[PATCH bpf-next v2] bpf: fix warning for crash_kexec

[Andrii Nakryiko]

On Tue, Mar 19, 2024 at 1:02 AM Hari Bathini <hbathini at linux.ibm.com> wrote:
>
> With [1], crash dump specific code is moved out of CONFIG_KEXEC_CORE
> and placed under CONFIG_CRASH_DUMP, where it is more appropriate.
> And since CONFIG_KEXEC & !CONFIG_CRASH_DUMP build option is supported
> with that, it led to the below warning:
>
>   "WARN: resolve_btfids: unresolved symbol crash_kexec"
>
> Fix it by using the appropriate #ifdef.
>
> [1] https://lore.kernel.org/all/20240124051254.67105-1-bhe@redhat.com/
>
> Acked-by: Baoquan He <bhe at redhat.com>
> Fixes: 29fd9ae62910 ("crash: split crash dumping code out from kexec_core.c")

I don't think either bpf or bpf-next have this commit just yet, so
landing it in the bpf/bpf-next tree doesn't make much sense. It
probably would be best to land it through the tree which does the
CONFIG_KEXEC_CORE -> CONFIG_CRASH_DUMP change in kernel/Makefile.

pw-bot: cr

> Acked-by: Jiri Olsa <jolsa at kernel.org>
> Acked-by: Stanislav Fomichev <sdf at google.com>
> Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
> ---
>
> Changes in v2:
> * Updated changelog.
> * Added Fixes and Acked-by tags.
>
>
>  kernel/bpf/helpers.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index a89587859571..449b9a5d3fe3 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -2548,7 +2548,7 @@ __bpf_kfunc void bpf_throw(u64 cookie)
>  __bpf_kfunc_end_defs();
>
>  BTF_KFUNCS_START(generic_btf_ids)
> -#ifdef CONFIG_KEXEC_CORE
> +#ifdef CONFIG_CRASH_DUMP
>  BTF_ID_FLAGS(func, crash_kexec, KF_DESTRUCTIVE)
>  #endif
>  BTF_ID_FLAGS(func, bpf_obj_new_impl, KF_ACQUIRE | KF_RET_NULL)
> --
> 2.44.0
>