The 'bpf -p <ID>' command shows truncated kprobe kernel function name

Issue

• The 'bpf -p ID' command shows truncated kprobe kernel function name.
• Execute the 'bpf -p ID' command from the "crash>" prompt.

crash> bpf -p 267                                                              
 ID      BPF_PROG       BPF_PROG_AUX   BPF_PROG_TYPE       TAG        USED_MAPS      
267  ffffb2f200039000 ffff8aa34267c000    KPROBE     1e982cb7ead83e56   95,96        
     XLATED: 712  JITED: 439  MEMLOCK: 4096                                          
     LOAD_TIME: Tue Jun 14 03:23:49 2022                                             
     GPL_COMPATIBLE: yes  NAME: "__blk_account_i"  UID: 0                            
                                 ^^^^^^^^^^^^^^^                                                                                                                      
crash> bpf -p 268                                                              
 ID      BPF_PROG       BPF_PROG_AUX   BPF_PROG_TYPE       TAG        USED_MAPS
268  ffffb2f200197000 ffff8aa34267e400    KPROBE     aa1489189b0a912d    95     
     XLATED: 120  JITED: 75  MEMLOCK: 4096
     LOAD_TIME: Tue Jun 14 03:23:48 2022
     GPL_COMPATIBLE: yes  NAME: "__blk_account_i"  UID: 0
                                 ^^^^^^^^^^^^^^^  

• The size of 'bpf_prog_info.name[BPF_OBJ_NAME_LEN]' and 'bpf_prog_aux.name[BPF_OBJ_NAME_LEN]' are limited to 16 chars which leads to truncated names since many BPF program have a much longer name.

crash> struct bpf_prog_info.name -ox
struct bpf_prog_info {
  [0x40] char name[16];
}

crash> struct bpf_prog_aux.name -ox
struct bpf_prog_aux {
  [0x210] char name[16];
}

• The actual kprobe kernel functions are "__blk_account_io_start" and "__blk_account_io_done" in RHEL 9.

• The actual kprobe kernel functions are "blk_account_io_start" and "blk_account_io_done" in RHEL 8.

crash> kprobe_table | grep 0xff | awk '{print "kprobe.symbol_name,pre_handler " $NF}' > kprobe

RHEL 9.0 :
crash> < kprobe | grep -v crash | paste - - | cat -n | column -t
1  symbol_name  =  0xffff8aa34409ff40  "__blk_account_io_start",  pre_handler  =  0xffffffff9c82b9e0  <kprobe_dispatcher>,
2  symbol_name  =  0xffff8aa34409fda0  "__blk_account_io_done",   pre_handler  =  0xffffffff9c82b9e0  <kprobe_dispatcher>,

RHEL 8 :
crash> < kprobe | grep -v crash | paste - - | cat -n | column -t
1  symbol_name  =  0xffff92f21b54a000  "blk_account_io_done"   pre_handler  =  0xffffffff9001bec0
2  symbol_name  =  0xffff92f21b54ade0  "blk_account_io_start"  pre_handler  =  0xffffffff9001bec0