[RFC PATCH 0/5] bpf: fprobe: rethook: Use ftrace_regs instead of pt_regs

Masami Hiramatsu (Google)
2023-08-05T14:58:00Z

Hi,

Here is RFC series to use ftrace_regs instead of pt_regs. But this includes
the generic part and minimum modifications of arch dependent code. (e.g. not
including rethook for arm64.) This series is based on the discussion at

https://lore.kernel.org/all/20230801112036.0d4ee60d@gandalf.local.home/

This has 5 patches,

- Simply replace pt_regs in fprobe_entry_handler with ftrace_regs.
- Replace pt_regs in rethook and fprobe_exit_handler with ftrace_regs. This
introduce a new HAVE_PT_REGS_COMPAT_FTRACE_REGS which means ftrace_regs is
just a wrapper of pt_regs (except for arm64, other architectures do this)
- Update fprobe-events to use ftrace_regs natively.
- Introduce ftrace_partial_regs(). (This changes ARM64 which needs a custom
implementation)
- Update bpf multi-kprobe handler use ftrace_partial_regs().

Florent, feel free to add your rethook for arm64, but please do not remove
kretprobe trampoline yet. It is another discussion point. We may be possible
to use ftrace_regs for kretprobe by ftrace_partial_regs() but kretprobe
allows nest probe. (maybe we can skip that case?)

Thank you,

---

Masami Hiramatsu (Google) (5):
fprobe: Use fprobe_regs in fprobe entry handler
fprobe: rethook: Use fprobe_regs in fprobe exit handler and rethook
tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled

arch/Kconfig | 1 +
arch/arm64/include/asm/ftrace.h | 11 ++++++
arch/loongarch/Kconfig | 1 +
arch/s390/Kconfig | 1 +
arch/x86/Kconfig | 1 +
arch/x86/kernel/rethook.c | 9 +++--
include/linux/fprobe.h | 4 +-
include/linux/ftrace.h | 11 ++++++
include/linux/rethook.h | 11 +++---
kernel/kprobes.c | 9 ++++-
kernel/trace/Kconfig | 9 ++++-
kernel/trace/bpf_trace.c | 14 +++++--
kernel/trace/fprobe.c | 8 ++--
kernel/trace/rethook.c | 16 ++++----
kernel/trace/trace_fprobe.c | 76 ++++++++++++++++++++++++---------------
kernel/trace/trace_probe_tmpl.h | 2 +
lib/test_fprobe.c | 10 +++--
samples/fprobe/fprobe_example.c | 4 +-
18 files changed, 130 insertions(+), 68 deletions(-)

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>