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)
115 lines
3.2 KiB
C
115 lines
3.2 KiB
C
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#ifndef _I386_HPET_H
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#define _I386_HPET_H
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#ifdef CONFIG_HPET_TIMER
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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <asm/io.h>
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#include <asm/smp.h>
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#include <asm/irq.h>
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#include <asm/msr.h>
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#include <asm/delay.h>
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#include <asm/mpspec.h>
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#include <asm/uaccess.h>
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#include <asm/processor.h>
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#include <linux/timex.h>
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#include <asm/fixmap.h>
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/*
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* Documentation on HPET can be found at:
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* http://www.intel.com/ial/home/sp/pcmmspec.htm
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* ftp://download.intel.com/ial/home/sp/mmts098.pdf
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*/
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#define HPET_MMAP_SIZE 1024
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#define HPET_ID 0x000
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#define HPET_PERIOD 0x004
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#define HPET_CFG 0x010
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#define HPET_STATUS 0x020
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#define HPET_COUNTER 0x0f0
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#define HPET_T0_CFG 0x100
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#define HPET_T0_CMP 0x108
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#define HPET_T0_ROUTE 0x110
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#define HPET_T1_CFG 0x120
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#define HPET_T1_CMP 0x128
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#define HPET_T1_ROUTE 0x130
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#define HPET_T2_CFG 0x140
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#define HPET_T2_CMP 0x148
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#define HPET_T2_ROUTE 0x150
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#define HPET_ID_LEGSUP 0x00008000
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#define HPET_ID_NUMBER 0x00001f00
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#define HPET_ID_REV 0x000000ff
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#define HPET_ID_NUMBER_SHIFT 8
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#define HPET_CFG_ENABLE 0x001
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#define HPET_CFG_LEGACY 0x002
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#define HPET_LEGACY_8254 2
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#define HPET_LEGACY_RTC 8
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#define HPET_TN_ENABLE 0x004
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#define HPET_TN_PERIODIC 0x008
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#define HPET_TN_PERIODIC_CAP 0x010
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#define HPET_TN_SETVAL 0x040
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#define HPET_TN_32BIT 0x100
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/* Use our own asm for 64 bit multiply/divide */
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#define ASM_MUL64_REG(eax_out,edx_out,reg_in,eax_in) \
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__asm__ __volatile__("mull %2" \
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:"=a" (eax_out), "=d" (edx_out) \
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:"r" (reg_in), "0" (eax_in))
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#define ASM_DIV64_REG(eax_out,edx_out,reg_in,eax_in,edx_in) \
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__asm__ __volatile__("divl %2" \
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:"=a" (eax_out), "=d" (edx_out) \
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:"r" (reg_in), "0" (eax_in), "1" (edx_in))
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#define KERNEL_TICK_USEC (1000000UL/HZ) /* tick value in microsec */
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/* Max HPET Period is 10^8 femto sec as in HPET spec */
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#define HPET_MAX_PERIOD (100000000UL)
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/*
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* Min HPET period is 10^5 femto sec just for safety. If it is less than this,
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* then 32 bit HPET counter wrapsaround in less than 0.5 sec.
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*/
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#define HPET_MIN_PERIOD (100000UL)
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#define HPET_TICK_RATE (HZ * 100000UL)
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extern unsigned long hpet_tick; /* hpet clks count per tick */
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extern unsigned long hpet_address; /* hpet memory map physical address */
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extern int hpet_use_timer;
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extern int hpet_rtc_timer_init(void);
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extern int hpet_enable(void);
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extern int hpet_reenable(void);
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extern int is_hpet_enabled(void);
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extern int is_hpet_capable(void);
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extern int hpet_readl(unsigned long a);
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#ifdef CONFIG_HPET_EMULATE_RTC
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extern int hpet_mask_rtc_irq_bit(unsigned long bit_mask);
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extern int hpet_set_rtc_irq_bit(unsigned long bit_mask);
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extern int hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec);
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extern int hpet_set_periodic_freq(unsigned long freq);
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extern int hpet_rtc_dropped_irq(void);
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extern int hpet_rtc_timer_init(void);
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extern irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id);
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#endif /* CONFIG_HPET_EMULATE_RTC */
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#endif /* CONFIG_HPET_TIMER */
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#endif /* _I386_HPET_H */
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