| Message ID | 20191214004746.1652586-1-kafai@fb.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | Introduce BPF STRUCT_OPS | expand |
On 12/13/19 4:47 PM, Martin KaFai Lau wrote: > 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) && This check '!(btf_member_bit_offset(t, member) % 8)' is not needed. > + size <= sizeof(u64) && This one is not needed since verifier gets 'size' from load/store instructions which is guaranteed to be <= 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); >
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);
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(-)