linux-kernel - Re: [PATCH] x86/stacktrace: export save_stack_trace_tsk

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Message-ID: <873cd5ca-1f88-499e-e8ed-9a93f42d8239@redhat.com>
Date:   Wed, 27 Feb 2019 18:20:14 -0500
From:   Joe Lawrence <joe.lawrence@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
        x86@...nel.org, Jiri Slaby <jslaby@...e.cz>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH] x86/stacktrace: export save_stack_trace_tsk_reliable

On 2/27/19 5:25 PM, Joe Lawrence wrote:
> On 2/27/19 4:31 PM, Thomas Gleixner wrote:
>> On Wed, 27 Feb 2019, Joe Lawrence wrote:
>>
>>> The ppc64le implementation of save_stack_trace_tsk_reliable() is
>>> exported, so do the same with x86.
>>
>> And what's the in tree module user of this? I can't find one and just
>> because PPC has an export with no user is not a convincing argument to add
>> another one. The proper solution is to remove the unused PPC export.
>>
> 
> Good point.
> 
> For that matter, I do see in-tree modules making use of
> save_stack_trace, but who is calling save_stack_trace_tsk (exported by
> most arches) and save_stack_trace_regs (exported by openrisc, powerpc,
> s390)?

Well, at least for save_stack_trace_tsk there is the out-of-tree kpatch 
core module[1].  (Kpatch drops that call if the kernel provides 
livepatch functionality.)

[1] https://github.com/dynup/kpatch/blob/master/kmod/core/core.c#L275

-- Joe