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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)
119 lines
2.9 KiB
C
119 lines
2.9 KiB
C
/*
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* smp.h: PowerPC-specific SMP code.
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*
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* Original was a copy of sparc smp.h. Now heavily modified
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* for PPC.
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*
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* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
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* Copyright (C) 1996-2001 Cort Dougan <cort@fsmlabs.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_POWERPC_SMP_H
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#define _ASM_POWERPC_SMP_H
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#ifdef __KERNEL__
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#include <linux/threads.h>
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#include <linux/cpumask.h>
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#include <linux/kernel.h>
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_PPC64
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#include <asm/paca.h>
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#endif
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extern int boot_cpuid;
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extern void cpu_die(void);
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#ifdef CONFIG_SMP
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extern void smp_send_debugger_break(int cpu);
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extern void smp_message_recv(int);
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#ifdef CONFIG_HOTPLUG_CPU
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extern void fixup_irqs(cpumask_t map);
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int generic_cpu_disable(void);
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int generic_cpu_enable(unsigned int cpu);
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void generic_cpu_die(unsigned int cpu);
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void generic_mach_cpu_die(void);
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#endif
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#ifdef CONFIG_PPC64
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#define raw_smp_processor_id() (get_paca()->paca_index)
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#define hard_smp_processor_id() (get_paca()->hw_cpu_id)
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#else
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/* 32-bit */
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extern int smp_hw_index[];
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#define raw_smp_processor_id() (current_thread_info()->cpu)
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#define hard_smp_processor_id() (smp_hw_index[smp_processor_id()])
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#define get_hard_smp_processor_id(cpu) (smp_hw_index[(cpu)])
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#define set_hard_smp_processor_id(cpu, phys)\
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(smp_hw_index[(cpu)] = (phys))
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#endif
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extern cpumask_t cpu_sibling_map[NR_CPUS];
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/* Since OpenPIC has only 4 IPIs, we use slightly different message numbers.
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*
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* Make sure this matches openpic_request_IPIs in open_pic.c, or what shows up
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* in /proc/interrupts will be wrong!!! --Troy */
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#define PPC_MSG_CALL_FUNCTION 0
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#define PPC_MSG_RESCHEDULE 1
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/* This is unused now */
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#if 0
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#define PPC_MSG_MIGRATE_TASK 2
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#endif
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#define PPC_MSG_DEBUGGER_BREAK 3
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void smp_init_iSeries(void);
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void smp_init_pSeries(void);
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void smp_init_cell(void);
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void smp_setup_cpu_maps(void);
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extern int __cpu_disable(void);
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extern void __cpu_die(unsigned int cpu);
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#else
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/* for UP */
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#define smp_setup_cpu_maps()
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#endif /* CONFIG_SMP */
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#ifdef CONFIG_PPC64
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#define get_hard_smp_processor_id(CPU) (paca[(CPU)].hw_cpu_id)
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#define set_hard_smp_processor_id(CPU, VAL) \
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do { (paca[(CPU)].hw_cpu_id = (VAL)); } while (0)
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extern void smp_release_cpus(void);
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#else
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/* 32-bit */
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#ifndef CONFIG_SMP
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extern int boot_cpuid_phys;
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#define get_hard_smp_processor_id(cpu) boot_cpuid_phys
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#define set_hard_smp_processor_id(cpu, phys)
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#endif
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#endif
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extern int smt_enabled_at_boot;
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extern int smp_mpic_probe(void);
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extern void smp_mpic_setup_cpu(int cpu);
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extern void smp_generic_kick_cpu(int nr);
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extern void smp_generic_give_timebase(void);
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extern void smp_generic_take_timebase(void);
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extern struct smp_ops_t *smp_ops;
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#endif /* __ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_SMP_H) */
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