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

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Date:   Tue,  2 Aug 2022 11:10:29 +0200
From:   Artem Savkov <asavkov@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Cc:     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>, Artem Savkov <asavkov@...hat.com>
Subject: [PATCH bpf-next v2 2/3] bpf: export crash_kexec() as destructive kfunc

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