> Am 02.07.2019 um 18:42 schrieb Y Song <ys114321@xxxxxxxxx>:
>
> On Tue, Jul 2, 2019 at 8:40 AM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote:
>>
>> -#elif defined(__s390x__)
>> - #define bpf_target_s930x
>
> I see in some other places (e.g., bcc) where
> macro __s390x__ is also used to indicate a s390 architecture.
> Could you explain the difference between __s390__ and
> __s390x__?
__s390__ is defined for 32-bit and 64-bit variants, __s390x__ is defined
for 64-bit variant only.
>> #if defined(bpf_target_x86)
>>
>> +#ifdef __KERNEL__
>
> In samples/bpf/, __KERNEL__ is defined at clang options and
> in selftests/bpf/, the __KERNEL__ is not defined.
>
> I checked x86 pt_regs definition with and without __KERNEL__.
> They are identical except some register name difference.
> I am wondering whether we can unify into all without
> __KERNEL__. Is __KERNEL__ really needed?
Right now removing it causes the build to fail, but the errors look
fixable. However, I wonder whether there is a plan regarding this:
should eBPF programs be built with user headers, kernel headers,
or both? Status quo appears to be "both", so I’ve decided to stick with
that in this patch.
>> +/* s390 provides user_pt_regs instead of struct pt_regs to userspace */
>> +struct pt_regs;
>> +#define PT_REGS_PARM1(x) (((const volatile user_pt_regs *)(x))->gprs[2])
>
> Is user_pt_regs a recent change or has been there for quite some time?
> I am asking since bcc did not use user_pt_regs yet.
It was added in late 2017 in commit 466698e654e8 ("s390/bpf: correct
broken uapi for BPF_PROG_TYPE_PERF_EVENT program type“).
