diff mbox series

[PATCHv3,4/7] libbpf: Add support for uprobe multi session attach

Message ID 20240909074554.2339984-5-jolsa@kernel.org (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series uprobe, bpf: Add session support | expand

Checks

Context Check Description
netdev/tree_selection success Guessing tree name failed - patch did not apply, async
bpf/vmtest-bpf-PR fail merge-conflict

Commit Message

Jiri Olsa Sept. 9, 2024, 7:45 a.m. UTC 
Adding support to attach program in uprobe session mode
with bpf_program__attach_uprobe_multi function.

Adding session bool to bpf_uprobe_multi_opts struct that allows
to load and attach the bpf program via uprobe session.
the attachment to create uprobe multi session.

Also adding new program loader section that allows:
  SEC("uprobe.session/bpf_fentry_test*")

and loads/attaches uprobe program as uprobe session.

Adding sleepable hook (uprobe.session.s) as well.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/bpf.c    |  1 +
 tools/lib/bpf/libbpf.c | 50 ++++++++++++++++++++++++++++++++++++++++--
 tools/lib/bpf/libbpf.h |  4 +++-
 3 files changed, 52 insertions(+), 3 deletions(-)

Comments

Andrii Nakryiko Sept. 9, 2024, 11:44 p.m. UTC | #1 
On Mon, Sep 9, 2024 at 12:46 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding support to attach program in uprobe session mode
> with bpf_program__attach_uprobe_multi function.
>
> Adding session bool to bpf_uprobe_multi_opts struct that allows
> to load and attach the bpf program via uprobe session.
> the attachment to create uprobe multi session.
>
> Also adding new program loader section that allows:
>   SEC("uprobe.session/bpf_fentry_test*")
>
> and loads/attaches uprobe program as uprobe session.
>
> Adding sleepable hook (uprobe.session.s) as well.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  tools/lib/bpf/bpf.c    |  1 +
>  tools/lib/bpf/libbpf.c | 50 ++++++++++++++++++++++++++++++++++++++++--
>  tools/lib/bpf/libbpf.h |  4 +++-
>  3 files changed, 52 insertions(+), 3 deletions(-)
>

[...]

> +static int attach_uprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link)
> +{
> +       LIBBPF_OPTS(bpf_uprobe_multi_opts, opts, .session = true);
> +       char *binary_path = NULL, *func_name = NULL;
> +       int n, ret = -EINVAL;
> +       const char *spec;
> +
> +       *link = NULL;
> +
> +       spec = prog->sec_name + sizeof("uprobe.session/") - 1;
> +       if (cookie & SEC_SLEEPABLE)
> +               spec += 2; /* extra '.s' */
> +       n = sscanf(spec, "%m[^:]:%m[^\n]", &binary_path, &func_name);
> +
> +       switch (n) {
> +       case 1:
> +               /* but auto-attach is impossible. */
> +               ret = 0;
> +               break;
> +       case 2:
> +               *link = bpf_program__attach_uprobe_multi(prog, -1, binary_path, func_name, &opts);
> +               ret = *link ? 0 : -errno;
> +               break;
> +       default:
> +               pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
> +                       prog->sec_name);
> +               break;
> +       }
> +       free(binary_path);
> +       free(func_name);
> +       return ret;
> +}

why adding this whole attach_uprobe_session if attach_uprobe_multi()
is almost exactly what you need. We just need to teach
attach_uprobe_multi to recognize uprobe.session prefix with strncmp(),
no? The rest of the logic is exactly the same.

BTW, maybe you can fix attach_uprobe_multi() while at it:

opts.retprobe = strcmp(probe_type, "uretprobe.multi") == 0;

that should be strncmp() to accommodate uretprobe.multi.s, no?
Original author (wink-wink) didn't account for that ".s", it seems...

(actually please send a small fix to bpf-next separately, so we can
apply it sooner)

> +
>  static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
>                                          const char *binary_path, uint64_t offset)
>  {
> @@ -11933,10 +11969,12 @@ bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
>         const unsigned long *ref_ctr_offsets = NULL, *offsets = NULL;
>         LIBBPF_OPTS(bpf_link_create_opts, lopts);
>         unsigned long *resolved_offsets = NULL;
> +       enum bpf_attach_type attach_type;
>         int err = 0, link_fd, prog_fd;
>         struct bpf_link *link = NULL;
>         char errmsg[STRERR_BUFSIZE];
>         char full_path[PATH_MAX];
> +       bool retprobe, session;
>         const __u64 *cookies;
>         const char **syms;
>         size_t cnt;

[...]
Jiri Olsa Sept. 10, 2024, 7:17 a.m. UTC | #2 
On Mon, Sep 09, 2024 at 04:44:44PM -0700, Andrii Nakryiko wrote:
> On Mon, Sep 9, 2024 at 12:46 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Adding support to attach program in uprobe session mode
> > with bpf_program__attach_uprobe_multi function.
> >
> > Adding session bool to bpf_uprobe_multi_opts struct that allows
> > to load and attach the bpf program via uprobe session.
> > the attachment to create uprobe multi session.
> >
> > Also adding new program loader section that allows:
> >   SEC("uprobe.session/bpf_fentry_test*")
> >
> > and loads/attaches uprobe program as uprobe session.
> >
> > Adding sleepable hook (uprobe.session.s) as well.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> >  tools/lib/bpf/bpf.c    |  1 +
> >  tools/lib/bpf/libbpf.c | 50 ++++++++++++++++++++++++++++++++++++++++--
> >  tools/lib/bpf/libbpf.h |  4 +++-
> >  3 files changed, 52 insertions(+), 3 deletions(-)
> >
> 
> [...]
> 
> > +static int attach_uprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link)
> > +{
> > +       LIBBPF_OPTS(bpf_uprobe_multi_opts, opts, .session = true);
> > +       char *binary_path = NULL, *func_name = NULL;
> > +       int n, ret = -EINVAL;
> > +       const char *spec;
> > +
> > +       *link = NULL;
> > +
> > +       spec = prog->sec_name + sizeof("uprobe.session/") - 1;
> > +       if (cookie & SEC_SLEEPABLE)
> > +               spec += 2; /* extra '.s' */
> > +       n = sscanf(spec, "%m[^:]:%m[^\n]", &binary_path, &func_name);
> > +
> > +       switch (n) {
> > +       case 1:
> > +               /* but auto-attach is impossible. */
> > +               ret = 0;
> > +               break;
> > +       case 2:
> > +               *link = bpf_program__attach_uprobe_multi(prog, -1, binary_path, func_name, &opts);
> > +               ret = *link ? 0 : -errno;
> > +               break;
> > +       default:
> > +               pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
> > +                       prog->sec_name);
> > +               break;
> > +       }
> > +       free(binary_path);
> > +       free(func_name);
> > +       return ret;
> > +}
> 
> why adding this whole attach_uprobe_session if attach_uprobe_multi()
> is almost exactly what you need. We just need to teach
> attach_uprobe_multi to recognize uprobe.session prefix with strncmp(),
>  no? The rest of the logic is exactly the same.

ok, that's better

> 
> BTW, maybe you can fix attach_uprobe_multi() while at it:
> 
> opts.retprobe = strcmp(probe_type, "uretprobe.multi") == 0;
> 
> that should be strncmp() to accommodate uretprobe.multi.s, no?
> Original author (wink-wink) didn't account for that ".s", it seems...
> 
> (actually please send a small fix to bpf-next separately, so we can
> apply it sooner)

hum, right.. I wonder why the test is passing, will send a fix

thanks,
jirka

> 
> > +
> >  static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
> >                                          const char *binary_path, uint64_t offset)
> >  {
> > @@ -11933,10 +11969,12 @@ bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
> >         const unsigned long *ref_ctr_offsets = NULL, *offsets = NULL;
> >         LIBBPF_OPTS(bpf_link_create_opts, lopts);
> >         unsigned long *resolved_offsets = NULL;
> > +       enum bpf_attach_type attach_type;
> >         int err = 0, link_fd, prog_fd;
> >         struct bpf_link *link = NULL;
> >         char errmsg[STRERR_BUFSIZE];
> >         char full_path[PATH_MAX];
> > +       bool retprobe, session;
> >         const __u64 *cookies;
> >         const char **syms;
> >         size_t cnt;
> 
> [...]
diff mbox series

Patch

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 2a4c71501a17..becdfa701c75 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -776,6 +776,7 @@  int bpf_link_create(int prog_fd, int target_fd,
 			return libbpf_err(-EINVAL);
 		break;
 	case BPF_TRACE_UPROBE_MULTI:
+	case BPF_TRACE_UPROBE_SESSION:
 		attr.link_create.uprobe_multi.flags = OPTS_GET(opts, uprobe_multi.flags, 0);
 		attr.link_create.uprobe_multi.cnt = OPTS_GET(opts, uprobe_multi.cnt, 0);
 		attr.link_create.uprobe_multi.path = ptr_to_u64(OPTS_GET(opts, uprobe_multi.path, 0));
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 274441674f92..7b72a29b09a7 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9345,6 +9345,7 @@  static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_
 static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_kprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_uprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 
@@ -9363,8 +9364,10 @@  static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("kprobe.session+",	KPROBE,	BPF_TRACE_KPROBE_SESSION, SEC_NONE, attach_kprobe_session),
 	SEC_DEF("uprobe.multi+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
 	SEC_DEF("uretprobe.multi+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
+	SEC_DEF("uprobe.session+",	KPROBE,	BPF_TRACE_UPROBE_SESSION, SEC_NONE, attach_uprobe_session),
 	SEC_DEF("uprobe.multi.s+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
 	SEC_DEF("uretprobe.multi.s+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
+	SEC_DEF("uprobe.session.s+",	KPROBE,	BPF_TRACE_UPROBE_SESSION, SEC_SLEEPABLE, attach_uprobe_session),
 	SEC_DEF("ksyscall+",		KPROBE,	0, SEC_NONE, attach_ksyscall),
 	SEC_DEF("kretsyscall+",		KPROBE, 0, SEC_NONE, attach_ksyscall),
 	SEC_DEF("usdt+",		KPROBE,	0, SEC_USDT, attach_usdt),
@@ -11699,6 +11702,39 @@  static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, stru
 	return ret;
 }
 
+static int attach_uprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts, .session = true);
+	char *binary_path = NULL, *func_name = NULL;
+	int n, ret = -EINVAL;
+	const char *spec;
+
+	*link = NULL;
+
+	spec = prog->sec_name + sizeof("uprobe.session/") - 1;
+	if (cookie & SEC_SLEEPABLE)
+		spec += 2; /* extra '.s' */
+	n = sscanf(spec, "%m[^:]:%m[^\n]", &binary_path, &func_name);
+
+	switch (n) {
+	case 1:
+		/* but auto-attach is impossible. */
+		ret = 0;
+		break;
+	case 2:
+		*link = bpf_program__attach_uprobe_multi(prog, -1, binary_path, func_name, &opts);
+		ret = *link ? 0 : -errno;
+		break;
+	default:
+		pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
+			prog->sec_name);
+		break;
+	}
+	free(binary_path);
+	free(func_name);
+	return ret;
+}
+
 static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
 					 const char *binary_path, uint64_t offset)
 {
@@ -11933,10 +11969,12 @@  bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
 	const unsigned long *ref_ctr_offsets = NULL, *offsets = NULL;
 	LIBBPF_OPTS(bpf_link_create_opts, lopts);
 	unsigned long *resolved_offsets = NULL;
+	enum bpf_attach_type attach_type;
 	int err = 0, link_fd, prog_fd;
 	struct bpf_link *link = NULL;
 	char errmsg[STRERR_BUFSIZE];
 	char full_path[PATH_MAX];
+	bool retprobe, session;
 	const __u64 *cookies;
 	const char **syms;
 	size_t cnt;
@@ -12007,12 +12045,20 @@  bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
 		offsets = resolved_offsets;
 	}
 
+	retprobe = OPTS_GET(opts, retprobe, false);
+	session  = OPTS_GET(opts, session, false);
+
+	if (retprobe && session)
+		return libbpf_err_ptr(-EINVAL);
+
+	attach_type = session ? BPF_TRACE_UPROBE_SESSION : BPF_TRACE_UPROBE_MULTI;
+
 	lopts.uprobe_multi.path = path;
 	lopts.uprobe_multi.offsets = offsets;
 	lopts.uprobe_multi.ref_ctr_offsets = ref_ctr_offsets;
 	lopts.uprobe_multi.cookies = cookies;
 	lopts.uprobe_multi.cnt = cnt;
-	lopts.uprobe_multi.flags = OPTS_GET(opts, retprobe, false) ? BPF_F_UPROBE_MULTI_RETURN : 0;
+	lopts.uprobe_multi.flags = retprobe ? BPF_F_UPROBE_MULTI_RETURN : 0;
 
 	if (pid == 0)
 		pid = getpid();
@@ -12026,7 +12072,7 @@  bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
 	}
 	link->detach = &bpf_link__detach_fd;
 
-	link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &lopts);
+	link_fd = bpf_link_create(prog_fd, 0, attach_type, &lopts);
 	if (link_fd < 0) {
 		err = -errno;
 		pr_warn("prog '%s': failed to attach multi-uprobe: %s\n",
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 64a6a3d323e3..f6a7835dc519 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -569,10 +569,12 @@  struct bpf_uprobe_multi_opts {
 	size_t cnt;
 	/* create return uprobes */
 	bool retprobe;
+	/* create session kprobes */
+	bool session;
 	size_t :0;
 };
 
-#define bpf_uprobe_multi_opts__last_field retprobe
+#define bpf_uprobe_multi_opts__last_field session
 
 /**
  * @brief **bpf_program__attach_uprobe_multi()** attaches a BPF program