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 <redacted>
---
 include/linux/bpf.h |   4 ++
 kernel/bpf/btf.c    | 108 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 95e07673cdc1..0f677fdcfcc7 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h

@@ -1461,6 +1461,7 @@ 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;

@@ -2565,6 +2566,9 @@ 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 170d017e8e4a..c2a0299d4358 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c

@@ -6125,19 +6125,24 @@ static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
 }

 static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto,
-                          int off)
+                          int off, int *aligned_idx)
 {
        const struct btf_param *args;
        const struct btf_type *t;
        u32 offset = 0, nr_args;
        int i;

+       if (aligned_idx)
+               *aligned_idx = -ENOENT;
+
        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 (aligned_idx && offset == off)
+                       *aligned_idx = i;
                t = btf_type_skip_modifiers(btf, args[i].type, NULL);
                offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
                if (off < offset)

@@ -6207,7 +6212,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
                        tname, off);
                return false;
        }
-       arg = get_ctx_arg_idx(btf, t, off);
+       arg = get_ctx_arg_idx(btf, t, off, NULL);
        args = (const struct btf_param *)(t + 1);
        /* if (t == NULL) Fall back to default BPF prog with
         * MAX_BPF_FUNC_REG_ARGS u64 arguments.

@@ -6217,6 +6222,9 @@ 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) {

@@ -7024,6 +7032,102 @@ 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;
+}
+
+/* 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)