linux-kernel - Re: [PATCH bpf-next v2 2/3] bpf: export crash

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Message-ID: <YukAkjqdAqr9x2Bs@krava>
Date:   Tue, 2 Aug 2022 12:46:42 +0200
From:   Jiri Olsa <olsajiri@...il.com>
To:     Artem Savkov <asavkov@...hat.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        Daniel Vacek <dvacek@...hat.com>,
        Jiri Olsa <olsajiri@...il.com>, Song Liu <song@...nel.org>,
        Daniel Xu <dxu@...uu.xyz>
Subject: Re: [PATCH bpf-next v2 2/3] bpf: export crash_kexec() as destructive
 kfunc

On Tue, Aug 02, 2022 at 11:10:29AM +0200, Artem Savkov wrote:
> Allow properly marked bpf programs to call crash_kexec().
> 
> Signed-off-by: Artem Savkov <asavkov@...hat.com>
> ---
>  kernel/kexec_core.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 4d34c78334ce..9259ea3bd693 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -39,6 +39,8 @@
>  #include <linux/hugetlb.h>
>  #include <linux/objtool.h>
>  #include <linux/kmsg_dump.h>
> +#include <linux/btf.h>
> +#include <linux/btf_ids.h>
>  
>  #include <asm/page.h>
>  #include <asm/sections.h>
> @@ -1238,3 +1240,22 @@ void __weak arch_kexec_protect_crashkres(void)
>  
>  void __weak arch_kexec_unprotect_crashkres(void)
>  {}
> +
> +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
> +BTF_SET8_START(kexec_btf_ids)
> +BTF_ID_FLAGS(func, crash_kexec, KF_DESTRUCTIVE)
> +BTF_SET8_END(kexec_btf_ids)
> +
> +static const struct btf_kfunc_id_set kexec_kfunc_set = {
> +	.owner = THIS_MODULE,
> +	.set   = &kexec_btf_ids,
> +};
> +
> +static int __init crash_kfunc_init(void)
> +{
> +	register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &kexec_kfunc_set);
> +	return 0;

should we do 'return register_btf_kfunc_id_set(...' in here?

jirka

> +}
> +
> +subsys_initcall(crash_kfunc_init);
> +#endif
> -- 
> 2.35.3
>