linux-stable.git/arch/m68k/kernel, branch linux-3.13.y

m68k: Simplify low level interrupt handling code

2013-11-13T19:21:46+00:00

The low level interrupt entry code of m68k contains the following:

    add_preempt_count(HARDIRQ_OFFSET);

    do_IRQ();
	irq_enter();
	    add_preempt_count(HARDIRQ_OFFSET);
	handle_interrupt();    
	irq_exit();    
	    sub_preempt_count(HARDIRQ_OFFSET);
	    if (in_interrupt())
       	       return; <---- On m68k always taken!
	    if (local_softirq_pending())
       	       do_softirq();

    sub_preempt_count(HARDIRQ_OFFSET);
    if (in_hardirq())
       return;
    if (status_on_stack_has_interrupt_priority_mask > 0)
       return;
    if (local_softirq_pending())
       do_softirq();

    ret_from_exception:
	if (interrupted_context_is_kernel)
	   return:
	....

I tried to find a proper explanation for this, but the changelog is
sparse and there are no mails explaining it further. But obviously
this relates to the interrupt priority levels of the m68k and tries to
be extra clever with nested interrupts. Though this cleverness just
adds code bloat to the interrupt hotpath.

For the common case of non nested interrupts the code runs through two
extra conditionals to the only important one, which checks whether the
return is to kernel or user space.

For the nested case the checks for in_hardirq() and the priority mask
value on stack catch only the case where the nested interrupt happens
inside the hard irq context of the first interrupt. If the nested
interrupt happens while the first interrupt handles soft interrupts,
then these extra checks buy nothing. The nested interrupt will fall
through to the final kernel/user space return check at
ret_from_exception.

Changing the code flow in the following way:

    do_IRQ();
	irq_enter();
	    add_preempt_count(HARDIRQ_OFFSET);
	handle_interrupt();    
	irq_exit();    
	    sub_preempt_count(HARDIRQ_OFFSET);
	    if (in_interrupt())
       	       return;
	    if (local_softirq_pending())
       	       do_softirq();

    ret_from_exception:
	if (interrupted_context_is_kernel)
	   return:

makes the region protected by the hardirq count slightly smaller and
the softirq handling is invoked with a minimal deeper stack. But
otherwise it's completely functional equivalent and saves 104 bytes of
text in arch/m68k/kernel/entry.o.

This modification allows us further to get rid of the limitations
which m68k puts on the preempt_count layout, so we can make the
preempt count bits completely generic.

Signed-off-by: Thomas Gleixner 
Tested-by: Michael Schmitz 
Acked-by: Geert Uytterhoeven 
Cc: Linux/m68k 
Cc: Andreas Schwab 
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311112052360.30673@ionos.tec.linutronix.de

Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu

2013-09-09T16:04:46+00:00

Pull m68knommu fixes from Greg Ungerer:
 "Just a small collection of cleanups and fixes this time, no big
  changes.  The most interresting are to make the m68k and m68knommu
  consistently use CONFIG_IOMAP, clean out some unused board config
  options and flush the cache on signal stack creation"

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
  m68k: remove 16 unused boards in Kconfig.machine
  m68k: define 'VM_DATA_DEFAULT_FLAGS' no matter whether has 'NOMMU' or not
  m68knommu: user generic iomap to support ioread*/iowrite*
  m68k/coldfire: flush cache when creating the signal stack frame
  m68knommu: Mark functions only called from setup_arch() __init

m68k/coldfire: flush cache when creating the signal stack frame

2013-08-26T06:51:13+00:00

When the signal stack frame is created, it must be flushed in order to
make sure the cache fetches the correct data.
Without cache flush the icache might pick up old cached data from an older
signal stack frame if the signal is raised again very fast.
In case of copyback the data cache muist be pushed first, but is untested.

Signed-off-by: Alexander Stein 
Signed-off-by: Greg Ungerer

m68knommu: Mark functions only called from setup_arch() __init

2013-08-26T06:51:13+00:00

Some functions that are only called (indirectly) from setup_arch() lack
__init annotations.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: Greg Ungerer

PTR_RET is now PTR_ERR_OR_ZERO(): Replace most.

2013-07-15T01:55:01+00:00

Sweep of the simple cases.

Cc: netdev@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: Julia Lawall 
Signed-off-by: Rusty Russell 
Acked-by: David S. Miller 
Acked-by: Benjamin Herrenschmidt

Merge branch 'exotic-arch-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k

2013-07-03T18:12:08+00:00

Pull "exotic" arch fixes from Geert Uytterhoeven:
 "This is a collection of several exotic architecture fixes, and a few
  other fixes for issues that were detected while doing the former"

* 'exotic-arch-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k: (35 commits)
  lib: Move fonts from drivers/video/console/ to lib/fonts/
  console/font: Refactor font support code selection logic
  Revert "staging/solo6x10: depend on CONFIG_FONTS"
  input: cros_ec_keyb_clear_keyboard() depends on CONFIG_PM_SLEEP
  score: Wire up asm-generic/xor.h
  score: Remove unneeded 
  openrisc: Wire up asm-generic/xor.h
  h8300/boot: Use POSIX "$((..))" instead of bashism "$[...]"
  h8300: Mark H83002 and H83048 CPU support broken
  h8300: Switch h8300 to drivers/Kconfig
  h8300: Limit timer channel ranges in Kconfig
  h8300: Wire up asm-generic/xor.h
  h8300: Fill the system call table using a CALL() macro
  h8300: Fix 
  h8300: Hardcode symbol prefixes in asm sources
  h8300: add missing definition for read_barries_depends()
  frv: head.S - Remove commented-out initialization code
  cris: Wire up asm-generic/vga.h
  parport: disable PC-style parallel port support on cris
  console: Disable VGA text console support on cris
  ...

lib: Move fonts from drivers/video/console/ to lib/fonts/

2013-06-28T08:28:22+00:00

Several drivers need font support independent of CONFIG_VT, cfr. commit
9cbce8d7e1dae0744ca4f68d62aa7de18196b6f4, "console/font: Refactor font
support code selection logic").
Hence move the fonts and their support logic from drivers/video/console/ to
its own library directory lib/fonts/.
This also allows to limit processing of drivers/video/console/Makefile to
CONFIG_VT=y again.

[Kevin Hilman : Update arch/arm/boot/compressed/Makefile]
Signed-off-by: Geert Uytterhoeven

m68k/irq: Vector ints need a valid interrupt handler

2013-06-24T17:44:19+00:00

To get vectored interrupts working we need to switch from the default
handler handle_bad_irq() to something more sensible. Tested on a MVME177
board.

Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Geert Uytterhoeven

m68k/mac: Fix unexpected interrupt with CONFIG_EARLY_PRINTK

2013-05-31T08:43:18+00:00

The present code does not wait for the SCC to finish resetting itself
before trying to initialise the device. The result is that the SCC
interrupt sources become enabled (if they weren't already). This leads to
an early boot crash (unexpected interrupt) given CONFIG_EARLY_PRINTK. Fix
this by adding a delay. A successful reset disables the interrupt sources.

Also, after the reset for channel A setup, the SCC then gets a second
reset for channel B setup which leaves channel A uninitialised again. Fix
this by performing the reset only once.

Signed-off-by: Finn Thain 
Cc: stable@vger.kernel.org
Signed-off-by: Geert Uytterhoeven

dump_stack: consolidate dump_stack() implementations and unify their behaviors

2013-05-01T00:04:02+00:00

Both dump_stack() and show_stack() are currently implemented by each
architecture.  show_stack(NULL, NULL) dumps the backtrace for the
current task as does dump_stack().  On some archs, dump_stack() prints
extra information - pid, utsname and so on - in addition to the
backtrace while the two are identical on other archs.

The usages in arch-independent code of the two functions indicate
show_stack(NULL, NULL) should print out bare backtrace while
dump_stack() is used for debugging purposes when something went wrong,
so it does make sense to print additional information on the task which
triggered dump_stack().

There's no reason to require archs to implement two separate but mostly
identical functions.  It leads to unnecessary subtle information.

This patch expands the dummy fallback dump_stack() implementation in
lib/dump_stack.c such that it prints out debug information (taken from
x86) and invokes show_stack(NULL, NULL) and drops arch-specific
dump_stack() implementations in all archs except blackfin.  Blackfin's
dump_stack() does something wonky that I don't understand.

Debug information can be printed separately by calling
dump_stack_print_info() so that arch-specific dump_stack()
implementation can still emit the same debug information.  This is used
in blackfin.

This patch brings the following behavior changes.

* On some archs, an extra level in backtrace for show_stack() could be
  printed.  This is because the top frame was determined in
  dump_stack() on those archs while generic dump_stack() can't do that
  reliably.  It can be compensated by inlining dump_stack() but not
  sure whether that'd be necessary.

* Most archs didn't use to print debug info on dump_stack().  They do
  now.

An example WARN dump follows.

 WARNING: at kernel/workqueue.c:4841 init_workqueues+0x35/0x505()
 Hardware name: empty
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #9
  0000000000000009 ffff88007c861e08 ffffffff81c614dc ffff88007c861e48
  ffffffff8108f50f ffffffff82228240 0000000000000040 ffffffff8234a03c
  0000000000000000 0000000000000000 0000000000000000 ffff88007c861e58
 Call Trace:
  [] dump_stack+0x19/0x1b
  [] warn_slowpath_common+0x7f/0xc0
  [] warn_slowpath_null+0x1a/0x20
  [] init_workqueues+0x35/0x505
  ...

v2: CPU number added to the generic debug info as requested by s390
    folks and dropped the s390 specific dump_stack().  This loses %ksp
    from the debug message which the maintainers think isn't important
    enough to keep the s390-specific dump_stack() implementation.

    dump_stack_print_info() is moved to kernel/printk.c from
    lib/dump_stack.c.  Because linkage is per objecct file,
    dump_stack_print_info() living in the same lib file as generic
    dump_stack() means that archs which implement custom dump_stack()
    - at this point, only blackfin - can't use dump_stack_print_info()
    as that will bring in the generic version of dump_stack() too.  v1
    The v1 patch broke build on blackfin due to this issue.  The build
    breakage was reported by Fengguang Wu.

Signed-off-by: Tejun Heo 
Acked-by: David S. Miller 
Acked-by: Vineet Gupta 
Acked-by: Jesper Nilsson 
Acked-by: Vineet Gupta 
Acked-by: Martin Schwidefsky 	[s390 bits]
Cc: Heiko Carstens 
Cc: Mike Frysinger 
Cc: Fengguang Wu 
Cc: Bjorn Helgaas 
Cc: Sam Ravnborg 
Acked-by: Richard Kuo 		[hexagon bits]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds