From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
<daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH v2 bpf-next 3/6] libbpf: support static map definitions
Date: Fri, 23 Apr 2021 11:53:54 -0700 [thread overview]
Message-ID: <20210423185357.1992756-4-andrii@kernel.org> (raw)
In-Reply-To: <20210423185357.1992756-1-andrii@kernel.org>
Change libbpf relocation logic to support references to static map
definitions. This allows to use static maps and, combined with static linking,
hide internal maps from other files, just like static variables. User-space
will still be able to look up and modify static maps.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/libbpf.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a1cddd17af7d..6c755c5f037d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3633,6 +3633,8 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
/* generic map reference relocation */
if (type == LIBBPF_MAP_UNSPEC) {
+ size_t map_offset = sym->st_value + insn->imm;
+
if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
@@ -3642,7 +3644,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
map = &obj->maps[map_idx];
if (map->libbpf_type != type ||
map->sec_idx != sym->st_shndx ||
- map->sec_offset != sym->st_value)
+ map->sec_offset != map_offset)
continue;
pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
prog->name, map_idx, map->name, map->sec_idx,
@@ -3657,7 +3659,8 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
reloc_desc->type = RELO_LD64;
reloc_desc->insn_idx = insn_idx;
reloc_desc->map_idx = map_idx;
- reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
+ /* sym->st_value + insn->imm determines map_idx */
+ reloc_desc->sym_off = 0;
return 0;
}
--
2.30.2
next prev parent reply other threads:[~2021-04-23 18:54 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 18:53 [PATCH v2 bpf-next 0/6] BPF static linker: support static vars and maps Andrii Nakryiko
2021-04-23 18:53 ` [PATCH v2 bpf-next 1/6] bpftool: strip const/volatile/restrict modifiers from .bss and .data vars Andrii Nakryiko
2021-04-23 20:02 ` Yonghong Song
2021-04-23 18:53 ` [PATCH v2 bpf-next 2/6] libbpf: rename static variables during linking Andrii Nakryiko
2021-04-23 20:24 ` Yonghong Song
2021-04-23 21:38 ` Andrii Nakryiko
2021-04-23 21:56 ` Yonghong Song
2021-04-23 23:05 ` Alexei Starovoitov
2021-04-23 23:26 ` Yonghong Song
2021-04-23 23:35 ` Alexei Starovoitov
2021-04-23 23:35 ` Andrii Nakryiko
2021-04-23 23:48 ` Alexei Starovoitov
2021-04-24 0:13 ` Andrii Nakryiko
2021-04-24 0:22 ` Alexei Starovoitov
2021-04-26 15:44 ` Andrii Nakryiko
2021-04-26 22:34 ` Alexei Starovoitov
2021-04-26 23:11 ` Andrii Nakryiko
2021-04-27 2:22 ` Alexei Starovoitov
2021-04-27 21:27 ` Andrii Nakryiko
2021-04-28 4:55 ` Alexei Starovoitov
2021-04-28 19:33 ` Andrii Nakryiko
2021-05-04 4:42 ` bpf libraries and static variables. Was: " Alexei Starovoitov
2021-05-05 5:22 ` Alexei Starovoitov
2021-05-06 22:54 ` Daniel Borkmann
2021-05-11 17:57 ` Andrii Nakryiko
2021-05-11 18:05 ` Andrii Nakryiko
2021-05-11 14:20 ` Lorenz Bauer
2021-05-11 18:04 ` Andrii Nakryiko
2021-05-11 18:59 ` Andrii Nakryiko
2021-05-11 23:05 ` Alexei Starovoitov
2021-05-12 13:40 ` Lorenz Bauer
2021-05-12 18:50 ` Andrii Nakryiko
2021-05-12 23:39 ` Alexei Starovoitov
2021-05-13 8:37 ` Lorenz Bauer
2021-05-13 15:41 ` Alexei Starovoitov
2021-04-24 2:36 ` Yonghong Song
2021-04-26 15:45 ` Andrii Nakryiko
2021-04-26 16:34 ` Yonghong Song
2021-04-23 18:53 ` Andrii Nakryiko [this message]
2021-04-23 20:25 ` [PATCH v2 bpf-next 3/6] libbpf: support static map definitions Yonghong Song
2021-04-23 18:53 ` [PATCH v2 bpf-next 4/6] bpftool: handle transformed static map names in BPF skeleton Andrii Nakryiko
2021-04-23 22:59 ` Yonghong Song
2021-04-23 18:53 ` [PATCH v2 bpf-next 5/6] selftests/bpf: extend linked_vars selftests with static variables Andrii Nakryiko
2021-04-23 23:03 ` Yonghong Song
2021-04-23 23:03 ` Yonghong Song
2021-04-23 18:53 ` [PATCH v2 bpf-next 6/6] selftests/bpf: extend linked_maps selftests with static maps Andrii Nakryiko
2021-04-23 23:11 ` Yonghong Song
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