Re: [PATCH v10 0/4] Add kprobe and kretprobe support for LoongArch

[Qing Zhang]

Hi, Hengqi

On 2022/12/12 下午4:41, Hengqi Chen wrote:
> Hi, Tiezhu:
>
> I tested this patchset from BPF side, failed with EINVAL:
>
>      $ cat /sys/kernel/tracing/error_log
>      [  262.299093] trace_kprobe: error: Failed to register probe event
>        Command: p:kprobes/libbpf_4609_inet_bind_0x0_0 inet_bind+0x0
This is because KPROBE_ON_FTRACE is not yet supported. Trace Event 
cannot be used now.
We will support it soon, if you want to test it by install 
kprobe_example.ko as jeff did.

Thanks
-Qing                                                ^
> --
> Hengqi
>
> On 2022/12/9 16:52, Tiezhu Yang wrote:
> > v10:
> >    -- Remove sign_extend() based on the latest code
> >    -- Rename insns_are_not_supported() to insns_not_supported()
> >    -- Rename insns_are_not_simulated() to insns_not_simulated()
> >    -- Set KPROBE_HIT_SSDONE if cur->post_handler is not NULL
> >    -- Enable preemption for KPROBE_REENTER in kprobe_fault_handler()
> >
> > v9:
> >    -- Rename sign_extended() to sign_extend()
> >    -- Modify kprobe_fault_handler() to handle all of kprobe_status
> >
> > v8:
> >    -- Put "regs->csr_prmd &= ~CSR_PRMD_PIE;" ahead to save one line
> >    -- Add code comment of preempt_disable()
> >    -- Put kprobe_page_fault() in __do_page_fault()
> >    -- Modify the check condition of break insn in kprobe_breakpoint_handler()
> >
> > v7:
> >    -- Remove stop_machine_cpuslocked() related code
> >
> > v6:
> >    -- Add a new patch to redefine larch_insn_patch_text() with
> >       stop_machine_cpuslocked()
> >    -- Modify kprobe_breakpoint_handler() to consider the original
> >       insn is break and return the correct value
> >    -- Modify do_bp() to refresh bcode when original insn is break
> >
> > v5:
> >    -- Rebase on the latest code
> >    -- Use stop_machine_cpuslocked() to modify insn to avoid CPU race
> >
> > v4:
> >    -- Remove kprobe_exceptions_notify() in kprobes.c
> >    -- Call kprobe_breakpoint_handler() and kprobe_singlestep_handler()
> >       in do_bp()
> >
> > v3:
> >    -- Rebase on the latest code
> >    -- Check the alignment of PC in simu_branch() and simu_pc()
> >    -- Add ibar in flush_insn_slot()
> >    -- Rename kprobe_{pre,post}_handler() to {post_}kprobe_handler
> >    -- Add preempt_disable() and preempt_enable_no_resched()
> >    -- Remove r0 save/restore and do some minor changes
> >       in kprobes_trampoline.S
> >    -- Do not enable CONFIG_KPROBES by default
> >
> > v2:
> >    -- Split simu_branch() and simu_pc() into a single patch
> >    -- Call kprobe_page_fault() in do_page_fault()
> >    -- Add kprobes_trampoline.S for kretprobe
> >
> > Tiezhu Yang (4):
> >    LoongArch: Simulate branch and PC instructions
> >    LoongArch: Add kprobe support
> >    LoongArch: Add kretprobe support
> >    samples/kprobes: Add LoongArch support
> >
> >   arch/loongarch/Kconfig                     |   2 +
> >   arch/loongarch/include/asm/inst.h          |  20 ++
> >   arch/loongarch/include/asm/kprobes.h       |  59 +++++
> >   arch/loongarch/include/asm/ptrace.h        |   1 +
> >   arch/loongarch/kernel/Makefile             |   2 +
> >   arch/loongarch/kernel/inst.c               | 123 ++++++++++
> >   arch/loongarch/kernel/kprobes.c            | 364 +++++++++++++++++++++++++++++
> >   arch/loongarch/kernel/kprobes_trampoline.S |  96 ++++++++
> >   arch/loongarch/kernel/traps.c              |  13 +-
> >   arch/loongarch/mm/fault.c                  |   3 +
> >   samples/kprobes/kprobe_example.c           |   8 +
> >   11 files changed, 687 insertions(+), 4 deletions(-)
> >   create mode 100644 arch/loongarch/include/asm/kprobes.h
> >   create mode 100644 arch/loongarch/kernel/kprobes.c
> >   create mode 100644 arch/loongarch/kernel/kprobes_trampoline.S