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libbpf: .text routines are subprograms in strict mode 

Currently, libbpf considers a single routine in .text to be a program. This
is particularly confusing when it comes to library objects - a single routine
meant to be used as an extern will instead be considered a bpf_program.

This patch hides this compatibility behavior behind the pre-existing
SEC_NAME strict mode flag.

Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/018de8d0d67c04bf436055270d35d394ba393505.1647473511.git.delyank@fb.com
This commit is contained in:
Delyan Kratunov 2022-03-16 23:37:24 +00:00 committed by Andrii Nakryiko
parent 5a5c11ee3e
commit bc380eb9d0
2 changed files with 11 additions and 0 deletions
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7
tools/lib/bpf/libbpf.c
View File

@ -3832,7 +3832,14 @@ static bool prog_is_subprog(const struct bpf_object *obj,
* .text programs are subprograms (even if they are not called from
* other programs), because libbpf never explicitly supported mixing
* SEC()-designated BPF programs and .text entry-point BPF programs.
*
* In libbpf 1.0 strict mode, we always consider .text
* programs to be subprograms.
*/
if (libbpf_mode & LIBBPF_STRICT_SEC_NAME)
return prog->sec_idx == obj->efile.text_shndx;
return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1;
}

4
tools/lib/bpf/libbpf_legacy.h
View File

@ -54,6 +54,10 @@ enum libbpf_strict_mode {
*
* Note, in this mode the program pin path will be based on the
* function name instead of section name.
*
* Additionally, routines in the .text section are always considered
* sub-programs. Legacy behavior allows for a single routine in .text
* to be a program.
*/
LIBBPF_STRICT_SEC_NAME = 0x04,
/*