From: Jeff Xie <xiehuan09@gmail.com>
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
Subject: Re: [PATCH v12 0/5] Add kprobe and kretprobe support for LoongArch
Date: Tue, 7 Feb 2023 12:32:08 +0800 [thread overview]
Message-ID: <CAEr6+EDRciZc1_QB7VZO8dhw78U_LZPAnkG24z5cY-oZJEQiLw@mail.gmail.com> (raw)
In-Reply-To: <CAAhV-H7O-R33AQvCXmZQXDb-ACjZ5MYdWULHuKXYdnvt+UPjJA@mail.gmail.com>
On Tue, Feb 7, 2023 at 12:03 PM Huacai Chen <chenhuacai@kernel.org> wrote:
>
> Hi, Jeff,
>
> The code has been updated here,
> https://github.com/loongson/linux/commits/loongarch-next, you can test
> again.
It looks good to me.
Tested-by: Jeff Xie <xiehuan09@gmail.com>
> Huacai
>
> On Tue, Feb 7, 2023 at 11:14 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
> >
> >
> >
> > On 02/06/2023 08:48 PM, Jeff Xie wrote:
> > > On Mon, Feb 6, 2023 at 8:13 PM Huacai Chen <chenhuacai@kernel.org> wrote:
> > >>
> > >> Hi, Jeff,
> > >>
> > >> Now I add kprobes on ftrace support in
> > >> https://github.com/loongson/linux/commits/loongarch-next, please test
> > >> again. Thank you.
> > >>
> > >
> > > When using the kprobe example module kprobe_example.ko, I haven't seen
> > > any errors.
> > >
> > > But when using the ftrace to probe the symbol + offset, the kernel will panic:
> > > e.g. probe the scheduler_tick+4 is fine, but when probe the
> > > scheduler_tick+5, the kernel will panic.
> > >
> >
> > Thanks for your test.
> >
> > We can see that the instruction address is 4-byte alignment,
> > this is because the instruction length is 32-bit on LoongArch.
> >
> > $ objdump -d vmlinux > dump.txt
> > $ grep -A 20 scheduler_tick dump.txt | head -21
> > 9000000000279fc8 <scheduler_tick>:
> > 9000000000279fc8: 03400000 andi $zero, $zero, 0x0
> > 9000000000279fcc: 03400000 andi $zero, $zero, 0x0
> > 9000000000279fd0: 02ff4063 addi.d $sp, $sp, -48(0xfd0)
> > 9000000000279fd4: 29c08077 st.d $s0, $sp, 32(0x20)
> > 9000000000279fd8: 29c06078 st.d $s1, $sp, 24(0x18)
> > 9000000000279fdc: 29c04079 st.d $s2, $sp, 16(0x10)
> > 9000000000279fe0: 29c0207a st.d $s3, $sp, 8(0x8)
> > 9000000000279fe4: 29c0a061 st.d $ra, $sp, 40(0x28)
> > 9000000000279fe8: 2700007b stptr.d $s4, $sp, 0
> > 9000000000279fec: 24001844 ldptr.w $a0, $tp, 24(0x18)
> > 9000000000279ff0: 1a02edd9 pcalau12i $s2, 5998(0x176e)
> > 9000000000279ff4: 1a034bac pcalau12i $t0, 6749(0x1a5d)
> > 9000000000279ff8: 02f56339 addi.d $s2, $s2, -680(0xd58)
> > 9000000000279ffc: 00410c9a slli.d $s3, $a0, 0x3
> > 900000000027a000: 28aae18d ld.w $t1, $t0, -1352(0xab8)
> > 900000000027a004: 380c6b2e ldx.d $t2, $s2, $s3
> > 900000000027a008: 1a022fcc pcalau12i $t0, 4478(0x117e)
> > 900000000027a00c: 02f20198 addi.d $s1, $t0, -896(0xc80)
> > 900000000027a010: 00150317 move $s0, $s1
> > 900000000027a014: 004081ac slli.w $t0, $t1, 0x0
> >
> > So we should check the probe address at the beginning of
> > arch_prepare_kprobe(), some other archs do the same thing.
> >
> > $ git diff
> > diff --git a/arch/loongarch/kernel/kprobes.c
> > b/arch/loongarch/kernel/kprobes.c
> > index bdab707b6edf..56c8c4b09a42 100644
> > --- a/arch/loongarch/kernel/kprobes.c
> > +++ b/arch/loongarch/kernel/kprobes.c
> > @@ -79,6 +79,9 @@ NOKPROBE_SYMBOL(arch_prepare_simulate);
> >
> > int arch_prepare_kprobe(struct kprobe *p)
> > {
> > + if ((unsigned long)p->addr & 0x3)
> > + return -EILSEQ;
> > +
> > /* copy instruction */
> > p->opcode = *p->addr;
> >
> >
> > Thanks,
> > Tiezhu
> >
> >
--
Thanks,
JeffXie
prev parent reply other threads:[~2023-02-07 4:32 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-18 2:00 [PATCH v12 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
2023-01-18 2:00 ` [PATCH v12 1/5] LoongArch: Simulate branch and PC* instructions Tiezhu Yang
2023-01-18 2:00 ` [PATCH v12 2/5] LoongArch: Add kprobe support Tiezhu Yang
2023-01-18 2:00 ` [PATCH v12 3/5] LoongArch: Add kretprobe support Tiezhu Yang
2023-01-18 2:01 ` [PATCH v12 4/5] LoongArch: Mark some assembler symbols as non-kprobe-able Tiezhu Yang
2023-01-18 4:14 ` Huacai Chen
2023-01-18 4:23 ` Tiezhu Yang
2023-01-18 6:05 ` Jinyang He
2023-01-18 6:24 ` Tiezhu Yang
2023-01-18 7:17 ` Huacai Chen
2023-01-19 15:31 ` Masami Hiramatsu
2023-01-20 13:23 ` Huacai Chen
2023-02-01 12:55 ` Masami Hiramatsu
2023-01-18 7:20 ` Jinyang He
2023-01-18 2:01 ` [PATCH v12 5/5] samples/kprobes: Add LoongArch support Tiezhu Yang
2023-01-18 3:30 ` [PATCH v12 0/5] Add kprobe and kretprobe support for LoongArch Huacai Chen
2023-02-01 4:56 ` Huacai Chen
2023-02-01 9:40 ` Jeff Xie
2023-02-02 2:23 ` Tiezhu Yang
2023-02-02 3:33 ` Jeff Xie
2023-02-02 23:59 ` Masami Hiramatsu
2023-02-06 12:13 ` Huacai Chen
2023-02-06 12:48 ` Jeff Xie
2023-02-07 3:14 ` Tiezhu Yang
2023-02-07 4:03 ` Huacai Chen
2023-02-07 4:32 ` Jeff Xie [this message]
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