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Message-ID: <76467c84-3c6b-4859-a815-bee018b3364d@gmail.com>
Date: Fri, 12 Apr 2024 18:28:34 -0700
From: Kui-Feng Lee <sinquersw@...il.com>
To: Jordan Rife <jrife@...gle.com>
Cc: bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
netdev@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman
<eddyz87@...il.com>, Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>,
Shuah Khan <shuah@...nel.org>, Kui-Feng Lee <thinker.li@...il.com>,
Artem Savkov <asavkov@...hat.com>, Dave Marchevsky <davemarchevsky@...com>,
Menglong Dong <imagedong@...cent.com>, Daniel Xu <dxu@...uu.xyz>,
David Vernet <void@...ifault.com>, Daan De Meyer <daan.j.demeyer@...il.com>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>
Subject: Re: [PATCH v2 bpf-next 1/6] selftests/bpf: Fix bind program for big
endian systems
On 4/12/24 18:17, Jordan Rife wrote:
> Kui-Feng,
>
> You are right. Maybe simply "load_word" and "load_byte" would be a
> better name here. WDYT?
Agree!
>
> -Jordan
>
>
> On Fri, Apr 12, 2024 at 6:01 PM Kui-Feng Lee <sinquersw@...il.com
> <mailto:sinquersw@...il.com>> wrote:
>
>
>
> On 4/12/24 09:52, Jordan Rife wrote:
> > Without this fix, the bind4 and bind6 programs will reject bind
> attempts
> > on big endian systems. This patch ensures that CI tests pass for the
> > s390x architecture.
> >
> > Signed-off-by: Jordan Rife <jrife@...gle.com
> <mailto:jrife@...gle.com>>
> > ---
> > .../testing/selftests/bpf/progs/bind4_prog.c | 18
> ++++++++++--------
> > .../testing/selftests/bpf/progs/bind6_prog.c | 18
> ++++++++++--------
> > tools/testing/selftests/bpf/progs/bind_prog.h | 19
> +++++++++++++++++++
> > 3 files changed, 39 insertions(+), 16 deletions(-)
> > create mode 100644 tools/testing/selftests/bpf/progs/bind_prog.h
> >
> > diff --git a/tools/testing/selftests/bpf/progs/bind4_prog.c
> b/tools/testing/selftests/bpf/progs/bind4_prog.c
> > index a487f60b73ac4..2bc052ecb6eef 100644
> > --- a/tools/testing/selftests/bpf/progs/bind4_prog.c
> > +++ b/tools/testing/selftests/bpf/progs/bind4_prog.c
> > @@ -12,6 +12,8 @@
> > #include <bpf/bpf_helpers.h>
> > #include <bpf/bpf_endian.h>
> >
> > +#include "bind_prog.h"
> > +
> > #define SERV4_IP 0xc0a801feU /* 192.168.1.254 */
> > #define SERV4_PORT 4040
> > #define SERV4_REWRITE_IP 0x7f000001U /* 127.0.0.1 */
> > @@ -118,23 +120,23 @@ int bind_v4_prog(struct bpf_sock_addr *ctx)
> >
> > // u8 narrow loads:
> > user_ip4 = 0;
> > - user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[0] << 0;
> > - user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[1] << 8;
> > - user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[2] << 16;
> > - user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[3] << 24;
> > + user_ip4 |= load_byte_ntoh(ctx->user_ip4, 0, sizeof(user_ip4));
> > + user_ip4 |= load_byte_ntoh(ctx->user_ip4, 1, sizeof(user_ip4));
> > + user_ip4 |= load_byte_ntoh(ctx->user_ip4, 2, sizeof(user_ip4));
> > + user_ip4 |= load_byte_ntoh(ctx->user_ip4, 3, sizeof(user_ip4));
> > if (ctx->user_ip4 != user_ip4)
> > return 0;
> >
> > user_port = 0;
> > - user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0;
> > - user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8;
> > + user_port |= load_byte_ntoh(ctx->user_port, 0,
> sizeof(user_port));
> > + user_port |= load_byte_ntoh(ctx->user_port, 1,
> sizeof(user_port));
> > if (ctx->user_port != user_port)
> > return 0;
> >
> > // u16 narrow loads:
> > user_ip4 = 0;
> > - user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[0] << 0;
> > - user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[1] << 16;
> > + user_ip4 |= load_word_ntoh(ctx->user_ip4, 0, sizeof(user_ip4));
> > + user_ip4 |= load_word_ntoh(ctx->user_ip4, 1, sizeof(user_ip4));
> > if (ctx->user_ip4 != user_ip4)
> > return 0;
> >
> > diff --git a/tools/testing/selftests/bpf/progs/bind6_prog.c
> b/tools/testing/selftests/bpf/progs/bind6_prog.c
> > index d62cd9e9cf0ea..194583e3375bf 100644
> > --- a/tools/testing/selftests/bpf/progs/bind6_prog.c
> > +++ b/tools/testing/selftests/bpf/progs/bind6_prog.c
> > @@ -12,6 +12,8 @@
> > #include <bpf/bpf_helpers.h>
> > #include <bpf/bpf_endian.h>
> >
> > +#include "bind_prog.h"
> > +
> > #define SERV6_IP_0 0xfaceb00c /*
> face:b00c:1234:5678::abcd */
> > #define SERV6_IP_1 0x12345678
> > #define SERV6_IP_2 0x00000000
> > @@ -129,25 +131,25 @@ int bind_v6_prog(struct bpf_sock_addr *ctx)
> > // u8 narrow loads:
> > for (i = 0; i < 4; i++) {
> > user_ip6 = 0;
> > - user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[0]
> << 0;
> > - user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[1]
> << 8;
> > - user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[2]
> << 16;
> > - user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[3]
> << 24;
> > + user_ip6 |= load_byte_ntoh(ctx->user_ip6[i], 0,
> sizeof(user_ip6));
> > + user_ip6 |= load_byte_ntoh(ctx->user_ip6[i], 1,
> sizeof(user_ip6));
> > + user_ip6 |= load_byte_ntoh(ctx->user_ip6[i], 2,
> sizeof(user_ip6));
> > + user_ip6 |= load_byte_ntoh(ctx->user_ip6[i], 3,
> sizeof(user_ip6));
> > if (ctx->user_ip6[i] != user_ip6)
> > return 0;
> > }
> >
> > user_port = 0;
> > - user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0;
> > - user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8;
> > + user_port |= load_byte_ntoh(ctx->user_port, 0,
> sizeof(user_port));
> > + user_port |= load_byte_ntoh(ctx->user_port, 1,
> sizeof(user_port));
> > if (ctx->user_port != user_port)
> > return 0;
> >
> > // u16 narrow loads:
> > for (i = 0; i < 4; i++) {
> > user_ip6 = 0;
> > - user_ip6 |= ((volatile __u16
> *)&ctx->user_ip6[i])[0] << 0;
> > - user_ip6 |= ((volatile __u16
> *)&ctx->user_ip6[i])[1] << 16;
> > + user_ip6 |= load_word_ntoh(ctx->user_ip6[i], 0,
> sizeof(user_ip6));
> > + user_ip6 |= load_word_ntoh(ctx->user_ip6[i], 1,
> sizeof(user_ip6));
> > if (ctx->user_ip6[i] != user_ip6)
> > return 0;
> > }
> > diff --git a/tools/testing/selftests/bpf/progs/bind_prog.h
> b/tools/testing/selftests/bpf/progs/bind_prog.h
> > new file mode 100644
> > index 0000000000000..0fdc466aec346
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/bind_prog.h
> > @@ -0,0 +1,19 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef __BIND_PROG_H__
> > +#define __BIND_PROG_H__
> > +
> > +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> > +#define load_byte_ntoh(src, b, s) \
> > + (((volatile __u8 *)&(src))[b] << 8 * b)
> > +#define load_word_ntoh(src, w, s) \
> > + (((volatile __u16 *)&(src))[w] << 16 * w)
> > +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> > +#define load_byte_ntoh(src, b, s) \
> > + (((volatile __u8 *)&(src))[(b) + (sizeof(src) - (s))] << 8
> * ((s) - (b) - 1))
> > +#define load_word_ntoh(src, w, s) \
> > + (((volatile __u16 *)&(src))[w] << 16 * (((s) / 2) - (w) - 1))
> These names, load_byte_ntoh() and load_word_ntoh(), are miss-leading.
>
> They don't actually do byte-order conversion from network order to host
> order. Network order is big endian. 0xdeadbeef in u32 should be stored
> as the sequence of
>
> 0xde, 0xad, 0xbe, 0xef
>
> The little endian implementation of load_word_ntoh() provided here will
> return 0xadde and 0xefbe0000. However, a network order to host order
> conversion should return 0xbeef and 0xdead0000 for little endian.
>
> The little endian implementation of load_byte_ntoh() here returns 0xde,
> 0xad00, 0xbe0000, and 0xef000000. However, a network to host order
> conversion should return 0xef, 0xbe00, 0xad0000, and 0xde00000.
>
> So, they just access raw data following the host byte order, not
> providing any byte order conversion.
>
>
> > +#else
> > +# error "Fix your compiler's __BYTE_ORDER__?!"
> > +#endif
> > +
> > +#endif
>
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