BPF example with ktrace and CO-RE #24
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Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Using bpf_core_type_id_kernel to find kernels BTF_ID for SKB. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Use this --debug to better understand what libbpf does of CO-RE relocation tricks and lookup of BTF-IDs. Example output: [...] libbpf: loading kernel BTF '/sys/kernel/btf/vmlinux': 0 libbpf: map 'ktrace01.data': created successfully, fd=4 libbpf: sec 'kprobe/udp_send_skb': found 4 CO-RE relocations libbpf: prog 'udp_send_skb': relo #0: kind <byte_off> (0), spec is [2] struct pt_regs.di (0:14 @ offset 112) libbpf: CO-RE relocating [0] struct pt_regs: found target candidate [176] struct pt_regs in [vmlinux] libbpf: prog 'udp_send_skb': relo #0: matching candidate #0 [176] struct pt_regs.di (0:14 @ offset 112) libbpf: prog 'udp_send_skb': relo #0: patched insn #0 (LDX/ST/STX) off 112 -> 112 libbpf: prog 'udp_send_skb': relo xdp-project#1: kind <byte_off> (0), spec is [7] struct sk_buff___local.hash (0:1 @ offset 4) libbpf: CO-RE relocating [0] struct sk_buff___local: found target candidate [2965] struct sk_buff in [vmlinux] [...] Notice how the BTF-ID of 'struct sk_buff' is resolved to be 2965. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
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Going to merge this as I need to reference some of the commits in emails. |
netoptimizer
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Aug 25, 2021
Fixes pull request #24 I had forgot to git add headers/vmlinux/vmlinux_arch.h in PR#24 which caused compile failures for ktrace-CO-RE. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
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"Learning by doing":
I had to change the Makefile system to handle
SEC("kprobe")and macroBPF_KPROBEas compiling with-target bpfresult inPT_REGS_PARM1not being defined. Asinclude <bpf/bpf_tracing.h>cannot determine the ARCH from compiler defines.To solve this detect the
ARCHour makefile system in file lib/common.mk (viauname -m) and defines the__TARGET_ARCH_$(ARCH)inBPF_CFLAGS.This PR also contains some
vmlinux.hheader variants for a number of ARCHs.Choose to splitup
vmlinux_*.hheaders and only include what was needed for this example.We will see how much maintenance this cause, and if this is the case we can consider adding the full
vmlinux.hlater.