-clcd: Allow RGB555 and RGB565 with 16bpp 2006-01-26 14:12:06 +00:00
amifb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
arcfb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
asiliantfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
atafb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
au1100fb.c [PATCH] au1100fb: Add option to enable/disable the cursor 2006-10-03 08:04:09 -07:00
au1100fb.h Au1100 FB driver uplift for 2.6. 2005-10-29 19:31:01 +01:00
au1200fb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
au1200fb.h [PATCH] au1200fb: Alchemy Au1200 framebuffer driver 2006-03-27 08:44:55 -08:00
bt431.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
bt455.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
bw2.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
c2p.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
c2p.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cfbcopyarea.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
cfbfillrect.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
cfbimgblt.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
cg3.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
cg6.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
cg14.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
chipsfb.c [PATCH] powermac: Combined fixes for backlight code 2006-07-10 13:24:20 -07:00
cirrusfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
clps711xfb.c [PATCH] fbcon/fbdev: Move softcursor out of fbdev to fbcon 2005-11-07 07:53:50 -08:00
controlfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
controlfb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cyber2000fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
cyber2000fb.h Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
cyberfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
cyberfb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cyblafb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
dnfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
edid.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
epson1355fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
fb_ddc.c [PATCH] fbdev: Add generic ddc read functionality 2006-10-03 08:04:09 -07:00
fb_notify.c [PATCH] fbdev: statically link the framebuffer notification functions 2006-07-31 13:28:44 -07:00
fbcmap.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
fbcvt.c [PATCH] fbdev: Remove unused exports 2006-06-26 09:58:31 -07:00
fbmem.c [PATCH] fbdev: correct buffer size limit in fbmem_read_proc() 2006-10-03 08:04:13 -07:00
fbmon.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
fbsysfs.c [PATCH] fbdev: Honor the return value of device_create_file 2006-10-03 08:04:10 -07:00
ffb.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
fm2fb.c [PATCH] fbcon/fbdev: Move softcursor out of fbdev to fbcon 2005-11-07 07:53:50 -08:00
g364fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
gbefb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
hgafb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
hitfb.c video: hitfb suspend/resume and updates. 2006-09-27 13:47:22 +09:00
hpfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
igafb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
imacfb.c [PATCH] x86: Fix dmi detection of MacBookPro and iMac 2006-08-27 11:01:29 -07:00
imsttfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
imxfb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
imxfb.h [PATCH] ARM: 2687/1: i.MX framebuffer: make dmacr register platform configurable 2005-07-17 20:15:36 +01:00
leo.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
macfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
macmodes.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
macmodes.h [PATCH] macmodes: Fix section warning 2006-06-26 09:58:31 -07:00
maxinefb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
modedb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
neofb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
offb.c Merge branch 'merge' 2006-08-01 10:37:25 +10:00
p9100.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
platinumfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
platinumfb.h [PATCH] powerpc: Fix platinumfb for some modes 2006-01-09 14:53:51 +11:00
pm2fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
pm3fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
pmag-aa-fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
pmag-ba-fb.c [PATCH] remove bogus asm/bug.h includes. 2006-02-07 20:56:35 -05:00
pmagb-b-fb.c [PATCH] drivers/video: Use ARRAY_SIZE macro 2006-03-27 08:44:58 -08:00
pvr2fb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
pxafb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
pxafb.h [ARM] 3848/1: pxafb: Add option of fixing video modes and spitz QVGA mode support 2006-10-02 13:33:37 +01:00
q40fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
retz3fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
retz3fb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
s1d13xxxfb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
s3c2410fb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
s3c2410fb.h fix file specification in comments 2006-10-03 23:01:26 +02:00
sa1100fb.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
sa1100fb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sbuslib.c [SPARC]: Respect vm_page_prot in io_remap_page_range(). 2006-03-22 01:15:13 -08:00
sbuslib.h [SPARC]: Fix sbusfb build. 2006-01-17 15:53:11 -08:00
sgivwfb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
skeletonfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
sstfb.c [PATCH] sstfb: cleanups 2006-10-03 08:04:13 -07:00
sticore.h [PARISC] Fix stifb with IOREMAP and a 64-bit kernel 2006-03-30 17:48:47 +00:00
stifb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
sun3fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
tcx.c [SPARC]: Convert all FB SBUS drivers to of_driver framework. 2006-06-29 16:37:18 -07:00
tdfxfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
tgafb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
tridentfb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
tx3912fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
valkyriefb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
valkyriefb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vesafb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
vfb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
vga16fb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
vgastate.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
virgefb.c [PATCH] vt: Remove VT-specific declarations and definitions from tty.h 2006-07-10 13:24:16 -07:00
virgefb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
w100fb.c [PATCH] w100fb: Add acceleration support to ATI Imageon 2006-03-31 12:19:00 -08:00
w100fb.h [PATCH] w100fb: Add acceleration support to ATI Imageon 2006-03-31 12:19:00 -08:00