ACK/Cmnt: [SRU][jammy][PULL] Kernel livepatch support for s390x

Stefan Bader stefan.bader at canonical.com
Thu Mar 9 08:01:01 UTC 2023


On 04.03.23 00:06, John Cabaj wrote:
> BugLink: https://bugs.launchpad.net/bugs/1639924 (Kernel livepatch support for s390x)
> 
> [Impact]
> * Enables Livepatch support for Jammy s390x generic kernel
> 
> [Fix]
> b56340e565fd ("UBUNTU: [Config] s390x: Removing UBSAN from configuration")
> f0bd174678a9 ("UBUNTU: [Config] Enable EXPOLINE_EXTERN on s390x")
> 145dd7c7bfc6 ("s390/nospec: build expoline.o for modules_prepare target")
> ad24b243a0be ("bug: Use normal relative pointers in 'struct bug_entry'")
> 9c018ab00f18 ("s390/nospec: align and size extern thunks")
> 110252959a61 ("s390/nospec: add an option to use thunk-extern")
> 9183918aabab ("s390/nospec: generate single register thunks if possible")
> f08372d421dd ("s390: remove unused expoline to BC instructions")
> d1de041f86ad ("s390/entry: remove unused expoline thunk")
> 376e067eb888 ("sched: Improve wake_up_all_idle_cpus() take #2")
> 16fa7242e5b9 ("sched,livepatch: Use wake_up_if_idle()")
> 3a133e568eea ("sched: Simplify wake_up_*idle*()")
> 360b90e726cd ("sched,livepatch: Use task_call_func()")
> 3c01d492a326 ("sched,rcu: Rework try_invoke_on_locked_down_task()")
> 2a989b8ace35 ("sched: Improve try_invoke_on_locked_down_task()")
> 
> [Test Case]
> * Boot test
> * Tested a Livepatch (patch to /proc/meminfo module)
> 
> [Other Info]
> * Requires patch to GCC-11.3, removing gcc-ibmz-plt-revert.diff from debian/patches and debian/rules.patch (LP#2002429)
> * UBSAN (Undefined Behavior Santizer) configuration was removed from s390x as kpatch-build could not find symbols
> * kpatch update being considered for UBSAN issue (https://github.com/dynup/kpatch/issues/1328)
> 
> [Where things could go wrong]
> * Functionality already exists upstream, kernel was boot and Livepatch tested - should have no regressions
> * s390x UBSAN functionality no longer included, may not catch previously caught undefined behavior
> 
> -----
> 
> The following changes since commit ed81d4519af756cfde8c3c02b495c6006b6ee0e9:
> 
>    UBUNTU: Start new release (2023-03-02 21:29:10 -0600)
> 
> are available in the git repository at:
> 
>    git+ssh://user@kathleen/home/john-cabaj/for-review/jammy-s390x-livepatch s390x-livepatch
> 
> for you to fetch changes up to b56340e565fdae9b6fc53b573e01194435a65e3e:
> 
>    UBUNTU: [Config] s390x: Removing UBSAN from configuration (2023-03-02 21:36:26 -0600)
> 
> ----------------------------------------------------------------
> Dimitri John Ledkov (1):
>        UBUNTU: [Config] Enable EXPOLINE_EXTERN on s390x
> 
> John Cabaj (1):
>        UBUNTU: [Config] s390x: Removing UBSAN from configuration
> 
> Josh Poimboeuf (1):
>        bug: Use normal relative pointers in 'struct bug_entry'
> 
> Peter Zijlstra (6):
>        sched: Improve try_invoke_on_locked_down_task()
>        sched,rcu: Rework try_invoke_on_locked_down_task()
>        sched,livepatch: Use task_call_func()
>        sched: Simplify wake_up_*idle*()
>        sched,livepatch: Use wake_up_if_idle()
>        sched: Improve wake_up_all_idle_cpus() take #2
> 
> Vasily Gorbik (6):
>        s390/entry: remove unused expoline thunk
>        s390: remove unused expoline to BC instructions
>        s390/nospec: generate single register thunks if possible
>        s390/nospec: add an option to use thunk-extern
>        s390/nospec: align and size extern thunks
>        s390/nospec: build expoline.o for modules_prepare target
> 
>   arch/arm64/include/asm/asm-bug.h          |  4 ++--
>   arch/powerpc/include/asm/bug.h            | 14 ++++++++------
>   arch/riscv/include/asm/bug.h              |  4 ++--
>   arch/s390/Kconfig                         | 15 +++++++++++++++
>   arch/s390/Makefile                        | 20 +++++++++++++++-----
>   arch/s390/include/asm/bug.h               |  5 +++--
>   arch/s390/include/asm/nospec-insn.h       | 91 +++++++++++++++++++++++++++++++++++--------------------------------------------------------
>   arch/s390/kernel/entry.S                  |  1 -
>   arch/s390/kernel/nospec-branch.c          | 25 +++++--------------------
>   arch/s390/lib/Makefile                    |  2 ++
>   arch/s390/lib/expoline/Makefile           |  3 +++
>   arch/s390/lib/expoline/expoline.S         | 12 ++++++++++++
>   arch/s390/tools/gcc-thunk-extern.sh       | 24 ++++++++++++++++++++++++
>   arch/x86/include/asm/bug.h                |  2 +-
>   debian.master/config/annotations          |  5 +++--
>   debian.master/config/config.common.ubuntu |  2 +-
>   debian/rules.d/2-binary-arch.mk           |  4 ++++
>   include/linux/sched/idle.h                |  4 ++++
>   include/linux/wait.h                      |  3 ++-
>   kernel/livepatch/transition.c             | 95 ++++++++++++++++++++++++++++++++++++++++++++++++-----------------------------------------------
>   kernel/rcu/tasks.h                        | 12 ++++++------
>   kernel/rcu/tree_stall.h                   |  8 ++++----
>   kernel/sched/core.c                       | 83 +++++++++++++++++++++++++++++++++++++++++++++++------------------------------------
>   kernel/smp.c                              | 12 +++++-------
>   lib/bug.c                                 | 15 +++++++--------
>   scripts/mod/modpost.c                     |  5 +++++
>   26 files changed, 263 insertions(+), 207 deletions(-)
>   create mode 100644 arch/s390/lib/expoline/Makefile
>   create mode 100644 arch/s390/lib/expoline/expoline.S
>   create mode 100755 arch/s390/tools/gcc-thunk-extern.sh
> 
Ok, from what I hear we have this running in some derivative for a while 
and also done some testing beforehand. So hopefully this is enough. And 
queuing this for next cycle should be past 20.04.6 which gets 5.15 as hwe.

Acked-by: Stefan Bader <stefan.bader at canonical.com>
-- 
- Stefan

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