Re: [PATCH net-next] selftests: bpf: modify urandom_read and link it non-statically
From: Stanislav Fomichev
Date: Fri Mar 15 2019 - 18:05:58 EST
On 03/15, Ivan Vecera wrote:
> ----- Stanislav Fomichev <sdf@xxxxxxxxxxx> wrote:
> > On 03/15, Ivan Vecera wrote:
> > > On 15. 03. 19 21:08, Stanislav Fomichev wrote:
> > > > On 03/15, Ivan Vecera wrote:
> > > > > After some experiences I found that urandom_read does not need to be
> > > > > linked statically. When the 'read' syscall call is moved to separate
> > > > > non-inlined function then bpf_get_stackid() is able to find
> > > > > the executable in stack trace and extract its build_id from it.
> > > > But why? Do you have some problems with it being linked statically?
> > > >
> > > Dependency... you don't need to install static glibc to compile the bpf
> > > samples. Shared libc is available everytime.
> > Oh, the distros that do -devel _and_ -static packages :-)
> > So your patch essentially adds a call, that leaves a trace on the stack
> > with our build-id. I guess that works as well.
> Without that additional call this does not work and build_id selftest fails.
Oh, yeah, I was just trying to clarify why it fails without -static and why
your patch makes it work for non-static :-)
You can put more details in the commit message; you'd have to resubmit
whenever net-next/bpf-next opens anyway.