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Wed, 09 Apr 2025 07:25:15 -0700 (PDT) Received: from localhost ([2601:646:9e00:f56e:123b:cea3:439a:b3e3]) by smtp.gmail.com with UTF8SMTPSA id 98e67ed59e1d1-306dd10c42asm1832714a91.7.2025.04.09.07.25.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Apr 2025 07:25:14 -0700 (PDT) Date: Wed, 9 Apr 2025 07:25:14 -0700 From: Stanislav Fomichev To: Daniel Xu Cc: andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC bpf-next 10/13] bpf: verifier: Add indirection to kallsyms_lookup_name() Message-ID: References: <7540678e9a46c13f680f2aacab28bb88446583f5.1744169424.git.dxu@dxuuu.xyz> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <7540678e9a46c13f680f2aacab28bb88446583f5.1744169424.git.dxu@dxuuu.xyz> On 04/08, Daniel Xu wrote: > kallsyms_lookup_name() cannot be exported from the kernel for policy > reasons, so add this layer of indirection to allow the verifier to still > do kfunc and global variable relocations. > > Signed-off-by: Daniel Xu > --- > include/linux/bpf.h | 2 ++ > kernel/bpf/core.c | 14 ++++++++++++++ > kernel/bpf/verifier.c | 13 +++++-------- > 3 files changed, 21 insertions(+), 8 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 44133727820d..a5806a7b31d3 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -2797,6 +2797,8 @@ static inline int kfunc_desc_cmp_by_id_off(const void *a, const void *b) > } > const struct bpf_kfunc_desc * > find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset); > +unsigned long bpf_lookup_type_addr(struct btf *btf, const struct btf_type *func, > + const char **name); > int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id, > u16 btf_fd_idx, u8 **func_addr); > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index e892e469061e..13301a668fe0 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -1639,6 +1639,20 @@ find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset) > } > EXPORT_SYMBOL_GPL(find_kfunc_desc); > > +unsigned long bpf_lookup_type_addr(struct btf *btf, const struct btf_type *t, > + const char **name) > +{ > + unsigned long addr; > + > + *name = btf_name_by_offset(btf, t->name_off); > + addr = kallsyms_lookup_name(*name); > + if (!addr) > + return -ENOENT; > + > + return addr; > +} > +EXPORT_SYMBOL_GPL(bpf_lookup_type_addr); Let's namespecify all these new exports? EXPORT_SYMBOL_NS_GPL