RE: [PATCH v5 5/9] test/bpf: add test for large shift

[Marat Khalili <marat.khalili@huawei.com>]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Wednesday 24 June 2026 18:55
> To: dev@dpdk.org
> Cc: Stephen Hemminger <stephen@networkplumber.org>; Konstantin Ananyev <konstantin.ananyev@huawei.com>;
> Marat Khalili <marat.khalili@huawei.com>
> Subject: [PATCH v5 5/9] test/bpf: add test for large shift
> 
> There were multiple bugs with immediate values in shift instructions.
> The code was not masking as required by RFC.
> 
> Add new tests that cover these instructions.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Acked-by: Marat Khalili <marat.khalili@huawei.com>

> ---
>  app/test/test_bpf.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/app/test/test_bpf.c b/app/test/test_bpf.c
> index 232e9e2a98..0e5894a532 100644
> --- a/app/test/test_bpf.c
> +++ b/app/test/test_bpf.c
> @@ -2005,6 +2005,51 @@ test_div1_check(uint64_t rc, const void *arg)
>  	return cmp_res(__func__, 0, rc, dve.out, dvt->out, sizeof(dve.out));
>  }
> 
> +/*
> + * Shift counts are masked to the operand width (RFC 9669: 0x3f for 64-bit,
> + * 0x1f for 32-bit). Counts >= 128 also exercise the x86 imm_size() path that
> + * used to desync the stream, and the arm64 UBFM/SBFM immediate encoding.
> + */
> +static const struct ebpf_insn test_shift_big_imm_prog[] = {
> +	{
> +		.code = (EBPF_ALU64 | EBPF_MOV | BPF_K),
> +		.dst_reg = EBPF_REG_0,
> +		.imm = 1
> +	},
> +	{
> +		.code = (EBPF_ALU64 | BPF_LSH | BPF_K),
> +		.dst_reg = EBPF_REG_0,
> +		.imm = 191
> +	},
> +	{
> +		.code = (EBPF_ALU64 | EBPF_ARSH | BPF_K),
> +		.dst_reg = EBPF_REG_0,
> +		.imm = 200
> +	},
> +	{
> +		.code = (EBPF_ALU64 | BPF_RSH | BPF_K),
> +		.dst_reg = EBPF_REG_0,
> +		.imm = 130
> +	},
> +	{
> +		.code = (BPF_JMP | EBPF_EXIT)
> +	},
> +};
> +
> +static void
> +test_shift_big_imm_prepare(void *arg)
> +{
> +	memset(arg, 0, sizeof(struct dummy_offset));
> +}
> +
> +static int
> +test_shift_big_imm_check(uint64_t rc, const void *arg)
> +{
> +	uint64_t expect = 0x3FE0000000000000ULL;
> +
> +	return cmp_res(__func__, expect, rc, arg, arg, 0);
> +}
> +
>  /* call test-cases */
>  static const struct ebpf_insn test_call1_prog[] = {
> 
> @@ -3409,6 +3454,20 @@ static const struct bpf_test tests[] = {
>  		.prepare = test_mul1_prepare,
>  		.check_result = test_div1_check,
>  	},
> +	{
> +		.name = "test_shift_big_imm",
> +		.arg_sz = sizeof(struct dummy_offset),
> +		.prm = {
> +			.ins = test_shift_big_imm_prog,
> +			.nb_ins = RTE_DIM(test_shift_big_imm_prog),
> +			.prog_arg = {
> +				.type = RTE_BPF_ARG_PTR,
> +				.size = sizeof(struct dummy_offset),
> +			},
> +		},
> +		.prepare = test_shift_big_imm_prepare,
> +		.check_result = test_shift_big_imm_check,
> +	},
>  	{
>  		.name = "test_call1",
>  		.arg_sz = sizeof(struct dummy_offset),
> --
> 2.53.0