[RFC PATCH v3 00/11] powerpc: Add support for ftrace direct and BPF trampolines

[Vishal Chourasia]

On Fri, Jun 21, 2024 at 12:24:03AM +0530, Naveen N Rao wrote:
> This is v3 of the patches posted here:
> http://lkml.kernel.org/r/cover.1718008093.git.naveen@kernel.org
> 
> Since v2, I have addressed review comments from Steven and Masahiro 
> along with a few fixes. Patches 7-11 are new in this series and add 
> support for ftrace direct and bpf trampolines. 
> 
> This series depends on the patch series from Benjamin Gray adding 
> support for patch_ulong():
> http://lkml.kernel.org/r/20240515024445.236364-1-bgray@linux.ibm.com

This patchset, along with its dependent patchset [2], enables support 
for BPF schedulers introduced by the sched_ext patchset [1] on 
Power Architecture.

Before this patchset, BPF schedulers were failing to load due to the 
lack of trampoline support.

GitHub repo for sched_ext: https://github.com/sched-ext/sched_ext
Note: This repo has been archived. Please refer to the description 
provided on the repo homepage for more details.

[1] v6 https://lore.kernel.org/lkml/20240501151312.635565-1-tj@kernel.org
[2] http://lkml.kernel.org/r/20240515024445.236364-1-bgray@linux.ibm.com

Thank you for the patch!
> 
> 
> - Naveen
> 
> 
> Naveen N Rao (11):
>   powerpc/kprobes: Use ftrace to determine if a probe is at function
>     entry
>   powerpc/ftrace: Unify 32-bit and 64-bit ftrace entry code
>   powerpc/module_64: Convert #ifdef to IS_ENABLED()
>   powerpc/ftrace: Remove pointer to struct module from dyn_arch_ftrace
>   kbuild: Add generic hook for architectures to use before the final
>     vmlinux link
>   powerpc64/ftrace: Move ftrace sequence out of line
>   powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS
>   powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_DIRECT_CALLS
>   samples/ftrace: Add support for ftrace direct samples on powerpc
>   powerpc64/bpf: Fold bpf_jit_emit_func_call_hlp() into
>     bpf_jit_emit_func_call_rel()
>   powerpc64/bpf: Add support for bpf trampolines
> 
>  arch/Kconfig                                |   3 +
>  arch/powerpc/Kconfig                        |   9 +
>  arch/powerpc/Makefile                       |   8 +
>  arch/powerpc/include/asm/ftrace.h           |  29 +-
>  arch/powerpc/include/asm/module.h           |   5 +
>  arch/powerpc/include/asm/ppc-opcode.h       |  14 +
>  arch/powerpc/kernel/asm-offsets.c           |  11 +
>  arch/powerpc/kernel/kprobes.c               |  18 +-
>  arch/powerpc/kernel/module_64.c             |  67 +-
>  arch/powerpc/kernel/trace/ftrace.c          | 269 +++++++-
>  arch/powerpc/kernel/trace/ftrace_64_pg.c    |  73 +-
>  arch/powerpc/kernel/trace/ftrace_entry.S    | 210 ++++--
>  arch/powerpc/kernel/vmlinux.lds.S           |   3 +-
>  arch/powerpc/net/bpf_jit.h                  |  11 +
>  arch/powerpc/net/bpf_jit_comp.c             | 702 +++++++++++++++++++-
>  arch/powerpc/net/bpf_jit_comp32.c           |   7 +-
>  arch/powerpc/net/bpf_jit_comp64.c           |  68 +-
>  arch/powerpc/tools/Makefile                 |  10 +
>  arch/powerpc/tools/gen-ftrace-pfe-stubs.sh  |  49 ++
>  samples/ftrace/ftrace-direct-modify.c       |  85 ++-
>  samples/ftrace/ftrace-direct-multi-modify.c | 101 ++-
>  samples/ftrace/ftrace-direct-multi.c        |  79 ++-
>  samples/ftrace/ftrace-direct-too.c          |  83 ++-
>  samples/ftrace/ftrace-direct.c              |  69 +-
>  scripts/Makefile.vmlinux                    |   8 +
>  scripts/link-vmlinux.sh                     |  11 +-
>  26 files changed, 1813 insertions(+), 189 deletions(-)
>  create mode 100644 arch/powerpc/tools/Makefile
>  create mode 100755 arch/powerpc/tools/gen-ftrace-pfe-stubs.sh
> 
> 
> base-commit: e2b06d707dd067509cdc9ceba783c06fa6a551c2
> prerequisite-patch-id: a1d50e589288239d5a8b1c1f354cd4737057c9d3
> prerequisite-patch-id: da4142d56880861bd0ad7ad7087c9e2670a2ee54
> prerequisite-patch-id: 609d292e054b2396b603890522a940fa0bdfb6d8
> prerequisite-patch-id: 6f7213fb77b1260defbf43be0e47bff9c80054cc
> prerequisite-patch-id: ad3b71bf071ae4ba1bee5b087e61a2055772a74f
> -- 
> 2.45.2
>