Eric Lee / smarc-fsl-linux-kernel

27 Aug, 2020

1 commit

  • 1196f12a2   s390: don't trace preemption in percpu macros ... Browse Code »

    Since commit a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context}
    to per-cpu variables") the lockdep code itself uses percpu variables. This
    leads to recursions because the percpu macros are calling preempt_enable()
    which might call trace_preempt_on().

    Signed-off-by: Sven Schnelle
    Reviewed-by: Vasily Gorbik
    Signed-off-by: Vasily Gorbik

    Sven Schnelle
     

07 Jun, 2019

1 commit

  • 67626fadd   s390: enforce CONFIG_SMP ... Browse Code »

    There never have been distributions that shiped with CONFIG_SMP=n for
    s390. In addition the kernel currently doesn't even compile with
    CONFIG_SMP=n for s390. Most likely it wouldn't even work, even if we
    fix the compile error, since nobody tests it, since there is no use
    case that I can think of.
    Therefore simply enforce CONFIG_SMP and get rid of some more or
    less unused code.

    Reviewed-by: Christian Borntraeger
    Signed-off-by: Heiko Carstens

    Heiko Carstens
     

02 Nov, 2017

1 commit

  • b24413180   License cleanup: add SPDX GPL-2.0 license identifier to files with no license ... Browse Code »

    Many source files in the tree are missing licensing information, which
    makes it harder for compliance tools to determine the correct license.

    By default all files without license information are under the default
    license of the kernel, which is GPL version 2.

    Update the files which contain no license information with the 'GPL-2.0'
    SPDX license identifier. The SPDX identifier is a legally binding
    shorthand, which can be used instead of the full boiler plate text.

    This patch is based on work done by Thomas Gleixner and Kate Stewart and
    Philippe Ombredanne.

    How this work was done:

    Patches were generated and checked against linux-4.14-rc6 for a subset of
    the use cases:
    - file had no licensing information it it.
    - file was a */uapi/* one with no licensing information in it,
    - file was a */uapi/* one with existing licensing information,

    Further patches will be generated in subsequent months to fix up cases
    where non-standard license headers were used, and references to license
    had to be inferred by heuristics based on keywords.

    The analysis to determine which SPDX License Identifier to be applied to
    a file was done in a spreadsheet of side by side results from of the
    output of two independent scanners (ScanCode & Windriver) producing SPDX
    tag:value files created by Philippe Ombredanne. Philippe prepared the
    base worksheet, and did an initial spot review of a few 1000 files.

    The 4.13 kernel was the starting point of the analysis with 60,537 files
    assessed. Kate Stewart did a file by file comparison of the scanner
    results in the spreadsheet to determine which SPDX license identifier(s)
    to be applied to the file. She confirmed any determination that was not
    immediately clear with lawyers working with the Linux Foundation.

    Criteria used to select files for SPDX license identifier tagging was:
    - Files considered eligible had to be source code files.
    - Make and config files were included as candidates if they contained >5
    lines of source
    - File already had some variant of a license header in it (even if
    Reviewed-by: Philippe Ombredanne
    Reviewed-by: Thomas Gleixner
    Signed-off-by: Greg Kroah-Hartman

    Greg Kroah-Hartman
     

02 Mar, 2016

1 commit

  • f369b98ee   s390/percpu: remove this_cpu_cmpxchg_double_4 ... Browse Code »

    git commit 26f15caaf993 ("s390/cmpxchg: simplify cmpxchg_double")
    removed support for cmpxchg_double for two consecutive four byte
    values, for which it would generate a cds instruction.

    However I forgot to remove the corresponding define in our percpu
    header file, which means that this_cpu_cmpxchg_double would now
    incorrectly generate a cdsg instruction if being used on a double four
    byte location. Therefore remove the percpu define as well.

    There is currently no user and therefore no bug fixed with
    this. Obviously any such user could and should simply use cmpxchg.

    Signed-off-by: Heiko Carstens
    Signed-off-by: Martin Schwidefsky

    Heiko Carstens
     

25 Mar, 2015

1 commit

  • 5a79859ae   s390: remove 31 bit support ... Browse Code »

    Remove the 31 bit support in order to reduce maintenance cost and
    effectively remove dead code. Since a couple of years there is no
    distribution left that comes with a 31 bit kernel.

    The 31 bit kernel also has been broken since more than a year before
    anybody noticed. In addition I added a removal warning to the kernel
    shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning
    message") which let everybody know about the plan to remove 31 bit
    code. We didn't get any response.

    Given that the last 31 bit only machine was introduced in 1999 let's
    remove the code.
    Anybody with 31 bit user space code can still use the compat mode.

    Signed-off-by: Heiko Carstens
    Signed-off-by: Martin Schwidefsky

    Heiko Carstens
     

27 Aug, 2014

1 commit

  • eb7e7d766   s390: Replace __get_cpu_var uses ... Browse Code »

    __get_cpu_var() is used for multiple purposes in the kernel source. One of
    them is address calculation via the form &__get_cpu_var(x). This calculates
    the address for the instance of the percpu variable of the current processor
    based on an offset.

    Other use cases are for storing and retrieving data from the current
    processors percpu area. __get_cpu_var() can be used as an lvalue when
    writing data or on the right side of an assignment.

    __get_cpu_var() is defined as :

    #define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

    __get_cpu_var() always only does an address determination. However, store
    and retrieve operations could use a segment prefix (or global register on
    other platforms) to avoid the address calculation.

    this_cpu_write() and this_cpu_read() can directly take an offset into a
    percpu area and use optimized assembly code to read and write per cpu
    variables.

    This patch converts __get_cpu_var into either an explicit address
    calculation using this_cpu_ptr() or into a use of this_cpu operations that
    use the offset. Thereby address calculations are avoided and less registers
    are used when code is generated.

    At the end of the patch set all uses of __get_cpu_var have been removed so
    the macro is removed too.

    The patch set includes passes over all arches as well. Once these operations
    are used throughout then specialized macros can be defined in non -x86
    arches as well in order to optimize per cpu access by f.e. using a global
    register that may be set to the per cpu base.

    Transformations done to __get_cpu_var()

    1. Determine the address of the percpu instance of the current processor.

    DEFINE_PER_CPU(int, y);
    int *x = &__get_cpu_var(y);

    Converts to

    int *x = this_cpu_ptr(&y);

    2. Same as #1 but this time an array structure is involved.

    DEFINE_PER_CPU(int, y[20]);
    int *x = __get_cpu_var(y);

    Converts to

    int *x = this_cpu_ptr(y);

    3. Retrieve the content of the current processors instance of a per cpu
    variable.

    DEFINE_PER_CPU(int, y);
    int x = __get_cpu_var(y)

    Converts to

    int x = __this_cpu_read(y);

    4. Retrieve the content of a percpu struct

    DEFINE_PER_CPU(struct mystruct, y);
    struct mystruct x = __get_cpu_var(y);

    Converts to

    memcpy(&x, this_cpu_ptr(&y), sizeof(x));

    5. Assignment to a per cpu variable

    DEFINE_PER_CPU(int, y)
    __get_cpu_var(y) = x;

    Converts to

    this_cpu_write(y, x);

    6. Increment/Decrement etc of a per cpu variable

    DEFINE_PER_CPU(int, y);
    __get_cpu_var(y)++

    Converts to

    this_cpu_inc(y)

    Cc: Martin Schwidefsky
    CC: linux390@de.ibm.com
    Acked-by: Heiko Carstens
    Signed-off-by: Christoph Lameter
    Signed-off-by: Tejun Heo

    Christoph Lameter
     

31 Oct, 2013

1 commit

24 Oct, 2013

2 commits

26 Sep, 2012

3 commits

24 May, 2012

1 commit

23 Dec, 2011

1 commit

  • 933393f58   percpu: Remove irqsafe_cpu_xxx variants ... Browse Code »
    43

    We simply say that regular this_cpu use must be safe regardless of
    preemption and interrupt state. That has no material change for x86
    and s390 implementations of this_cpu operations. However, arches that
    do not provide their own implementation for this_cpu operations will
    now get code generated that disables interrupts instead of preemption.

    -tj: This is part of on-going percpu API cleanup. For detailed
    discussion of the subject, please refer to the following thread.

    http://thread.gmane.org/gmane.linux.kernel/1222078

    Signed-off-by: Christoph Lameter
    Signed-off-by: Tejun Heo
    LKML-Reference:

    Christoph Lameter
     

23 May, 2011

1 commit

  • 4c2241fd4   [S390] percpu: implement arch specific irqsafe_cpu_ops ... Browse Code »

    Implement arch specific irqsafe_cpu ops. The arch specific ops do not
    disable/enable interrupts since that is an expensive operation. Instead
    we disable preemption and perform a compare and swap loop.
    Since on server distros (the ones we care about) preemption is disabled
    the preempt_disable()/preempt_enable() pair is a nop.
    In the end this code should be faster than the generic one.

    Signed-off-by: Heiko Carstens
    Signed-off-by: Martin Schwidefsky

    Heiko Carstens
     

24 Jun, 2009

1 commit

  • 9a0ef2923   s390: switch to dynamic percpu allocator ... Browse Code »

    64bit s390 shares the same problem with alpha regarding percpu symbol
    addressing from modules. It needs assembly magic to force GOTENT
    reference when building module as the percpu address will be outside
    the usual 4G range from the module text. This can be solved by using
    weak percpu variable definitions.

    This patch makes s390 use weak definitions and switch to dynamic
    percpu allocator. Please note that weak attribute is not added if
    !SMP as percpu variables behave exactly the same as normal variables
    on UP.

    Compile tested. Generation of GOTENT reference verified.

    This patch is based on Ivan Kokshaysky's alpha percpu patch.

    [ Impact: use dynamic percpu allocator ]

    Signed-off-by: Tejun Heo
    Cc: Martin Schwidefsky
    Cc: Heiko Carstens

    Tejun Heo
     

02 Aug, 2008

1 commit