From: "Björn Töpel" <bjorn@kernel.org>
To: Guo Ren <guoren@kernel.org>
Cc: palmer@dabbelt.com, paul.walmsley@sifive.com,
mhiramat@kernel.org, conor.dooley@microchip.com,
penberg@kernel.org, mark.rutland@arm.com,
liaochang <liaochang1@huawei.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
Guo Ren <guoren@linux.alibaba.com>
Subject: Re: [PATCH] riscv: kprobe: Fixup kernel panic when probing an illegal position
Date: Wed, 01 Feb 2023 10:30:14 +0100 [thread overview]
Message-ID: <87357pravt.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <CAJF2gTQHDmT=XWE=j8+5Y5ogKh4qNMpXCwAa+7wXEkBit0ujXw@mail.gmail.com>
Guo Ren <guoren@kernel.org> writes:
>> > + if (!arch_check_kprobe(p))
>> > + return -EILSEQ;
>> > +
>> > /* copy instruction */
>> > p->opcode = *p->addr;
>>
>> Not related to your patch, but this can also trigger a misaligned load.
> After rereading the spec, misaligned load/store is not mandatory
> supported. (Although my machines and qemu are correct)
Yes. It would be great if it could be turned on by QEMU (you can with
Spike).
> So I need fixup:
>
> diff --git a/arch/riscv/kernel/probes/kprobes.c
> b/arch/riscv/kernel/probes/kprobes.c
> index 27f8960c321c..0c016d496746 100644
> --- a/arch/riscv/kernel/probes/kprobes.c
> +++ b/arch/riscv/kernel/probes/kprobes.c
> @@ -58,12 +58,14 @@ static bool __kprobes arch_check_kprobe(struct kprobe *p)
> {
> unsigned long tmp = (unsigned long)p->addr - p->offset;
> unsigned long addr = (unsigned long)p->addr;
> + kprobe_opcode_t opcode;
>
> while (tmp <= addr) {
> if (tmp == addr)
> return true;
>
> - tmp += GET_INSN_LENGTH(*(kprobe_opcode_t *)tmp);
> + memcpy(&opcode, (void *)tmp, sizeof(kprobe_opcode_t));
> + tmp += GET_INSN_LENGTH(opcode);
I'd prefer sizeof(opcode).
> }
>
> return false;
> @@ -80,7 +82,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
> return -EILSEQ;
>
> /* copy instruction */
> - p->opcode = *p->addr;
> + memcpy(&p->opcode, p->addr, sizeof(kprobe_opcode_t));
Same comment as above, and this would ideally be a separate patch.
Björn
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next prev parent reply other threads:[~2023-02-01 9:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-26 13:05 [PATCH] riscv: kprobe: Fixup kernel panic when probing an illegal position guoren
2023-01-28 2:55 ` liaochang (A)
2023-01-28 3:46 ` Guo Ren
2023-01-28 3:52 ` Guo Ren
2023-01-28 9:53 ` liaochang (A)
2023-01-28 5:22 ` Guo Ren
2023-01-28 9:53 ` liaochang (A)
2023-01-31 12:32 ` Björn Töpel
2023-01-31 13:01 ` Guo Ren
2023-02-01 2:57 ` Guo Ren
2023-02-01 9:30 ` Björn Töpel [this message]
2023-02-02 6:06 ` Guo Ren
2023-02-02 8:32 ` Björn Töpel
2023-02-01 3:49 ` liaochang (A)
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