| Message ID | 20220408203433.2988727-2-andrii@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | BPF |
| Headers | show |
| Series | Add target-less tracing SEC() definitions | expand |
On Fri, Apr 8, 2022 at 1:34 PM Andrii Nakryiko <andrii@kernel.org> wrote: > > 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> > --- > tools/lib/bpf/libbpf.c | 69 +++++++++++++++++++++++++++++++----------- > 1 file changed, 51 insertions(+), 18 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 9deb1fc67f19..81911a1e1f3e 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -8668,22 +8668,22 @@ 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), > @@ -10411,6 +10411,12 @@ 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; > @@ -10441,6 +10447,13 @@ 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; > @@ -11145,6 +11158,12 @@ 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; > @@ -11196,20 +11215,34 @@ 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; Maybe introduce a sec_has_pfx() function with tri-state return value: 1 for match with tp_name, 0, for match without tp_name, -1 for no match. > + > + 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); > -- > 2.30.2 >
On Fri, Apr 8, 2022 at 1:46 PM Song Liu <song@kernel.org> wrote: > > On Fri, Apr 8, 2022 at 1:34 PM Andrii Nakryiko <andrii@kernel.org> wrote: > > > > 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> > > --- > > tools/lib/bpf/libbpf.c | 69 +++++++++++++++++++++++++++++++----------- > > 1 file changed, 51 insertions(+), 18 deletions(-) > > > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > > index 9deb1fc67f19..81911a1e1f3e 100644 > > --- a/tools/lib/bpf/libbpf.c > > +++ b/tools/lib/bpf/libbpf.c > > @@ -8668,22 +8668,22 @@ 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), > > @@ -10411,6 +10411,12 @@ 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; > > @@ -10441,6 +10447,13 @@ 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; > > @@ -11145,6 +11158,12 @@ 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; > > @@ -11196,20 +11215,34 @@ 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; > > Maybe introduce a sec_has_pfx() function with tri-state return value: > 1 for match with tp_name, 0, for match without tp_name, -1 for no match. > Hm.. tri-state might be quite confusing, but there might be some clean ups to be done around this prefix handling for SEC_DEF()s. I'm planning to do some more work on SEC() handling, I'll do this clean up as a follow up, if you don't mind. Need to see how to best consolidate this across all the places where we do this prefix matching. > > + > > + 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); > > -- > > 2.30.2 > >
> On Apr 8, 2022, at 3:21 PM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Fri, Apr 8, 2022 at 1:46 PM Song Liu <song@kernel.org> wrote: >> >> On Fri, Apr 8, 2022 at 1:34 PM Andrii Nakryiko <andrii@kernel.org> wrote: >>> >>> 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> >>> --- >>> tools/lib/bpf/libbpf.c | 69 +++++++++++++++++++++++++++++++----------- >>> 1 file changed, 51 insertions(+), 18 deletions(-) >>> >>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >>> index 9deb1fc67f19..81911a1e1f3e 100644 >>> --- a/tools/lib/bpf/libbpf.c >>> +++ b/tools/lib/bpf/libbpf.c >>> @@ -8668,22 +8668,22 @@ 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), >>> @@ -10411,6 +10411,12 @@ 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; >>> @@ -10441,6 +10447,13 @@ 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; >>> @@ -11145,6 +11158,12 @@ 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; >>> @@ -11196,20 +11215,34 @@ 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; >> >> Maybe introduce a sec_has_pfx() function with tri-state return value: >> 1 for match with tp_name, 0, for match without tp_name, -1 for no match. >> > > Hm.. tri-state might be quite confusing, but there might be some clean > ups to be done around this prefix handling for SEC_DEF()s. I'm > planning to do some more work on SEC() handling, I'll do this clean up > as a follow up, if you don't mind. Need to see how to best consolidate > this across all the places where we do this prefix matching. Sounds good to me. Acked-by: Song Liu <songliubraving@fb.com>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 9deb1fc67f19..81911a1e1f3e 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8668,22 +8668,22 @@ 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), @@ -10411,6 +10411,12 @@ 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; @@ -10441,6 +10447,13 @@ 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; @@ -11145,6 +11158,12 @@ 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; @@ -11196,20 +11215,34 @@ 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);
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> --- tools/lib/bpf/libbpf.c | 69 +++++++++++++++++++++++++++++++----------- 1 file changed, 51 insertions(+), 18 deletions(-)