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

[Hengqi Chen]

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
                                                 ^
--
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
>