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495d2d81 |
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26-Dec-2023 |
Alexei Starovoitov <ast@kernel.org> |
selftests/bpf: Attempt to build BPF programs with -Wsign-compare GCC's -Wall includes -Wsign-compare while clang does not. Since BPF programs are built with clang we need to add this flag explicitly to catch problematic comparisons like: int i = -1; unsigned int j = 1; if (i < j) // this is false. long i = -1; unsigned int j = 1; if (i < j) // this is true. C standard for reference: - If either operand is unsigned long the other shall be converted to unsigned long. - Otherwise, if one operand is a long int and the other unsigned int, then if a long int can represent all the values of an unsigned int, the unsigned int shall be converted to a long int; otherwise both operands shall be converted to unsigned long int. - Otherwise, if either operand is long, the other shall be converted to long. - Otherwise, if either operand is unsigned, the other shall be converted to unsigned. Unfortunately clang's -Wsign-compare is very noisy. It complains about (s32)a == (u32)b which is safe and doen't have surprising behavior. This patch fixes some of the issues. It needs a follow up to fix the rest. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/bpf/20231226191148.48536-2-alexei.starovoitov@gmail.com
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5640b6d8 |
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16-Mar-2023 |
Alexander Lobakin <aleksander.lobakin@intel.com> |
selftests/bpf: fix "metadata marker" getting overwritten by the netstack Alexei noticed xdp_do_redirect test on BPF CI started failing on BE systems after skb PP recycling was enabled: test_xdp_do_redirect:PASS:prog_run 0 nsec test_xdp_do_redirect:PASS:pkt_count_xdp 0 nsec test_xdp_do_redirect:PASS:pkt_count_zero 0 nsec test_xdp_do_redirect:FAIL:pkt_count_tc unexpected pkt_count_tc: actual 220 != expected 9998 test_max_pkt_size:PASS:prog_run_max_size 0 nsec test_max_pkt_size:PASS:prog_run_too_big 0 nsec close_netns:PASS:setns 0 nsec #289 xdp_do_redirect:FAIL Summary: 270/1674 PASSED, 30 SKIPPED, 1 FAILED and it doesn't happen on LE systems. Ilya then hunted it down to: #0 0x0000000000aaeee6 in neigh_hh_output (hh=0x83258df0, skb=0x88142200) at linux/include/net/neighbour.h:503 #1 0x0000000000ab2cda in neigh_output (skip_cache=false, skb=0x88142200, n=<optimized out>) at linux/include/net/neighbour.h:544 #2 ip6_finish_output2 (net=net@entry=0x88edba00, sk=sk@entry=0x0, skb=skb@entry=0x88142200) at linux/net/ipv6/ip6_output.c:134 #3 0x0000000000ab4cbc in __ip6_finish_output (skb=0x88142200, sk=0x0, net=0x88edba00) at linux/net/ipv6/ip6_output.c:195 #4 ip6_finish_output (net=0x88edba00, sk=0x0, skb=0x88142200) at linux/net/ipv6/ip6_output.c:206 xdp_do_redirect test places a u32 marker (0x42) right before the Ethernet header to check it then in the XDP program and return %XDP_ABORTED if it's not there. Neigh xmit code likes to round up hard header length to speed up copying the header, so it overwrites two bytes in front of the Eth header. On LE systems, 0x42 is one byte at `data - 4`, while on BE it's `data - 1`, what explains why it happens only there. It didn't happen previously due to that %XDP_PASS meant the page will be discarded and replaced by a new one, but now it can be recycled as well, while bpf_test_run code doesn't reinitialize the content of recycled pages. This mark is limited to this particular test and its setup though, so there's no need to predict 1000 different possible cases. Just move it 4 bytes to the left, still keeping it 32 bit to match on more bytes. Fixes: 9c94bbf9a87b ("xdp: recycle Page Pool backed skbs built from XDP frames") Reported-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/CAADnVQ+B_JOU+EpP=DKhbY9yXdN6GiRPnpTTXfEZ9sNkUeb-yQ@mail.gmail.com Reported-by: Ilya Leoshkevich <iii@linux.ibm.com> # + debugging Link: https://lore.kernel.org/bpf/8341c1d9f935f410438e79d3bd8a9cc50aefe105.camel@linux.ibm.com Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> Link: https://lore.kernel.org/r/20230316175051.922550-3-aleksander.lobakin@intel.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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487deb3e |
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13-Mar-2023 |
Alexander Lobakin <aleksander.lobakin@intel.com> |
selftests/bpf: robustify test_xdp_do_redirect with more payload magics Currently, the test relies on that only dropped ("xmitted") frames will be recycled and if a frame became an skb, it will be freed later by the stack and never come back to its page_pool. So, it easily gets broken by trying to recycle skbs[0]: test_xdp_do_redirect:PASS:pkt_count_xdp 0 nsec test_xdp_do_redirect:FAIL:pkt_count_zero unexpected pkt_count_zero: actual 9936 != expected 2 test_xdp_do_redirect:PASS:pkt_count_tc 0 nsec That huge mismatch happened because after the TC ingress hook zeroes the magic, the page gets recycled when skb is freed, not returned to the MM layer. "Live frames" mode initializes only new pages and keeps the recycled ones as is by design, so they appear with zeroed magic on the Rx path again. Expand the possible magic values from two: 0 (was "xmitted"/dropped or did hit the TC hook) and 0x42 (hit the input XDP prog) to three: the new one will mark frames hit the TC hook, so that they will elide both @pkt_count_zero and @pkt_count_xdp. They can then be recycled to their page_pool or returned to the page allocator, this won't affect the counters anyhow. Just make sure to mark them as "input" (0x42) when they appear on the Rx path again. Also make an enum from those magics, so that they will be always visible and can be changed in just one place anytime. This also eases adding any new marks later on. Link: https://github.com/kernel-patches/bpf/actions/runs/4386538411/jobs/7681081789 Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> Link: https://lore.kernel.org/r/20230313215553.1045175-2-aleksander.lobakin@intel.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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55fcacca |
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09-Mar-2022 |
Toke Høiland-Jørgensen <toke@redhat.com> |
selftests/bpf: Add selftest for XDP_REDIRECT in BPF_PROG_RUN This adds a selftest for the XDP_REDIRECT facility in BPF_PROG_RUN, that redirects packets into a veth and counts them using an XDP program on the other side of the veth pair and a TC program on the local side of the veth. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20220309105346.100053-6-toke@redhat.com
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