On Mon, Nov 09, 2020 at 03:06:55PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Nov 09, 2020 at 03:05:00PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Fri, Nov 06, 2020 at 11:25:10PM +0100, Jiri Olsa escreveu:
> > > With upcoming changes to pahole, that change the way how and
> > > which kernel functions are stored in BTF data, we need a way
> > > to recognize iterator functions.
> > >
> > > Iterator functions need to be in BTF data, but have no real
> > > body and are currently placed in .init.text section, so they
> > > are freed after kernel init and are filtered out of BTF data
> > > because of that.
> > >
> > > The solution is to place these functions under new section:
> > > .init.bpf.preserve_type
> > >
> > > And add 2 new symbols to mark that area:
> > > __init_bpf_preserve_type_begin
> > > __init_bpf_preserve_type_end
> > >
> > > The code in pahole responsible for picking up the functions will
> > > be able to recognize functions from this section and add them to
> > > the BTF data and filter out all other .init.text functions.
> >
> > This isn't applying on torvalds/master:
> >
> > [acme@five linux]$ patch -p1 < /wb/1.patch
> > patching file include/asm-generic/vmlinux.lds.h
> > Hunk #2 succeeded at 754 (offset 1 line).
> > patching file include/linux/bpf.h
> > Hunk #1 succeeded at 1276 (offset -1 lines).
> > patching file include/linux/init.h
> > Hunk #1 FAILED at 52.
> > 1 out of 1 hunk FAILED -- saving rejects to file include/linux/init.h.rej
> > [acme@five linux]$
> > [acme@five linux]$ cat include/linux/init.h.rej
> > --- include/linux/init.h
> > +++ include/linux/init.h
> > @@ -52,6 +52,7 @@
> > #define __initconst __section(.init.rodata)
> > #define __exitdata __section(.exit.data)
> > #define __exit_call __used __section(.exitcall.exit)
> > +#define __init_bpf_preserve_type __section(.init.bpf.preserve_type)
> >
> > /*
> > * modpost check for section mismatches during the kernel build.
> > [acme@five linux]$
> >
> >
> > I'm fixing it up by hand to try together with pahole's patches.
>
> Due to:
>
> 33def8498fdde180 ("treewide: Convert macro and uses of __section(foo) to __section("foo")")
ok, I'll send new version for the kernel patch
thanks,
jirka
