Commit 2c3a3681 authored by Alexei Starovoitov's avatar Alexei Starovoitov

Merge branch 'set_attach_target'

Eelco Chaudron says:

====================
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)

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
v3 -> v4: Split up patch, update libbpf.map version
v4 -> v5: Fix return code, and prog assignment in test case
====================
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 53276446 933ce62d
...@@ -4937,8 +4937,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) ...@@ -4937,8 +4937,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
{ {
int err = 0, fd, i, btf_id; int err = 0, fd, i, btf_id;
if (prog->type == BPF_PROG_TYPE_TRACING || if ((prog->type == BPF_PROG_TYPE_TRACING ||
prog->type == BPF_PROG_TYPE_EXT) { prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) {
btf_id = libbpf_find_attach_btf_id(prog); btf_id = libbpf_find_attach_btf_id(prog);
if (btf_id <= 0) if (btf_id <= 0)
return btf_id; return btf_id;
...@@ -6581,6 +6581,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name, ...@@ -6581,6 +6581,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name,
else else
err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); 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; return err;
} }
...@@ -6653,8 +6656,6 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog) ...@@ -6653,8 +6656,6 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog)
err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux,
name + section_defs[i].len, name + section_defs[i].len,
attach_type); attach_type);
if (err <= 0)
pr_warn("%s is not found in vmlinux BTF\n", name);
return err; return err;
} }
pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name); pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name);
...@@ -8130,6 +8131,31 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear) ...@@ -8130,6 +8131,31 @@ 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 parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
{ {
int err = 0, n, len, start, end = -1; int err = 0, n, len, start, end = -1;
......
...@@ -334,6 +334,10 @@ LIBBPF_API void ...@@ -334,6 +334,10 @@ LIBBPF_API void
bpf_program__set_expected_attach_type(struct bpf_program *prog, bpf_program__set_expected_attach_type(struct bpf_program *prog,
enum bpf_attach_type type); 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_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_tracepoint(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog); LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog);
......
...@@ -235,3 +235,8 @@ LIBBPF_0.0.7 { ...@@ -235,3 +235,8 @@ LIBBPF_0.0.7 {
btf__align_of; btf__align_of;
libbpf_find_kernel_btf; libbpf_find_kernel_btf;
} LIBBPF_0.0.6; } LIBBPF_0.0.6;
LIBBPF_0.0.8 {
global:
bpf_program__set_attach_target;
} LIBBPF_0.0.7;
...@@ -14,7 +14,7 @@ void test_xdp_bpf2bpf(void) ...@@ -14,7 +14,7 @@ void test_xdp_bpf2bpf(void)
struct test_xdp *pkt_skel = NULL; struct test_xdp *pkt_skel = NULL;
struct test_xdp_bpf2bpf *ftrace_skel = NULL; struct test_xdp_bpf2bpf *ftrace_skel = NULL;
struct vip key4 = {.protocol = 6, .family = AF_INET}; 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 */ /* Load XDP program to introspect */
pkt_skel = test_xdp__open_and_load(); pkt_skel = test_xdp__open_and_load();
...@@ -27,11 +27,21 @@ void test_xdp_bpf2bpf(void) ...@@ -27,11 +27,21 @@ void test_xdp_bpf2bpf(void)
bpf_map_update_elem(map_fd, &key4, &value4, 0); bpf_map_update_elem(map_fd, &key4, &value4, 0);
/* Load trace program */ /* Load trace program */
opts.attach_prog_fd = pkt_fd, ftrace_skel = test_xdp_bpf2bpf__open();
ftrace_skel = test_xdp_bpf2bpf__open_opts(&opts);
if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n")) if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n"))
goto out; 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->progs.trace_on_entry;
bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY);
bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel");
prog = ftrace_skel->progs.trace_on_exit;
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); err = test_xdp_bpf2bpf__load(ftrace_skel);
if (CHECK(err, "__load", "ftrace skeleton failed\n")) if (CHECK(err, "__load", "ftrace skeleton failed\n"))
goto out; goto out;
......
...@@ -28,7 +28,7 @@ struct xdp_buff { ...@@ -28,7 +28,7 @@ struct xdp_buff {
} __attribute__((preserve_access_index)); } __attribute__((preserve_access_index));
__u64 test_result_fentry = 0; __u64 test_result_fentry = 0;
SEC("fentry/_xdp_tx_iptunnel") SEC("fentry/FUNC")
int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) int BPF_PROG(trace_on_entry, struct xdp_buff *xdp)
{ {
test_result_fentry = xdp->rxq->dev->ifindex; test_result_fentry = xdp->rxq->dev->ifindex;
...@@ -36,7 +36,7 @@ int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) ...@@ -36,7 +36,7 @@ int BPF_PROG(trace_on_entry, struct xdp_buff *xdp)
} }
__u64 test_result_fexit = 0; __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) int BPF_PROG(trace_on_exit, struct xdp_buff *xdp, int ret)
{ {
test_result_fexit = ret; test_result_fexit = ret;
......
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