linux-stable.git/arch/tile/kernel, branch v3.16.40

tile: avoid using clocksource_cyc2ns with absolute cycle count

2017-02-23T03:54:39+00:00

commit e658a6f14d7c0243205f035979d0ecf6c12a036f upstream.

For large values of "mult" and long uptimes, the intermediate
result of "cycles * mult" can overflow 64 bits.  For example,
the tile platform calls clocksource_cyc2ns with a 1.2 GHz clock;
we have mult = 853, and after 208.5 days, we overflow 64 bits.

Since clocksource_cyc2ns() is intended to be used for relative
cycle counts, not absolute cycle counts, performance is more
importance than accepting a wider range of cycle values.  So,
just use mult_frac() directly in tile's sched_clock().

Commit 4cecf6d401a0 ("sched, x86: Avoid unnecessary overflow
in sched_clock") by Salman Qazi results in essentially the same
generated code for x86 as this change does for tile.  In fact,
a follow-on change by Salman introduced mult_frac() and switched
to using it, so the C code was largely identical at that point too.

Peter Zijlstra then added mul_u64_u32_shr() and switched x86
to use it.  This is, in principle, better; by optimizing the
64x64->64 multiplies to be 32x32->64 multiplies we can potentially
save some time.  However, the compiler piplines the 64x64->64
multiplies pretty well, and the conditional branch in the generic
mul_u64_u32_shr() causes some bubbles in execution, with the
result that it's pretty much a wash.  If tilegx provided its own
implementation of mul_u64_u32_shr() without the conditional branch,
we could potentially save 3 cycles, but that seems like small gain
for a fair amount of additional build scaffolding; no other platform
currently provides a mul_u64_u32_shr() override, and tile doesn't
currently have an  header to put the override in.

Additionally, gcc currently has an optimization bug that prevents
it from recognizing the opportunity to use a 32x32->64 multiply,
and so the result would be no better than the existing mult_frac()
until such time as the compiler is fixed.

For now, just using mult_frac() seems like the right answer.

Signed-off-by: Chris Metcalf 
Signed-off-by: Ben Hutchings

tile: use free_bootmem_late() for initrd

2015-08-11T08:57:43+00:00

commit 3f81d2447b37ac697b3c600039f2c6b628c06e21 upstream.

We were previously using free_bootmem() and just getting lucky
that nothing too bad happened.

Signed-off-by: Chris Metcalf 
Signed-off-by: Luis Henriques

Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile

2014-06-11T23:50:01+00:00

Pull arch/tile changes from Chris Metcalf:
 "These mostly just address smaller issues reported to me"

* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
  arch: tile: kernel: unaligned.c: Cleaning up uninitialized variables
  drivers/tty/hvc/hvc_tile.c: use PTR_ERR_OR_ZERO
  replace strict_strto* call with kstrto*
  tile: Update comments for generic idle conversion
  tile: cleanup the comment in init_pgprot
  tile: use BOOTMEM_DEFAULT instead of magic number 0 for reserve_bootmem flags

arch: tile: kernel: unaligned.c: Cleaning up uninitialized variables

2014-06-08T01:39:11+00:00

There is a risk that the variable will be used without being initialized.

This was largely found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist 
Signed-off-by: Chris Metcalf  [minor cleanups]

tile: convert use of typedef ctl_table to struct ctl_table

2014-06-06T23:08:15+00:00

This typedef is unnecessary and should just be removed.

Signed-off-by: Joe Perches 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

replace strict_strto* call with kstrto*

2014-05-28T19:47:16+00:00

remove obsolete calls to strict_strto* and replace them
with kstrto* calls accordingly.

Signed-off-by: Daniel Walter 
Signed-off-by: Chris Metcalf

tile: Use SPARSE_IRQ

2014-05-16T12:05:21+00:00

Get rid of the private allocator and switch over to sparse IRQs.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Grant Likely 
Cc: Tony Luck 
Cc: Peter Zijlstra 
Acked-by: Chris Metcalf 
Link: http://lkml.kernel.org/r/20140507154338.423715783@linutronix.de
Signed-off-by: Thomas Gleixner

tile: pci: Use irq_alloc/free_hwirq()

2014-05-16T12:05:21+00:00

No functional change. Just convert to the new interface.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Grant Likely 
Cc: Tony Luck 
Cc: Peter Zijlstra 
Acked-by: Chris Metcalf 
Link: http://lkml.kernel.org/r/20140507154338.132662495@linutronix.de
Signed-off-by: Thomas Gleixner

tile: Implement irq_alloc/free_hwirq() for migration

2014-05-16T12:05:20+00:00

We want to convert the drivers over to the new interface and finally
tile to sparse irqs. Implement irq_alloc/free_hwirq() for step by step
migration.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Grant Likely 
Cc: Tony Luck 
Cc: Peter Zijlstra 
Acked-by: Chris Metcalf 
Link: http://lkml.kernel.org/r/20140507154336.947853241@linutronix.de
Signed-off-by: Thomas Gleixner

tile: use BOOTMEM_DEFAULT instead of magic number 0 for reserve_bootmem flags

2014-05-02T16:26:32+00:00

Use macro flag BOOTMEM_DEFAULT instead of magic number 0 for reserve_bootmem.

Signed-off-by: Wang Sheng-Hui 
Signed-off-by: Chris Metcalf