2015-06-29 09:16:24

by Pratyush Anand

[permalink] [raw]
Subject: Query: How to blacklist asm symbols for kprobe

Hi,

There might be some symbols defined in asm file, which need to be
prevented for kprobe-ing.

For example, el0_sync, el1_sync, el0_dbg, el1_dbg etc (in
arch/arm64/kernel/entry.S) should be added to the kprobe blacklist
table. How can we do that?

~Pratyush


2015-07-03 10:07:50

by Pratyush Anand

[permalink] [raw]
Subject: Re: Query: How to blacklist asm symbols for kprobe

On 29/06/2015:02:46:13 PM, Pratyush Anand wrote:
> Hi,
>
> There might be some symbols defined in asm file, which need to be
> prevented for kprobe-ing.
>
> For example, el0_sync, el1_sync, el0_dbg, el1_dbg etc (in
> arch/arm64/kernel/entry.S) should be added to the kprobe blacklist
> table. How can we do that?

I think, we need to define them under "section .entry.text" and then
to use arch_within_kprobe_blacklist to prevent such symbols from kprobing.

~Pratyush

Subject: Re: Query: How to blacklist asm symbols for kprobe

On 2015/06/29 18:16, Pratyush Anand wrote:
> Hi,
>
> There might be some symbols defined in asm file, which need to be
> prevented for kprobe-ing.
>
> For example, el0_sync, el1_sync, el0_dbg, el1_dbg etc (in
> arch/arm64/kernel/entry.S) should be added to the kprobe blacklist
> table. How can we do that?
>

You can port and use _ASM_NOKPROBE(symbol) macro in .S file.

In arch/x86/include/asm/asm.h, it is defined as below.

# define _ASM_NOKPROBE(entry) \
.pushsection "_kprobe_blacklist","aw" ; \
_ASM_ALIGN ; \
_ASM_PTR (entry); \
.popsection

Thank you,


--
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: [email protected]