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SubjectRe: [PATCH v11 2/9] btf: Handle dynamic pointer parameter in kfuncs
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On 8/12/22 12:18 PM, Roberto Sassu wrote:
> Allow the bpf_dynptr_kern parameter to be specified in kfuncs. Also, ensure
> that the dynamic pointer is valid and initialized.
>
> Cc: Joanne Koong <joannelkoong@gmail.com>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
> include/linux/bpf_verifier.h | 3 +++
> kernel/bpf/btf.c | 22 ++++++++++++++++++++++
> kernel/bpf/verifier.c | 4 ++--
> 3 files changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
> index 2e3bad8640dc..55876fbdbae2 100644
> --- a/include/linux/bpf_verifier.h
> +++ b/include/linux/bpf_verifier.h
> @@ -560,6 +560,9 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state
> u32 regno);
> int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
> u32 regno, u32 mem_size);
> +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
> + struct bpf_reg_state *reg,
> + enum bpf_arg_type arg_type);
>
> /* this lives here instead of in bpf.h because it needs to dereference tgt_prog */
> static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog,
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index e49b3b6d48ad..86e63f2ee5da 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -195,6 +195,10 @@
> i < btf_type_vlen(struct_type); \
> i++, member++)
>
> +#define stringify_struct(x) \
> + ({ BUILD_BUG_ON(sizeof(struct x) < 0); \
> + __stringify(x); })
> +

I'd say lets move this to include/linux/btf.h with a comment explaining the BUILD_BUG_ON()
which ensures the struct actually exits.

If there's ever use outside of BTF, it could be relocated to include/linux/stringify.h.

> DEFINE_IDR(btf_idr);
> DEFINE_SPINLOCK(btf_idr_lock);
>

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