Commit bc380eb9 authored Mar 16, 2022 by Delyan Kratunov Committed by Andrii Nakryiko Mar 17, 2022

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

parent 5a5c11ee

tools/lib/bpf/libbpf.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}

tools/lib/bpf/libbpf_legacy.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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,
		/*