On Wed, Oct 4, 2023 at 1:43 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>
> ---
> tools/bpf/bpftool/gen.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
CI is not happy still, see [0]
[0] https://github.com/kernel-patches/bpf/actions/runs/6411371996/job/17406696212
> 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\
> --
> 2.42.0.609.gbb76f46606-goog
>
