linux/drivers/acpi
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
..
dispatcher ACPI: ACPICA 20060707 2006-07-09 15:15:40 -04:00
events ACPI: ACPICA 20060707 2006-07-09 15:15:40 -04:00
executer Pull acpica-20060707 into test branch 2006-07-10 02:39:41 -04:00
hardware ACPI: ACPICA 20060623 2006-06-28 03:11:38 -04:00
namespace ACPI: ACPICA 20060707 2006-07-09 15:15:40 -04:00
parser ACPI: acpi_os_allocate() fixes 2006-07-10 02:37:22 -04:00
resources ACPI: ACPICA 20060526 2006-06-14 02:44:35 -04:00
sleep ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
tables ACPI: ACPICA 20060707 2006-07-09 15:15:40 -04:00
utilities Pull acpi_os_allocate into test branch 2006-07-10 02:39:47 -04:00
ac.c ACPI: fix boot with acpi=off 2006-08-15 23:16:43 -04:00
acpi_memhotplug.c [PATCH] hot-add-mem x86_64: memory_add_physaddr_to_nid node fixup 2006-10-01 00:39:18 -07:00
asus_acpi.c ACPI: asus_acpi: correct M6N/M6R display nodes 2006-07-01 16:20:10 -04:00
battery.c ACPI: fix boot with acpi=off 2006-08-15 23:16:43 -04:00
blacklist.c [PATCH] x86_64: Clean up and tweak ACPI blacklist year code 2006-03-25 09:10:54 -08:00
bus.c ACPI: add message if firmware_register() init fails 2006-08-15 23:27:38 -04:00
button.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
cm_sbs.c ACPI: SBS: fix initialization, sem2mutex 2006-07-10 02:34:45 -04:00
container.c ACPI: delete acpi_os_free(), use kfree() directly 2006-06-30 03:19:10 -04:00
debug.c ACPI: delete tracing macros from drivers/acpi/*.c 2006-06-27 00:41:40 -04:00
dock.c PCI: docking station: remove dock uevents 2006-08-03 13:20:06 -07:00
ec.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
event.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
fan.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
glue.c ACPI: delete acpi_os_free(), use kfree() directly 2006-06-30 03:19:10 -04:00
hotkey.c ACPI: hotkey.c fixes, fix for potential crash of hotkey.c 2006-08-16 18:08:06 -04:00
i2c_ec.c i2c: Constify i2c_algorithm declarations, part 2 2006-09-26 15:38:52 -07:00
i2c_ec.h ACPI: add support for Smart Battery 2006-07-01 16:36:14 -04:00
ibm_acpi.c ACPI: Allow a WAN module enable/disable on a Thinkpad X60. 2006-06-01 20:42:32 -04:00
Kconfig fix drivers/acpi/Kconfig typos 2006-10-03 22:24:43 +02:00
Makefile Revert "Revert "ACPI: dock driver"" 2006-07-09 17:22:28 -04:00
motherboard.c ACPI: delete tracing macros from drivers/acpi/*.c 2006-06-27 00:41:40 -04:00
numa.c ACPI: remove function tracing macros from drivers/acpi/*.c 2006-07-01 16:48:23 -04:00
osl.c IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
pci_bind.c ACPI: delete tracing macros from drivers/acpi/*.c 2006-06-27 00:41:40 -04:00
pci_irq.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial 2006-06-30 15:39:30 -07:00
pci_link.c ACPI: acpi_os_allocate() fixes 2006-07-10 02:37:22 -04:00
pci_root.c ACPI: pci_root: Remove unneeded acpi_handle from driver. 2006-06-30 02:51:34 -04:00
power.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
processor_core.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
processor_idle.c [PATCH] maximum latency tracking infrastructure 2006-10-01 00:39:19 -07:00
processor_perflib.c ACPI: delete acpi_os_free(), use kfree() directly 2006-06-30 03:19:10 -04:00
processor_thermal.c ACPI: delete tracing macros from drivers/acpi/*.c 2006-06-27 00:41:40 -04:00
processor_throttling.c ACPI: delete tracing macros from drivers/acpi/*.c 2006-06-27 00:41:40 -04:00
sbs.c ACPI: skip smart battery init when acpi=off 2006-08-15 23:21:37 -04:00
scan.c ACPI: verbose on kset/kobject_register errors 2006-08-15 23:32:24 -04:00
system.c ACPI: add 'const' to several ACPI file_operations 2006-07-10 00:04:29 -04:00
tables.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
thermal.c Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2006-07-10 15:14:38 -07:00
toshiba_acpi.c [ACPI] Lindent all ACPI files 2005-08-05 00:45:14 -04:00
utils.c ACPI: avoid irqrouter_resume might_sleep oops on resume from S4 2006-08-16 19:23:00 -04:00
video.c Pull acpi_device_handle_cleanup into release branch 2006-07-01 17:19:34 -04:00