| Message ID | 158193725120.96608.9449808053785640511.stgit@xdp-tutorial |
|---|---|
| State | Superseded |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf-next,v3] libbpf: Add support for dynamic program attach target | expand |
!! IGNORE THIS ONE, FORGOR TO UPDATE libbpf.map AS NET-NEXT IS OPEN !! On 17 Feb 2020, at 12:01, Eelco Chaudron wrote: > Currently when you want to attach a trace program to a bpf program > the section name needs to match the tracepoint/function semantics. > > However the addition of the bpf_program__set_attach_target() API > allows you to specify the tracepoint/function dynamically. > > The call flow would look something like this: > > xdp_fd = bpf_prog_get_fd_by_id(id); > trace_obj = bpf_object__open_file("func.o", NULL); > prog = bpf_object__find_program_by_title(trace_obj, > "fentry/myfunc"); > bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); > bpf_program__set_attach_target(prog, xdp_fd, > "xdpfilt_blk_all"); > bpf_object__load(trace_obj) > > Signed-off-by: Eelco Chaudron <echaudro@redhat.com> > --- > v1 -> v2: Remove requirement for attach type hint in API > v2 -> v3: Moved common warning to __find_vmlinux_btf_id, requested by > Andrii > Updated the xdp_bpf2bpf test to use this new API > > tools/lib/bpf/libbpf.c | 34 > ++++++++++++++++++-- > tools/lib/bpf/libbpf.h | 4 ++ > tools/lib/bpf/libbpf.map | 1 + > .../testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c | 16 ++++++++- > .../testing/selftests/bpf/progs/test_xdp_bpf2bpf.c | 4 +- > 5 files changed, 50 insertions(+), 9 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 514b1a524abb..0c25d78fb5d8 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -4939,8 +4939,8 @@ int bpf_program__load(struct bpf_program *prog, > char *license, __u32 kern_ver) > { > int err = 0, fd, i, btf_id; > > - if (prog->type == BPF_PROG_TYPE_TRACING || > - prog->type == BPF_PROG_TYPE_EXT) { > + if ((prog->type == BPF_PROG_TYPE_TRACING || > + prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) { > btf_id = libbpf_find_attach_btf_id(prog); > if (btf_id <= 0) > return btf_id; > @@ -6583,6 +6583,9 @@ static inline int __find_vmlinux_btf_id(struct > btf *btf, const char *name, > else > err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > + if (err <= 0) > + pr_warn("%s is not found in vmlinux BTF\n", name); > + > return err; > } > > @@ -6655,8 +6658,6 @@ static int libbpf_find_attach_btf_id(struct > bpf_program *prog) > err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, > name + section_defs[i].len, > attach_type); > - if (err <= 0) > - pr_warn("%s is not found in vmlinux BTF\n", name); > return err; > } > pr_warn("failed to identify btf_id based on ELF section name > '%s'\n", name); > @@ -8132,6 +8133,31 @@ void bpf_program__bpil_offs_to_addr(struct > bpf_prog_info_linear *info_linear) > } > } > > +int bpf_program__set_attach_target(struct bpf_program *prog, > + int attach_prog_fd, > + const char *attach_func_name) > +{ > + int btf_id; > + > + if (!prog || attach_prog_fd < 0 || !attach_func_name) > + return -EINVAL; > + > + if (attach_prog_fd) > + btf_id = libbpf_find_prog_btf_id(attach_func_name, > + attach_prog_fd); > + else > + btf_id = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, > + attach_func_name, > + prog->expected_attach_type); > + > + if (btf_id <= 0) > + return btf_id; > + > + prog->attach_btf_id = btf_id; > + prog->attach_prog_fd = attach_prog_fd; > + return 0; > +} > + > int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz) > { > int err = 0, n, len, start, end = -1; > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index 3fe12c9d1f92..02fc58a21a7f 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -334,6 +334,10 @@ LIBBPF_API void > bpf_program__set_expected_attach_type(struct bpf_program *prog, > enum bpf_attach_type type); > > +LIBBPF_API int > +bpf_program__set_attach_target(struct bpf_program *prog, int > attach_prog_fd, > + const char *attach_func_name); > + > LIBBPF_API bool bpf_program__is_socket_filter(const struct > bpf_program *prog); > LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program > *prog); > LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct > bpf_program *prog); > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > index b035122142bb..8aba5438a3f0 100644 > --- a/tools/lib/bpf/libbpf.map > +++ b/tools/lib/bpf/libbpf.map > @@ -230,6 +230,7 @@ LIBBPF_0.0.7 { > bpf_program__name; > bpf_program__is_extension; > bpf_program__is_struct_ops; > + bpf_program__set_attach_target; > bpf_program__set_extension; > bpf_program__set_struct_ops; > btf__align_of; > diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c > b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c > index 6b56bdc73ebc..513fdbf02b81 100644 > --- a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c > +++ b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c > @@ -14,7 +14,7 @@ void test_xdp_bpf2bpf(void) > struct test_xdp *pkt_skel = NULL; > struct test_xdp_bpf2bpf *ftrace_skel = NULL; > struct vip key4 = {.protocol = 6, .family = AF_INET}; > - DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts); > + struct bpf_program *prog; > > /* Load XDP program to introspect */ > pkt_skel = test_xdp__open_and_load(); > @@ -27,11 +27,21 @@ void test_xdp_bpf2bpf(void) > bpf_map_update_elem(map_fd, &key4, &value4, 0); > > /* Load trace program */ > - opts.attach_prog_fd = pkt_fd, > - ftrace_skel = test_xdp_bpf2bpf__open_opts(&opts); > + ftrace_skel = test_xdp_bpf2bpf__open(); > if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n")) > goto out; > > + /* Demonstrate the bpf_program__set_attach_target() API rather than > + * the load with options, i.e. opts.attach_prog_fd. > + */ > + prog = *ftrace_skel->skeleton->progs[0].prog; > + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); > + bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel"); > + > + prog = *ftrace_skel->skeleton->progs[1].prog; > + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FEXIT); > + bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel"); > + > err = test_xdp_bpf2bpf__load(ftrace_skel); > if (CHECK(err, "__load", "ftrace skeleton failed\n")) > goto out; > diff --git a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c > b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c > index cb8a04ab7a78..b840fc9e3ed5 100644 > --- a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c > +++ b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c > @@ -28,7 +28,7 @@ struct xdp_buff { > } __attribute__((preserve_access_index)); > > __u64 test_result_fentry = 0; > -SEC("fentry/_xdp_tx_iptunnel") > +SEC("fentry/FUNC") > int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) > { > test_result_fentry = xdp->rxq->dev->ifindex; > @@ -36,7 +36,7 @@ int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) > } > > __u64 test_result_fexit = 0; > -SEC("fexit/_xdp_tx_iptunnel") > +SEC("fexit/FUNC") > int BPF_PROG(trace_on_exit, struct xdp_buff *xdp, int ret) > { > test_result_fexit = ret;
Eelco Chaudron <echaudro@redhat.com> writes: > Currently when you want to attach a trace program to a bpf program > the section name needs to match the tracepoint/function semantics. > > However the addition of the bpf_program__set_attach_target() API > allows you to specify the tracepoint/function dynamically. > > The call flow would look something like this: > > xdp_fd = bpf_prog_get_fd_by_id(id); > trace_obj = bpf_object__open_file("func.o", NULL); > prog = bpf_object__find_program_by_title(trace_obj, > "fentry/myfunc"); > bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); > bpf_program__set_attach_target(prog, xdp_fd, > "xdpfilt_blk_all"); > bpf_object__load(trace_obj) > > Signed-off-by: Eelco Chaudron <echaudro@redhat.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 514b1a524abb..0c25d78fb5d8 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4939,8 +4939,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) { int err = 0, fd, i, btf_id; - if (prog->type == BPF_PROG_TYPE_TRACING || - prog->type == BPF_PROG_TYPE_EXT) { + if ((prog->type == BPF_PROG_TYPE_TRACING || + prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) { btf_id = libbpf_find_attach_btf_id(prog); if (btf_id <= 0) return btf_id; @@ -6583,6 +6583,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name, else err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); + if (err <= 0) + pr_warn("%s is not found in vmlinux BTF\n", name); + return err; } @@ -6655,8 +6658,6 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog) err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, name + section_defs[i].len, attach_type); - if (err <= 0) - pr_warn("%s is not found in vmlinux BTF\n", name); return err; } pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name); @@ -8132,6 +8133,31 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear) } } +int bpf_program__set_attach_target(struct bpf_program *prog, + int attach_prog_fd, + const char *attach_func_name) +{ + int btf_id; + + if (!prog || attach_prog_fd < 0 || !attach_func_name) + return -EINVAL; + + if (attach_prog_fd) + btf_id = libbpf_find_prog_btf_id(attach_func_name, + attach_prog_fd); + else + btf_id = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, + attach_func_name, + prog->expected_attach_type); + + if (btf_id <= 0) + return btf_id; + + prog->attach_btf_id = btf_id; + prog->attach_prog_fd = attach_prog_fd; + return 0; +} + int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz) { int err = 0, n, len, start, end = -1; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 3fe12c9d1f92..02fc58a21a7f 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -334,6 +334,10 @@ LIBBPF_API void bpf_program__set_expected_attach_type(struct bpf_program *prog, enum bpf_attach_type type); +LIBBPF_API int +bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd, + const char *attach_func_name); + LIBBPF_API bool bpf_program__is_socket_filter(const struct bpf_program *prog); LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program *prog); LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index b035122142bb..8aba5438a3f0 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -230,6 +230,7 @@ LIBBPF_0.0.7 { bpf_program__name; bpf_program__is_extension; bpf_program__is_struct_ops; + bpf_program__set_attach_target; bpf_program__set_extension; bpf_program__set_struct_ops; btf__align_of; diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c index 6b56bdc73ebc..513fdbf02b81 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c @@ -14,7 +14,7 @@ void test_xdp_bpf2bpf(void) struct test_xdp *pkt_skel = NULL; struct test_xdp_bpf2bpf *ftrace_skel = NULL; struct vip key4 = {.protocol = 6, .family = AF_INET}; - DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts); + struct bpf_program *prog; /* Load XDP program to introspect */ pkt_skel = test_xdp__open_and_load(); @@ -27,11 +27,21 @@ void test_xdp_bpf2bpf(void) bpf_map_update_elem(map_fd, &key4, &value4, 0); /* Load trace program */ - opts.attach_prog_fd = pkt_fd, - ftrace_skel = test_xdp_bpf2bpf__open_opts(&opts); + ftrace_skel = test_xdp_bpf2bpf__open(); if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n")) goto out; + /* Demonstrate the bpf_program__set_attach_target() API rather than + * the load with options, i.e. opts.attach_prog_fd. + */ + prog = *ftrace_skel->skeleton->progs[0].prog; + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); + bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel"); + + prog = *ftrace_skel->skeleton->progs[1].prog; + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FEXIT); + bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel"); + err = test_xdp_bpf2bpf__load(ftrace_skel); if (CHECK(err, "__load", "ftrace skeleton failed\n")) goto out; diff --git a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c index cb8a04ab7a78..b840fc9e3ed5 100644 --- a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c @@ -28,7 +28,7 @@ struct xdp_buff { } __attribute__((preserve_access_index)); __u64 test_result_fentry = 0; -SEC("fentry/_xdp_tx_iptunnel") +SEC("fentry/FUNC") int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) { test_result_fentry = xdp->rxq->dev->ifindex; @@ -36,7 +36,7 @@ int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) } __u64 test_result_fexit = 0; -SEC("fexit/_xdp_tx_iptunnel") +SEC("fexit/FUNC") int BPF_PROG(trace_on_exit, struct xdp_buff *xdp, int ret) { test_result_fexit = ret;
Currently when you want to attach a trace program to a bpf program the section name needs to match the tracepoint/function semantics. However the addition of the bpf_program__set_attach_target() API allows you to specify the tracepoint/function dynamically. The call flow would look something like this: xdp_fd = bpf_prog_get_fd_by_id(id); trace_obj = bpf_object__open_file("func.o", NULL); prog = bpf_object__find_program_by_title(trace_obj, "fentry/myfunc"); bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); bpf_program__set_attach_target(prog, xdp_fd, "xdpfilt_blk_all"); bpf_object__load(trace_obj) Signed-off-by: Eelco Chaudron <echaudro@redhat.com> --- v1 -> v2: Remove requirement for attach type hint in API v2 -> v3: Moved common warning to __find_vmlinux_btf_id, requested by Andrii Updated the xdp_bpf2bpf test to use this new API tools/lib/bpf/libbpf.c | 34 ++++++++++++++++++-- tools/lib/bpf/libbpf.h | 4 ++ tools/lib/bpf/libbpf.map | 1 + .../testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c | 16 ++++++++- .../testing/selftests/bpf/progs/test_xdp_bpf2bpf.c | 4 +- 5 files changed, 50 insertions(+), 9 deletions(-)