Re: [PATCH bpf-next 2/2] selftests/bpf: Add tests for ldsx of pkt data/data_end/data_meta accesses

[Yonghong Song <yonghong.song@linux.dev>]

On 7/16/24 12:54 PM, Eduard Zingerman wrote:
> On Mon, 2024-07-15 at 13:18 -0700, Yonghong Song wrote:
>
> [...]
>
>> +SEC("xdp")
>> +__description("LDSX, xdp s32 xdp_md->data")
>> +__failure __msg("invalid bpf_context access")
>> +__naked void ldsx_ctx_1(void)
>> +{
>> +        asm volatile (
>> +        "r2 = *(s32 *)(r1 + %[xdp_md_data]);"
> Nit: this test fails at the first instruction,
>       hence there is no need to include it's tail.
>       I think it would be good to keep these tests minimal.

Okay, I will shorten the test to have minimum instructions
to reproduce the issue.

>
>> +        "r3 = *(u32 *)(r1 + %[xdp_md_data_end]);"
>> +        "r1 = r2;"
>> +        "r1 += 8;"
>> +        "if r1 > r3 goto l0_%=;"
>> +        "r0 = *(u64 *)(r1 - 8);"
>> +"l0_%=:"
>> +	"r0 = 0;"
>> +        "exit;"
>> +	:
>> +        : __imm_const(xdp_md_data, offsetof(struct xdp_md, data)),
>> +	  __imm_const(xdp_md_data_end, offsetof(struct xdp_md, data_end))
>> +        : __clobber_all);
>> +}
> [...]