7d12e780e0
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)
158 lines
3.3 KiB
C
158 lines
3.3 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Code to handle x86 style IRQs plus some generic interrupt stuff.
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*
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* Copyright (C) 1992 Linus Torvalds
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* Copyright (C) 1994 - 2000 Ralf Baechle
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*/
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/module.h>
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#include <linux/proc_fs.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/kallsyms.h>
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#include <asm/atomic.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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/*
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* 'what should we do if we get a hw irq event on an illegal vector'.
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* each architecture has to answer this themselves.
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*/
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void ack_bad_irq(unsigned int irq)
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{
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printk("unexpected IRQ # %d\n", irq);
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}
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atomic_t irq_err_count;
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#ifdef CONFIG_MIPS_MT_SMTC
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/*
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* SMTC Kernel needs to manipulate low-level CPU interrupt mask
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* in do_IRQ. These are passed in setup_irq_smtc() and stored
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* in this table.
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*/
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unsigned long irq_hwmask[NR_IRQS];
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#endif /* CONFIG_MIPS_MT_SMTC */
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#undef do_IRQ
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/*
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* do_IRQ handles all normal device IRQ's (the special
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* SMP cross-CPU interrupts have their own specific
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* handlers).
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*/
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asmlinkage unsigned int do_IRQ(unsigned int irq, struct pt_regs *regs)
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{
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struct pt_regs *old_regs = set_irq_regs(regs);
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irq_enter();
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__DO_IRQ_SMTC_HOOK();
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__do_IRQ(irq);
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irq_exit();
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set_irq_regs(old_regs);
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return 1;
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}
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/*
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* Generic, controller-independent functions:
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*/
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int show_interrupts(struct seq_file *p, void *v)
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{
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int i = *(loff_t *) v, j;
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struct irqaction * action;
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unsigned long flags;
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if (i == 0) {
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seq_printf(p, " ");
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for_each_online_cpu(j)
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seq_printf(p, "CPU%d ",j);
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seq_putc(p, '\n');
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}
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if (i < NR_IRQS) {
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spin_lock_irqsave(&irq_desc[i].lock, flags);
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action = irq_desc[i].action;
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if (!action)
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goto skip;
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seq_printf(p, "%3d: ",i);
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#ifndef CONFIG_SMP
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seq_printf(p, "%10u ", kstat_irqs(i));
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#else
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for_each_online_cpu(j)
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seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
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#endif
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seq_printf(p, " %14s", irq_desc[i].chip->typename);
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seq_printf(p, " %s", action->name);
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for (action=action->next; action; action = action->next)
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seq_printf(p, ", %s", action->name);
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seq_putc(p, '\n');
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skip:
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spin_unlock_irqrestore(&irq_desc[i].lock, flags);
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} else if (i == NR_IRQS) {
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seq_putc(p, '\n');
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seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
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}
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return 0;
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}
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asmlinkage void spurious_interrupt(struct pt_regs *regs)
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{
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atomic_inc(&irq_err_count);
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}
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#ifdef CONFIG_KGDB
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extern void breakpoint(void);
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extern void set_debug_traps(void);
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static int kgdb_flag = 1;
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static int __init nokgdb(char *str)
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{
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kgdb_flag = 0;
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return 1;
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}
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__setup("nokgdb", nokgdb);
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#endif
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void __init init_IRQ(void)
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{
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int i;
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for (i = 0; i < NR_IRQS; i++) {
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irq_desc[i].status = IRQ_DISABLED;
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irq_desc[i].action = NULL;
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irq_desc[i].depth = 1;
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irq_desc[i].chip = &no_irq_chip;
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spin_lock_init(&irq_desc[i].lock);
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#ifdef CONFIG_MIPS_MT_SMTC
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irq_hwmask[i] = 0;
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#endif /* CONFIG_MIPS_MT_SMTC */
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}
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arch_init_irq();
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#ifdef CONFIG_KGDB
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if (kgdb_flag) {
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printk("Wait for gdb client connection ...\n");
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set_debug_traps();
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breakpoint();
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}
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#endif
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}
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