[SRU][jammy][PULL] Kernel livepatch support for s390x
Stefan Bader
stefan.bader at canonical.com
Mon Mar 6 10:32:09 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
I find this whole block of generic scheduler changes concerning. I have
not looked into the actual changes but the delta but changing something
related to RCU sounds potentially dangerous for any architecture. Even
those not doing livepatch. Some more explanation about why this is
needed and roughly what the purpose of those changes is would be much
better. So not everyone checking has to go through the same research.
>
> 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
>
- Stefan
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