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Tue, 06 Feb 2024 14:04:53 -0800 (PST) X-Forwarded-Encrypted: i=0; AJvYcCWUQoVkIthQQOsy6U4eSoQ5WdjVc0nJCVsDbkA2v0JGF6Yabw2lW6vfJzu68baFahsluKlv1NXHpG3TR+PKOZ23wdIUvI68+73W6afFYOGp3111MbSF540b1PZ6MPixqg3IhHR0uNOvN8cle0tWOioXnGsAI2TDADOi5Fif9LN8YHbGgy0QINttwPB4URjcnMqY8BB11Ij1d6XI/7mcn2HIpchSHafTgbAynmFH5kUNenEDFjaaPYgtauQDqNmqat3SfznSOSAwQYvn61xLPdSXcFtvHj6P1zvY Received: from localhost.localdomain ([2620:10d:c090:400::4:27bf]) by smtp.gmail.com with ESMTPSA id y20-20020aa78554000000b006e0322f072asm2488200pfn.35.2024.02.06.14.04.51 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 06 Feb 2024 14:04:53 -0800 (PST) From: Alexei Starovoitov To: bpf@vger.kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, memxor@gmail.com, eddyz87@gmail.com, tj@kernel.org, brho@google.com, hannes@cmpxchg.org, linux-mm@kvack.org, kernel-team@fb.com Subject: [PATCH bpf-next 02/16] bpf: Recognize '__map' suffix in kfunc arguments Date: Tue, 6 Feb 2024 14:04:27 -0800 Message-Id: <20240206220441.38311-3-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) In-Reply-To: <20240206220441.38311-1-alexei.starovoitov@gmail.com> References: <20240206220441.38311-1-alexei.starovoitov@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov Recognize 'void *p__map' kfunc argument as 'struct bpf_map *p__map'. It allows kfunc to have 'void *' argument for maps, since bpf progs will call them as: struct { __uint(type, BPF_MAP_TYPE_ARENA); ... } arena SEC(".maps"); bpf_kfunc_with_map(... &arena ...); Underneath libbpf will load CONST_PTR_TO_MAP into the register via ld_imm64 insn. If kfunc was defined with 'struct bpf_map *' it would pass the verifier, but bpf prog would need to use '(void *)&arena'. Which is not clean. Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d9c2dbb3939f..db569ce89fb1 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10741,6 +10741,11 @@ static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *a return __kfunc_param_match_suffix(btf, arg, "__ign"); } +static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__map"); +} + static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg) { return __kfunc_param_match_suffix(btf, arg, "__alloc"); @@ -11064,7 +11069,7 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, return KF_ARG_PTR_TO_CONST_STR; if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { - if (!btf_type_is_struct(ref_t)) { + if (!btf_type_is_struct(ref_t) && !btf_type_is_void(ref_t)) { verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", meta->func_name, argno, btf_type_str(ref_t), ref_tname); return -EINVAL; @@ -11660,6 +11665,13 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ if (kf_arg_type < 0) return kf_arg_type; + if (is_kfunc_arg_map(btf, &args[i])) { + /* If argument has '__map' suffix expect 'struct bpf_map *' */ + ref_id = *reg2btf_ids[CONST_PTR_TO_MAP]; + ref_t = btf_type_by_id(btf_vmlinux, ref_id); + ref_tname = btf_name_by_offset(btf, ref_t->name_off); + } + switch (kf_arg_type) { case KF_ARG_PTR_TO_NULL: continue;