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([2600:1700:6cf8:1240:bb79:f43d:510d:5ec7]) by smtp.gmail.com with ESMTPSA id c2-20020a0df302000000b006046bd562a5sm2218036ywf.128.2024.02.20.10.22.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Feb 2024 10:22:44 -0800 (PST) Message-ID: <81431b5d-0e0f-485a-a3ce-af8e63169552@gmail.com> Date: Tue, 20 Feb 2024 10:22:42 -0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next 1/5] bpf: tracing: add support to record and check the accessed args Content-Language: en-US To: Menglong Dong , andrii@kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, mykolal@fb.com, shuah@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, thinker.li@gmail.com, zhoufeng.zf@bytedance.com, davemarchevsky@fb.com, dxu@dxuuu.xyz, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org References: <20240220035105.34626-1-dongmenglong.8@bytedance.com> <20240220035105.34626-2-dongmenglong.8@bytedance.com> From: Kui-Feng Lee In-Reply-To: <20240220035105.34626-2-dongmenglong.8@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/19/24 19:51, Menglong Dong wrote: > In this commit, we add the 'accessed_args' field to struct bpf_prog_aux, > which is used to record the accessed index of the function args in > btf_ctx_access(). > > Meanwhile, we add the function btf_check_func_part_match() to compare the > accessed function args of two function prototype. This function will be > used in the following commit. > > Signed-off-by: Menglong Dong > --- > include/linux/bpf.h | 4 ++ > kernel/bpf/btf.c | 121 ++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 125 insertions(+) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index c7aa99b44dbd..0225b8dbdd9d 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -1464,6 +1464,7 @@ struct bpf_prog_aux { > const struct btf_type *attach_func_proto; > /* function name for valid attach_btf_id */ > const char *attach_func_name; > + u64 accessed_args; > struct bpf_prog **func; > void *jit_data; /* JIT specific data. arch dependent */ > struct bpf_jit_poke_descriptor *poke_tab; > @@ -2566,6 +2567,9 @@ struct bpf_reg_state; > int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog); > int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog, > struct btf *btf, const struct btf_type *t); > +int btf_check_func_part_match(struct btf *btf1, const struct btf_type *t1, > + struct btf *btf2, const struct btf_type *t2, > + u64 func_args); > const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type *pt, > int comp_idx, const char *tag_key); > int btf_find_next_decl_tag(const struct btf *btf, const struct btf_type *pt, > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 6ff0bd1a91d5..3a6931402fe4 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -6203,6 +6203,9 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, > /* skip first 'void *__data' argument in btf_trace_##name typedef */ > args++; > nr_args--; > + prog->aux->accessed_args |= (1 << (arg + 1)); > + } else { > + prog->aux->accessed_args |= (1 << arg); > } > > if (arg > nr_args) { > @@ -7010,6 +7013,124 @@ int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *pr > return btf_check_func_type_match(log, btf1, t1, btf2, t2); > } > > +static u32 get_ctx_arg_total_size(struct btf *btf, const struct btf_type *t) > +{ > + const struct btf_param *args; > + u32 size = 0, nr_args; > + int i; > + > + nr_args = btf_type_vlen(t); > + args = (const struct btf_param *)(t + 1); > + for (i = 0; i < nr_args; i++) { > + t = btf_type_skip_modifiers(btf, args[i].type, NULL); > + size += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8); > + } > + > + return size; > +} > + > +static int get_ctx_arg_idx_aligned(struct btf *btf, const struct btf_type *t, > + int off) > +{ > + const struct btf_param *args; > + u32 offset = 0, nr_args; > + int i; > + > + nr_args = btf_type_vlen(t); > + args = (const struct btf_param *)(t + 1); > + for (i = 0; i < nr_args; i++) { > + if (offset == off) > + return i; > + > + t = btf_type_skip_modifiers(btf, args[i].type, NULL); > + offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8); > + if (offset > off) > + return -1; > + } > + return -1; > +} This one is very similar to get_ctx_arg_idx(). How about to refactor get_ctx_arg_idx() and share the code between get_ctx_arg_idx() and get_ctx_arg_idx_aligned(). For example, -static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto, - int off) +static u32 _get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto, + int off, u32 *arg_off) { const struct btf_param *args; const struct btf_type *t; u32 offset = 0, nr_args; int i; if (!func_proto) return off / 8; nr_args = btf_type_vlen(func_proto); args = (const struct btf_param *)(func_proto + 1); for (i = 0; i < nr_args; i++) { + if (arg_off) + *arg_off = offset; t = btf_type_skip_modifiers(btf, args[i].type, NULL); offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8); if (off < offset) return i; } + if (arg_off) + *arg_off = offset; t = btf_type_skip_modifiers(btf, func_proto->type, NULL); offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8); if (off < offset) return nr_args; return nr_args + 1; } +static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto, + int off) +{ + return _get_ctx_arg_idx(btf, func_proto, off, NULL); +} + +static u32 get_ctx_arg_idx_aligned(struct btf *btf, + const struct btf_type *func_proto, + int off) +{ + u32 arg_off; + u32 arg_idx = _get_ctx_arg_idx(btf, func_proto, off, &arg_off); + return arg_off == off ? arg_idx : -1; +} + > + > +/* This function is similar to btf_check_func_type_match(), except that it > + * only compare some function args of the function prototype t1 and t2. > + */ > +int btf_check_func_part_match(struct btf *btf1, const struct btf_type *func1, > + struct btf *btf2, const struct btf_type *func2, > + u64 func_args) > +{ > + const struct btf_param *args1, *args2; > + u32 nargs1, i, offset = 0; > + const char *s1, *s2; > + > + if (!btf_type_is_func_proto(func1) || !btf_type_is_func_proto(func2)) > + return -EINVAL; > + > + args1 = (const struct btf_param *)(func1 + 1); > + args2 = (const struct btf_param *)(func2 + 1); > + nargs1 = btf_type_vlen(func1); > + > + for (i = 0; i <= nargs1; i++) { > + const struct btf_type *t1, *t2; > + > + if (!(func_args & (1 << i))) > + goto next; > + > + if (i < nargs1) { > + int t2_index; > + > + /* get the index of the arg corresponding to args1[i] > + * by the offset. > + */ > + t2_index = get_ctx_arg_idx_aligned(btf2, func2, > + offset); > + if (t2_index < 0) > + return -EINVAL; > + > + t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL); > + t2 = btf_type_skip_modifiers(btf2, args2[t2_index].type, > + NULL); > + } else { > + /* i == nargs1, this is the index of return value of t1 */ > + if (get_ctx_arg_total_size(btf1, func1) != > + get_ctx_arg_total_size(btf2, func2)) > + return -EINVAL; > + > + /* check the return type of t1 and t2 */ > + t1 = btf_type_skip_modifiers(btf1, func1->type, NULL); > + t2 = btf_type_skip_modifiers(btf2, func2->type, NULL); > + } > + > + if (t1->info != t2->info || > + (btf_type_has_size(t1) && t1->size != t2->size)) > + return -EINVAL; > + if (btf_type_is_int(t1) || btf_is_any_enum(t1)) > + goto next; > + > + if (btf_type_is_struct(t1)) > + goto on_struct; > + > + if (!btf_type_is_ptr(t1)) > + return -EINVAL; > + > + t1 = btf_type_skip_modifiers(btf1, t1->type, NULL); > + t2 = btf_type_skip_modifiers(btf2, t2->type, NULL); > + if (!btf_type_is_struct(t1) || !btf_type_is_struct(t2)) > + return -EINVAL; > + > +on_struct: > + s1 = btf_name_by_offset(btf1, t1->name_off); > + s2 = btf_name_by_offset(btf2, t2->name_off); > + if (strcmp(s1, s2)) > + return -EINVAL; > +next: > + if (i < nargs1) { > + t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL); > + offset += btf_type_is_ptr(t1) ? 8 : roundup(t1->size, 8); > + } > + } > + > + return 0; > +} > + > static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t) > { > const char *name;