Bad kfunc argument handling for functions with multiple BTF entries

[ajor]

My kernel contains multiple BTF entries representing functions of the same name, for several different functions. This can be confirmed with sudo bpftool btf dump file /boot/vmlinux-xxx.

Some of these BTF entries appear to be duplicates of a single function, where the arguments are given different names in different source files:

# bpftrace -lv 'kfunc:bpf_arch_text_poke'
kfunc:vmlinux:bpf_arch_text_poke
    void * ip
    enum bpf_text_poke_type t
    void * old_addr
    void * new_addr
    int retval
    void * ip
    enum bpf_text_poke_type t
    void * addr1
    void * addr2
    int retval

Others functions actually have multiple entries in kallsyms and versions with different numbers of arguments:

# bpftrace -lv 'kfunc:check_version'
kfunc:vmlinux:check_version
    unsigned int cmd
    struct dm_ioctl __attribute__((btf_type_tag("user"))) * user
    int retval
    const struct load_info * info
    const char * symname
    struct module * mod
    const s32 * crc
    int retval

There can be more than two BTF entries for a given function:

# bpftrace -lv 'kfunc:s_next'
kfunc:vmlinux:s_next
    struct seq_file * m
    void * v
    loff_t * pos
    void * retval
    struct seq_file * f
    void * data
    loff_t * pos
    void * retval
    struct seq_file * m
    void * p
    loff_t * pos
    void * retval

A sample of some others on my kernel (there are many more):

kfunc:vmlinux:c_next
kfunc:vmlinux:cgroup_storage_lookup
kfunc:vmlinux:check_extent_item
kfunc:vmlinux:cookie_hash
kfunc:vmlinux:s_show
kfunc:vmlinux:type_show
kfunc:vmlinux:user_read
kfunc:vmlinux:version_show