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SubjectRe: bpf: test_verifier: sanitation: alu with different scalars
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On 06/25/2019 10:29 AM, Yauheni Kaliuta wrote:
> Hi!
>
> I'm wondering, how the sanitaion tests (#903 5.2-rc6 for example)
> are supposed to work on BE arches:
>
> {
> "sanitation: alu with different scalars 1",
> .insns = {
> BPF_MOV64_IMM(BPF_REG_0, 1),
> BPF_LD_MAP_FD(BPF_REG_ARG1, 0),
> BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP),
> BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -16),
> BPF_ST_MEM(BPF_DW, BPF_REG_FP, -16, 0),
> BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
> BPF_EXIT_INSN(),
> BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0),
>
> reads one byte 0 on BE and 28 on LE (from ->index) since
>
> struct test_val {
> unsigned int index;
> int foo[MAX_ENTRIES];
> };
>
> struct test_val value = {
> .index = (6 + 1) * sizeof(int),
> .foo[6] = 0xabcdef12,
> };
>
> BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3),
>
> So different branches are taken depending of the endianness.
>
> BPF_MOV64_IMM(BPF_REG_2, 0),
> BPF_MOV64_IMM(BPF_REG_3, 0x100000),
> BPF_JMP_A(2),
> BPF_MOV64_IMM(BPF_REG_2, 42),
> BPF_MOV64_IMM(BPF_REG_3, 0x100001),
> BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_3),
> BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
> BPF_EXIT_INSN(),
> },
> .fixup_map_array_48b = { 1 },
> .result = ACCEPT,
> .retval = 0x100000,
> },

Let me get my hands on a s390x box later today and get back to you.

Thanks,
Daniel

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