linux.git/arch/arc/include/asm/processor.h, branch v6.18.21

ARC: Replace ASSEMBLY with ASSEMBLER in the non-uapi headers

2025-06-09T16:18:12+00:00

While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembly code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This can be very confusing when switching between userspace
and kernelspace coding, or when dealing with uapi headers that
rather should use __ASSEMBLER__ instead. So let's standardize on
the __ASSEMBLER__ macro that is provided by the compilers now.

This is a completely mechanical patch (done with a simple "sed -i"
statement).

Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Thomas Huth 
Signed-off-by: Vineet Gupta

ARC: __switch_to: move ksp to thread_info from thread_struct

2023-08-18T03:31:59+00:00

task's arch specific bits are carried in 2 places
 - embedded thread_struct in task_struct
 - associated thread_info (hoisted in task's stack page) and
   syntactically: (thread_info *)(task_struct->stack)

ksp (dynamic kernel stack top) currently lives in thread_struct but
given its deep location in task struct likely to cache miss when
accessed from  __switch_to(). Moving it to thread_info would be more
efficient given proximity to frequently accessed items such as
preempt_count thus very likely to be in cache, specially in schedular
code.

Note however that currently tsk.thread.ksp takes 1 memory access (off
of tsk pointer) while new code tsk->stack.ksp would take 2, but likely
to be in cache. Moreover if task is current the 2nd reference can be
elided and instead derived from SP as (SP & ~(THREAD_SIZE - 1))

All of this also makes __switch_to() code simpler and we can see the 2
ways of retirving ksp (descrobed above) in new code.

Signed-off-by: Vineet Gupta

ARC: kernel stack: INIT_THREAD need not setup @init_stack in @ksp

2023-08-18T03:31:59+00:00

There are 2 pointers to kernel mode stack of a task
 - task_struct.stack: base address of stack page (max possible stack top)
 - thread_info.ksp  : runtime stack top in __switch_to

INIT_THREAD was setting up ksp to stack base which was not really needed
 - it would get overwritten with dynamic value on first call to
   __switch_to when init is switched out for the very first time.
 - generic code already does
      init_task.stack = init_stack
   and ARC code uses that to retrieve task's stack base.

Signed-off-by: Vineet Gupta

kernel: exit: cleanup release_thread()

2022-09-12T04:55:07+00:00

Only x86 has own release_thread(), introduce a new weak release_thread()
function to clean empty definitions in other ARCHs.

Link: https://lkml.kernel.org/r/20220819014406.32266-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Acked-by: Guo Ren 				[csky]
Acked-by: Russell King (Oracle) 
Acked-by: Geert Uytterhoeven 
Acked-by: Brian Cain 
Acked-by: Michael Ellerman 			[powerpc]
Acked-by: Stafford Horne 			[openrisc]
Acked-by: Catalin Marinas 		[arm64]
Acked-by: Huacai Chen 			[LoongArch]
Cc: Alexander Gordeev 
Cc: Anton Ivanov 
Cc: Borislav Petkov 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Chris Zankel 
Cc: Dave Hansen 
Cc: "David S. Miller" 
Cc: Dinh Nguyen 
Cc: Guo Ren  [csky]
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: James Bottomley 
Cc: Johannes Berg 
Cc: Jonas Bonn 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michal Simek 
Cc: Nicholas Piggin 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Richard Henderson 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Stefan Kristiansson 
Cc: Sven Schnelle 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Xuerui Wang 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton

sched: Add wrapper for get_wchan() to keep task blocked

2021-10-15T09:25:14+00:00

Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.

Suggested-by: Peter Zijlstra 
Signed-off-by: Kees Cook 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Geert Uytterhoeven 
Acked-by: Russell King (Oracle)  [arm]
Tested-by: Mark Rutland  [arm64]
Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org

ARC: mm: support 3 levels of page tables

2021-08-26T20:43:19+00:00

ARCv2 MMU is software walked and Linux implements 2 levels of paging: pgd/pte.
Forthcoming hw will have multiple levels, so this change preps mm code
for same. It is also fun to try multi levels even on soft-walked code to
ensure generic mm code is robust to handle.

overview
________

2 levels {pgd, pte} : pmd is folded but pmd_* macros are valid and operate on pgd
3 levels {pgd, pmd, pte}:
  - pud is folded and pud_* macros point to pgd
  - pmd_* macros operate on actual pmd

code changes
____________

1. #include 

2. Define CONFIG_PGTABLE_LEVELS 3

3a. Define PMD_SHIFT, PMD_SIZE, PMD_MASK, pmd_t
3b. Define pmd_val() which actually deals with pmd
    (pmd_offset(), pmd_index() are provided by generic code)
3c. pmd_alloc_one()/pmd_free() also provided by generic code
    (pmd_populate/pmd_free already exist)

4. Define pud_none(), pud_bad() macros based on generic pud_val() which
   internally pertains to pgd now.
4b. define pud_populate() to just setup pgd

Acked-by: Mike Rapoport 
Signed-off-by: Vineet Gupta

ARC: [plat-eznps]: Drop support for EZChip NPS platform

2020-10-06T04:02:29+00:00

NPS customers are no longer doing active development, as evident from
rand config build failures reported in recent times, so drop support
for NPS platform.

Tested-by: kernel test robot 
Signed-off-by: Vineet Gupta

ARC: add support for DSP-enabled userspace applications

2020-03-16T17:30:49+00:00

To be able to run DSP-enabled userspace applications we need to
save and restore following DSP-related registers:
At IRQ/exception entry/exit:
 * DSP_CTRL (save it and reset to value suitable for kernel)
 * ACC0_LO, ACC0_HI (we already save them as r58, r59 pair)
At context switch:
 * ACC0_GLO, ACC0_GHI
 * DSP_BFLY0, DSP_FFT_CTRL

Reviewed-by: Vineet Gupta 
Signed-off-by: Eugeniy Paltsev 
Signed-off-by: Vineet Gupta

ARC: fpu: declutter code, move bits out into fpu.h

2020-01-18T00:53:38+00:00

Signed-off-by: Vineet Gupta

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 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 version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman