kernel_optimize_test/arch/frv/kernel/irq.c
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

207 lines
4.8 KiB
C

/* irq.c: FRV IRQ handling
*
* Copyright (C) 2003, 2004, 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/irq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <asm/atomic.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/delay.h>
#include <asm/irq.h>
#include <asm/irc-regs.h>
#include <asm/gdb-stub.h>
#define set_IRR(N,A,B,C,D) __set_IRR(N, (A << 28) | (B << 24) | (C << 20) | (D << 16))
extern void __init fpga_init(void);
#ifdef CONFIG_FUJITSU_MB93493
extern void __init mb93493_init(void);
#endif
#define __reg16(ADDR) (*(volatile unsigned short *)(ADDR))
atomic_t irq_err_count;
/*
* Generic, controller-independent functions:
*/
int show_interrupts(struct seq_file *p, void *v)
{
int i = *(loff_t *) v, cpu;
struct irqaction * action;
unsigned long flags;
if (i == 0) {
char cpuname[12];
seq_printf(p, " ");
for_each_present_cpu(cpu) {
sprintf(cpuname, "CPU%d", cpu);
seq_printf(p, " %10s", cpuname);
}
seq_putc(p, '\n');
}
if (i < NR_IRQS) {
spin_lock_irqsave(&irq_desc[i].lock, flags);
action = irq_desc[i].action;
if (action) {
seq_printf(p, "%3d: ", i);
for_each_present_cpu(cpu)
seq_printf(p, "%10u ", kstat_cpu(cpu).irqs[i]);
seq_printf(p, " %10s", irq_desc[i].chip->name ? : "-");
seq_printf(p, " %s", action->name);
for (action = action->next;
action;
action = action->next)
seq_printf(p, ", %s", action->name);
seq_putc(p, '\n');
}
spin_unlock_irqrestore(&irq_desc[i].lock, flags);
} else if (i == NR_IRQS) {
seq_printf(p, "Err: %10u\n", atomic_read(&irq_err_count));
}
return 0;
}
/*
* on-CPU PIC operations
*/
static void frv_cpupic_ack(unsigned int irqlevel)
{
__clr_RC(irqlevel);
__clr_IRL();
}
static void frv_cpupic_mask(unsigned int irqlevel)
{
__set_MASK(irqlevel);
}
static void frv_cpupic_mask_ack(unsigned int irqlevel)
{
__set_MASK(irqlevel);
__clr_RC(irqlevel);
__clr_IRL();
}
static void frv_cpupic_unmask(unsigned int irqlevel)
{
__clr_MASK(irqlevel);
}
static void frv_cpupic_end(unsigned int irqlevel)
{
__clr_MASK(irqlevel);
}
static struct irq_chip frv_cpu_pic = {
.name = "cpu",
.ack = frv_cpupic_ack,
.mask = frv_cpupic_mask,
.mask_ack = frv_cpupic_mask_ack,
.unmask = frv_cpupic_unmask,
.end = frv_cpupic_end,
};
/*
* handles all normal device IRQ's
* - registers are referred to by the __frame variable (GR28)
* - IRQ distribution is complicated in this arch because of the many PICs, the
* way they work and the way they cascade
*/
asmlinkage void do_IRQ(void)
{
irq_enter();
generic_handle_irq(__get_IRL());
irq_exit();
}
/*
* handles all NMIs when not co-opted by the debugger
* - registers are referred to by the __frame variable (GR28)
*/
asmlinkage void do_NMI(void)
{
}
/*
* initialise the interrupt system
*/
void __init init_IRQ(void)
{
int level;
for (level = 1; level <= 14; level++)
set_irq_chip_and_handler(level, &frv_cpu_pic,
handle_level_irq);
set_irq_handler(IRQ_CPU_TIMER0, handle_edge_irq);
/* set the trigger levels for internal interrupt sources
* - timers all falling-edge
* - ERR0 is rising-edge
* - all others are high-level
*/
__set_IITMR(0, 0x003f0000); /* DMA0-3, TIMER0-2 */
__set_IITMR(1, 0x20000000); /* ERR0-1, UART0-1, DMA4-7 */
/* route internal interrupts */
set_IRR(4, IRQ_DMA3_LEVEL, IRQ_DMA2_LEVEL, IRQ_DMA1_LEVEL,
IRQ_DMA0_LEVEL);
set_IRR(5, 0, IRQ_TIMER2_LEVEL, IRQ_TIMER1_LEVEL, IRQ_TIMER0_LEVEL);
set_IRR(6, IRQ_GDBSTUB_LEVEL, IRQ_GDBSTUB_LEVEL,
IRQ_UART1_LEVEL, IRQ_UART0_LEVEL);
set_IRR(7, IRQ_DMA7_LEVEL, IRQ_DMA6_LEVEL, IRQ_DMA5_LEVEL,
IRQ_DMA4_LEVEL);
/* route external interrupts */
set_IRR(2, IRQ_XIRQ7_LEVEL, IRQ_XIRQ6_LEVEL, IRQ_XIRQ5_LEVEL,
IRQ_XIRQ4_LEVEL);
set_IRR(3, IRQ_XIRQ3_LEVEL, IRQ_XIRQ2_LEVEL, IRQ_XIRQ1_LEVEL,
IRQ_XIRQ0_LEVEL);
#if defined(CONFIG_MB93091_VDK)
__set_TM1(0x55550000); /* XIRQ7-0 all active low */
#elif defined(CONFIG_MB93093_PDK)
__set_TM1(0x15550000); /* XIRQ7 active high, 6-0 all active low */
#else
#error dont know external IRQ trigger levels for this setup
#endif
fpga_init();
#ifdef CONFIG_FUJITSU_MB93493
mb93493_init();
#endif
}