Re: [PATCH] kprobes: x86_64: blacklist non-attachable interrupt functions

From: Masami Hiramatsu <mhiramat@kernel.org>
To: Andrea Righi <righi.andrea@gmail.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Yonghong Song <yhs@fb.com>, Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kprobes: x86_64: blacklist non-attachable interrupt functions
Date: Fri, 7 Dec 2018 23:47:31 +0900	[thread overview]
Message-ID: <20181207234731.f52a8c1eff6c0e72c073ad40@kernel.org> (raw)
In-Reply-To: <20181206095648.GA8249@Dell>

On Thu, 6 Dec 2018 10:56:48 +0100
Andrea Righi <righi.andrea@gmail.com> wrote:

> These interrupt functions are already non-attachable by kprobes.
> Blacklist them explicitly so that they can show up in
> /sys/kernel/debug/kprobes/blacklist and tools like BCC can use this
> additional information.
> 
> Signed-off-by: Andrea Righi <righi.andrea@gmail.com>

For the short term, this is OK. But this is not the best way to cover
other functions which are also prohibited by arch_within_kprobe_blacklist().
I'll fix this issue later.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> ---
>  arch/x86/entry/entry_64.S | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
> index ce25d84023c0..1f0efdb7b629 100644
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -566,6 +566,7 @@ ENTRY(interrupt_entry)
>  
>  	ret
>  END(interrupt_entry)
> +_ASM_NOKPROBE(interrupt_entry)
>  
>  
>  /* Interrupt entry/exit. */
> @@ -766,6 +767,7 @@ native_irq_return_ldt:
>  	jmp	native_irq_return_iret
>  #endif
>  END(common_interrupt)
> +_ASM_NOKPROBE(common_interrupt)
>  
>  /*
>   * APIC interrupts.
> @@ -780,6 +782,7 @@ ENTRY(\sym)
>  	call	\do_sym	/* rdi points to pt_regs */
>  	jmp	ret_from_intr
>  END(\sym)
> +_ASM_NOKPROBE(\sym)
>  .endm
>  
>  /* Make sure APIC interrupt handlers end up in the irqentry section: */
> @@ -960,6 +963,7 @@ ENTRY(\sym)
>  
>  	jmp	error_exit
>  	.endif
> +_ASM_NOKPROBE(\sym)
>  END(\sym)
>  .endm
>  
> -- 
> 2.17.1

-- 
Masami Hiramatsu <mhiramat@kernel.org>