[PATCHv4 bpf-next 0/6] bpf: Add link_info support for uprobe multi link

[PATCHv4 bpf-next 0/6] bpf: Add link_info support for uprobe multi link

[Jiri Olsa]

hi,
this patchset adds support to get bpf_link_info details for
uprobe_multi links and adding support for bpftool link to
display them.

v4 changes:
  - move flags field up in bpf_uprobe_multi_link [Andrii]
  - include zero terminating byte in path_size [Andrii]
  - return d_path error directly [Yonghong]
  - use SEC(".probes") for semaphores [Yonghong]
  - fix ref_ctr_offsets leak in test [Yonghong]
  - other smaller fixes [Yonghong]

thanks,
jirka


---
Jiri Olsa (6):
      libbpf: Add st_type argument to elf_resolve_syms_offsets function
      bpf: Store ref_ctr_offsets values in bpf_uprobe array
      bpf: Add link_info support for uprobe multi link
      selftests/bpf: Use bpf_link__destroy in fill_link_info tests
      selftests/bpf: Add link_info test for uprobe_multi link
      bpftool: Add support to display uprobe_multi links

 include/uapi/linux/bpf.h                                   |  10 ++++
 kernel/trace/bpf_trace.c                                   |  86 ++++++++++++++++++++++++++++-----
 tools/bpf/bpftool/link.c                                   | 105 +++++++++++++++++++++++++++++++++++++++-
 tools/include/uapi/linux/bpf.h                             |  10 ++++
 tools/lib/bpf/elf.c                                        |   5 +-
 tools/lib/bpf/libbpf.c                                     |   2 +-
 tools/lib/bpf/libbpf_internal.h                            |   3 +-
 tools/testing/selftests/bpf/prog_tests/fill_link_info.c    | 242 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c |   2 +-
 tools/testing/selftests/bpf/progs/test_fill_link_info.c    |   6 +++
 10 files changed, 432 insertions(+), 39 deletions(-)

[PATCHv4 bpf-next 1/6] libbpf: Add st_type argument to elf_resolve_syms_offsets function

[Jiri Olsa]

We need to get offsets for static variables in following changes,
so making elf_resolve_syms_offsets to take st_type value as argument
and passing it to elf_sym_iter_new.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/elf.c                                        | 5 +++--
 tools/lib/bpf/libbpf.c                                     | 2 +-
 tools/lib/bpf/libbpf_internal.h                            | 3 ++-
 tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c | 2 +-
 4 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c
index 2a62bf411bb3..b02faec748a5 100644
--- a/tools/lib/bpf/elf.c
+++ b/tools/lib/bpf/elf.c
@@ -407,7 +407,8 @@ static int symbol_cmp(const void *a, const void *b)
  * size, that needs to be released by the caller.
  */
 int elf_resolve_syms_offsets(const char *binary_path, int cnt,
-			     const char **syms, unsigned long **poffsets)
+			     const char **syms, unsigned long **poffsets,
+			     int st_type)
 {
 	int sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
 	int err = 0, i, cnt_done = 0;
@@ -438,7 +439,7 @@ int elf_resolve_syms_offsets(const char *binary_path, int cnt,
 		struct elf_sym_iter iter;
 		struct elf_sym *sym;
 
-		err = elf_sym_iter_new(&iter, elf_fd.elf, binary_path, sh_types[i], STT_FUNC);
+		err = elf_sym_iter_new(&iter, elf_fd.elf, binary_path, sh_types[i], st_type);
 		if (err == -ENOENT)
 			continue;
 		if (err)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e067be95da3c..ea9b8158c20d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11447,7 +11447,7 @@ bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
 			return libbpf_err_ptr(err);
 		offsets = resolved_offsets;
 	} else if (syms) {
-		err = elf_resolve_syms_offsets(path, cnt, syms, &resolved_offsets);
+		err = elf_resolve_syms_offsets(path, cnt, syms, &resolved_offsets, STT_FUNC);
 		if (err < 0)
 			return libbpf_err_ptr(err);
 		offsets = resolved_offsets;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index f0f08635adb0..b5d334754e5d 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -594,7 +594,8 @@ int elf_open(const char *binary_path, struct elf_fd *elf_fd);
 void elf_close(struct elf_fd *elf_fd);
 
 int elf_resolve_syms_offsets(const char *binary_path, int cnt,
-			     const char **syms, unsigned long **poffsets);
+			     const char **syms, unsigned long **poffsets,
+			     int st_type);
 int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
 				 unsigned long **poffsets, size_t *pcnt);
 
diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
index cd051d3901a9..ece260cf2c0b 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -249,7 +249,7 @@ static void __test_link_api(struct child *child)
 	int link_extra_fd = -1;
 	int err;
 
-	err = elf_resolve_syms_offsets(path, 3, syms, (unsigned long **) &offsets);
+	err = elf_resolve_syms_offsets(path, 3, syms, (unsigned long **) &offsets, STT_FUNC);
 	if (!ASSERT_OK(err, "elf_resolve_syms_offsets"))
 		return;
 
-- 
2.42.0

[PATCHv4 bpf-next 2/6] bpf: Store ref_ctr_offsets values in bpf_uprobe array

[Jiri Olsa]

We will need to return ref_ctr_offsets values through link_info
interface in following change, so we need to keep them around.

Storing ref_ctr_offsets values directly into bpf_uprobe array.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/trace/bpf_trace.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f0b8b7c29126..ad0323f27288 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3033,6 +3033,7 @@ struct bpf_uprobe_multi_link;
 struct bpf_uprobe {
 	struct bpf_uprobe_multi_link *link;
 	loff_t offset;
+	unsigned long ref_ctr_offset;
 	u64 cookie;
 	struct uprobe_consumer consumer;
 };
@@ -3172,7 +3173,6 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 {
 	struct bpf_uprobe_multi_link *link = NULL;
 	unsigned long __user *uref_ctr_offsets;
-	unsigned long *ref_ctr_offsets = NULL;
 	struct bpf_link_primer link_primer;
 	struct bpf_uprobe *uprobes = NULL;
 	struct task_struct *task = NULL;
@@ -3245,18 +3245,12 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	if (!uprobes || !link)
 		goto error_free;
 
-	if (uref_ctr_offsets) {
-		ref_ctr_offsets = kvcalloc(cnt, sizeof(*ref_ctr_offsets), GFP_KERNEL);
-		if (!ref_ctr_offsets)
-			goto error_free;
-	}
-
 	for (i = 0; i < cnt; i++) {
 		if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) {
 			err = -EFAULT;
 			goto error_free;
 		}
-		if (uref_ctr_offsets && __get_user(ref_ctr_offsets[i], uref_ctr_offsets + i)) {
+		if (uref_ctr_offsets && __get_user(uprobes[i].ref_ctr_offset, uref_ctr_offsets + i)) {
 			err = -EFAULT;
 			goto error_free;
 		}
@@ -3287,7 +3281,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	for (i = 0; i < cnt; i++) {
 		err = uprobe_register_refctr(d_real_inode(link->path.dentry),
 					     uprobes[i].offset,
-					     ref_ctr_offsets ? ref_ctr_offsets[i] : 0,
+					     uprobes[i].ref_ctr_offset,
 					     &uprobes[i].consumer);
 		if (err) {
 			bpf_uprobe_unregister(&path, uprobes, i);
@@ -3299,11 +3293,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	if (err)
 		goto error_free;
 
-	kvfree(ref_ctr_offsets);
 	return bpf_link_settle(&link_primer);
 
 error_free:
-	kvfree(ref_ctr_offsets);
 	kvfree(uprobes);
 	kfree(link);
 	if (task)
-- 
2.42.0

[PATCHv4 bpf-next 3/6] bpf: Add link_info support for uprobe multi link

[Jiri Olsa]

Adding support to get uprobe_link details through bpf_link_info
interface.

Adding new struct uprobe_multi to struct bpf_link_info to carry
the uprobe_multi link details.

The uprobe_multi.count is passed from user space to denote size
of array fields (offsets/ref_ctr_offsets/cookies). The actual
array size is stored back to uprobe_multi.count (allowing user
to find out the actual array size) and array fields are populated
up to the user passed size.

All the non-array fields (path/count/flags/pid) are always set.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/uapi/linux/bpf.h       | 10 +++++
 kernel/trace/bpf_trace.c       | 72 ++++++++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h | 10 +++++
 3 files changed, 92 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7a5498242eaa..e88746ba7d21 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6562,6 +6562,16 @@ struct bpf_link_info {
 			__u32 flags;
 			__u64 missed;
 		} kprobe_multi;
+		struct {
+			__aligned_u64 path;
+			__aligned_u64 offsets;
+			__aligned_u64 ref_ctr_offsets;
+			__aligned_u64 cookies;
+			__u32 path_size; /* in/out: real path size on success, including zero byte */
+			__u32 count; /* in/out: uprobe_multi offsets/ref_ctr_offsets/cookies count */
+			__u32 flags;
+			__u32 pid;
+		} uprobe_multi;
 		struct {
 			__u32 type; /* enum bpf_perf_event_type */
 			__u32 :32;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ad0323f27288..c284a4ad0315 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3042,6 +3042,7 @@ struct bpf_uprobe_multi_link {
 	struct path path;
 	struct bpf_link link;
 	u32 cnt;
+	u32 flags;
 	struct bpf_uprobe *uprobes;
 	struct task_struct *task;
 };
@@ -3083,9 +3084,79 @@ static void bpf_uprobe_multi_link_dealloc(struct bpf_link *link)
 	kfree(umulti_link);
 }
 
+static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link,
+						struct bpf_link_info *info)
+{
+	u64 __user *uref_ctr_offsets = u64_to_user_ptr(info->uprobe_multi.ref_ctr_offsets);
+	u64 __user *ucookies = u64_to_user_ptr(info->uprobe_multi.cookies);
+	u64 __user *uoffsets = u64_to_user_ptr(info->uprobe_multi.offsets);
+	u64 __user *upath = u64_to_user_ptr(info->uprobe_multi.path);
+	u32 upath_size = info->uprobe_multi.path_size;
+	struct bpf_uprobe_multi_link *umulti_link;
+	u32 ucount = info->uprobe_multi.count;
+	int err = 0, i;
+	long left;
+
+	if (!upath ^ !upath_size)
+		return -EINVAL;
+
+	if ((uoffsets || uref_ctr_offsets || ucookies) && !ucount)
+		return -EINVAL;
+
+	umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
+	info->uprobe_multi.count = umulti_link->cnt;
+	info->uprobe_multi.flags = umulti_link->flags;
+	info->uprobe_multi.pid = umulti_link->task ?
+				 task_pid_nr_ns(umulti_link->task, task_active_pid_ns(current)) : 0;
+
+	if (upath) {
+		char *p, *buf;
+
+		upath_size = min_t(u32, upath_size, PATH_MAX);
+
+		buf = kmalloc(upath_size, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+		p = d_path(&umulti_link->path, buf, upath_size);
+		if (IS_ERR(p)) {
+			kfree(buf);
+			return PTR_ERR(p);
+		}
+		upath_size = buf + upath_size - p;
+		left = copy_to_user(upath, p, upath_size);
+		kfree(buf);
+		if (left)
+			return -EFAULT;
+		info->uprobe_multi.path_size = upath_size;
+	}
+
+	if (!uoffsets && !ucookies && !uref_ctr_offsets)
+		return 0;
+
+	if (ucount < umulti_link->cnt)
+		err = -ENOSPC;
+	else
+		ucount = umulti_link->cnt;
+
+	for (i = 0; i < ucount; i++) {
+		if (uoffsets &&
+		    put_user(umulti_link->uprobes[i].offset, uoffsets + i))
+			return -EFAULT;
+		if (uref_ctr_offsets &&
+		    put_user(umulti_link->uprobes[i].ref_ctr_offset, uref_ctr_offsets + i))
+			return -EFAULT;
+		if (ucookies &&
+		    put_user(umulti_link->uprobes[i].cookie, ucookies + i))
+			return -EFAULT;
+	}
+
+	return err;
+}
+
 static const struct bpf_link_ops bpf_uprobe_multi_link_lops = {
 	.release = bpf_uprobe_multi_link_release,
 	.dealloc = bpf_uprobe_multi_link_dealloc,
+	.fill_link_info = bpf_uprobe_multi_link_fill_link_info,
 };
 
 static int uprobe_prog_run(struct bpf_uprobe *uprobe,
@@ -3274,6 +3345,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	link->uprobes = uprobes;
 	link->path = path;
 	link->task = task;
+	link->flags = flags;
 
 	bpf_link_init(&link->link, BPF_LINK_TYPE_UPROBE_MULTI,
 		      &bpf_uprobe_multi_link_lops, prog);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7a5498242eaa..e88746ba7d21 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6562,6 +6562,16 @@ struct bpf_link_info {
 			__u32 flags;
 			__u64 missed;
 		} kprobe_multi;
+		struct {
+			__aligned_u64 path;
+			__aligned_u64 offsets;
+			__aligned_u64 ref_ctr_offsets;
+			__aligned_u64 cookies;
+			__u32 path_size; /* in/out: real path size on success, including zero byte */
+			__u32 count; /* in/out: uprobe_multi offsets/ref_ctr_offsets/cookies count */
+			__u32 flags;
+			__u32 pid;
+		} uprobe_multi;
 		struct {
 			__u32 type; /* enum bpf_perf_event_type */
 			__u32 :32;
-- 
2.42.0

[PATCHv4 bpf-next 4/6] selftests/bpf: Use bpf_link__destroy in fill_link_info tests

[Jiri Olsa]

The fill_link_info test keeps skeleton open and just creates
various links. We are wrongly calling bpf_link__detach after
each test to close them, we need to call bpf_link__destroy.

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../selftests/bpf/prog_tests/fill_link_info.c | 44 ++++++++++---------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
index 97142a4db374..9294cb8d7743 100644
--- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
+++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
@@ -140,14 +140,14 @@ static void test_kprobe_fill_link_info(struct test_fill_link_info *skel,
 		.retprobe = type == BPF_PERF_EVENT_KRETPROBE,
 	);
 	ssize_t entry_offset = 0;
+	struct bpf_link *link;
 	int link_fd, err;
 
-	skel->links.kprobe_run = bpf_program__attach_kprobe_opts(skel->progs.kprobe_run,
-								 KPROBE_FUNC, &opts);
-	if (!ASSERT_OK_PTR(skel->links.kprobe_run, "attach_kprobe"))
+	link = bpf_program__attach_kprobe_opts(skel->progs.kprobe_run, KPROBE_FUNC, &opts);
+	if (!ASSERT_OK_PTR(link, "attach_kprobe"))
 		return;
 
-	link_fd = bpf_link__fd(skel->links.kprobe_run);
+	link_fd = bpf_link__fd(link);
 	if (!invalid) {
 		/* See also arch_adjust_kprobe_addr(). */
 		if (skel->kconfig->CONFIG_X86_KERNEL_IBT)
@@ -157,39 +157,41 @@ static void test_kprobe_fill_link_info(struct test_fill_link_info *skel,
 	} else {
 		kprobe_fill_invalid_user_buffer(link_fd);
 	}
-	bpf_link__detach(skel->links.kprobe_run);
+	bpf_link__destroy(link);
 }
 
 static void test_tp_fill_link_info(struct test_fill_link_info *skel)
 {
+	struct bpf_link *link;
 	int link_fd, err;
 
-	skel->links.tp_run = bpf_program__attach_tracepoint(skel->progs.tp_run, TP_CAT, TP_NAME);
-	if (!ASSERT_OK_PTR(skel->links.tp_run, "attach_tp"))
+	link = bpf_program__attach_tracepoint(skel->progs.tp_run, TP_CAT, TP_NAME);
+	if (!ASSERT_OK_PTR(link, "attach_tp"))
 		return;
 
-	link_fd = bpf_link__fd(skel->links.tp_run);
+	link_fd = bpf_link__fd(link);
 	err = verify_perf_link_info(link_fd, BPF_PERF_EVENT_TRACEPOINT, 0, 0, 0);
 	ASSERT_OK(err, "verify_perf_link_info");
-	bpf_link__detach(skel->links.tp_run);
+	bpf_link__destroy(link);
 }
 
 static void test_uprobe_fill_link_info(struct test_fill_link_info *skel,
 				       enum bpf_perf_event_type type)
 {
+	struct bpf_link *link;
 	int link_fd, err;
 
-	skel->links.uprobe_run = bpf_program__attach_uprobe(skel->progs.uprobe_run,
-							    type == BPF_PERF_EVENT_URETPROBE,
-							    0, /* self pid */
-							    UPROBE_FILE, uprobe_offset);
-	if (!ASSERT_OK_PTR(skel->links.uprobe_run, "attach_uprobe"))
+	link = bpf_program__attach_uprobe(skel->progs.uprobe_run,
+					  type == BPF_PERF_EVENT_URETPROBE,
+					  0, /* self pid */
+					  UPROBE_FILE, uprobe_offset);
+	if (!ASSERT_OK_PTR(link, "attach_uprobe"))
 		return;
 
-	link_fd = bpf_link__fd(skel->links.uprobe_run);
+	link_fd = bpf_link__fd(link);
 	err = verify_perf_link_info(link_fd, type, 0, uprobe_offset, 0);
 	ASSERT_OK(err, "verify_perf_link_info");
-	bpf_link__detach(skel->links.uprobe_run);
+	bpf_link__destroy(link);
 }
 
 static int verify_kmulti_link_info(int fd, bool retprobe)
@@ -278,24 +280,24 @@ static void test_kprobe_multi_fill_link_info(struct test_fill_link_info *skel,
 					     bool retprobe, bool invalid)
 {
 	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+	struct bpf_link *link;
 	int link_fd, err;
 
 	opts.syms = kmulti_syms;
 	opts.cnt = KMULTI_CNT;
 	opts.retprobe = retprobe;
-	skel->links.kmulti_run = bpf_program__attach_kprobe_multi_opts(skel->progs.kmulti_run,
-								       NULL, &opts);
-	if (!ASSERT_OK_PTR(skel->links.kmulti_run, "attach_kprobe_multi"))
+	link = bpf_program__attach_kprobe_multi_opts(skel->progs.kmulti_run, NULL, &opts);
+	if (!ASSERT_OK_PTR(link, "attach_kprobe_multi"))
 		return;
 
-	link_fd = bpf_link__fd(skel->links.kmulti_run);
+	link_fd = bpf_link__fd(link);
 	if (!invalid) {
 		err = verify_kmulti_link_info(link_fd, retprobe);
 		ASSERT_OK(err, "verify_kmulti_link_info");
 	} else {
 		verify_kmulti_invalid_user_buffer(link_fd);
 	}
-	bpf_link__detach(skel->links.kmulti_run);
+	bpf_link__destroy(link);
 }
 
 void test_fill_link_info(void)
-- 
2.42.0

[PATCHv4 bpf-next 5/6] selftests/bpf: Add link_info test for uprobe_multi link

[Jiri Olsa]

Adding fill_link_info test for uprobe_multi link.

Setting up uprobes with bogus ref_ctr_offsets and cookie values
to test all the bpf_link_info::uprobe_multi fields.

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../selftests/bpf/prog_tests/fill_link_info.c | 198 ++++++++++++++++++
 .../selftests/bpf/progs/test_fill_link_info.c |   6 +
 2 files changed, 204 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
index 9294cb8d7743..d4b1901f7879 100644
--- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
+++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
@@ -7,6 +7,7 @@
 #include <test_progs.h>
 #include "trace_helpers.h"
 #include "test_fill_link_info.skel.h"
+#include "bpf/libbpf_internal.h"
 
 #define TP_CAT "sched"
 #define TP_NAME "sched_switch"
@@ -300,6 +301,196 @@ static void test_kprobe_multi_fill_link_info(struct test_fill_link_info *skel,
 	bpf_link__destroy(link);
 }
 
+#define SEC(name) __attribute__((section(name), used))
+
+static short uprobe_link_info_sema_1 SEC(".probes");
+static short uprobe_link_info_sema_2 SEC(".probes");
+static short uprobe_link_info_sema_3 SEC(".probes");
+
+noinline void uprobe_link_info_func_1(void)
+{
+	asm volatile ("");
+	uprobe_link_info_sema_1++;
+}
+
+noinline void uprobe_link_info_func_2(void)
+{
+	asm volatile ("");
+	uprobe_link_info_sema_2++;
+}
+
+noinline void uprobe_link_info_func_3(void)
+{
+	asm volatile ("");
+	uprobe_link_info_sema_3++;
+}
+
+static int
+verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets,
+			__u64 *cookies, __u64 *ref_ctr_offsets)
+{
+	char path[PATH_MAX], path_buf[PATH_MAX];
+	struct bpf_link_info info;
+	__u32 len = sizeof(info);
+	__u64 ref_ctr_offsets_buf[3];
+	__u64 offsets_buf[3];
+	__u64 cookies_buf[3];
+	int i, err, bit;
+	__u32 count = 0;
+
+	memset(path, 0, sizeof(path));
+	err = readlink("/proc/self/exe", path, sizeof(path));
+	if (!ASSERT_NEQ(err, -1, "readlink"))
+		return -1;
+
+	for (bit = 0; bit < 8; bit++) {
+		memset(&info, 0, sizeof(info));
+		info.uprobe_multi.path = ptr_to_u64(path_buf);
+		info.uprobe_multi.path_size = sizeof(path_buf);
+		info.uprobe_multi.count = count;
+
+		if (bit & 0x1)
+			info.uprobe_multi.offsets = ptr_to_u64(offsets_buf);
+		if (bit & 0x2)
+			info.uprobe_multi.cookies = ptr_to_u64(cookies_buf);
+		if (bit & 0x4)
+			info.uprobe_multi.ref_ctr_offsets = ptr_to_u64(ref_ctr_offsets_buf);
+
+		err = bpf_link_get_info_by_fd(fd, &info, &len);
+		if (!ASSERT_OK(err, "bpf_link_get_info_by_fd"))
+			return -1;
+
+		if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_UPROBE_MULTI, "info.type"))
+			return -1;
+
+		ASSERT_EQ(info.uprobe_multi.pid, getpid(), "info.uprobe_multi.pid");
+		ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count");
+		ASSERT_EQ(info.uprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN,
+			  retprobe, "info.uprobe_multi.flags.retprobe");
+		ASSERT_EQ(info.uprobe_multi.path_size, strlen(path) + 1, "info.uprobe_multi.path_size");
+		ASSERT_STREQ(path_buf, path, "info.uprobe_multi.path");
+
+		for (i = 0; i < info.uprobe_multi.count; i++) {
+			if (info.uprobe_multi.offsets)
+				ASSERT_EQ(offsets_buf[i], offsets[i], "info.uprobe_multi.offsets");
+			if (info.uprobe_multi.cookies)
+				ASSERT_EQ(cookies_buf[i], cookies[i], "info.uprobe_multi.cookies");
+			if (info.uprobe_multi.ref_ctr_offsets) {
+				ASSERT_EQ(ref_ctr_offsets_buf[i], ref_ctr_offsets[i],
+					  "info.uprobe_multi.ref_ctr_offsets");
+			}
+		}
+		count = count ?: info.uprobe_multi.count;
+	}
+
+	return 0;
+}
+
+static void verify_umulti_invalid_user_buffer(int fd)
+{
+	struct bpf_link_info info;
+	__u32 len = sizeof(info);
+	__u64 buf[3];
+	int err;
+
+	/* upath_size defined, not path */
+	memset(&info, 0, sizeof(info));
+	info.uprobe_multi.path_size = 3;
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_EQ(err, -EINVAL, "failed_upath_size");
+
+	/* path defined, but small */
+	memset(&info, 0, sizeof(info));
+	info.uprobe_multi.path = ptr_to_u64(buf);
+	info.uprobe_multi.path_size = 3;
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_LT(err, 0, "failed_upath_small");
+
+	/* path has wrong pointer */
+	memset(&info, 0, sizeof(info));
+	info.uprobe_multi.path_size = PATH_MAX;
+	info.uprobe_multi.path = 123;
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_EQ(err, -EFAULT, "failed_bad_path_ptr");
+
+	/* count zero, with offsets */
+	memset(&info, 0, sizeof(info));
+	info.uprobe_multi.offsets = ptr_to_u64(buf);
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_EQ(err, -EINVAL, "failed_count");
+
+	/* offsets not big enough */
+	memset(&info, 0, sizeof(info));
+	info.uprobe_multi.offsets = ptr_to_u64(buf);
+	info.uprobe_multi.count = 2;
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_EQ(err, -ENOSPC, "failed_small_count");
+
+	/* offsets has wrong pointer */
+	memset(&info, 0, sizeof(info));
+	info.uprobe_multi.offsets = 123;
+	info.uprobe_multi.count = 3;
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	ASSERT_EQ(err, -EFAULT, "failed_wrong_offsets");
+}
+
+static void test_uprobe_multi_fill_link_info(struct test_fill_link_info *skel,
+					     bool retprobe, bool invalid)
+{
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts,
+		.retprobe = retprobe,
+	);
+	const char *syms[3] = {
+		"uprobe_link_info_func_1",
+		"uprobe_link_info_func_2",
+		"uprobe_link_info_func_3",
+	};
+	__u64 cookies[3] = {
+		0xdead,
+		0xbeef,
+		0xcafe,
+	};
+	const char *sema[3] = {
+		"uprobe_link_info_sema_1",
+		"uprobe_link_info_sema_2",
+		"uprobe_link_info_sema_3",
+	};
+	__u64 *offsets = NULL, *ref_ctr_offsets;
+	struct bpf_link *link;
+	int link_fd, err;
+
+	err = elf_resolve_syms_offsets("/proc/self/exe", 3, sema,
+				       (unsigned long **) &ref_ctr_offsets, STT_OBJECT);
+	if (!ASSERT_OK(err, "elf_resolve_syms_offsets_object"))
+		return;
+
+	err = elf_resolve_syms_offsets("/proc/self/exe", 3, syms,
+				       (unsigned long **) &offsets, STT_FUNC);
+	if (!ASSERT_OK(err, "elf_resolve_syms_offsets_func"))
+		goto out;
+
+	opts.syms = syms;
+	opts.cookies = &cookies[0];
+	opts.ref_ctr_offsets = (unsigned long *) &ref_ctr_offsets[0];
+	opts.cnt = ARRAY_SIZE(syms);
+
+	link = bpf_program__attach_uprobe_multi(skel->progs.umulti_run, 0,
+						"/proc/self/exe", NULL, &opts);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_multi"))
+		goto out;
+
+	link_fd = bpf_link__fd(link);
+	if (invalid)
+		verify_umulti_invalid_user_buffer(link_fd);
+	else
+		verify_umulti_link_info(link_fd, retprobe, offsets, cookies, ref_ctr_offsets);
+
+	bpf_link__destroy(link);
+out:
+	free(ref_ctr_offsets);
+	free(offsets);
+}
+
 void test_fill_link_info(void)
 {
 	struct test_fill_link_info *skel;
@@ -339,6 +530,13 @@ void test_fill_link_info(void)
 	if (test__start_subtest("kprobe_multi_invalid_ubuff"))
 		test_kprobe_multi_fill_link_info(skel, true, true);
 
+	if (test__start_subtest("uprobe_multi_link_info"))
+		test_uprobe_multi_fill_link_info(skel, false, false);
+	if (test__start_subtest("uretprobe_multi_link_info"))
+		test_uprobe_multi_fill_link_info(skel, true, false);
+	if (test__start_subtest("uprobe_multi_invalid"))
+		test_uprobe_multi_fill_link_info(skel, false, true);
+
 cleanup:
 	test_fill_link_info__destroy(skel);
 }
diff --git a/tools/testing/selftests/bpf/progs/test_fill_link_info.c b/tools/testing/selftests/bpf/progs/test_fill_link_info.c
index 564f402d56fe..69509f8bb680 100644
--- a/tools/testing/selftests/bpf/progs/test_fill_link_info.c
+++ b/tools/testing/selftests/bpf/progs/test_fill_link_info.c
@@ -39,4 +39,10 @@ int BPF_PROG(kmulti_run)
 	return 0;
 }
 
+SEC("uprobe.multi")
+int BPF_PROG(umulti_run)
+{
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.42.0

[PATCHv4 bpf-next 6/6] bpftool: Add support to display uprobe_multi links

[Jiri Olsa]

Adding support to display details for uprobe_multi links,
both plain:

  # bpftool link -p
  ...
  24: uprobe_multi  prog 126
          uprobe.multi  path /home/jolsa/bpf/test_progs  func_cnt 3  pid 4143
          offset             ref_ctr_offset     cookies
          0xd1f88            0xf5d5a8           0xdead
          0xd1f8f            0xf5d5aa           0xbeef
          0xd1f96            0xf5d5ac           0xcafe

and json:

  # bpftool link -p
  [{
  ...
      },{
          "id": 24,
          "type": "uprobe_multi",
          "prog_id": 126,
          "retprobe": false,
          "path": "/home/jolsa/bpf/test_progs",
          "func_cnt": 3,
          "pid": 4143,
          "funcs": [{
                  "offset": 860040,
                  "ref_ctr_offset": 16111016,
                  "cookie": 57005
              },{
                  "offset": 860047,
                  "ref_ctr_offset": 16111018,
                  "cookie": 48879
              },{
                  "offset": 860054,
                  "ref_ctr_offset": 16111020,
                  "cookie": 51966
              }
          ]
      }
  ]

Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/bpf/bpftool/link.c | 105 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 103 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index a1528cde81ab..cb46667a6b2e 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -294,6 +294,37 @@ show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_end_array(json_wtr);
 }
 
+static __u64 *u64_to_arr(__u64 val)
+{
+	return (__u64 *) u64_to_ptr(val);
+}
+
+static void
+show_uprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
+{
+	__u32 i;
+
+	jsonw_bool_field(json_wtr, "retprobe",
+			 info->uprobe_multi.flags & BPF_F_UPROBE_MULTI_RETURN);
+	jsonw_string_field(json_wtr, "path", (char *) u64_to_ptr(info->uprobe_multi.path));
+	jsonw_uint_field(json_wtr, "func_cnt", info->uprobe_multi.count);
+	jsonw_int_field(json_wtr, "pid", (int) info->uprobe_multi.pid);
+	jsonw_name(json_wtr, "funcs");
+	jsonw_start_array(json_wtr);
+
+	for (i = 0; i < info->uprobe_multi.count; i++) {
+		jsonw_start_object(json_wtr);
+		jsonw_uint_field(json_wtr, "offset",
+				 u64_to_arr(info->uprobe_multi.offsets)[i]);
+		jsonw_uint_field(json_wtr, "ref_ctr_offset",
+				 u64_to_arr(info->uprobe_multi.ref_ctr_offsets)[i]);
+		jsonw_uint_field(json_wtr, "cookie",
+				 u64_to_arr(info->uprobe_multi.cookies)[i]);
+		jsonw_end_object(json_wtr);
+	}
+	jsonw_end_array(json_wtr);
+}
+
 static void
 show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
 {
@@ -465,6 +496,9 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
 	case BPF_LINK_TYPE_KPROBE_MULTI:
 		show_kprobe_multi_json(info, json_wtr);
 		break;
+	case BPF_LINK_TYPE_UPROBE_MULTI:
+		show_uprobe_multi_json(info, json_wtr);
+		break;
 	case BPF_LINK_TYPE_PERF_EVENT:
 		switch (info->perf_event.type) {
 		case BPF_PERF_EVENT_EVENT:
@@ -674,6 +708,33 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
 	}
 }
 
+static void show_uprobe_multi_plain(struct bpf_link_info *info)
+{
+	__u32 i;
+
+	if (!info->uprobe_multi.count)
+		return;
+
+	if (info->uprobe_multi.flags & BPF_F_UPROBE_MULTI_RETURN)
+		printf("\n\turetprobe.multi  ");
+	else
+		printf("\n\tuprobe.multi  ");
+
+	printf("path %s  ", (char *) u64_to_ptr(info->uprobe_multi.path));
+	printf("func_cnt %u  ", info->uprobe_multi.count);
+
+	if (info->uprobe_multi.pid)
+		printf("pid %d  ", info->uprobe_multi.pid);
+
+	printf("\n\t%-16s   %-16s   %-16s", "offset", "ref_ctr_offset", "cookies");
+	for (i = 0; i < info->uprobe_multi.count; i++) {
+		printf("\n\t0x%-16llx 0x%-16llx 0x%-16llx",
+			u64_to_arr(info->uprobe_multi.offsets)[i],
+			u64_to_arr(info->uprobe_multi.ref_ctr_offsets)[i],
+			u64_to_arr(info->uprobe_multi.cookies)[i]);
+	}
+}
+
 static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
 {
 	const char *buf;
@@ -807,6 +868,9 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
 	case BPF_LINK_TYPE_KPROBE_MULTI:
 		show_kprobe_multi_plain(info);
 		break;
+	case BPF_LINK_TYPE_UPROBE_MULTI:
+		show_uprobe_multi_plain(info);
+		break;
 	case BPF_LINK_TYPE_PERF_EVENT:
 		switch (info->perf_event.type) {
 		case BPF_PERF_EVENT_EVENT:
@@ -846,8 +910,10 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
 
 static int do_show_link(int fd)
 {
+	__u64 *ref_ctr_offsets = NULL, *offsets = NULL, *cookies = NULL;
 	struct bpf_link_info info;
 	__u32 len = sizeof(info);
+	char path_buf[PATH_MAX];
 	__u64 *addrs = NULL;
 	char buf[PATH_MAX];
 	int count;
@@ -889,6 +955,39 @@ static int do_show_link(int fd)
 			goto again;
 		}
 	}
+	if (info.type == BPF_LINK_TYPE_UPROBE_MULTI &&
+	    !info.uprobe_multi.offsets) {
+		count = info.uprobe_multi.count;
+		if (count) {
+			offsets = calloc(count, sizeof(__u64));
+			if (!offsets) {
+				p_err("mem alloc failed");
+				close(fd);
+				return -ENOMEM;
+			}
+			info.uprobe_multi.offsets = ptr_to_u64(offsets);
+			ref_ctr_offsets = calloc(count, sizeof(__u64));
+			if (!ref_ctr_offsets) {
+				p_err("mem alloc failed");
+				free(offsets);
+				close(fd);
+				return -ENOMEM;
+			}
+			info.uprobe_multi.ref_ctr_offsets = ptr_to_u64(ref_ctr_offsets);
+			cookies = calloc(count, sizeof(__u64));
+			if (!cookies) {
+				p_err("mem alloc failed");
+				free(cookies);
+				free(offsets);
+				close(fd);
+				return -ENOMEM;
+			}
+			info.uprobe_multi.cookies = ptr_to_u64(cookies);
+			info.uprobe_multi.path = ptr_to_u64(path_buf);
+			info.uprobe_multi.path_size = sizeof(path_buf);
+			goto again;
+		}
+	}
 	if (info.type == BPF_LINK_TYPE_PERF_EVENT) {
 		switch (info.perf_event.type) {
 		case BPF_PERF_EVENT_TRACEPOINT:
@@ -924,8 +1023,10 @@ static int do_show_link(int fd)
 	else
 		show_link_close_plain(fd, &info);
 
-	if (addrs)
-		free(addrs);
+	free(ref_ctr_offsets);
+	free(cookies);
+	free(offsets);
+	free(addrs);
 	close(fd);
 	return 0;
 }
-- 
2.42.0

Re: [PATCHv4 bpf-next 3/6] bpf: Add link_info support for uprobe multi link

[Yonghong Song]

On 11/25/23 2:31 PM, Jiri Olsa wrote:
> Adding support to get uprobe_link details through bpf_link_info
> interface.
>
> Adding new struct uprobe_multi to struct bpf_link_info to carry
> the uprobe_multi link details.
>
> The uprobe_multi.count is passed from user space to denote size
> of array fields (offsets/ref_ctr_offsets/cookies). The actual
> array size is stored back to uprobe_multi.count (allowing user
> to find out the actual array size) and array fields are populated
> up to the user passed size.
>
> All the non-array fields (path/count/flags/pid) are always set.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Acked-by: Yonghong Song <yonghong.song@linux.dev>

Re: [PATCHv4 bpf-next 5/6] selftests/bpf: Add link_info test for uprobe_multi link

[Yonghong Song]

On 11/25/23 2:31 PM, Jiri Olsa wrote:
> Adding fill_link_info test for uprobe_multi link.
>
> Setting up uprobes with bogus ref_ctr_offsets and cookie values
> to test all the bpf_link_info::uprobe_multi fields.
>
> Acked-by: Song Liu <song@kernel.org>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Acked-by: Yonghong Song <yonghong.song@linux.dev>

Re: [PATCHv4 bpf-next 0/6] bpf: Add link_info support for uprobe multi link

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Sat, 25 Nov 2023 20:31:24 +0100 you wrote:
> hi,
> this patchset adds support to get bpf_link_info details for
> uprobe_multi links and adding support for bpftool link to
> display them.
> 
> v4 changes:
>   - move flags field up in bpf_uprobe_multi_link [Andrii]
>   - include zero terminating byte in path_size [Andrii]
>   - return d_path error directly [Yonghong]
>   - use SEC(".probes") for semaphores [Yonghong]
>   - fix ref_ctr_offsets leak in test [Yonghong]
>   - other smaller fixes [Yonghong]
> 
> [...]

Here is the summary with links:
  - [PATCHv4,bpf-next,1/6] libbpf: Add st_type argument to elf_resolve_syms_offsets function
    https://git.kernel.org/bpf/bpf-next/c/48f0dfd8d3e2
  - [PATCHv4,bpf-next,2/6] bpf: Store ref_ctr_offsets values in bpf_uprobe array
    https://git.kernel.org/bpf/bpf-next/c/4930b7f53a29
  - [PATCHv4,bpf-next,3/6] bpf: Add link_info support for uprobe multi link
    https://git.kernel.org/bpf/bpf-next/c/e56fdbfb06e2
  - [PATCHv4,bpf-next,4/6] selftests/bpf: Use bpf_link__destroy in fill_link_info tests
    https://git.kernel.org/bpf/bpf-next/c/170361288572
  - [PATCHv4,bpf-next,5/6] selftests/bpf: Add link_info test for uprobe_multi link
    https://git.kernel.org/bpf/bpf-next/c/147c69307bcf
  - [PATCHv4,bpf-next,6/6] bpftool: Add support to display uprobe_multi links
    https://git.kernel.org/bpf/bpf-next/c/a7795698f8b6

You are awesome, thank you!
-- 
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