From bc380eb9d04812eda23fd1d2904389012b50d946 Mon Sep 17 00:00:00 2001 From: Delyan Kratunov Date: Wed, 16 Mar 2022 23:37:24 +0000 Subject: [PATCH] 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 Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/018de8d0d67c04bf436055270d35d394ba393505.1647473511.git.delyank@fb.com --- tools/lib/bpf/libbpf.c | 7 +++++++ tools/lib/bpf/libbpf_legacy.h | 4 ++++ 2 files changed, 11 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index f3a31478e23b..3b7eb6dcc2f4 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -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; } diff --git a/tools/lib/bpf/libbpf_legacy.h b/tools/lib/bpf/libbpf_legacy.h index a283cf031665..d7bcbd01f66f 100644 --- a/tools/lib/bpf/libbpf_legacy.h +++ b/tools/lib/bpf/libbpf_legacy.h @@ -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, /*