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From:   Jeff Xie <xiehuan09@gmail.com>
Date:   Wed, 1 Feb 2023 17:40:36 +0800
Message-ID: <CAEr6+ECO-=jfhzHrcdKGx0MsjMBMiN6wsBPCfv7CaXo_amAWWg@mail.gmail.com>
Subject: Re: [PATCH v12 0/5] Add kprobe and kretprobe support for LoongArch
To:     Huacai Chen <chenhuacai@kernel.org>
Cc:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        WANG Xuerui <kernel@xen0n.name>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        loongarch@lists.linux.dev, linux-kernel@vger.kernel.org
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On Wed, Feb 1, 2023 at 12:56 PM Huacai Chen <chenhuacai@kernel.org> wrote:
>
> Hi, Jeff,
>
> Could you please pay some time to test this series? Thank you.

Thanks for notifying me about the test.

I have tested the patchset(based on the
https://github.com/loongson/linux/tree/loongarch-next),
I found that some functions can't  be probed e.g. scheduler_tick() or
uart_write_wakeup()
the two functions have the same point,  they are all run in the hardirq context.

I don't know if it's related to the hardirq context, I haven't had
time to study this patchset carefully.
and they can be probed in the x86_64 arch.

root@loongarch modules]# insmod ./kprobe_example.ko symbol=scheduler_tick
insmod: can't insert './kprobe_example.ko': invalid parameter

dmesg:
[   39.806435] kprobe_init: register_kprobe failed, returned -22


>
> Huacai
>
> On Wed, Jan 18, 2023 at 11:30 AM Huacai Chen <chenhuacai@kernel.org> wrote:
> >
> > Hi, Masami,
> >
> > Could you please pay some time to review this series? Thank you.
> >
> > Huacai
> >
> > On Wed, Jan 18, 2023 at 10:01 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
> > >
> > > v12:
> > >   -- Rebase on the latest code
> > >   -- Fix -Wmissing-prototypes warning when make W=1
> > >   -- Drop patch #6 "Use common function sign_extend64()"
> > >      since it has been applied yet
> > >
> > > v11:
> > >   -- Rebase on the latest code
> > >   -- Address all the review comments, thank you all
> > >   -- Modify arch_prepare_kprobe() and setup_singlestep()
> > >      to make the probe logic more clear
> > >   -- Mark some assembler symbols as non-kprobe-able
> > >   -- Use common function sign_extend64()
> > >   -- Test 20 times about 36 hours for all the 71 assembler
> > >      functions annotated with SYM_CODE_START and SYM_FUNC_START
> > >      under arch/loongarch, especially test memset alone for 10
> > >      hours, no hang problems
> > >
> > > 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 (5):
> > >   LoongArch: Simulate branch and PC* instructions
> > >   LoongArch: Add kprobe support
> > >   LoongArch: Add kretprobe support
> > >   LoongArch: Mark some assembler symbols as non-kprobe-able
> > >   samples/kprobes: Add LoongArch support
> > >
> > >  arch/loongarch/Kconfig                     |   2 +
> > >  arch/loongarch/include/asm/asm.h           |  10 +
> > >  arch/loongarch/include/asm/inst.h          |  20 ++
> > >  arch/loongarch/include/asm/kprobes.h       |  61 +++++
> > >  arch/loongarch/include/asm/ptrace.h        |   1 +
> > >  arch/loongarch/kernel/Makefile             |   2 +
> > >  arch/loongarch/kernel/entry.S              |   1 +
> > >  arch/loongarch/kernel/inst.c               | 123 +++++++++
> > >  arch/loongarch/kernel/kprobes.c            | 405 +++++++++++++++++++++++++++++
> > >  arch/loongarch/kernel/kprobes_trampoline.S |  96 +++++++
> > >  arch/loongarch/kernel/traps.c              |  11 +-
> > >  arch/loongarch/lib/memcpy.S                |   3 +
> > >  arch/loongarch/mm/fault.c                  |   3 +
> > >  samples/kprobes/kprobe_example.c           |   8 +
> > >  14 files changed, 741 insertions(+), 5 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
> > >
> > > --
> > > 2.1.0
> > >
> > >


-- 
Thanks,
JeffXie