From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH v3 bpf 3/9] libbpf: fix BTF-defined map-in-map initialization on 32-bit host arches
Date: Thu, 13 Aug 2020 13:49:39 -0700 [thread overview]
Message-ID: <20200813204945.1020225-4-andriin@fb.com> (raw)
In-Reply-To: <20200813204945.1020225-1-andriin@fb.com>
Libbpf built in 32-bit mode should be careful about not conflating 64-bit BPF
pointers in BPF ELF file and host architecture pointers. This patch fixes
issue of incorrect initializating of map-in-map inner map slots due to such
difference.
Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/lib/bpf/libbpf.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0a06124f7999..4a8524b2dda1 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5194,7 +5194,8 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
static int bpf_object__collect_map_relos(struct bpf_object *obj,
GElf_Shdr *shdr, Elf_Data *data)
{
- int i, j, nrels, new_sz, ptr_sz = sizeof(void *);
+ const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
+ int i, j, nrels, new_sz;
const struct btf_var_secinfo *vi = NULL;
const struct btf_type *sec, *var, *def;
const struct btf_member *member;
@@ -5243,7 +5244,7 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
vi = btf_var_secinfos(sec) + map->btf_var_idx;
if (vi->offset <= rel.r_offset &&
- rel.r_offset + sizeof(void *) <= vi->offset + vi->size)
+ rel.r_offset + bpf_ptr_sz <= vi->offset + vi->size)
break;
}
if (j == obj->nr_maps) {
@@ -5279,17 +5280,20 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
return -EINVAL;
moff = rel.r_offset - vi->offset - moff;
- if (moff % ptr_sz)
+ /* here we use BPF pointer size, which is always 64 bit, as we
+ * are parsing ELF that was built for BPF target
+ */
+ if (moff % bpf_ptr_sz)
return -EINVAL;
- moff /= ptr_sz;
+ moff /= bpf_ptr_sz;
if (moff >= map->init_slots_sz) {
new_sz = moff + 1;
- tmp = realloc(map->init_slots, new_sz * ptr_sz);
+ tmp = realloc(map->init_slots, new_sz * host_ptr_sz);
if (!tmp)
return -ENOMEM;
map->init_slots = tmp;
memset(map->init_slots + map->init_slots_sz, 0,
- (new_sz - map->init_slots_sz) * ptr_sz);
+ (new_sz - map->init_slots_sz) * host_ptr_sz);
map->init_slots_sz = new_sz;
}
map->init_slots[moff] = targ_map;
--
2.24.1
next prev parent reply other threads:[~2020-08-13 20:50 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 20:49 [PATCH v3 bpf 0/9] Fix various issues with 32-bit libbpf Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 1/9] tools/bpftool: fix compilation warnings in 32-bit mode Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 2/9] selftest/bpf: " Andrii Nakryiko
2020-08-13 20:49 ` Andrii Nakryiko [this message]
2020-08-13 20:49 ` [PATCH v3 bpf 4/9] libbpf: handle BTF pointer sizes more carefully Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 5/9] selftests/bpf: fix btf_dump test cases on 32-bit arches Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 6/9] libbpf: enforce 64-bitness of BTF for BPF object files Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 7/9] selftests/bpf: correct various core_reloc 64-bit assumptions Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 8/9] tools/bpftool: generate data section struct with conservative alignment Andrii Nakryiko
2020-08-13 20:49 ` [PATCH v3 bpf 9/9] selftests/bpf: make test_varlen work with 32-bit user-space arch Andrii Nakryiko
2020-08-14 0:08 ` [PATCH v3 bpf 0/9] Fix various issues with 32-bit libbpf Alexei Starovoitov
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