linux.git/arch/csky/kernel/smp.c, branch v6.2

profile: setup_profiling_timer() is moslty not implemented

2022-07-30T01:12:36+00:00

The setup_profiling_timer() is mostly un-implemented by many
architectures.  In many places it isn't guarded by CONFIG_PROFILE which is
needed for it to be used.  Make it a weak symbol in kernel/profile.c and
remove the 'return -EINVAL' implementations from the kenrel.

There are a couple of architectures which do return 0 from the
setup_profiling_timer() function but they don't seem to do anything else
with it.  To keep the /proc compatibility for now, leave these for a
future update or removal.

On ARM, this fixes the following sparse warning:
arch/arm/kernel/smp.c:793:5: warning: symbol 'setup_profiling_timer' was not declared. Should it be static?

Link: https://lkml.kernel.org/r/20220721195509.418205-1-ben-linux@fluff.org
Signed-off-by: Ben Dooks 
Signed-off-by: Andrew Morton

csky: Use of_get_cpu_hwid()

2021-10-20T18:37:24+00:00

Replace open coded parsing of CPU nodes 'reg' property with
of_get_cpu_hwid().

Cc: Guo Ren 
Cc: linux-csky@vger.kernel.org
Signed-off-by: Rob Herring 
Link: https://lore.kernel.org/r/20211006164332.1981454-6-robh@kernel.org

sched/core: Initialize the idle task with preemption disabled

2021-05-12T11:01:45+00:00

As pointed out by commit

  de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread")

init_idle() can and will be invoked more than once on the same idle
task. At boot time, it is invoked for the boot CPU thread by
sched_init(). Then smp_init() creates the threads for all the secondary
CPUs and invokes init_idle() on them.

As the hotplug machinery brings the secondaries to life, it will issue
calls to idle_thread_get(), which itself invokes init_idle() yet again.
In this case it's invoked twice more per secondary: at _cpu_up(), and at
bringup_cpu().

Given smp_init() already initializes the idle tasks for all *possible*
CPUs, no further initialization should be required. Now, removing
init_idle() from idle_thread_get() exposes some interesting expectations
with regards to the idle task's preempt_count: the secondary startup always
issues a preempt_disable(), requiring some reset of the preempt count to 0
between hot-unplug and hotplug, which is currently served by
idle_thread_get() -> idle_init().

Given the idle task is supposed to have preemption disabled once and never
see it re-enabled, it seems that what we actually want is to initialize its
preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove
init_idle() from idle_thread_get().

Secondary startups were patched via coccinelle:

  @begone@
  @@

  -preempt_disable();
  ...
  cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

Signed-off-by: Valentin Schneider 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com

csky: Add memory layout 2.5G(user):1.5G(kernel)

2021-01-12T01:52:40+00:00

There are two ways for translating va to pa for csky:
 - Use TLB(Translate Lookup Buffer) and PTW (Page Table Walk)
 - Use SSEG0/1 (Simple Segment Mapping)

We use tlb mapping 0-2G and 3G-4G virtual address area and SSEG0/1
are for 2G-2.5G and 2.5G-3G translation. We could disable SSEG0
to use 2G-2.5G as TLB user mapping.

Signed-off-by: Guo Ren

mm: remove unneeded includes of

2020-08-07T18:33:26+00:00

Patch series "mm: cleanup usage of "

Most architectures have very similar versions of pXd_alloc_one() and
pXd_free_one() for intermediate levels of page table.  These patches add
generic versions of these functions in  and enable
use of the generic functions where appropriate.

In addition, functions declared and defined in  headers are
used mostly by core mm and early mm initialization in arch and there is no
actual reason to have the  included all over the place.
The first patch in this series removes unneeded includes of


In the end it didn't work out as neatly as I hoped and moving
pXd_alloc_track() definitions to  would require
unnecessary changes to arches that have custom page table allocations, so
I've decided to move lib/ioremap.c to mm/ and make pgalloc-track.h local
to mm/.

This patch (of 8):

In most cases  header is required only for allocations of
page table memory.  Most of the .c files that include that header do not
use symbols declared in  and do not require that header.

As for the other header files that used to include , it is
possible to move that include into the .c file that actually uses symbols
from  and drop the include from the header file.

The process was somewhat automated using

	sed -i -E '/[<"]asm\/pgalloc\.h/d' \
                $(grep -L -w -f /tmp/xx \
                        $(git grep -E -l '[<"]asm/pgalloc\.h'))

where /tmp/xx contains all the symbols defined in
arch/*/include/asm/pgalloc.h.

[rppt@linux.ibm.com: fix powerpc warning]

Signed-off-by: Mike Rapoport 
Signed-off-by: Andrew Morton 
Reviewed-by: Pekka Enberg 
Acked-by: Geert Uytterhoeven 	[m68k]
Cc: Abdul Haleem 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Christophe Leroy 
Cc: Joerg Roedel 
Cc: Max Filippov 
Cc: Peter Zijlstra 
Cc: Satheesh Rajendran 
Cc: Stafford Horne 
Cc: Stephen Rothwell 
Cc: Steven Rostedt 
Cc: Joerg Roedel 
Cc: Matthew Wilcox 
Link: http://lkml.kernel.org/r/20200627143453.31835-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200627143453.31835-2-rppt@kernel.org
Signed-off-by: Linus Torvalds

csky: Add arch_show_interrupts for IPI interrupts

2020-07-31T01:56:01+00:00

Here is the result:

 cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3
 15:       1348       1299        952       1076  C-SKY SMP Intc  15  IPI Interrupt
 16:       1203       1825       1598       1307  C-SKY SMP Intc  16  csky_mp_timer
 43:        292          0          0          0  C-SKY SMP Intc  43  ttyS0
 57:        106          0          0          0  C-SKY SMP Intc  57  virtio0
IPI0:         0          0          0          0  Empty interrupts
IPI1:        19         41         45         27  Rescheduling interrupts
IPI2:      1330       1259        908       1050  Function call interrupts
IPI3:         0          0          0          0  Irq work interrupts

Signed-off-by: Guo Ren 
Cc: Arnd Bergmann

csky: Add irq_work support

2020-07-31T01:55:46+00:00

Running work in hardware interrupt context for csky. Implement:
 - arch_irq_work_raise()
 - arch_irq_work_has_interrupt()

Signed-off-by: Guo Ren 
Cc: Arnd Bergmann

csky: Add cpu feature register hint for smp

2020-07-31T01:51:29+00:00

CPU features registers are setup by customers' bootloader, but
Linux must help transfer them from the primary to secondary cores.
This patch add hint2 CPU feature register supported.

Signed-off-by: Guo Ren 
Cc: Arnd Bergmann

csky: Fixup cpu speculative execution to IO area

2020-04-03T04:40:07+00:00

For the memory size ( > 512MB, < 1GB), the MSA setting is:

 - SSEG0: PHY_START        , PHY_START + 512MB
 - SSEG1: PHY_START + 512MB, PHY_START + 1GB

But the real memory is no more than 1GB, there is a gap between the
end size of memory and border of 1GB. CPU could speculatively
execute to that gap and if the gap of the bus couldn't respond to
the CPU request, then the crash will happen.

Now make the setting with:

 - SSEG0: PHY_START        , PHY_START + 512MB (no change)
 - SSEG1: Disabled (We use highmem to use the memory of 512MB~1GB)

We also deprecated zhole_szie[] settings, it's only used by arm
style CPUs. All memory gap should use Reserved setting of dts in
csky system.

Signed-off-by: Guo Ren

csky: Fixup init_fpu compile warning with __init

2020-03-08T12:55:14+00:00

WARNING: vmlinux.o(.text+0x2366): Section mismatch in reference from the
function csky_start_secondary() to the function .init.text:init_fpu()

The function csky_start_secondary() references
the function __init init_fpu().
This is often because csky_start_secondary lacks a __init
annotation or the annotation of init_fpu is wrong.

Reported-by: Lu Chongzhi 
Signed-off-by: Guo Ren