kpatch/doc/s390-upstream-prerequisites.md

s390 backporting

Prerequisite gcc patches (all backported to releases/gcc-11 branch):

• gcc-mirror/gcc@a1c1b7a IBM Z: Define NO_PROFILE_COUNTERS
• gcc-mirror/gcc@0990d93 IBM Z: Use @PLT symbols for local functions in 64-bit mode
• gcc-mirror/gcc@935b522 S/390: New option -mpic-data-is-text-relative
• gcc-mirror/gcc@8753b13 IBM Z: fix section type conflict with -mindirect-branch-table

Prerequisite kernel patches: v5.19:

• 69505e3d9a39 bug: Use normal relative pointers in 'struct bug_entry'

v5.18:

• 602bf1687e6f s390/nospec: align and size extern thunks
• 1d2ad084800e s390/nospec: add an option to use thunk-extern
• eed38cd2f46f s390/nospec: generate single register thunks if possible
• 2268169c14e5 s390: remove unused expoline to BC instructions
• f0003a9e4c18 s390/entry: remove unused expoline thunk

v5.16:

• torvalds/linux@f6ac18f sched: Improve try_invoke_on_locked_down_task()
• torvalds/linux@9b3c4ab sched,rcu: Rework try_invoke_on_locked_down_task()
• torvalds/linux@00619f7 sched,livepatch: Use task_call_func()
• torvalds/linux@8850cb6 sched: Simplify wake_up_idle()
• torvalds/linux@5de62ea sched,livepatch: Use wake_up_if_idle()
• torvalds/linux@96611c2 sched: Improve wake_up_all_idle_cpus() take #2

v5.15

• torvalds/linux@de5012b s390/ftrace: implement hotpatching
• torvalds/linux@67ccddf ftrace: Introduce ftrace_need_init_nop()

v5.14:

• torvalds/linux@7561c14 s390/vdso: add .got.plt in vdso linker script