Date:   Sun, 24 Sep 2023 22:35:47 +0900
From:   "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Florent Revest <revest@...omium.org>
Cc:     linux-trace-kernel@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        bpf <bpf@...r.kernel.org>, Sven Schnelle <svens@...ux.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alan Maguire <alan.maguire@...cle.com>,
        Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Guo Ren <guoren@...nel.org>
Subject: [PATCH v5 00/12] tracing: fprobe: rethook: Use ftrace_regs instead of pt_regs

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@...nel.org>

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