Hi,
I was experimenting with struct_ops for my use-case but the programs
would not load because of "program of this type cannot use helper
xyz" error. However, [1] suggests that the ones I tried *are* supported.
Is the doc outdated or my steps are simply wrong here?
Andrii suggested to report the case here with reproduce steps so here
it goes.
with:
diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops_success.c b/tools/testing/selftests/bpf/progs/dummy_st_ops_success.c
index ec0c595d47af..c3ca873957f0 100644
--- a/tools/testing/selftests/bpf/progs/dummy_st_ops_success.c
+++ b/tools/testing/selftests/bpf/progs/dummy_st_ops_success.c
@@ -39,6 +39,7 @@ int BPF_PROG(test_2, struct bpf_dummy_ops_state *state, int a1, unsigned short a
test_2_args[2] = a2;
test_2_args[3] = a3;
test_2_args[4] = a4;
+ bpf_printk("struct_ops/test_2");
return 0;
}
and:
tools/testing/selftests/bpf/vmtest.sh -- ./test_progs -t dummy_st_ops/dummy_st_ops_attach
I get:
[build + VM boot cut out]
./test_progs -t dummy_st_ops/dummy_st_ops_attach
[ 1.068102] bpf_testmod: loading out-of-tree module taints kernel.
[ 1.068733] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
tester_init:PASS:tester_log_buf 0 nsec
process_subtest:PASS:obj_open_mem 0 nsec
process_subtest:PASS:specs_alloc 0 nsec
libbpf: prog 'test_2': BPF program load failed: Invalid argument
libbpf: prog 'test_2': -- BEGIN PROG LOAD LOG --
0: R1=ctx() R10=fp0
; int BPF_PROG(test_2, struct bpf_dummy_ops_state *state, int a1, unsigned short a2, @ dummy_st_ops_success.c:40
0: (79) r2 = *(u64 *)(r1 +0)
func 'test_2' arg0 has btf_id 83075 type STRUCT 'bpf_dummy_ops_state'
1: R1=ctx() R2_w=trusted_ptr_bpf_dummy_ops_state()
; test_2_args[0] = state->val; @ dummy_st_ops_success.c:43
1: (61) r2 = *(u32 *)(r2 +0) ; R2_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
; int BPF_PROG(test_2, struct bpf_dummy_ops_state *state, int a1, unsigned short a2, @ dummy_st_ops_success.c:40
2: (79) r3 = *(u64 *)(r1 +8) ; R1=ctx() R3_w=scalar()
3: (79) r4 = *(u64 *)(r1 +16) ; R1=ctx() R4_w=scalar()
4: (79) r5 = *(u64 *)(r1 +24) ; R1=ctx() R5_w=scalar()
5: (79) r1 = *(u64 *)(r1 +32) ; R1_w=scalar()
; test_2_args[0] = state->val; @ dummy_st_ops_success.c:43
6: (18) r0 = 0xffffb456400f6000 ; R0_w=map_value(map=dummy_st.bss,ks=4,vs=40)
; test_2_args[4] = a4; @ dummy_st_ops_success.c:47
8: (7b) *(u64 *)(r0 +32) = r1 ; R0_w=map_value(map=dummy_st.bss,ks=4,vs=40) R1_w=scalar()
; test_2_args[3] = a3; @ dummy_st_ops_success.c:46
9: (67) r5 <<= 56 ; R5_w=scalar(smax=0x7f00000000000000,umax=0xff00000000000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xff00000000000000))
10: (c7) r5 s>>= 56 ; R5_w=scalar(smin=smin32=-128,smax=smax32=127)
11: (7b) *(u64 *)(r0 +24) = r5 ; R0_w=map_value(map=dummy_st.bss,ks=4,vs=40) R5_w=scalar(smin=smin32=-128,smax=smax32=127)
; int BPF_PROG(test_2, struct bpf_dummy_ops_state *state, int a1, unsigned short a2, @ dummy_st_ops_success.c:40
12: (57) r4 &= 65535 ; R4_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff))
; test_2_args[2] = a2; @ dummy_st_ops_success.c:45
13: (7b) *(u64 *)(r0 +16) = r4 ; R0_w=map_value(map=dummy_st.bss,ks=4,vs=40) R4_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff))
; test_2_args[1] = a1; @ dummy_st_ops_success.c:44
14: (67) r3 <<= 32 ; R3_w=scalar(smax=0x7fffffff00000000,umax=0xffffffff00000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xffffffff00000000))
15: (c7) r3 s>>= 32 ; R3_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff)
16: (7b) *(u64 *)(r0 +8) = r3 ; R0_w=map_value(map=dummy_st.bss,ks=4,vs=40) R3_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff)
; test_2_args[0] = state->val; @ dummy_st_ops_success.c:43
17: (67) r2 <<= 32 ; R2_w=scalar(smax=0x7fffffff00000000,umax=0xffffffff00000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xffffffff00000000))
18: (c7) r2 s>>= 32 ; R2_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff)
19: (7b) *(u64 *)(r0 +0) = r2 ; R0_w=map_value(map=dummy_st.bss,ks=4,vs=40) R2_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff)
; bpf_printk("struct_ops/test_2"); @ dummy_st_ops_success.c:48
20: (18) r1 = 0xffff9481c114e5d8 ; R1_w=map_value(map=dummy_st.rodata,ks=4,vs=18)
22: (b4) w2 = 18 ; R2_w=18
23: (85) call bpf_trace_printk#6
program of this type cannot use helper bpf_trace_printk#6
processed 22 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
-- END PROG LOAD LOG --
libbpf: prog 'test_2': failed to load: -22
libbpf: failed to load object 'dummy_st_ops_success'
libbpf: failed to load BPF skeleton 'dummy_st_ops_success': -22
test_dummy_st_ops_attach:FAIL:dummy_st_ops_load unexpected error: -22
#84/1 dummy_st_ops/dummy_st_ops_attach:FAIL
#84 dummy_st_ops:FAIL
I can reproduce this with 6.12-rc6 and 6.11.6 source (6.11 I needed to
patch with 424ebaa3678 to get test_loader.c to compile, though).
FWIW, adding the same change to progs/bpf_dctcp.c and running
bpf_tcp_ca tests passed OK for some reason.
Mikko
[1] https://docs.ebpf.io/linux/program-type/BPF_PROG_TYPE_STRUCT_OPS/#helper-functions
