From d6f39601ec5e708fb666a2ad437c7bef4cfab39b Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 14 Nov 2019 10:57:20 -0800 Subject: selftests/bpf: Add a test for attaching BPF prog to another BPF prog and subprog Add a test that attaches one FEXIT program to main sched_cls networking program and two other FEXIT programs to subprograms. All three tracing programs access return values and skb->len of networking program and subprograms. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20191114185720.1641606-21-ast@kernel.org --- tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c | 91 +++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c (limited to 'tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c') diff --git a/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c new file mode 100644 index 000000000000..981f0474da5a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ +#include +#include "bpf_helpers.h" + +struct sk_buff { + unsigned int len; +}; + +struct args { + struct sk_buff *skb; + ks32 ret; +}; +static volatile __u64 test_result; +SEC("fexit/test_pkt_access") +int test_main(struct args *ctx) +{ + struct sk_buff *skb = ctx->skb; + int len; + + __builtin_preserve_access_index(({ + len = skb->len; + })); + if (len != 74 || ctx->ret != 0) + return 0; + test_result = 1; + return 0; +} + +struct args_subprog1 { + struct sk_buff *skb; + ks32 ret; +}; +static volatile __u64 test_result_subprog1; +SEC("fexit/test_pkt_access_subprog1") +int test_subprog1(struct args_subprog1 *ctx) +{ + struct sk_buff *skb = ctx->skb; + int len; + + __builtin_preserve_access_index(({ + len = skb->len; + })); + if (len != 74 || ctx->ret != 148) + return 0; + test_result_subprog1 = 1; + return 0; +} + +/* Though test_pkt_access_subprog2() is defined in C as: + * static __attribute__ ((noinline)) + * int test_pkt_access_subprog2(int val, volatile struct __sk_buff *skb) + * { + * return skb->len * val; + * } + * llvm optimizations remove 'int val' argument and generate BPF assembly: + * r0 = *(u32 *)(r1 + 0) + * w0 <<= 1 + * exit + * In such case the verifier falls back to conservative and + * tracing program can access arguments and return value as u64 + * instead of accurate types. + */ +struct args_subprog2 { + ku64 args[5]; + ku64 ret; +}; +static volatile __u64 test_result_subprog2; +SEC("fexit/test_pkt_access_subprog2") +int test_subprog2(struct args_subprog2 *ctx) +{ + struct sk_buff *skb = (void *)ctx->args[0]; + __u64 ret; + int len; + + bpf_probe_read_kernel(&len, sizeof(len), + __builtin_preserve_access_index(&skb->len)); + + ret = ctx->ret; + /* bpf_prog_load() loads "test_pkt_access.o" with BPF_F_TEST_RND_HI32 + * which randomizes upper 32 bits after BPF_ALU32 insns. + * Hence after 'w0 <<= 1' upper bits of $rax are random. + * That is expected and correct. Trim them. + */ + ret = (__u32) ret; + if (len != 74 || ret != 148) + return 0; + test_result_subprog2 = 1; + return 0; +} +char _license[] SEC("license") = "GPL"; -- cgit v1.2.3 From f9a7cf6eb17cd0110c8c47d9e7969fc2716e5772 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Sat, 23 Nov 2019 12:25:04 -0800 Subject: bpf: Introduce BPF_TRACE_x helper for the tracing tests For BPF_PROG_TYPE_TRACING, the bpf_prog's ctx is an array of u64. This patch borrows the idea from BPF_CALL_x in filter.h to convert a u64 to the arg type of the traced function. The new BPF_TRACE_x has an arg to specify the return type of a bpf_prog. It will be used in the future TCP-ops bpf_prog that may return "void". The new macros are defined in the new header file "bpf_trace_helpers.h". It is under selftests/bpf/ for now. It could be moved to libbpf later after seeing more upcoming non-tracing use cases. The tests are changed to use these new macros also. Hence, the k[s]u8/16/32/64 are no longer needed and they are removed from the bpf_helpers.h. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20191123202504.1502696-1-kafai@fb.com --- tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c | 27 ++++++++--------------- 1 file changed, 9 insertions(+), 18 deletions(-) (limited to 'tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c') diff --git a/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c index 981f0474da5a..525d47d7b589 100644 --- a/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c @@ -2,46 +2,37 @@ /* Copyright (c) 2019 Facebook */ #include #include "bpf_helpers.h" +#include "bpf_trace_helpers.h" struct sk_buff { unsigned int len; }; -struct args { - struct sk_buff *skb; - ks32 ret; -}; static volatile __u64 test_result; -SEC("fexit/test_pkt_access") -int test_main(struct args *ctx) +BPF_TRACE_2("fexit/test_pkt_access", test_main, + struct sk_buff *, skb, int, ret) { - struct sk_buff *skb = ctx->skb; int len; __builtin_preserve_access_index(({ len = skb->len; })); - if (len != 74 || ctx->ret != 0) + if (len != 74 || ret != 0) return 0; test_result = 1; return 0; } -struct args_subprog1 { - struct sk_buff *skb; - ks32 ret; -}; static volatile __u64 test_result_subprog1; -SEC("fexit/test_pkt_access_subprog1") -int test_subprog1(struct args_subprog1 *ctx) +BPF_TRACE_2("fexit/test_pkt_access_subprog1", test_subprog1, + struct sk_buff *, skb, int, ret) { - struct sk_buff *skb = ctx->skb; int len; __builtin_preserve_access_index(({ len = skb->len; })); - if (len != 74 || ctx->ret != 148) + if (len != 74 || ret != 148) return 0; test_result_subprog1 = 1; return 0; @@ -62,8 +53,8 @@ int test_subprog1(struct args_subprog1 *ctx) * instead of accurate types. */ struct args_subprog2 { - ku64 args[5]; - ku64 ret; + __u64 args[5]; + __u64 ret; }; static volatile __u64 test_result_subprog2; SEC("fexit/test_pkt_access_subprog2") -- cgit v1.2.3