From: Will Deacon <will@kernel.org>
To: Chen Lin <chen45464546@163.com>
Cc: catalin.marinas@arm.com, mark.rutland@arm.com,
joey.gouly@arm.com, maz@kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Chen Lin <chen.lin5@zte.com.cn>
Subject: Re: [PATCH] arm64: traps: add dump instr before BUG in kernel
Date: Thu, 30 Sep 2021 09:42:47 +0100 [thread overview]
Message-ID: <20210930084247.GC23389@willie-the-truck> (raw)
In-Reply-To: <1632922186-3116-1-git-send-email-chen45464546@163.com>
On Wed, Sep 29, 2021 at 09:29:46PM +0800, Chen Lin wrote:
> From: Chen Lin <chen.lin5@zte.com.cn>
>
> we should dump the real instructions before BUG in kernel mode, and
> compare this to the instructions from objdump.
>
> Signed-off-by: Chen Lin <chen.lin5@zte.com.cn>
> ---
> arch/arm64/kernel/traps.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index b03e383..621a9dd 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -495,7 +495,12 @@ void do_undefinstr(struct pt_regs *regs)
> if (call_undef_hook(regs) == 0)
> return;
>
> - BUG_ON(!user_mode(regs));
> + if (!user_mode(regs)) {
> + pr_emerg("Undef instruction in kernel, dump instr:");
> + dump_kernel_instr(KERN_EMERG, regs);
> + BUG();
> + }
Hmm, I'm not completely convinced about this as the instruction in the
i-cache could be completely different. I think the PC value (for addr2line)
is a lot more useful, and we should be printing that already.
Maybe you can elaborate on a situation where this information was helpful?
Thanks,
Will
next prev parent reply other threads:[~2021-09-30 8:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 13:29 [PATCH] arm64: traps: add dump instr before BUG in kernel Chen Lin
2021-09-30 8:42 ` Will Deacon [this message]
2021-09-30 14:41 ` Chen Lin
2021-10-11 10:06 ` Will Deacon
2021-10-13 13:08 ` Chen Lin
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