From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v2 bpf-next 07/11] libbpf: add BPF static linker BTF and BTF.ext support
Date: Wed, 17 Mar 2021 15:10:06 -0700 [thread overview]
Message-ID: <CAEf4BzbLtWcgex0+zEfy=6n2783N3nWCX2RkE3Nh1peUHaFXkw@mail.gmail.com> (raw)
In-Reply-To: <20210317052540.3f6epwcm6o5zwsdi@ast-mbp>
On Tue, Mar 16, 2021 at 10:25 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sat, Mar 13, 2021 at 11:35:33AM -0800, Andrii Nakryiko wrote:
> > + for (j = 0; j < n; j++, src_var++) {
> > + void *sec_vars = dst_sec->sec_vars;
> > +
> > + sec_vars = libbpf_reallocarray(sec_vars,
> > + dst_sec->sec_var_cnt + 1,
> > + sizeof(*dst_sec->sec_vars));
> > + if (!sec_vars)
> > + return -ENOMEM;
> > +
> > + dst_sec->sec_vars = sec_vars;
> > + dst_sec->sec_var_cnt++;
> > +
> > + dst_var = &dst_sec->sec_vars[dst_sec->sec_var_cnt - 1];
> > + dst_var->type = obj->btf_type_map[src_var->type];
> > + dst_var->size = src_var->size;
> > + dst_var->offset = src_sec->dst_off + src_var->offset;
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void *add_btf_ext_rec(struct btf_ext_sec_data *ext_data, const void *src_rec)
> > +{
> > + size_t new_sz = (ext_data->rec_cnt + 1) * ext_data->rec_sz;
> > + void *tmp;
> > +
> > + tmp = realloc(ext_data->recs, new_sz);
> > + if (!tmp)
> > + return NULL;
> > +
> > + ext_data->recs = tmp;
> > + ext_data->rec_cnt++;
> > +
> > + tmp += new_sz - ext_data->rec_sz;
> > + memcpy(tmp, src_rec, ext_data->rec_sz);
>
> while reading this and previous patch the cnt vs sz difference was
> constantly throwing me off. Not a big deal, of course.
> Did you consider using _cnt everywhere and use finalize method
> to convert everything to size?
> Like in this function libbpf_reallocarray() instead of realloc() would
> probably be easier to read and more consistent, since btf_ext_sec_data
> is measuring things in _cnt.
will switch this and add_sym() to reallocarray, given both are dealing
with real fixed-size records (not just bytes)
> In the previous patch the section is in _sz which I guess is necessary
> because sections can contain differently sized objects?
yes, it could be records of different sizes (e.g., relocations,
symbols), or just unstructured data (e.g., .data, string table, etc).
>
> btw, strset abstraction is really nice. It made the patches much easier
> to read.
Thanks. Yeah, it simplified existing BTF/btf_dedup logic quite a bit
as well, it was a good suggestion!
next prev parent reply other threads:[~2021-03-17 22:19 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 19:35 [PATCH v2 bpf-next 00/11] BPF static linking Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 01/11] libbpf: expose btf_type_by_id() internally Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 02/11] libbpf: generalize BTF and BTF.ext type ID and strings iteration Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 03/11] libbpf: rename internal memory-management helpers Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 04/11] libbpf: extract internal set-of-strings datastructure APIs Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 05/11] libbpf: add generic BTF type shallow copy API Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 06/11] libbpf: add BPF static linker APIs Andrii Nakryiko
2021-06-07 23:11 ` Tom Stellard
2021-06-08 0:25 ` Andrii Nakryiko
[not found] ` <b1bdf1df-e3a8-1ce8-fc33-4ab40b39fb06@redhat.com>
2021-06-08 2:41 ` Tom Stellard
2021-06-08 4:08 ` Andrii Nakryiko
2021-06-08 6:47 ` Yonghong Song
2021-06-09 3:44 ` Tom Stellard
2021-06-09 4:41 ` Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 07/11] libbpf: add BPF static linker BTF and BTF.ext support Andrii Nakryiko
2021-03-17 5:25 ` Alexei Starovoitov
2021-03-17 22:10 ` Andrii Nakryiko [this message]
2021-03-13 19:35 ` [PATCH v2 bpf-next 08/11] bpftool: add `gen object` command to perform BPF static linking Andrii Nakryiko
2021-03-15 9:24 ` Quentin Monnet
2021-03-16 5:16 ` Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 09/11] selftests/bpf: re-generate vmlinux.h and BPF skeletons if bpftool changed Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 10/11] selftests/bpf: pass all BPF .o's through BPF static linker Andrii Nakryiko
2021-03-17 5:34 ` Alexei Starovoitov
2021-03-17 20:47 ` Andrii Nakryiko
2021-03-17 21:00 ` Alexei Starovoitov
2021-03-17 21:22 ` Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 11/11] selftests/bpf: add multi-file statically linked BPF object file test Andrii Nakryiko
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