From: Masami Hiramatsu <mhiramat@kernel.org>
To: Alexei Starovoitov <ast@fb.com>, Josef Bacik <jbacik@fb.com>
Cc: rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
ast@kernel.org, kernel-team@fb.com, daniel@iogearbox.net,
linux-btrfs@vger.kernel.org, darrick.wong@oracle.com,
mhiramat@kernel.org, Josef Bacik <josef@toxicpanda.com>
Subject: [RFC PATCH bpf-next 0/3] Separate error injection framework from kprobes
Date: Fri, 22 Dec 2017 20:38:13 +0900 [thread overview]
Message-ID: <151394269314.5598.6344820223613246849.stgit@devbox> (raw)
Hi Josef and Alexei,
Here are the patches which describe what I think more "natural"
introduction of error injection APIs. Basically what I did on
this series is to separate error injection from kprobes and put
it on new error-injection small subsystem which is currently
provide whitelists and just-return function stub.
There are 2 main reasons why I separate it from kprobes.
- kprobes users can modify execution path not only at
error-injection whitelist functions but also other
functions. I don't like to suggest user that such
limitation is from kprobes itself.
- This error injection information is also useful for
ftrace (function-hook) and livepatch. It should not
be limited by CONFIG_KPROBES.
So I introduced CONFIG_FUNCTION_ERROR_INJECTION for this feature.
This series also have some improvement suggestions.
- [1/3] "kprobe override function" feature is not limited by
ftrace-based kprobe, but also you can use it on sw-breakpoint
based kprobe too. Also, you must check the kprobe is on the
entry of function right before setting up the stackframe.
- [2/3] If we store original instruction pointer and compare
it with regs->ip, we don't need per-cpu bpf_kprobe_override.
Also, reset_current_kprobe() and preempt_enable_no_resched()
are no need to separate.
Any thoughts?
If it is good, I also add MAINTAINERS entry for this feature
and add some testcases using kprobes and ftrace to inject
error. (And maybe we also need a document how to use)
BTW, it seems there are many error injection frameworks in
lib/. We may also consider these distinctions.
Thank you,
---
Masami Hiramatsu (3):
tracing/kprobe: bpf: Check error injectable event is on function entry
tracing/kprobe: bpf: Compare instruction pointer with original one
error-injection: Separate error-injection from kprobe
arch/Kconfig | 2
arch/x86/Kconfig | 2
arch/x86/include/asm/error-injection.h | 12 ++
arch/x86/kernel/kprobes/ftrace.c | 14 --
arch/x86/lib/Makefile | 2
arch/x86/lib/error-inject.c | 19 +++
fs/btrfs/disk-io.c | 2
fs/btrfs/free-space-cache.c | 2
include/asm-generic/error-injection.h | 20 +++
include/asm-generic/vmlinux.lds.h | 14 +-
include/linux/bpf.h | 12 --
include/linux/error-injection.h | 21 +++
include/linux/kprobes.h | 1
include/linux/module.h | 6 -
kernel/kprobes.c | 163 --------------------------
kernel/module.c | 8 +
kernel/trace/Kconfig | 4 -
kernel/trace/bpf_trace.c | 9 +
kernel/trace/trace_kprobe.c | 32 ++---
kernel/trace/trace_probe.h | 12 +-
lib/Kconfig.debug | 4 +
lib/Makefile | 1
lib/error-inject.c | 200 ++++++++++++++++++++++++++++++++
23 files changed, 323 insertions(+), 239 deletions(-)
create mode 100644 arch/x86/include/asm/error-injection.h
create mode 100644 arch/x86/lib/error-inject.c
create mode 100644 include/asm-generic/error-injection.h
create mode 100644 include/linux/error-injection.h
create mode 100644 lib/error-inject.c
--
Signature
next reply other threads:[~2017-12-22 11:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-22 11:38 Masami Hiramatsu [this message]
2017-12-22 11:38 ` [RFC PATCH bpf-next 1/3] tracing/kprobe: bpf: Check error injectable event is on function entry Masami Hiramatsu
2017-12-22 11:39 ` [RFC PATCH bpf-next 2/3] tracing/kprobe: bpf: Compare instruction pointer with original one Masami Hiramatsu
2017-12-22 11:39 ` [RFC PATCH bpf-next 3/3] error-injection: Separate error-injection from kprobe Masami Hiramatsu
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