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authorAndrii Nakryiko <andrii@kernel.org>2022-04-28 20:53:47 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2022-04-28 23:45:59 +0200
commit9af8efc45eb12c3f24a7053f994985ad28b4f29b (patch)
tree84d4746943e67e4195480a1266901efcf6c7bc48 /tools/lib
parentbpf, sockmap: Call skb_linearize only when required in sk_psock_skb_ingress_e... (diff)
downloadlinux-9af8efc45eb12c3f24a7053f994985ad28b4f29b.tar.xz
linux-9af8efc45eb12c3f24a7053f994985ad28b4f29b.zip
libbpf: Allow "incomplete" basic tracing SEC() definitions
In a lot of cases the target of kprobe/kretprobe, tracepoint, raw tracepoint, etc BPF program might not be known at the compilation time and will be discovered at runtime. This was always a supported case by libbpf, with APIs like bpf_program__attach_{kprobe,tracepoint,etc}() accepting full target definition, regardless of what was defined in SEC() definition in BPF source code. Unfortunately, up till now libbpf still enforced users to specify at least something for the fake target, e.g., SEC("kprobe/whatever"), which is cumbersome and somewhat misleading. This patch allows target-less SEC() definitions for basic tracing BPF program types: - kprobe/kretprobe; - multi-kprobe/multi-kretprobe; - tracepoints; - raw tracepoints. Such target-less SEC() definitions are meant to specify declaratively proper BPF program type only. Attachment of them will have to be handled programmatically using correct APIs. As such, skeleton's auto-attachment of such BPF programs is skipped and generic bpf_program__attach() will fail, if attempted, due to the lack of enough target information. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20220428185349.3799599-2-andrii@kernel.org
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c69
1 files changed, 51 insertions, 18 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 73a5192defb3..e840e48d3a76 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8853,22 +8853,22 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE | SEC_SLOPPY_PFX),
SEC_DEF("sk_reuseport/migrate", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE | SEC_SLOPPY_PFX),
SEC_DEF("sk_reuseport", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE | SEC_SLOPPY_PFX),
- SEC_DEF("kprobe/", KPROBE, 0, SEC_NONE, attach_kprobe),
+ SEC_DEF("kprobe+", KPROBE, 0, SEC_NONE, attach_kprobe),
SEC_DEF("uprobe+", KPROBE, 0, SEC_NONE, attach_uprobe),
- SEC_DEF("kretprobe/", KPROBE, 0, SEC_NONE, attach_kprobe),
+ SEC_DEF("kretprobe+", KPROBE, 0, SEC_NONE, attach_kprobe),
SEC_DEF("uretprobe+", KPROBE, 0, SEC_NONE, attach_uprobe),
- SEC_DEF("kprobe.multi/", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
- SEC_DEF("kretprobe.multi/", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+ SEC_DEF("kprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+ SEC_DEF("kretprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("usdt+", KPROBE, 0, SEC_NONE, attach_usdt),
SEC_DEF("tc", SCHED_CLS, 0, SEC_NONE),
SEC_DEF("classifier", SCHED_CLS, 0, SEC_NONE | SEC_SLOPPY_PFX | SEC_DEPRECATED),
SEC_DEF("action", SCHED_ACT, 0, SEC_NONE | SEC_SLOPPY_PFX),
- SEC_DEF("tracepoint/", TRACEPOINT, 0, SEC_NONE, attach_tp),
- SEC_DEF("tp/", TRACEPOINT, 0, SEC_NONE, attach_tp),
- SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
- SEC_DEF("raw_tp/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
- SEC_DEF("raw_tracepoint.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
- SEC_DEF("raw_tp.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+ SEC_DEF("tracepoint+", TRACEPOINT, 0, SEC_NONE, attach_tp),
+ SEC_DEF("tp+", TRACEPOINT, 0, SEC_NONE, attach_tp),
+ SEC_DEF("raw_tracepoint+", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+ SEC_DEF("raw_tp+", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+ SEC_DEF("raw_tracepoint.w+", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+ SEC_DEF("raw_tp.w+", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
SEC_DEF("tp_btf/", TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fentry/", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fmod_ret/", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
@@ -10595,6 +10595,12 @@ static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf
char *func;
int n;
+ *link = NULL;
+
+ /* no auto-attach for SEC("kprobe") and SEC("kretprobe") */
+ if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0)
+ return 0;
+
opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
if (opts.retprobe)
func_name = prog->sec_name + sizeof("kretprobe/") - 1;
@@ -10625,6 +10631,13 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
char *pattern;
int n;
+ *link = NULL;
+
+ /* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */
+ if (strcmp(prog->sec_name, "kprobe.multi") == 0 ||
+ strcmp(prog->sec_name, "kretprobe.multi") == 0)
+ return 0;
+
opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/");
if (opts.retprobe)
spec = prog->sec_name + sizeof("kretprobe.multi/") - 1;
@@ -11329,6 +11342,12 @@ static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_lin
if (!sec_name)
return -ENOMEM;
+ *link = NULL;
+
+ /* no auto-attach for SEC("tp") or SEC("tracepoint") */
+ if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
+ return 0;
+
/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
if (str_has_pfx(prog->sec_name, "tp/"))
tp_cat = sec_name + sizeof("tp/") - 1;
@@ -11380,20 +11399,34 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr
static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
static const char *const prefixes[] = {
- "raw_tp/",
- "raw_tracepoint/",
- "raw_tp.w/",
- "raw_tracepoint.w/",
+ "raw_tp",
+ "raw_tracepoint",
+ "raw_tp.w",
+ "raw_tracepoint.w",
};
size_t i;
const char *tp_name = NULL;
+ *link = NULL;
+
for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
- if (str_has_pfx(prog->sec_name, prefixes[i])) {
- tp_name = prog->sec_name + strlen(prefixes[i]);
- break;
- }
+ size_t pfx_len;
+
+ if (!str_has_pfx(prog->sec_name, prefixes[i]))
+ continue;
+
+ pfx_len = strlen(prefixes[i]);
+ /* no auto-attach case of, e.g., SEC("raw_tp") */
+ if (prog->sec_name[pfx_len] == '\0')
+ return 0;
+
+ if (prog->sec_name[pfx_len] != '/')
+ continue;
+
+ tp_name = prog->sec_name + pfx_len + 1;
+ break;
}
+
if (!tp_name) {
pr_warn("prog '%s': invalid section name '%s'\n",
prog->name, prog->sec_name);