1. 19 Oct, 2007 2 commits
  2. 08 May, 2007 1 commit
  3. 05 Oct, 2006 1 commit
    • David Howells's avatar
      IRQ: Maintain regs pointer globally rather than passing to IRQ handlers · 7d12e780
      David Howells authored
      
      
      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: default avatarDavid Howells <dhowells@redhat.com>
      (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
      7d12e780
  4. 26 Sep, 2006 2 commits
  5. 02 Jul, 2006 1 commit
  6. 30 Jun, 2006 1 commit
  7. 23 Jun, 2006 1 commit
  8. 23 Mar, 2006 1 commit
    • Andrew Morton's avatar
      [PATCH] more for_each_cpu() conversions · 394e3902
      Andrew Morton authored
      
      
      When we stop allocating percpu memory for not-possible CPUs we must not touch
      the percpu data for not-possible CPUs at all.  The correct way of doing this
      is to test cpu_possible() or to use for_each_cpu().
      
      This patch is a kernel-wide sweep of all instances of NR_CPUS.  I found very
      few instances of this bug, if any.  But the patch converts lots of open-coded
      test to use the preferred helper macros.
      
      Cc: Mikael Starvik <starvik@axis.com>
      Cc: David Howells <dhowells@redhat.com>
      Acked-by: default avatarKyle McMartin <kyle@parisc-linux.org>
      Cc: Anton Blanchard <anton@samba.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Cc: "David S. Miller" <davem@davemloft.net>
      Cc: William Lee Irwin III <wli@holomorphy.com>
      Cc: Andi Kleen <ak@muc.de>
      Cc: Christian Zankel <chris@zankel.net>
      Cc: Philippe Elie <phil.el@wanadoo.fr>
      Cc: Nathan Scott <nathans@sgi.com>
      Cc: Jens Axboe <axboe@suse.de>
      Cc: Eric Dumazet <dada1@cosmosbay.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      394e3902
  9. 14 Feb, 2006 1 commit
    • David Howells's avatar
      [PATCH] FRV: Use virtual interrupt disablement · 28baebae
      David Howells authored
      
      
      Make the FRV arch use virtual interrupt disablement because accesses to the
      processor status register (PSR) are relatively slow and because we will
      soon have the need to deal with multiple interrupt controls at the same
      time (separate h/w and inter-core interrupts).
      
      The way this is done is to dedicate one of the four integer condition code
      registers (ICC2) to maintaining a virtual interrupt disablement state
      whilst inside the kernel.  This uses the ICC2.Z flag (Zero) to indicate
      whether the interrupts are virtually disabled and the ICC2.C flag (Carry)
      to indicate whether the interrupts are physically disabled.
      
      ICC2.Z is set to indicate interrupts are virtually disabled.  ICC2.C is set
      to indicate interrupts are physically enabled.  Under normal running
      conditions Z==0 and C==1.
      
      Disabling interrupts with local_irq_disable() doesn't then actually
      physically disable interrupts - it merely sets ICC2.Z to 1.  Should an
      interrupt then happen, the exception prologue will note ICC2.Z is set and
      branch out of line using one instruction (an unlikely BEQ).  Here it will
      physically disable interrupts and clear ICC2.C.
      
      When it comes time to enable interrupts (local_irq_enable()), this simply
      clears the ICC2.Z flag and invokes a trap #2 if both Z and C flags are
      clear (the HI integer condition).  This can be done with the TIHI
      conditional trap instruction.
      
      The trap then physically reenables interrupts and sets ICC2.C again.  Upon
      returning the interrupt will be taken as interrupts will then be enabled.
      Note that whilst processing the trap, the whole exceptions system is
      disabled, and so an interrupt can't happen till it returns.
      
      If no pending interrupt had happened, ICC2.C would still be set, the HI
      condition would not be fulfilled, and no trap will happen.
      
      Saving interrupts (local_irq_save) is simply a matter of pulling the ICC2.Z
      flag out of the CCR register, shifting it down and masking it off.  This
      gives a result of 0 if interrupts were enabled and 1 if they weren't.
      
      Restoring interrupts (local_irq_restore) is then a matter of taking the
      saved value mentioned previously and XOR'ing it against 1.  If it was one,
      the result will be zero, and if it was zero the result will be non-zero.
      This result is then used to affect the ICC2.Z flag directly (it is a
      condition code flag after all).  An XOR instruction does not affect the
      Carry flag, and so that bit of state is unchanged.  The two flags can then
      be sampled to see if they're both zero using the trap (TIHI) as for the
      unconditional reenablement (local_irq_enable).
      
      This patch also:
      
       (1) Modifies the debugging stub (break.S) to handle single-stepping crossing
           into the trap #2 handler and into virtually disabled interrupts.
      
       (2) Removes superseded fixup pointers from the second instructions in the trap
           tables (there's no a separate fixup table for this).
      
       (3) Declares the trap #3 vector for use in .org directives in the trap table.
      
       (4) Moves irq_enter() and irq_exit() in do_IRQ() to avoid problems with
           virtual interrupt handling, and removes the duplicate code that has now
           been folded into irq_exit() (softirq and preemption handling).
      
       (5) Tells the compiler in the arch Makefile that ICC2 is now reserved.
      
       (6) Documents the in-kernel ABI, including the virtual interrupts.
      
       (7) Renames the old irq management functions to different names.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      28baebae
  10. 08 Jan, 2006 1 commit
  11. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4