From fd264ca020948a743e4c36731dfdecc4a812153c Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Sun, 20 Nov 2022 11:54:32 -0800 Subject: bpf: Add a kfunc to type cast from bpf uapi ctx to kernel ctx Implement bpf_cast_to_kern_ctx() kfunc which does a type cast of a uapi ctx object to the corresponding kernel ctx. Previously if users want to access some data available in kctx but not in uapi ctx, bpf_probe_read_kernel() helper is needed. The introduction of bpf_cast_to_kern_ctx() allows direct memory access which makes code simpler and easier to understand. Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20221120195432.3113982-1-yhs@fb.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel/bpf/helpers.c') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 8e0d80b6bf09..e45e72676f5a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1879,6 +1879,11 @@ void bpf_task_release(struct task_struct *p) put_task_struct_rcu_user(p); } +void *bpf_cast_to_kern_ctx(void *obj) +{ + return obj; +} + __diag_pop(); BTF_SET8_START(generic_btf_ids) @@ -1907,6 +1912,7 @@ BTF_ID(struct, task_struct) BTF_ID(func, bpf_task_release) BTF_SET8_START(common_btf_ids) +BTF_ID_FLAGS(func, bpf_cast_to_kern_ctx) BTF_SET8_END(common_btf_ids) static const struct btf_kfunc_id_set common_kfunc_set = { -- cgit v1.2.3