On Tue, Oct 3, 2023 at 5:20 PM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Tue, Oct 3, 2023 at 12:15 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:
> >
> > libbpf accesses the ELF data requiring at least 8 byte alignment,
> > however, the data is generated into a C string that doesn't guarantee
> > alignment. Fix this by assigning to an aligned char array. Use sizeof
> > on the array, less one for the \0 terminator, rather than generating a
> > constant.
> >
> > Fixes: a6cc6b34b93e ("bpftool: Provide a helper method for accessing skeleton's embedded ELF data")
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> > ---
>
> See CI failures ([0]). You messed up tabs somewhere.
>
> [0] https://github.com/kernel-patches/bpf/actions/runs/6397510833/job/17365616392?pr=5756
Thanks, I messed up (also) somewhere else in patch 2/2 as I broke some
Google code. Working on a v3.
Ian
>
> > tools/bpf/bpftool/gen.c | 15 +++++++++------
> > 1 file changed, 9 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
> > index 2883660d6b67..b8ebcee9bc56 100644
> > --- a/tools/bpf/bpftool/gen.c
> > +++ b/tools/bpf/bpftool/gen.c
> > @@ -1209,7 +1209,7 @@ static int do_skeleton(int argc, char **argv)
> > codegen("\
> > \n\
> > \n\
> > - s->data = (void *)%2$s__elf_bytes(&s->data_sz); \n\
> > + s->data = (void *)%1$s__elf_bytes(&s->data_sz); \n\
> > \n\
> > obj->skeleton = s; \n\
> > return 0; \n\
> > @@ -1218,12 +1218,12 @@ static int do_skeleton(int argc, char **argv)
> > return err; \n\
> > } \n\
> > \n\
> > - static inline const void *%2$s__elf_bytes(size_t *sz) \n\
> > + static inline const void *%1$s__elf_bytes(size_t *sz) \n\
> > { \n\
> > - *sz = %1$d; \n\
> > - return (const void *)\"\\ \n\
> > - "
> > - , file_sz, obj_name);
> > + static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
> > + ",
> > + obj_name
> > + );
> >
> > /* embed contents of BPF object file */
> > print_hex(obj_data, file_sz);
> > @@ -1231,6 +1231,9 @@ static int do_skeleton(int argc, char **argv)
> > codegen("\
> > \n\
> > \"; \n\
> > + \n\
> > + *sz = sizeof(data) - 1; \n\
> > + return (const void *)data; \n\
> > } \n\
> > \n\
> > #ifdef __cplusplus \n\
> > --
> > 2.42.0.582.g8ccd20d70d-goog
> >
