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From: Martin KaFai Lau <kafai@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	David Miller <davem@davemloft.net>, <kernel-team@fb.com>,
	<netdev@vger.kernel.org>
Subject: [PATCH bpf-next 04/13] bpf: Support bitfield read access in btf_struct_access
Date: Fri, 13 Dec 2019 16:47:46 -0800	[thread overview]
Message-ID: <20191214004746.1652586-1-kafai@fb.com> (raw)
In-Reply-To: <20191214004737.1652076-1-kafai@fb.com>

This patch allows bitfield access as a scalar.  It currently limits
the access to sizeof(u64) and upto the end of the struct.  It is needed
in a later bpf-tcp-cc example that reads bitfield from
inet_connection_sock and tcp_sock.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 kernel/bpf/btf.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6e652643849b..011194831499 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3744,10 +3744,6 @@ int btf_struct_access(struct bpf_verifier_log *log,
 	}
 
 	for_each_member(i, t, member) {
-		if (btf_member_bitfield_size(t, member))
-			/* bitfields are not supported yet */
-			continue;
-
 		/* offset of the field in bytes */
 		moff = btf_member_bit_offset(t, member) / 8;
 		if (off + size <= moff)
@@ -3757,6 +3753,15 @@ int btf_struct_access(struct bpf_verifier_log *log,
 		if (off < moff)
 			continue;
 
+		if (btf_member_bitfield_size(t, member)) {
+			if (off == moff &&
+			    !(btf_member_bit_offset(t, member) % 8) &&
+			    size <= sizeof(u64) &&
+			    off + size <= t->size)
+				return SCALAR_VALUE;
+			continue;
+		}
+
 		/* type of the field */
 		mtype = btf_type_by_id(btf_vmlinux, member->type);
 		mname = __btf_name_by_offset(btf_vmlinux, member->name_off);
-- 
2.17.1


  parent reply	other threads:[~2019-12-14  0:47 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-14  0:47 [PATCH bpf-next 00/13] Introduce BPF STRUCT_OPS Martin KaFai Lau
2019-12-14  0:47 ` [PATCH bpf-next 01/13] bpf: Save PTR_TO_BTF_ID register state when spilling to stack Martin KaFai Lau
2019-12-16 19:48   ` Yonghong Song
2019-12-14  0:47 ` [PATCH bpf-next 02/13] bpf: Avoid storing modifier to info->btf_id Martin KaFai Lau
2019-12-16 21:34   ` Yonghong Song
2019-12-14  0:47 ` [PATCH bpf-next 03/13] bpf: Add enum support to btf_ctx_access() Martin KaFai Lau
2019-12-16 21:36   ` Yonghong Song
2019-12-14  0:47 ` Martin KaFai Lau [this message]
2019-12-16 22:05   ` [PATCH bpf-next 04/13] bpf: Support bitfield read access in btf_struct_access Yonghong Song
2019-12-14  0:47 ` [PATCH bpf-next 05/13] bpf: Introduce BPF_PROG_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-17  6:14   ` Yonghong Song
2019-12-18 16:41     ` Martin Lau
2019-12-14  0:47 ` [PATCH bpf-next 06/13] bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-17  7:48   ` [Potential Spoof] " Yonghong Song
2019-12-20  7:22     ` Martin Lau
2019-12-20 16:52       ` Martin Lau
2019-12-20 18:41         ` Andrii Nakryiko
2019-12-14  0:47 ` [PATCH bpf-next 07/13] bpf: tcp: Support tcp_congestion_ops in bpf Martin KaFai Lau
2019-12-17 17:36   ` Yonghong Song
2019-12-14  0:47 ` [PATCH bpf-next 08/13] bpf: Add BPF_FUNC_tcp_send_ack helper Martin KaFai Lau
2019-12-17 17:41   ` Yonghong Song
2019-12-14  0:47 ` [PATCH bpf-next 09/13] bpf: Add BPF_FUNC_jiffies Martin KaFai Lau
2019-12-14  1:59   ` Eric Dumazet
2019-12-14 19:25     ` Neal Cardwell
2019-12-16 19:30       ` Martin Lau
2019-12-17  8:26       ` Jakub Sitnicki
2019-12-17 18:22         ` Martin Lau
2019-12-17 21:04           ` Eric Dumazet
2019-12-18  9:03           ` Jakub Sitnicki
2019-12-16 19:14     ` Martin Lau
2019-12-16 19:33       ` Eric Dumazet
2019-12-16 21:17         ` Martin Lau
2019-12-16 23:08       ` Alexei Starovoitov
2019-12-17  0:34         ` Eric Dumazet
2019-12-14  0:48 ` [PATCH bpf-next 10/13] bpf: Synch uapi bpf.h to tools/ Martin KaFai Lau
2019-12-14  0:48 ` [PATCH bpf-next 11/13] bpf: libbpf: Add STRUCT_OPS support Martin KaFai Lau
2019-12-18  3:07   ` Andrii Nakryiko
2019-12-18  7:03     ` Martin Lau
2019-12-18  7:20       ` Martin Lau
2019-12-18 16:36         ` Andrii Nakryiko
2019-12-18 16:34       ` Andrii Nakryiko
2019-12-18 17:33         ` Martin Lau
2019-12-18 18:14           ` Andrii Nakryiko
2019-12-18 20:19             ` Martin Lau
2019-12-19  8:53             ` Toke Høiland-Jørgensen
2019-12-19 20:49               ` Andrii Nakryiko
2019-12-20 10:16                 ` Toke Høiland-Jørgensen
2019-12-20 17:34                   ` Andrii Nakryiko
2019-12-14  0:48 ` [PATCH bpf-next 12/13] bpf: Add bpf_dctcp example Martin KaFai Lau
2019-12-14  0:48 ` [PATCH bpf-next 13/13] bpf: Add bpf_cubic example Martin KaFai Lau
2019-12-14  2:26 ` [PATCH bpf-next 00/13] Introduce BPF STRUCT_OPS Eric Dumazet

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