* [PATCH bpf-next] libbpf: avoid mmap for size 0 sections
@ 2022-07-27 20:48 David Faust
2022-07-28 14:15 ` Jiri Olsa
0 siblings, 1 reply; 3+ messages in thread
From: David Faust @ 2022-07-27 20:48 UTC (permalink / raw)
To: bpf; +Cc: david.faust
When populating maps in bpf_object__init_global_data_maps(), recognized
sections with no data (e.g. a .bss with size 0) lead to an mmap of 0
bytes which fails with EINVAL.
Add a check to skip mapping sections which are present, but empty.
Signed-off-by: David Faust <david.faust@oracle.com>
---
tools/lib/bpf/libbpf.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b01fe01b0761..4e7ceb4f5a27 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
sec_desc = &obj->efile.secs[sec_idx];
+ /* Skip recognized sections with size 0. */
+ if (sec_desc->data && sec_desc->data->d_size == 0)
+ continue;
+
switch (sec_desc->sec_type) {
case SEC_DATA:
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
--
2.36.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] libbpf: avoid mmap for size 0 sections
2022-07-27 20:48 [PATCH bpf-next] libbpf: avoid mmap for size 0 sections David Faust
@ 2022-07-28 14:15 ` Jiri Olsa
2022-07-28 19:29 ` David Faust
0 siblings, 1 reply; 3+ messages in thread
From: Jiri Olsa @ 2022-07-28 14:15 UTC (permalink / raw)
To: David Faust; +Cc: bpf
On Wed, Jul 27, 2022 at 01:48:08PM -0700, David Faust wrote:
> When populating maps in bpf_object__init_global_data_maps(), recognized
> sections with no data (e.g. a .bss with size 0) lead to an mmap of 0
> bytes which fails with EINVAL.
>
> Add a check to skip mapping sections which are present, but empty.
>
> Signed-off-by: David Faust <david.faust@oracle.com>
> ---
> tools/lib/bpf/libbpf.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index b01fe01b0761..4e7ceb4f5a27 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
> for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
> sec_desc = &obj->efile.secs[sec_idx];
>
> + /* Skip recognized sections with size 0. */
> + if (sec_desc->data && sec_desc->data->d_size == 0)
> + continue;
nit missing tab indent
also we seem to check for size in bpf_object__elf_collect
before adding SEC_DATA/SEC_RODATA but not SEC_BSS
I think the check should be rather in bpf_object__elf_collect
before we add the desc for it
jirka
> +
> switch (sec_desc->sec_type) {
> case SEC_DATA:
> sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
> --
> 2.36.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] libbpf: avoid mmap for size 0 sections
2022-07-28 14:15 ` Jiri Olsa
@ 2022-07-28 19:29 ` David Faust
0 siblings, 0 replies; 3+ messages in thread
From: David Faust @ 2022-07-28 19:29 UTC (permalink / raw)
To: Jiri Olsa; +Cc: bpf
On 7/28/22 07:15, Jiri Olsa wrote:
> On Wed, Jul 27, 2022 at 01:48:08PM -0700, David Faust wrote:
>> When populating maps in bpf_object__init_global_data_maps(), recognized
>> sections with no data (e.g. a .bss with size 0) lead to an mmap of 0
>> bytes which fails with EINVAL.
>>
>> Add a check to skip mapping sections which are present, but empty.
>>
>> Signed-off-by: David Faust <david.faust@oracle.com>
>> ---
>> tools/lib/bpf/libbpf.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> index b01fe01b0761..4e7ceb4f5a27 100644
>> --- a/tools/lib/bpf/libbpf.c
>> +++ b/tools/lib/bpf/libbpf.c
>> @@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
>> for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
>> sec_desc = &obj->efile.secs[sec_idx];
>>
>> + /* Skip recognized sections with size 0. */
>> + if (sec_desc->data && sec_desc->data->d_size == 0)
>> + continue;
>
> nit missing tab indent
>
> also we seem to check for size in bpf_object__elf_collect
> before adding SEC_DATA/SEC_RODATA but not SEC_BSS
>
> I think the check should be rather in bpf_object__elf_collect
> before we add the desc for it
I see, thanks. Will send an updated patch.
David
>
> jirka
>
>> +
>> switch (sec_desc->sec_type) {
>> case SEC_DATA:
>> sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
>> --
>> 2.36.1
>>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-07-28 19:29 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-07-27 20:48 [PATCH bpf-next] libbpf: avoid mmap for size 0 sections David Faust
2022-07-28 14:15 ` Jiri Olsa
2022-07-28 19:29 ` David Faust
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).