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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)
80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/* ptrace.h: ptrace() relevant definitions
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*
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* Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.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_PTRACE_H
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#define _ASM_PTRACE_H
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#include <asm/registers.h>
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#include <asm/irq_regs.h>
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#define in_syscall(regs) (((regs)->tbr & TBR_TT) == TBR_TT_TRAP0)
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#define PT_PSR 0
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#define PT_ISR 1
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#define PT_CCR 2
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#define PT_CCCR 3
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#define PT_LR 4
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#define PT_LCR 5
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#define PT_PC 6
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#define PT__STATUS 7 /* exception status */
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#define PT_SYSCALLNO 8 /* syscall number or -1 */
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#define PT_ORIG_GR8 9 /* saved GR8 for signal handling */
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#define PT_GNER0 10
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#define PT_GNER1 11
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#define PT_IACC0H 12
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#define PT_IACC0L 13
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#define PT_GR(j) ( 14 + (j)) /* GRj for 0<=j<=63 */
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#define PT_FR(j) ( 78 + (j)) /* FRj for 0<=j<=63 */
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#define PT_FNER(j) (142 + (j)) /* FNERj for 0<=j<=1 */
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#define PT_MSR(j) (144 + (j)) /* MSRj for 0<=j<=2 */
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#define PT_ACC(j) (146 + (j)) /* ACCj for 0<=j<=7 */
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#define PT_ACCG(jklm) (154 + (jklm)) /* ACCGjklm for 0<=jklm<=1 (reads four regs per slot) */
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#define PT_FSR(j) (156 + (j)) /* FSRj for 0<=j<=0 */
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#define PT__GPEND 78
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#define PT__END 157
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#define PT_TBR PT_GR(0)
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#define PT_SP PT_GR(1)
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#define PT_FP PT_GR(2)
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#define PT_PREV_FRAME PT_GR(28) /* previous exception frame pointer (old gr28 value) */
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#define PT_CURR_TASK PT_GR(29) /* current task */
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/* Arbitrarily choose the same ptrace numbers as used by the Sparc code. */
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#define PTRACE_GETREGS 12
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#define PTRACE_SETREGS 13
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#define PTRACE_GETFPREGS 14
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#define PTRACE_SETFPREGS 15
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#define PTRACE_GETFDPIC 31 /* get the ELF fdpic loadmap address */
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#define PTRACE_GETFDPIC_EXEC 0 /* [addr] request the executable loadmap */
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#define PTRACE_GETFDPIC_INTERP 1 /* [addr] request the interpreter loadmap */
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#ifndef __ASSEMBLY__
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/*
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* we dedicate GR28 to keeping a pointer to the current exception frame
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* - gr28 is destroyed on entry to the kernel from userspace
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*/
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register struct pt_regs *__frame asm("gr28");
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#define user_mode(regs) (!((regs)->psr & PSR_S))
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#define instruction_pointer(regs) ((regs)->pc)
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extern unsigned long user_stack(const struct pt_regs *);
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extern void show_regs(struct pt_regs *);
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#define profile_pc(regs) ((regs)->pc)
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_PTRACE_H */
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