Merge branch 'bpf-add-cookies-retrieval-for-perf-kprobe-multi-links'

Jiri Olsa says:

====================
bpf: Add cookies retrieval for perf/kprobe multi links

hi,
this patchset adds support to retrieve cookies from existing tracing
links that still did not support it plus changes to bpftool to display
them. It's leftover we discussed some time ago [1].

thanks,
jirka

v2 changes:
 - added review/ack tags
 - fixed memory leak [Quentin]
 - align the uapi fields properly [Yafang Shao]

[1] https://lore.kernel.org/bpf/CALOAHbAZ6=A9j3VFCLoAC_WhgQKU7injMf06=cM2sU4Hi4Sx+Q@mail.gmail.com/
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
---
====================

Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20240119110505.400573-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 19 insertions, 0 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a1f18681721c..13193aaafb64 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3501,6 +3501,7 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
 	if (!kallsyms_show_value(current_cred()))
 		addr = 0;
 	info->perf_event.kprobe.addr = addr;
+	info->perf_event.kprobe.cookie = event->bpf_cookie;
 	return 0;
 }
 #endif
@@ -3526,6 +3527,7 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
 	else
 		info->perf_event.type = BPF_PERF_EVENT_UPROBE;
 	info->perf_event.uprobe.offset = offset;
+	info->perf_event.uprobe.cookie = event->bpf_cookie;
 	return 0;
 }
 #endif
@@ -3553,6 +3555,7 @@ static int bpf_perf_link_fill_tracepoint(const struct perf_event *event,
 	uname = u64_to_user_ptr(info->perf_event.tracepoint.tp_name);
 	ulen = info->perf_event.tracepoint.name_len;
 	info->perf_event.type = BPF_PERF_EVENT_TRACEPOINT;
+	info->perf_event.tracepoint.cookie = event->bpf_cookie;
 	return bpf_perf_link_fill_common(event, uname, ulen, NULL, NULL, NULL, NULL);
 }
 
@@ -3561,6 +3564,7 @@ static int bpf_perf_link_fill_perf_event(const struct perf_event *event,
 {
 	info->perf_event.event.type = event->attr.type;
 	info->perf_event.event.config = event->attr.config;
+	info->perf_event.event.cookie = event->bpf_cookie;
 	info->perf_event.type = BPF_PERF_EVENT_EVENT;
 	return 0;
 }
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 7ac6c52b25eb..c98c20abaf99 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2679,6 +2679,7 @@ static void bpf_kprobe_multi_link_dealloc(struct bpf_link *link)
 static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 						struct bpf_link_info *info)
 {
+	u64 __user *ucookies = u64_to_user_ptr(info->kprobe_multi.cookies);
 	u64 __user *uaddrs = u64_to_user_ptr(info->kprobe_multi.addrs);
 	struct bpf_kprobe_multi_link *kmulti_link;
 	u32 ucount = info->kprobe_multi.count;
@@ -2686,6 +2687,8 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 
 	if (!uaddrs ^ !ucount)
 		return -EINVAL;
+	if (ucookies && !ucount)
+		return -EINVAL;
 
 	kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
 	info->kprobe_multi.count = kmulti_link->cnt;
@@ -2699,6 +2702,18 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 	else
 		ucount = kmulti_link->cnt;
 
+	if (ucookies) {
+		if (kmulti_link->cookies) {
+			if (copy_to_user(ucookies, kmulti_link->cookies, ucount * sizeof(u64)))
+				return -EFAULT;
+		} else {
+			for (i = 0; i < ucount; i++) {
+				if (put_user(0, ucookies + i))
+					return -EFAULT;
+			}
+		}
+	}
+
 	if (kallsyms_show_value(current_cred())) {
 		if (copy_to_user(uaddrs, kmulti_link->addrs, ucount * sizeof(u64)))
 			return -EFAULT;