linux-toradex.git/arch/ia64/kernel/traps.c, branch v4.2.7

ia64: Replace __get_cpu_var uses

2014-08-26T17:45:52+00:00

__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: linux-ia64@vger.kernel.org
Signed-off-by: Christoph Lameter 
Signed-off-by: Tejun Heo

[IA64] Fix trap #45 handling

2013-06-03T22:47:42+00:00

In this case, the original author did not provide the related reason
string for die_if_kernel(), so the 'buf' is not initialized.

The original author wants to generic a 'SIGSEGV' and 'return', not want
to 'break' to fall to die.

[Probably irrelevent since we no longer support IA-32 execution. -Tony]

Signed-off-by: Chen Gang 
Signed-off-by: Tony Luck

taint: add explicit flag to show whether lock dep is still OK.

2013-01-21T06:47:57+00:00

Fix up all callers as they were before, with make one change: an
unsigned module taints the kernel, but doesn't turn off lockdep.

Signed-off-by: Rusty Russell

Disintegrate asm/system.h for IA64

2012-03-28T17:30:02+00:00

Disintegrate asm/system.h for IA64.

Signed-off-by: David Howells 
Acked-by: Tony Luck 
cc: linux-ia64@vger.kernel.org

[IA64] Remove COMPAT_IA32 support

2010-02-08T18:42:17+00:00

This has been broken since May 2008 when Al Viro killed altroot support.
Since nobody has complained, it would appear that there are no users of
this code (A plausible theory since the main OSVs that support ia64 prefer
to use the IA32-EL software emulation).

Signed-off-by: Tony Luck

[IA64] honor notify_die() returning NOTIFY_STOP

2008-02-05T16:26:44+00:00

This requires making die() and die_if_kernel() return a value, and their
callers to honor this (and be prepared that it returns).

Signed-off-by: Jan Beulich 
Signed-off-by: Andrew Morton 
Signed-off-by: Tony Luck

Use helpers to obtain task pid in printks (arch code)

2007-10-19T18:53:43+00:00

One of the easiest things to isolate is the pid printed in kernel log.
There was a patch, that made this for arch-independent code, this one makes
so for arch/xxx files.

It took some time to cross-compile it, but hopefully these are all the
printks in arch code.

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Pavel Emelyanov 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Report that kernel is tainted if there was an OOPS

2007-07-17T17:23:02+00:00

If the kernel OOPSed or BUGed then it probably should be considered as
tainted.  Thus, all subsequent OOPSes and SysRq dumps will report the
tainted kernel.  This saves a lot of time explaining oddities in the
calltraces.

Signed-off-by: Pavel Emelianov 
Acked-by: Randy Dunlap 
Cc: 
Signed-off-by: Andrew Morton 
[ Added parisc patch from Matthew Wilson  -Linus ]
Signed-off-by: Linus Torvalds

[IA64] spelling fixes: arch/ia64/

2007-05-11T21:55:43+00:00

Spelling and apostrophe fixes in arch/ia64/.

Signed-off-by: Simon Arlott 
Signed-off-by: Tony Luck

Merge git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6

2007-05-09T20:38:45+00:00

* git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
  [IA64] wire up pselect, ppoll
  [IA64] Add TIF_RESTORE_SIGMASK
  [IA64] unwind did not work for processes born with CLONE_STOPPED
  [IA64] Optional method to purge the TLB on SN systems
  [IA64] SPIN_LOCK_UNLOCKED macro cleanup in arch/ia64
  [IA64-SN2][KJ] mmtimer.c-kzalloc
  [IA64] fix stack alignment for ia32 signal handlers
  [IA64] - Altix: hotplug after intr redirect can crash system
  [IA64] save and restore cpus_allowed in cpu_idle_wait
  [IA64] Removal of percpu TR cleanup in kexec code
  [IA64] Fix some section mismatch errors