linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2020-01-20	selftests: Use consistent include paths for libbpf	Toke Høiland-Jørgensen	1	-1/+1
	Fix all selftests to include libbpf header files with the bpf/ prefix, to be consistent with external users of the library. Also ensure that all includes of exported libbpf header files (those that are exported on 'make install' of the library) use bracketed includes instead of quoted. To not break the build, keep the old include path until everything has been changed to the new one; a subsequent patch will remove that. Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/157952560568.1683545.9649335788846513446.stgit@toke.dk
2019-11-19	libbpf: Fix call relocation offset calculation bug	Andrii Nakryiko	1	-2/+2
	When relocating subprogram call, libbpf doesn't take into account relo->text_off, which comes from symbol's value. This generally works fine for subprograms implemented as static functions, but breaks for global functions. Taking a simplified test_pkt_access.c as an example: __attribute__ ((noinline)) static int test_pkt_access_subprog1(volatile struct __sk_buff skb) { return skb->len 2; } __attribute__ ((noinline)) static int test_pkt_access_subprog2(int val, volatile struct __sk_buff skb) { return skb->len + val; } SEC("classifier/test_pkt_access") int test_pkt_access(struct __sk_buff skb) { if (test_pkt_access_subprog1(skb) != skb->len * 2) return TC_ACT_SHOT; if (test_pkt_access_subprog2(2, skb) != skb->len + 2) return TC_ACT_SHOT; return TC_ACT_UNSPEC; } When compiled, we get two relocations, pointing to '.text' symbol. .text has st_value set to 0 (it points to the beginning of .text section): 0000000000000008 000000050000000a R_BPF_64_32 0000000000000000 .text 0000000000000040 000000050000000a R_BPF_64_32 0000000000000000 .text test_pkt_access_subprog1 and test_pkt_access_subprog2 offsets (targets of two calls) are encoded within call instruction's imm32 part as -1 and 2, respectively: 0000000000000000 test_pkt_access_subprog1: 0: 61 10 00 00 00 00 00 00 r0 = (u32 )(r1 + 0) 1: 64 00 00 00 01 00 00 00 w0 <<= 1 2: 95 00 00 00 00 00 00 00 exit 0000000000000018 test_pkt_access_subprog2: 3: 61 10 00 00 00 00 00 00 r0 = (u32 )(r1 + 0) 4: 04 00 00 00 02 00 00 00 w0 += 2 5: 95 00 00 00 00 00 00 00 exit 0000000000000000 test_pkt_access: 0: bf 16 00 00 00 00 00 00 r6 = r1 ===> 1: 85 10 00 00 ff ff ff ff call -1 2: bc 01 00 00 00 00 00 00 w1 = w0 3: b4 00 00 00 02 00 00 00 w0 = 2 4: 61 62 00 00 00 00 00 00 r2 = (u32 )(r6 + 0) 5: 64 02 00 00 01 00 00 00 w2 <<= 1 6: 5e 21 08 00 00 00 00 00 if w1 != w2 goto +8 <LBB0_3> 7: bf 61 00 00 00 00 00 00 r1 = r6 ===> 8: 85 10 00 00 02 00 00 00 call 2 9: bc 01 00 00 00 00 00 00 w1 = w0 10: 61 62 00 00 00 00 00 00 r2 = (u32 )(r6 + 0) 11: 04 02 00 00 02 00 00 00 w2 += 2 12: b4 00 00 00 ff ff ff ff w0 = -1 13: 1e 21 01 00 00 00 00 00 if w1 == w2 goto +1 <LBB0_3> 14: b4 00 00 00 02 00 00 00 w0 = 2 0000000000000078 LBB0_3: 15: 95 00 00 00 00 00 00 00 exit Now, if we compile example with global functions, the setup changes. Relocations are now against specifically test_pkt_access_subprog1 and test_pkt_access_subprog2 symbols, with test_pkt_access_subprog2 pointing 24 bytes into its respective section (.text), i.e., 3 instructions in: 0000000000000008 000000070000000a R_BPF_64_32 0000000000000000 test_pkt_access_subprog1 0000000000000048 000000080000000a R_BPF_64_32 0000000000000018 test_pkt_access_subprog2 Calls instructions now encode offsets relative to function symbols and are both set ot -1: 0000000000000000 test_pkt_access_subprog1: 0: 61 10 00 00 00 00 00 00 r0 = (u32 )(r1 + 0) 1: 64 00 00 00 01 00 00 00 w0 <<= 1 2: 95 00 00 00 00 00 00 00 exit 0000000000000018 test_pkt_access_subprog2: 3: 61 20 00 00 00 00 00 00 r0 = (u32 )(r2 + 0) 4: 0c 10 00 00 00 00 00 00 w0 += w1 5: 95 00 00 00 00 00 00 00 exit 0000000000000000 test_pkt_access: 0: bf 16 00 00 00 00 00 00 r6 = r1 ===> 1: 85 10 00 00 ff ff ff ff call -1 2: bc 01 00 00 00 00 00 00 w1 = w0 3: b4 00 00 00 02 00 00 00 w0 = 2 4: 61 62 00 00 00 00 00 00 r2 = (u32 )(r6 + 0) 5: 64 02 00 00 01 00 00 00 w2 <<= 1 6: 5e 21 09 00 00 00 00 00 if w1 != w2 goto +9 <LBB2_3> 7: b4 01 00 00 02 00 00 00 w1 = 2 8: bf 62 00 00 00 00 00 00 r2 = r6 ===> 9: 85 10 00 00 ff ff ff ff call -1 10: bc 01 00 00 00 00 00 00 w1 = w0 11: 61 62 00 00 00 00 00 00 r2 = (u32 )(r6 + 0) 12: 04 02 00 00 02 00 00 00 w2 += 2 13: b4 00 00 00 ff ff ff ff w0 = -1 14: 1e 21 01 00 00 00 00 00 if w1 == w2 goto +1 <LBB2_3> 15: b4 00 00 00 02 00 00 00 w0 = 2 0000000000000080 LBB2_3: 16: 95 00 00 00 00 00 00 00 exit Thus the right formula to calculate target call offset after relocation should take into account relocation's target symbol value (offset within section), call instruction's imm32 offset, and (subtracting, to get relative instruction offset) instruction index of call instruction itself. All that is shifted by number of instructions in main program, given all sub-programs are copied over after main program. Convert few selftests relying on bpf-to-bpf calls to use global functions instead of static ones. Fixes: 48cca7e44f9f ("libbpf: add support for bpf_call") Reported-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191119224447.3781271-1-andriin@fb.com
2019-10-08	selftests/bpf: samples/bpf: Split off legacy stuff from bpf_helpers.h	Andrii Nakryiko	1	-0/+1
	Split off few legacy things from bpf_helpers.h into separate bpf_legacy.h file: - load_{byte\|half\|word}; - remove extra inner_idx and numa_node fields from bpf_map_def and introduce bpf_map_def_legacy for use in samples; - move BPF_ANNOTATE_KV_PAIR into bpf_legacy.h. Adjust samples and selftests accordingly by either including bpf_legacy.h and using bpf_map_def_legacy, or switching to BTF-defined maps altogether. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20191008175942.1769476-3-andriin@fb.com
2019-02-11	selftests: bpf: centre kernel bpf objects under new subdir "progs"	Jiong Wang	1	-0/+57
	At the moment, all kernel bpf objects are listed under BPF_OBJ_FILES. Listing them manually sometimes causing patch conflict when people are adding new testcases simultaneously. It is better to centre all the related source files under a subdir "progs", then auto-generate the object file list. Suggested-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>