[PATCH v5 00/12] tracing: fprobe: rethook: Use ftrace_regs instead of pt_regs

Masami Hiramatsu (Google)
2023-09-24T13:35:53Z

Hi,

Here is the 5th version of the series to use ftrace_regs instead of pt_regs
in fprobe.
The previous version is here;

https://lore.kernel.org/all/169280372795.282662.9784422934484459769.stgit@devnote2/

In this version, I decided to use perf's own per-cpu pt_regs array to
copy the required registers[8/12]. Thus this version adds a patch which
adds a new ftrace_fill_perf_regs() API. So the ftrace_partial_regs() will
be used for BPF and ftrace_fill_perf_regs() is used for perf events.

This also adds a fix for RISCV ftrace[1/12]. When kernel is built with
disabling CONFIG_DYNAMIC_FTRACE_WITH_REGS on RISCV, it stores partial
registers on the stack, but it doesn't make it fit to struct ftrace_regs.
But since the 4th argument of ftrace_func_t is ftrace_regs *, it breaks
the ABI. So fixing it to save registers on ftrace_regs (== pt_regs on RISCV).

Another new patch [3/12] is adding a comment about the requirements for
the ftrace_regs.

- RISCV ftrace fix to save registers on struct ftrace_regs correctly.
- Document fix for the current fprobe callback prototype.
- Add a comment of requirement for the ftrace_regs.
- Simply replace pt_regs in fprobe_entry_handler with ftrace_regs.
- Expose ftrace_regs even if CONFIG_FUNCTION_TRACER=n.
- Introduce ftrace_partial_regs(). (This changes ARM64 which needs a custom
implementation)
- Introduce ftrace_fill_perf_regs() for perf pt_regs.
- Replace pt_regs in rethook and fprobe_exit_handler with ftrace_regs. This
introduce a new HAVE_PT_REGS_TO_FTRACE_REGS_CAST 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.
- Update bpf multi-kprobe handler use ftrace_partial_regs().
- Update document for new fprobe callbacks.
- Add notes for the $argN and $retval.

This series can be applied against the trace-v6.6-rc2 on linux-trace tree.

This series can also be found below branch.

https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/log/?h=topic/fprobe-ftrace-regs

Thank you,

---

Masami Hiramatsu (Google) (12):
riscv: ftrace: Fix to pass correct ftrace_regs to ftrace_func_t functions
Documentation: probes: Add a new ret_ip callback parameter
tracing: Add a comment about the requirements of the ftrace_regs
fprobe: Use ftrace_regs in fprobe entry handler
tracing: Expose ftrace_regs regardless of CONFIG_FUNCTION_TRACER
fprobe: rethook: Use ftrace_regs in fprobe exit handler and rethook
tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
tracing: Add ftrace_fill_perf_regs() for perf event
tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
Documentation: probes: Update fprobe document to use ftrace_regs
Documentation: tracing: Add a note about argument and retval access

Documentation/trace/fprobe.rst | 18 +++--
Documentation/trace/fprobetrace.rst | 8 ++
Documentation/trace/kprobetrace.rst | 8 ++
arch/Kconfig | 1
arch/arm64/include/asm/ftrace.h | 18 +++++
arch/loongarch/Kconfig | 1
arch/loongarch/kernel/rethook.c | 10 +--
arch/loongarch/kernel/rethook.h | 4 +
arch/powerpc/include/asm/ftrace.h | 7 ++
arch/riscv/kernel/mcount-dyn.S | 67 ++++++++----------
arch/riscv/kernel/probes/rethook.c | 12 ++-
arch/riscv/kernel/probes/rethook.h | 6 +-
arch/s390/Kconfig | 1
arch/s390/include/asm/ftrace.h | 9 ++
arch/s390/kernel/rethook.c | 10 ++-
arch/s390/kernel/rethook.h | 2 -
arch/x86/Kconfig | 1
arch/x86/include/asm/ftrace.h | 7 ++
arch/x86/kernel/rethook.c | 13 ++--
include/linux/fprobe.h | 4 +
include/linux/ftrace.h | 128 +++++++++++++++++++++++++++++------
include/linux/rethook.h | 11 ++-
kernel/kprobes.c | 10 ++-
kernel/trace/Kconfig | 9 ++
kernel/trace/bpf_trace.c | 14 ++--
kernel/trace/fprobe.c | 10 +--
kernel/trace/rethook.c | 16 ++--
kernel/trace/trace_fprobe.c | 70 +++++++++++--------
kernel/trace/trace_probe_tmpl.h | 2 -
lib/test_fprobe.c | 10 +--
samples/fprobe/fprobe_example.c | 4 +
31 files changed, 327 insertions(+), 164 deletions(-)

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