eBPF C: cannot use strcmp and strncmp

[duyuchao]

   I met an issue of cannot use strcmp(strcmp(key.comm, "xxx");), eBPF verify show below error, I traced strcmp realized in strcmp.S. 
   After I rewrite the strcmp function with C language, it works well, but I think this is inconvenient, so I want ask whether you have good idea, thank you.

========================error log============================
root@localhost:/# ./submit_bio.py
bpf: Failed to load program: Invalid argument
0: (79) r6 = *(u64 *)(r1 +0)
1: (b7) r1 = 0
2: (7b) *(u64 *)(r10 -8) = r1
3: (7b) *(u64 *)(r10 -16) = r1
4: (7b) *(u64 *)(r10 -24) = r1
5: (7b) *(u64 *)(r10 -32) = r1
6: (7b) *(u64 *)(r10 -40) = r1
7: (7b) *(u64 *)(r10 -48) = r1
8: (7b) *(u64 *)(r10 -56) = r1
9: (7b) *(u64 *)(r10 -64) = r1
10: (7b) *(u64 *)(r10 -72) = r1
11: (bf) r7 = r10
12: (07) r7 += -68
13: (bf) r1 = r7
14: (b7) r2 = 16
15: (85) call bpf_get_current_comm#16
16: (85) call bpf_get_current_pid_tgid#14
17: (63) *(u32 *)(r10 -52) = r0
18: (bf) r1 = r7
19: BUG_ld_00
invalid BPF_LD_IMM insn

Traceback (most recent call last):
File "./submit_bio.py", line 92, in
b.attach_kprobe(event="submit_bio", fn_name="print_submit_bio")
File "/usr/lib/python2.7/dist-packages/bcc/init.py", line 592, in attach_kprobe
fn = self.load_func(fn_name, BPF.KPROBE)
File "/usr/lib/python2.7/dist-packages/bcc/init.py", line 377, in load_func
(func_name, errstr))
Exception: Failed to load BPF program print_submit_bio: Invalid argument

[joelagnel]

Could you open an issue on BCC project directly and we discuss there?

…

On Sun, May 5, 2019 at 5:57 AM duyuchao ***@***.***> wrote: I met an issue of cannot use strcmp(strcmp(key.comm, "xxx");), eBPF verify show below error, I traced strcmp realized in strcmp.S. After I rewrite the strcmp function with C language, it works well, but I think this is inconvenient, so I want ask whether you have good idea, thank you. ========================error log============================ ***@***.***:/# ./submit_bio.py bpf: Failed to load program: Invalid argument 0: (79) r6 = *(u64 *)(r1 +0) 1: (b7) r1 = 0 2: (7b) *(u64 *)(r10 -8) = r1 3: (7b) *(u64 *)(r10 -16) = r1 4: (7b) *(u64 *)(r10 -24) = r1 5: (7b) *(u64 *)(r10 -32) = r1 6: (7b) *(u64 *)(r10 -40) = r1 7: (7b) *(u64 *)(r10 -48) = r1 8: (7b) *(u64 *)(r10 -56) = r1 9: (7b) *(u64 *)(r10 -64) = r1 10: (7b) *(u64 *)(r10 -72) = r1 11: (bf) r7 = r10 12: (07) r7 += -68 13: (bf) r1 = r7 14: (b7) r2 = 16 15: (85) call bpf_get_current_comm#16 16: (85) call bpf_get_current_pid_tgid#14 17: (63) *(u32 *)(r10 -52) = r0 18: (bf) r1 = r7 19: BUG_ld_00 invalid BPF_LD_IMM insn Traceback (most recent call last): File "./submit_bio.py", line 92, in b.attach_kprobe(event="submit_bio", fn_name="print_submit_bio") File "/usr/lib/python2.7/dist-packages/bcc/*init*.py", line 592, in attach_kprobe fn = self.load_func(fn_name, BPF.KPROBE) File "/usr/lib/python2.7/dist-packages/bcc/*init*.py", line 377, in load_func (func_name, errstr)) Exception: Failed to load BPF program print_submit_bio: Invalid argument — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#26>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAJEVHF5EWSCEDTB4TLX7TPT2VRVANCNFSM4HK23YCQ> .

[duyuchao]

ok