linux-stable.git/arch/tile/kernel, branch v3.12.69

tile: avoid using clocksource_cyc2ns with absolute cycle count

2016-12-12T12:55:51+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: Jiri Slaby

tile: use free_bootmem_late() for initrd

2015-08-19T06:36:38+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: Jiri Slaby

arch: tile: re-use kbasename() helper

2013-09-30T14:34:46+00:00

kbasename() returns the filename part of a pathname.

Signed-off-by: Andy Shevchenko

tile: ensure interrupts disabled for preempt_schedule_irq()

2013-09-27T20:09:43+00:00

When coming from a page fault (for example), interrupts might
be enabled as we enter the code to return from interrupt.

Cc: stable@vger.kernel.org
Signed-off-by: Chris Metcalf

tile: change lock initalization in hardwall

2013-09-27T20:09:38+00:00

hardwall used __SPIN_LOCK_INITIALIZER directly instead of the preferred
__SPIN_LOCK_UNLOCKED. This also has the benefit that it will compile
when applying the preempt-rt patch series.

Signed-off-by: Henrik Austad 
Signed-off-by: Chris Metcalf

tile: remove stray blank space

2013-09-16T19:47:32+00:00

The compat sys_llseek() definition addition added a bogus space
on an otherwise-blank line.

Signed-off-by: Chris Metcalf

tile: remove stale arch/tile/kernel/futex_64.S

2013-09-13T15:15:24+00:00

This should have been removed with commit 47d632f9f8f3, but
it was overlooked.

Signed-off-by: Chris Metcalf

tile: remove HUGE_VMAP dead code

2013-09-13T15:15:24+00:00

A config option to allow a variant vmap() using huge pages that was never
upstreamed had some bits of code related to it scattered around the tile
architecture; the config option was removed downstream and this commit
cleans up the scattered evidence of it from the upstream as well.

Signed-off-by: Chris Metcalf

tile: fix typos in comment in arch/tile/kernel/unaligned.c

2013-09-13T14:57:54+00:00

Signed-off-by: Chris Metcalf

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

2013-09-06T18:14:33+00:00

Pull Tile arch updates from Chris Metcalf:
 "These changes bring in a bunch of new functionality that has been
  maintained internally at Tilera over the last year, plus other stray
  bits of work that I've taken into the tile tree from other folks.

  The changes include some PCI root complex work, interrupt-driven
  console support, support for performing fast-path unaligned data
  fixups by kernel-based JIT code generation, CONFIG_PREEMPT support,
  vDSO support for gettimeofday(), a serial driver for the tilegx
  on-chip UART, KGDB support, more optimized string routines, support
  for ftrace and kprobes, improved ASLR, and many bug fixes.

  We also remove support for the old TILE64 chip, which is no longer
  buildable"

* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile: (85 commits)
  tile: refresh tile defconfig files
  tile: rework 
  tile PCI RC: make default consistent DMA mask 32-bit
  tile: add null check for kzalloc in tile/kernel/setup.c
  tile: make __write_once a synonym for __read_mostly
  tile: remove support for TILE64
  tile: use asm-generic/bitops/builtin-*.h
  tile: eliminate no-op "noatomichash" boot argument
  tile: use standard tile_bundle_bits type in traps.c
  tile: simplify code referencing hypervisor API addresses
  tile: change  to  in comments
  tile: mark pcibios_init() as __init
  tile: check for correct compiler earlier in asm-offsets.c
  tile: use standard 'generic-y' model for 
  tile: use asm-generic version of 
  tile PCI RC: add comment about "PCI hole" problem
  tile: remove DEBUG_EXTRA_FLAGS kernel config option
  tile: add virt_to_kpte() API and clean up and document behavior
  tile: support FRAME_POINTER
  tile: support reporting Tilera hypervisor statistics
  ...