On Tue, Jul 13, 2021 at 5:43 AM Shuyi Cheng <chengshuyi@xxxxxxxxxxxxxxxxx> wrote: > > This patch set adds the ability to point to a custom BTF for the > purposes of BPF CO-RE relocations. This is useful for using BPF CO-RE > on old kernels that don't yet natively support kernel (vmlinux) BTF > and thus libbpf needs application's help in locating kernel BTF > generated separately from the kernel itself. This was already possible > to do through bpf_object__load's attribute struct, but that makes it > inconvenient to use with BPF skeleton, which only allows to specify > bpf_object_open_opts during the open step. Thus, add the ability to > override vmlinux BTF at open time. > > Patch #1 adds libbpf changes. > Patch #2 fixes pre-existing memory leak detected during the code review. > Patch #3 switches existing selftests to using open_opts for custom BTF. > LGTM with some minor things I'll adjust while applying (which I'll point out in respective patches). So no need to re-send anything. Thanks. > Changelog: > ---------- > > v3: https://lore.kernel.org/bpf/CAEf4BzY2cdT44bfbMus=gei27ViqGE1BtGo6XrErSsOCnqtVJg@xxxxxxxxxxxxxx/T/#m877eed1d4cf0a1d3352d3f3d6c5ff158be45c542 > v3->v4: > --- Follow Andrii's suggestion to modify cover letter description. > --- Delete function bpf_object__load_override_btf. > --- Follow Dan's suggestion to add fixes tag and modify commit msg to patch #2. > --- Add pathch #3 to switch existing selftests to using open_opts. > > v2: https://lore.kernel.org/bpf/CAEf4Bza_ua+tjxdhyy4nZ8Boeo+scipWmr_1xM1pC6N5wyuhAA@xxxxxxxxxxxxxx/T/#mf9cf86ae0ffa96180ac29e4fd12697eb70eccd0f > v2->v3: > --- Load the BTF specified by btf_custom_path to btf_vmlinux_override > instead of btf_bmlinux. > --- Fix the memory leak that may be introduced by the second version > of the patch. > --- Add a new patch to fix the possible memory leak caused by > obj->kconfig. > > v1: https://lore.kernel.org/bpf/CAEf4BzaGjEC4t1OefDo11pj2-HfNy0BLhs_G2UREjRNTmb2u=A@xxxxxxxxxxxxxx/t/#m4d9f7c6761fbd2b436b5dfe491cd864b70225804 > v1->v2: > -- Change custom_btf_path to btf_custom_path. > -- If the length of btf_custom_path of bpf_obj_open_opts is too long, > return ERR_PTR(-ENAMETOOLONG). > -- Add `custom BTF is in addition to vmlinux BTF` > with btf_custom_path field. > > Shuyi Cheng (3): > libbpf: Introduce 'btf_custom_path' to 'bpf_obj_open_opts' > libbpf: Fix the possible memory leak on error > selftests/bpf: switches existing selftests to using open_opts for custom BTF > > tools/lib/bpf/libbpf.c | 42 +++++++++++++++++----- > tools/lib/bpf/libbpf.h | 9 ++++- > .../selftests/bpf/prog_tests/core_autosize.c | 22 ++++++------ > .../testing/selftests/bpf/prog_tests/core_reloc.c | 28 +++++++-------- > 4 files changed, 66 insertions(+), 35 deletions(-) > > -- > 1.8.3.1 >
