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

From: Josef Bacik
Date: Tue Nov 28 2017 - 15:02:50 EST


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@xxxxxxxxxxxxxx> wrote:
>
> > From: Josef Bacik <jbacik@xxxxxx>
> >
> > 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@xxxxxx>
> > Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
> > ---
> > 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