linux.git/arch/parisc/kernel/processor.c, branch v6.0

parisc: fix a crash with multicore scheduler

2022-06-03T07:54:01+00:00

With the kernel 5.18, the system will hang on boot if it is compiled with
CONFIG_SCHED_MC. The last printed message is "Brought up 1 node, 1 CPU".

The crash happens in sd_init
tl->mask (which is cpu_coregroup_mask) returns an empty mask. This happens
	because cpu_topology[0].core_sibling is empty.
Consequently, sd_span is set to an empty mask
sd_id = cpumask_first(sd_span) sets sd_id == NR_CPUS (because the mask is
	empty)
sd->shared = *per_cpu_ptr(sdd->sds, sd_id); sets sd->shared to NULL
	because sd_id is out of range
atomic_inc(&sd->shared->ref); crashes without printing anything

We can fix it by calling reset_cpu_topology() from init_cpu_topology() -
this will initialize the sibling masks on CPUs, so that they're not empty.

This patch also removes the variable "dualcores_found", it is useless,
because during boot, init_cpu_topology is called before
store_cpu_topology. Thus, set_sched_topology(parisc_mc_topology) is never
called. We don't need to call it at all because default_topology in
kernel/sched/topology.c contains the same items as parisc_mc_topology.

Note that we should not call store_cpu_topology() from init_per_cpu()
because it is called too early in the kernel initialization process and it
results in the message "Failure to register CPU0 device". Before this
patch, store_cpu_topology() would exit immediatelly because
cpuid_topo->core id was uninitialized and it was 0.

Signed-off-by: Mikulas Patocka 
Cc: stable@vger.kernel.org	# v5.18
Signed-off-by: Helge Deller

parisc: Merge model and model name into one line in /proc/cpuinfo

2022-05-08T18:01:11+00:00

The Linux tool "lscpu" shows the double amount of CPUs if we have
"model" and "model name" in two different lines in /proc/cpuinfo.
This change combines the model and the model name into one line.

Signed-off-by: Helge Deller 
Cc: stable@vger.kernel.org

parisc: Only list existing CPUs in cpu_possible_mask

2022-05-08T18:01:11+00:00

The inventory knows which CPUs are in the system, so this bitmask should
be in cpu_possible_mask instead of the bitmask based on CONFIG_NR_CPUS.

Reset the cpu_possible_mask before scanning the system for CPUs, and
mark each existing CPU as possible during initialization of that CPU.

This avoids those warnings later on too:

 register_cpu_capacity_sysctl: too early to get CPU4 device!

Signed-off-by: Helge Deller 
Noticed-by: John David Anglin

parisc: Move CPU startup-related functions into .text section

2022-03-29T19:37:12+00:00

If CONFIG_HOTPLUG_CPU is enabled, those functions will be run again
after bootup. So they need to reside in the .text section.

Signed-off-by: Helge Deller

parisc: Switch from GENERIC_CPU_DEVICES to GENERIC_ARCH_TOPOLOGY

2022-03-29T19:37:12+00:00

Switch away from the own cpu topology code to common code which is used
by ARM64 and RISCV. That will allow us to enable CPU hotplug later on.

Signed-off-by: Helge Deller

parisc: Drop loops_per_jiffy from per_cpu struct

2020-11-11T13:57:30+00:00

There is no need to keep a loops_per_jiffy value per cpu. Drop it.

Signed-off-by: Helge Deller

parisc: Replace cpu_up/down() with add/remove_cpu()

2020-03-25T11:59:36+00:00

The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down().

See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and
serialization during LPM") for an example description of what might go
wrong.

This also prepares to make cpu_up/down() a private interface of the CPU
subsystem.

Signed-off-by: Qais Yousef 
Signed-off-by: Thomas Gleixner 
Acked-by: Helge Deller 
Link: https://lkml.kernel.org/r/20200323135110.30522-13-qais.yousef@arm.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 153

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 or at your option any
  later version this program is distributed in the hope that it will
  be useful but without any warranty without even the implied warranty
  of merchantability or fitness for a particular purpose see the gnu
  general public license for more details you should have received a
  copy of the gnu general public license along with this program if
  not write to the free software foundation inc 675 mass ave cambridge
  ma 02139 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 77 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Armijn Hemel 
Reviewed-by: Richard Fontana 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.837555891@linutronix.de
Signed-off-by: Greg Kroah-Hartman

parisc: Use __ro_after_init in processor.c

2019-05-10T19:00:45+00:00

Signed-off-by: Helge Deller

parisc: Show n/a if product number not available

2019-05-03T21:47:39+00:00

Signed-off-by: Helge Deller