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)
122 lines
3 KiB
C
122 lines
3 KiB
C
#ifndef __ASM_APIC_H
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#define __ASM_APIC_H
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#include <linux/pm.h>
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#include <asm/fixmap.h>
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#include <asm/apicdef.h>
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#include <asm/processor.h>
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#include <asm/system.h>
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#define Dprintk(x...)
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/*
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* Debugging macros
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*/
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#define APIC_QUIET 0
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#define APIC_VERBOSE 1
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#define APIC_DEBUG 2
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extern int apic_verbosity;
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/*
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* Define the default level of output to be very little
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* This can be turned up by using apic=verbose for more
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* information and apic=debug for _lots_ of information.
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* apic_verbosity is defined in apic.c
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*/
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#define apic_printk(v, s, a...) do { \
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if ((v) <= apic_verbosity) \
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printk(s, ##a); \
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} while (0)
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extern void generic_apic_probe(void);
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#ifdef CONFIG_X86_LOCAL_APIC
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/*
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* Basic functions accessing APICs.
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*/
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static __inline void apic_write(unsigned long reg, unsigned long v)
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{
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*((volatile unsigned long *)(APIC_BASE+reg)) = v;
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}
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static __inline void apic_write_atomic(unsigned long reg, unsigned long v)
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{
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xchg((volatile unsigned long *)(APIC_BASE+reg), v);
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}
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static __inline unsigned long apic_read(unsigned long reg)
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{
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return *((volatile unsigned long *)(APIC_BASE+reg));
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}
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static __inline__ void apic_wait_icr_idle(void)
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{
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while ( apic_read( APIC_ICR ) & APIC_ICR_BUSY )
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cpu_relax();
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}
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int get_physical_broadcast(void);
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#ifdef CONFIG_X86_GOOD_APIC
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# define FORCE_READ_AROUND_WRITE 0
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# define apic_read_around(x)
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# define apic_write_around(x,y) apic_write((x),(y))
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#else
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# define FORCE_READ_AROUND_WRITE 1
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# define apic_read_around(x) apic_read(x)
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# define apic_write_around(x,y) apic_write_atomic((x),(y))
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#endif
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static inline void ack_APIC_irq(void)
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{
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/*
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* ack_APIC_irq() actually gets compiled as a single instruction:
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* - a single rmw on Pentium/82489DX
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* - a single write on P6+ cores (CONFIG_X86_GOOD_APIC)
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* ... yummie.
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*/
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/* Docs say use 0 for future compatibility */
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apic_write_around(APIC_EOI, 0);
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}
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extern void (*wait_timer_tick)(void);
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extern int get_maxlvt(void);
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extern void clear_local_APIC(void);
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extern void connect_bsp_APIC (void);
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extern void disconnect_bsp_APIC (int virt_wire_setup);
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extern void disable_local_APIC (void);
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extern void lapic_shutdown (void);
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extern int verify_local_APIC (void);
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extern void cache_APIC_registers (void);
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extern void sync_Arb_IDs (void);
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extern void init_bsp_APIC (void);
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extern void setup_local_APIC (void);
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extern void init_apic_mappings (void);
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extern void smp_local_timer_interrupt (void);
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extern void setup_boot_APIC_clock (void);
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extern void setup_secondary_APIC_clock (void);
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extern int APIC_init_uniprocessor (void);
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extern void disable_APIC_timer(void);
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extern void enable_APIC_timer(void);
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extern void enable_NMI_through_LVT0 (void * dummy);
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void smp_send_timer_broadcast_ipi(void);
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void switch_APIC_timer_to_ipi(void *cpumask);
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void switch_ipi_to_APIC_timer(void *cpumask);
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#define ARCH_APICTIMER_STOPS_ON_C3 1
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extern int timer_over_8254;
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#else /* !CONFIG_X86_LOCAL_APIC */
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static inline void lapic_shutdown(void) { }
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#endif /* !CONFIG_X86_LOCAL_APIC */
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#endif /* __ASM_APIC_H */
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