linux-kernel - Re: [PATCH v7 1/5] add infrastructure for tagging functions as error injectable

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Date:   Tue, 28 Nov 2017 15:02:42 -0500
From:   Josef Bacik <josef@...icpanda.com>
To:     Jonathan Corbet <corbet@....net>
Cc:     Josef Bacik <josef@...icpanda.com>, rostedt@...dmis.org,
        mingo@...hat.com, davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, ast@...nel.org, kernel-team@...com,
        daniel@...earbox.net, linux-btrfs@...r.kernel.org,
        Josef Bacik <jbacik@...com>
Subject: Re: [PATCH v7 1/5] add infrastructure for tagging functions as error
 injectable

On Tue, Nov 28, 2017 at 11:58:41AM -0700, Jonathan Corbet wrote:
> On Wed, 22 Nov 2017 16:23:30 -0500
> Josef Bacik <josef@...icpanda.com> wrote:
> 
> > From: Josef Bacik <jbacik@...com>
> > 
> > Using BPF we can override kprob'ed functions and return arbitrary
> > values.  Obviously this can be a bit unsafe, so make this feature opt-in
> > for functions.  Simply tag a function with KPROBE_ERROR_INJECT_SYMBOL in
> > order to give BPF access to that function for error injection purposes.
> > 
> > Signed-off-by: Josef Bacik <jbacik@...com>
> > Acked-by: Ingo Molnar <mingo@...nel.org>
> > ---
> >  arch/x86/include/asm/asm.h        |   6 ++
> >  include/asm-generic/vmlinux.lds.h |  10 +++
> >  include/linux/bpf.h               |  11 +++
> >  include/linux/kprobes.h           |   1 +
> >  include/linux/module.h            |   5 ++
> >  kernel/kprobes.c                  | 163 ++++++++++++++++++++++++++++++++++++++
> >  kernel/module.c                   |   6 +-
> >  7 files changed, 201 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
> > index b0dc91f4bedc..340f4cc43255 100644
> > --- a/arch/x86/include/asm/asm.h
> > +++ b/arch/x86/include/asm/asm.h
> > @@ -85,6 +85,12 @@
> >  	_ASM_PTR (entry);					\
> >  	.popsection
> >  
> > +# define _ASM_KPROBE_ERROR_INJECT(entry)			\
> > +	.pushsection "_kprobe_error_inject_list","aw" ;		\
> > +	_ASM_ALIGN ;						\
> > +	_ASM_PTR (entry);					\
> > +	.popseciton
> 
> So this stuff is not my area of greatest expertise, but I do have to wonder
> how ".popseciton" can work ... ?
> 

Well fuck, do you want me to send a increment Daniel/Alexei or resend this patch
fixed?  Thanks,

Josef