linux.git/arch/ia64/kernel/time.c, branch master

arch: Remove Itanium (IA-64) architecture

2023-09-11T08:13:17+00:00

The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.

None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.

While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.

There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.

So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.

[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/

Acked-by: Tony Luck 
Signed-off-by: Ard Biesheuvel

sched/cputime: Fix IA64 build error of missing arch_vtime_task_switch() prototype

2023-01-11T09:31:57+00:00

The following commit:

  c89970202a11 ("cputime: remove cputime_to_nsecs fallback")

Removed an  inclusion from , but this
broke the IA64 build:

    arch/ia64/kernel/time.c:110:6: warning: no previous prototype for 'arch_vtime_task_switch' [-Wmissing-prototypes]

Add in the missing  header to fix it.

Fixes: c89970202a11 ("cputime: remove cputime_to_nsecs fallback")
Reported-by: kernel test robot 
Signed-off-by: Ingo Molnar 
Cc: linux-kernel@vger.kernel.org
Cc: Nicholas Piggin 
Cc: Peter Zijlstra (Intel) 
Cc: Alexander Gordeev 
Signed-off-by: Ingo Molnar

Merge tag 'efi-next-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-02-21T03:09:26+00:00

Pull EFI updates from Ard Biesheuvel via Borislav Petkov:
 "A few cleanups left and right, some of which were part of a initrd
  measured boot series that needs some more work, and so only the
  cleanup patches have been included for this release"

* tag 'efi-next-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/arm64: Update debug prints to reflect other entropy sources
  efi: x86: clean up previous struct mm switching
  efi: x86: move mixed mode stack PA variable out of 'efi_scratch'
  efi/libstub: move TPM related prototypes into efistub.h
  efi/libstub: fix prototype of efi_tcg2_protocol::get_event_log()
  efi/libstub: whitespace cleanup
  efi: ia64: move IA64-only declarations to new asm/efi.h header

efi: ia64: move IA64-only declarations to new asm/efi.h header

2021-01-18T12:50:37+00:00

Move some EFI related declarations that are only referenced on IA64 to
a new asm/efi.h arch header.

Cc: Tony Luck 
Cc: Fenghua Yu 
Signed-off-by: Ard Biesheuvel

ia64: fix timer cleanup regression

2021-01-12T16:01:42+00:00

A cleanup patch from my legacy timer series broke ia64 and led
to RCU stall errors and a fast system clock:

[  909.360108] INFO: task systemd-sysv-ge:200 blocked for more than 127 seconds.
[  909.360108]       Not tainted 5.10.0+ #130
[  909.360108] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  909.360108] task:systemd-sysv-ge state:D stack:    0 pid:  200 ppid:   189 flags:0x00000000
[  909.364108]
[  909.364108] Call Trace:
[  909.364423]  [] __schedule+0x890/0x21e0
[  909.364423]                                 sp=e0000100487d7b70 bsp=e0000100487d1748
[  909.368423]  [] schedule+0xa0/0x240
[  909.368423]                                 sp=e0000100487d7b90 bsp=e0000100487d16e0
[  909.368558]  [] io_schedule+0x70/0xa0
[  909.368558]                                 sp=e0000100487d7b90 bsp=e0000100487d16c0
[  909.372290]  [] bit_wait_io+0x20/0xe0
[  909.372290]                                 sp=e0000100487d7b90 bsp=e0000100487d1698
[  909.374168] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[  909.376290]  [] __wait_on_bit+0xc0/0x1c0
[  909.376290]                                 sp=e0000100487d7b90 bsp=e0000100487d1648
[  909.374168] rcu:     3-....: (2 ticks this GP) idle=19e/1/0x4000000000000002 softirq=1581/1581 fqs=2
[  909.374168]  (detected by 0, t=5661 jiffies, g=1089, q=3)
[  909.376290]  [] out_of_line_wait_on_bit+0x120/0x140
[  909.376290]                                 sp=e0000100487d7b90 bsp=e0000100487d1610
[  909.374168] Task dump for CPU 3:
[  909.374168] task:khungtaskd      state:R  running task

Revert most of my patch to make this work again, including the extra
update_process_times()/profile_tick() and the local_irq_enable() in the
loop that I expected not to be needed here.

I have not found out exactly what goes wrong, and would suggest that
someone with hardware access tries to convert this code into a singleshot
clockevent driver, which should give better behavior in all cases.

Reported-by: John Paul Adrian Glaubitz 
Fixes: 2b49ddcef297 ("ia64: convert to legacy_timer_tick")
Cc: John Stultz 
Cc: Thomas Gleixner 
Cc: Stephen Boyd 
Cc: Frederic Weisbecker 
Signed-off-by: Arnd Bergmann

Merge tag 'asm-generic-timers-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2020-12-16T08:07:17+00:00

Pull asm-generic cross-architecture timer cleanup from Arnd Bergmann:
 "This cleans up two ancient timer features that were never completed in
  the past, CONFIG_GENERIC_CLOCKEVENTS and CONFIG_ARCH_USES_GETTIMEOFFSET.

  There was only one user left for the ARCH_USES_GETTIMEOFFSET variant
  of clocksource implementations, the ARM EBSA110 platform. Rather than
  changing to use modern timekeeping, we remove the platform entirely as
  Russell no longer uses his machine and nobody else seems to have one
  any more.

  The conditional code for using arch_gettimeoffset() is removed as a
  result.

  For CONFIG_GENERIC_CLOCKEVENTS, there are still a couple of platforms
  not using clockevent drivers: parisc, ia64, most of m68k, and one Arm
  platform. These all do timer ticks slighly differently, and this gets
  cleaned up to the point they at least all call the same helper
  function.

  Instead of most platforms using 'select GENERIC_CLOCKEVENTS' in
  Kconfig, the polarity is now reversed, with the few remaining ones
  selecting LEGACY_TIMER_TICK instead"

* tag 'asm-generic-timers-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  timekeeping: default GENERIC_CLOCKEVENTS to enabled
  timekeeping: remove xtime_update
  m68k: remove timer_interrupt() function
  m68k: change remaining timers to legacy_timer_tick
  m68k: m68328: use legacy_timer_tick()
  m68k: sun3/sun3c: use legacy_timer_tick
  m68k: split heartbeat out of timer function
  m68k: coldfire: use legacy_timer_tick()
  parisc: use legacy_timer_tick
  ARM: rpc: use legacy_timer_tick
  ia64: convert to legacy_timer_tick
  timekeeping: add CONFIG_LEGACY_TIMER_TICK
  timekeeping: remove arch_gettimeoffset
  net: remove am79c961a driver
  ARM: remove ebsa110 platform

sched/vtime: Consolidate IRQ time accounting

2020-12-02T19:20:05+00:00

The 3 architectures implementing CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
all have their own version of irq time accounting that dispatch the
cputime to the appropriate index: hardirq, softirq, system, idle,
guest... from an all-in-one function.

Instead of having these ad-hoc versions, move the cputime destination
dispatch decision to the core code and leave only the actual per-index
cputime accounting to the architecture.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20201202115732.27827-4-frederic@kernel.org

ia64: convert to legacy_timer_tick

2020-10-30T20:57:04+00:00

ia64 is the only architecture that calls xtime_update() in a loop,
once for each jiffie that has passed since the last event.

Before commit 3171a0305d62 ("[PATCH] simplify update_times (avoid
jiffies/jiffies_64 aliasing problem)") in 2006, it could not actually do
this any differently, but now it seems simpler to just pass the number
of jiffies that passed in the meantime.

While this loses the ability process interrupts in the middle of
the timer tick by calling local_irq_enable(), doing so is fairly
peculiar anyway and it seems better to just do what everyone
else does here.

Reviewed-by: Linus Walleij 
Signed-off-by: Arnd Bergmann

ia64: replace setup_irq() by request_irq()

2020-03-13T22:21:28+00:00

request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

Per tglx[1], setup_irq() existed in olden days when allocators were not
ready by the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

Changing 'ia64_native_register_percpu_irq' decleration to include
'irq_handler_t' as an argument type in arch/ia64/include/asm/hw_irq.h
was causing build error - 'unknown type name 'irq_handler_t''

This was due to below header file sequence,
+ include/interrupt.h
 + include/hardirq.h
  + asm/hardirq.h
   + include/irq.h
    + asm/hw_irq.h
       [ 'ia64_native_register_percpu_irq' declared w/ 'irq_handler_t']
 [ 'irq_handler_t' typedef'ed here in 'include/interrupt.h']

'register_percpu_irq' defined to 'ia64_native_register_percpu_irq' is
the one invoked by the caller, not the latter directly. This was done
to support paravirtualization which was removed around 4 years back.
And 'register_percpu_irq' is invoked only inside 'arch/ia64/kernel'.

So 'register_percpu_irq' define to 'ia64_native_register_percpu_irq' is
removed, instead 'ia64_native_register_percpu_irq' is renamed to
'register_precpu_irq()' & it is directly invoked. Also,
'register_precpu_irq()' is declared in a new header file 'irq.h' inside
'arch/ia64/kernel/', this header file is included by C files invoking
'register_percpu_irq()'.

[1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanos

Signed-off-by: afzal mohammed 
Signed-off-by: Tony Luck

sched/cputime: Rename vtime_account_system() to vtime_account_kernel()

2019-10-09T10:39:25+00:00

vtime_account_system() decides if we need to account the time to the
system (__vtime_account_system()) or to the guest (vtime_account_guest()).

So this function is a misnomer as we are on a higher level than
"system". All we know when we call that function is that we are
accounting kernel cputime. Whether it belongs to guest or system time
is a lower level detail.

Rename this function to vtime_account_kernel(). This will clarify things
and avoid too many underscored vtime_account_system() versions.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Cc: Wanpeng Li 
Cc: Yauheni Kaliuta 
Link: https://lkml.kernel.org/r/20191003161745.28464-2-frederic@kernel.org
Signed-off-by: Ingo Molnar