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)
Because we play this trick where we use ttyS? in increasing minor
numbers for different sunfoo.c drivers, we have to inform the TTY
layer of this.
Do so by setting the tty->name_base appropriately.
Probably there should be a generic way to do this in the serial core,
but for now...
Signed-off-by: David S. Miller <davem@davemloft.net>
Caller takes the lock already.
Also, fixup the poll loop in sunhv_break_ctl(). Just
like in console write, we udelay(2) and use a loop
limit of 1000000 iterations.
Signed-off-by: David S. Miller <davem@davemloft.net>
By calling uart_handle_break(). We'll still do the
"sun_do_break()" handling if the user gives two
breaks in a row.
We should probably do this in the other Sparc serial
drivers too.
Signed-off-by: David S. Miller <davem@davemloft.net>
Until the uart is openned, port->info is NULL.
Also, init the port->irq properly and give a non-zero
port->membase so that the uart device reporting is done.
Signed-off-by: David S. Miller <davem@davemloft.net>
Add udelay to polling console write loop, and increment
the loop limit.
Name the device "ttyHV" and pass that to add_preferred_console()
when we're using hypervisor console.
Kill sunhv_console_setup(), it's empty.
Handle the case where we don't want to use hypervisor console.
(ie. we have a head attached to a sun4v machine)
Signed-off-by: David S. Miller <davem@davemloft.net>
Since it can do things like BREAK and HUP, we implement
this as a serial uart driver.
This still needs interrupt probing code, as I haven't figured
out how interrupts will work or be probed for on SUN4V yet.
Signed-off-by: David S. Miller <davem@davemloft.net>
David Howells
David S. Miller
Greg Kroah-Hartman