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libbpf: Fix BTF-defined map-in-map initialization on 32-bit host arches

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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: 646f02ffdd ("libbpf: Add BTF-defined map-in-map support")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200813204945.1020225-4-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-08-13 13:49:39 -07:00 committed by Alexei Starovoitov
parent 9028bbcc3e
commit 15728ad3e7
1 changed files with 10 additions and 6 deletions
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16
tools/lib/bpf/libbpf.c
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@ -5195,7 +5195,8 @@ 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;
@ -5244,7 +5245,7 @@ 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) {
@ -5280,17 +5281,20 @@ 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;