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edb79903 |
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23-Jan-2024 |
Jose E. Marchesi <jose.marchesi@oracle.com> |
bpf: avoid VLAs in progs/test_xdp_dynptr.c VLAs are not supported by either the BPF port of clang nor GCC. The selftest test_xdp_dynptr.c contains the following code: const size_t tcphdr_sz = sizeof(struct tcphdr); const size_t udphdr_sz = sizeof(struct udphdr); const size_t ethhdr_sz = sizeof(struct ethhdr); const size_t iphdr_sz = sizeof(struct iphdr); const size_t ipv6hdr_sz = sizeof(struct ipv6hdr); [...] static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr) { __u8 eth_buffer[ethhdr_sz + iphdr_sz + ethhdr_sz]; __u8 iph_buffer_tcp[iphdr_sz + tcphdr_sz]; __u8 iph_buffer_udp[iphdr_sz + udphdr_sz]; [...] } The eth_buffer, iph_buffer_tcp and other automatics are fixed size only if the compiler optimizes away the constant global variables. clang does this, but GCC does not, turning these automatics into variable length arrays. This patch removes the global variables and turns these values into preprocessor constants. This makes the selftest to build properly with GCC. Tested in bpf-next master. No regressions. Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com> Cc: Yonghong Song <yhs@meta.com> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: david.faust@oracle.com Cc: cupertino.miranda@oracle.com Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240123201729.16173-1-jose.marchesi@oracle.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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12852f8e |
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16-May-2023 |
Yonghong Song <yhs@fb.com> |
selftests/bpf: Fix dynptr/test_dynptr_is_null With latest llvm17, dynptr/test_dynptr_is_null subtest failed in my testing VM. The failure log looks like below: All error logs: tester_init:PASS:tester_log_buf 0 nsec process_subtest:PASS:obj_open_mem 0 nsec process_subtest:PASS:Can't alloc specs array 0 nsec verify_success:PASS:dynptr_success__open 0 nsec verify_success:PASS:bpf_object__find_program_by_name 0 nsec verify_success:PASS:dynptr_success__load 0 nsec verify_success:PASS:bpf_program__attach 0 nsec verify_success:FAIL:err unexpected err: actual 4 != expected 0 #65/9 dynptr/test_dynptr_is_null:FAIL The error happens for bpf prog test_dynptr_is_null in dynptr_success.c: if (bpf_dynptr_is_null(&ptr2)) { err = 4; goto exit; } The bpf_dynptr_is_null(&ptr) unexpectedly returned a non-zero value and the control went to the error path. Digging further, I found the root cause is due to function signature difference between kernel and user space. In kernel, we have ... __bpf_kfunc bool bpf_dynptr_is_null(struct bpf_dynptr_kern *ptr) ... while in bpf_kfuncs.h we have: extern int bpf_dynptr_is_null(const struct bpf_dynptr *ptr) __ksym; The kernel bpf_dynptr_is_null disasm code: ffffffff812f1a90 <bpf_dynptr_is_null>: ffffffff812f1a90: f3 0f 1e fa endbr64 ffffffff812f1a94: 0f 1f 44 00 00 nopl (%rax,%rax) ffffffff812f1a99: 53 pushq %rbx ffffffff812f1a9a: 48 89 fb movq %rdi, %rbx ffffffff812f1a9d: e8 ae 29 17 00 callq 0xffffffff81464450 <__asan_load8_noabort> ffffffff812f1aa2: 48 83 3b 00 cmpq $0x0, (%rbx) ffffffff812f1aa6: 0f 94 c0 sete %al ffffffff812f1aa9: 5b popq %rbx ffffffff812f1aaa: c3 retq Note that only 1-byte register %al is set and the other 7-bytes are not touched. In bpf program, the asm code for the above bpf_dynptr_is_null(&ptr2): 266: 85 10 00 00 ff ff ff ff call -0x1 267: b4 01 00 00 04 00 00 00 w1 = 0x4 268: 16 00 03 00 00 00 00 00 if w0 == 0x0 goto +0x3 <LBB9_8> Basically, 4-byte subregister is tested. This might cause error as the value other than the lowest byte might not be 0. This patch fixed the issue by using the identical func prototype across kernel and selftest user space. The fixed bpf asm code: 267: 85 10 00 00 ff ff ff ff call -0x1 268: 54 00 00 00 01 00 00 00 w0 &= 0x1 269: b4 01 00 00 04 00 00 00 w1 = 0x4 270: 16 00 03 00 00 00 00 00 if w0 == 0x0 goto +0x3 <LBB9_8> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20230517040404.4023912-1-yhs@fb.com
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c8ed6685 |
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08-Mar-2023 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: fix lots of silly mistakes pointed out by compiler Once we enable -Wall for BPF sources, compiler will complain about lots of unused variables, variables that are set but never read, etc. Fix all these issues first before enabling -Wall in Makefile. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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cfa7b011 |
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01-Mar-2023 |
Joanne Koong <joannelkoong@gmail.com> |
selftests/bpf: tests for using dynptrs to parse skb and xdp buffers Test skb and xdp dynptr functionality in the following ways: 1) progs/test_cls_redirect_dynptr.c * Rewrite "progs/test_cls_redirect.c" test to use dynptrs to parse skb data * This is a great example of how dynptrs can be used to simplify a lot of the parsing logic for non-statically known values. When measuring the user + system time between the original version vs. using dynptrs, and averaging the time for 10 runs (using "time ./test_progs -t cls_redirect"): original version: 0.092 sec with dynptrs: 0.078 sec 2) progs/test_xdp_dynptr.c * Rewrite "progs/test_xdp.c" test to use dynptrs to parse xdp data When measuring the user + system time between the original version vs. using dynptrs, and averaging the time for 10 runs (using "time ./test_progs -t xdp_attach"): original version: 0.118 sec with dynptrs: 0.094 sec 3) progs/test_l4lb_noinline_dynptr.c * Rewrite "progs/test_l4lb_noinline.c" test to use dynptrs to parse skb data When measuring the user + system time between the original version vs. using dynptrs, and averaging the time for 10 runs (using "time ./test_progs -t l4lb_all"): original version: 0.062 sec with dynptrs: 0.081 sec For number of processed verifier instructions: original version: 6268 insns with dynptrs: 2588 insns 4) progs/test_parse_tcp_hdr_opt_dynptr.c * Add sample code for parsing tcp hdr opt lookup using dynptrs. This logic is lifted from a real-world use case of packet parsing in katran [0], a layer 4 load balancer. The original version "progs/test_parse_tcp_hdr_opt.c" (not using dynptrs) is included here as well, for comparison. When measuring the user + system time between the original version vs. using dynptrs, and averaging the time for 10 runs (using "time ./test_progs -t parse_tcp_hdr_opt"): original version: 0.031 sec with dynptrs: 0.045 sec 5) progs/dynptr_success.c * Add test case "test_skb_readonly" for testing attempts at writes on a prog type with read-only skb ctx. * Add "test_dynptr_skb_data" for testing that bpf_dynptr_data isn't supported for skb progs. 6) progs/dynptr_fail.c * Add test cases "skb_invalid_data_slice{1,2,3,4}" and "xdp_invalid_data_slice{1,2}" for testing that helpers that modify the underlying packet buffer automatically invalidate the associated data slice. * Add test cases "skb_invalid_ctx" and "xdp_invalid_ctx" for testing that prog types that do not support bpf_dynptr_from_skb/xdp don't have access to the API. * Add test case "dynptr_slice_var_len{1,2}" for testing that variable-sized len can't be passed in to bpf_dynptr_slice * Add test case "skb_invalid_slice_write" for testing that writes to a read-only data slice are rejected by the verifier. * Add test case "data_slice_out_of_bounds_skb" for testing that writes to an area outside the slice are rejected. * Add test case "invalid_slice_rdwr_rdonly" for testing that prog types that don't allow writes to packet data don't accept any calls to bpf_dynptr_slice_rdwr. [0] https://github.com/facebookincubator/katran/blob/main/katran/lib/bpf/pckt_parsing.h Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230301154953.641654-11-joannelkoong@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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