On Fri, Apr 08, 2022 at 09:50:35AM +0900, Masami Hiramatsu wrote: > Hi, Hi, > Here is the 2nd version of the series for replacing kretprobe trampoline > with rethook on ARM/arm64. I fixed some compiler warnings in this version. What tree is this based on? It doesn't cleanly apply atop v5.18-rc1: | [mark@lakrids:~/src/linux]% git am v2_20220408_mhiramat_kprobes_rethook_arm_arm64_replace_kretprobe_trampoline_with_rethook.mbx | Applying: ARM: unwind: Initialize the lr_addr field of unwind_ctrl_block | Applying: rethook,fprobe,kprobes: Check a failure in the rethook_hook() | Applying: ARM: rethook: Replace kretprobe trampoline with rethook | error: patch failed: arch/arm/kernel/stacktrace.c:66 | error: arch/arm/kernel/stacktrace.c: patch does not apply | Patch failed at 0003 ARM: rethook: Replace kretprobe trampoline with rethook | hint: Use 'git am --show-current-patch=diff' to see the failed patch | When you have resolved this problem, run "git am --continue". | If you prefer to skip this patch, run "git am --skip" instead. | To restore the original branch and stop patching, run "git am --abort". I've done a `git am -3` locally to make that work for now. > The previous version is here[1]; > > [1] https://lore.kernel.org/all/164915121498.982637.12787715964983738566.stgit@devnote2/T/#u > > This series includes a trivial bugfix for the arm unwinder to initialize > an internal data structure([1/4]). This is not critical for stack trace, > but required for rethook to find the LR register from the stack. > This also have an update for the rethook interface, which allows us to > check the rethook_hook() failure ([2/4]). This is also required for the > rethook on arm because unwinder is able to fail. > The rest of patches are replacing kretprobe trampoline with rethook on > ARM ([3/4]) and arm64 ([4/4]). Generally, the arm and arm64 bits go via different trees, and for unwinding the two are quite different. IIUC the dependency between the two is just because patch 2 changes the prototypes of some functions. Is that right? > Background: > > This rethook came from Jiri's request of multiple kprobe for bpf[2]. > He tried to solve an issue that starting bpf with multiple kprobe will > take a long time because bpf-kprobe will wait for RCU grace period for > sync rcu events. > > Jiri wanted to attach a single bpf handler to multiple kprobes and > he tried to introduce multiple-probe interface to kprobe. So I asked > him to use ftrace and kretprobe-like hook if it is only for the > function entry and exit, instead of adding ad-hoc interface > to kprobes. > For this purpose, I introduced the fprobe (kprobe like interface for > ftrace) with the rethook (this is a generic return hook feature for > fprobe exit handler)[3]. > > [2] https://lore.kernel.org/all/20220104080943.113249-1-jolsa@xxxxxxxxxx/T/#u > [3] https://lore.kernel.org/all/164191321766.806991.7930388561276940676.stgit@devnote2/T/#u > > The rethook is basically same as the kretprobe trampoline. I just made > it decoupled from kprobes. Eventually, the all arch dependent kretprobe > trampolines will be replaced with the rethook trampoline instead of > cloning the code. > > When I port the rethook for all arch which supports kretprobe, the > legacy kretprobe specific code (which is for CONFIG_KRETPROBE_ON_RETHOOK=n) > will be removed eventually. > > BTW, the arm Clang support for rethook is for kretprobes only. fprobe > and ftrace seems not working with Clang yet. Do you mean that's an existing issue? Thanks, Mark. > > Thank you, > > --- > > Masami Hiramatsu (4): > ARM: unwind: Initialize the lr_addr field of unwind_ctrl_block > rethook,fprobe,kprobes: Check a failure in the rethook_hook() > ARM: rethook: Replace kretprobe trampoline with rethook > arm64: rethook: Replace kretprobe trampoline with rethook > > > arch/arm/Kconfig | 1 > arch/arm/include/asm/stacktrace.h | 5 + > arch/arm/kernel/stacktrace.c | 13 +-- > arch/arm/kernel/unwind.c | 1 > arch/arm/probes/Makefile | 1 > arch/arm/probes/kprobes/core.c | 62 ------------ > arch/arm/probes/rethook.c | 127 +++++++++++++++++++++++++ > arch/arm64/Kconfig | 1 > arch/arm64/include/asm/kprobes.h | 2 > arch/arm64/include/asm/stacktrace.h | 2 > arch/arm64/kernel/Makefile | 1 > arch/arm64/kernel/probes/Makefile | 1 > arch/arm64/kernel/probes/kprobes.c | 15 --- > arch/arm64/kernel/probes/kprobes_trampoline.S | 86 ----------------- > arch/arm64/kernel/rethook.c | 28 ++++++ > arch/arm64/kernel/rethook_trampoline.S | 87 +++++++++++++++++ > arch/arm64/kernel/stacktrace.c | 9 +- > arch/x86/kernel/rethook.c | 4 + > include/linux/rethook.h | 4 - > kernel/kprobes.c | 8 +- > kernel/trace/fprobe.c | 5 + > kernel/trace/rethook.c | 12 ++ > 22 files changed, 287 insertions(+), 188 deletions(-) > create mode 100644 arch/arm/probes/rethook.c > delete mode 100644 arch/arm64/kernel/probes/kprobes_trampoline.S > create mode 100644 arch/arm64/kernel/rethook.c > create mode 100644 arch/arm64/kernel/rethook_trampoline.S > > -- > Masami Hiramatsu (Linaro) <mhiramat@xxxxxxxxxx>
