Re: [PATCH v2 0/8] Implement EBPF on powerpc32

[Christophe Leroy]

Le 22/03/2021 à 18:53, Andrii Nakryiko a écrit :
> On Mon, Mar 22, 2021 at 9:37 AM Christophe Leroy
> <christophe.leroy@xxxxxxxxxx> wrote:
> > This series implements extended BPF on powerpc32. For the implementation
> > details, see the patch before the last.
> >
> > The following operations are not implemented:
> >
> >                  case BPF_ALU64 | BPF_DIV | BPF_X: /* dst /= src */
> >                  case BPF_ALU64 | BPF_MOD | BPF_X: /* dst %= src */
> >                  case BPF_STX | BPF_XADD | BPF_DW: /* *(u64 *)(dst + off) += src */
> >
> > The following operations are only implemented for power of two constants:
> >
> >                  case BPF_ALU64 | BPF_MOD | BPF_K: /* dst %= imm */
> >                  case BPF_ALU64 | BPF_DIV | BPF_K: /* dst /= imm */
> >
> > Below are the results on a powerpc 885:
> > - with the patch, with and without bpf_jit_enable
> > - without the patch, with bpf_jit_enable (ie with CBPF)
> >
> > With the patch, with bpf_jit_enable = 1 :
> >
> > [   60.826529] test_bpf: Summary: 378 PASSED, 0 FAILED, [354/366 JIT'ed]
> > [   60.832505] test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED
> >
> > With the patch, with bpf_jit_enable = 0 :
> >
> > [   75.186337] test_bpf: Summary: 378 PASSED, 0 FAILED, [0/366 JIT'ed]
> > [   75.192325] test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED
> >
> > Without the patch, with bpf_jit_enable = 1 :
> >
> > [  186.112429] test_bpf: Summary: 371 PASSED, 7 FAILED, [119/366 JIT'ed]
> >
> > Couldn't run test_progs because it doesn't build (clang 11 crashes during the build).
>
> Can you please try checking out the latest clang from sources and use
> that one instead?

The crash is fixed, it builds one step more, then fails at:

[root@PC-server-ldb bpf]# make CROSS_COMPILE=ppc-linux- ARCH=powerpc V=1
/root/gen_ldb/linux-powerpc/tools/testing/selftests/bpf/host-tools/sbin/bpftool gen skeleton 
/root/gen_ldb/linux-powerpc/tools/testing/selftests/bpf/atomic_bounds.o > 
/root/gen_ldb/linux-powerpc/tools/testing/selftests/bpf/atomic_bounds.skel.h
libbpf: elf: endianness mismatch in atomic_bounds.
Error: failed to open BPF object file: Endian mismatch

I'm cross-building on x86 for powerpc/32

[root@PC-server-ldb bpf]# file atomic_bounds.o
atomic_bounds.o: ELF 64-bit MSB relocatable, eBPF, version 1 (SYSV), with debug_info, not stripped

Christophe