diff mbox series

program of this type cannot use helper xyz with bpf_struct_ops

Message ID ZykIaV1yyTUOI8yF@himmelriiki (mailing list archive)
State Not Applicable
Delegated to: BPF
Headers show
Series program of this type cannot use helper xyz with bpf_struct_ops | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Mikko Ylinen Nov. 4, 2024, 5:46 p.m. UTC 
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Is the doc outdated or my steps are simply wrong here?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:

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

Comments

Alexei Starovoitov Nov. 4, 2024, 6:23 p.m. UTC | #1 
On Mon, Nov 4, 2024 at 9:46 AM Mikko Ylinen
<mikko.ylinen@linux.intel.com> wrote:
>
> 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
>

This is expected.
Each struct_ops has its own .get_func_proto callback.
This is a dummy struct_ops for testing. It doesn't allow
calling any helpers. get_func_proto is not set:

static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
        .is_valid_access = bpf_dummy_ops_is_valid_access,
        .btf_struct_access = bpf_dummy_ops_btf_struct_access,
};
diff mbox series

Patch

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;
 }